Refactor native code.

README.md

@@ -4,23 +4,73 @@
 [![Go Report](https://goreportcard.com/badge/github.com/ncruces/go-sqlite3)](https://goreportcard.com/report/github.com/ncruces/go-sqlite3)
 [![Go Coverage](https://github.com/ncruces/go-sqlite3/wiki/coverage.svg)](https://raw.githack.com/wiki/ncruces/go-sqlite3/coverage.html)
 
-⚠️ CAUTION ⚠️
+Go module `github.com/ncruces/go-sqlite3` wraps a [WASM](https://webassembly.org/) build of [SQLite](https://sqlite.org/),
+and uses [wazero](https://wazero.io/) to provide `cgo`-free SQLite bindings.
 
-This is a WIP.\
-DO NOT USE with data you care about.
+- Package [`github.com/ncruces/go-sqlite3`](https://pkg.go.dev/github.com/ncruces/go-sqlite3)
+wraps the [C SQLite API](https://www.sqlite.org/cintro.html)
+([example usage](https://pkg.go.dev/github.com/ncruces/go-sqlite3#example-package)).
+- Package [`github.com/ncruces/go-sqlite3/driver`](https://pkg.go.dev/github.com/ncruces/go-sqlite3/driver)
+provides a [`database/sql`](https://pkg.go.dev/database/sql) driver
+([example usage](https://pkg.go.dev/github.com/ncruces/go-sqlite3/driver#example-package)).
+- Package [`github.com/ncruces/go-sqlite3/embed`](https://pkg.go.dev/github.com/ncruces/go-sqlite3/embed)
+embeds a build of SQLite into your application.
+
+### Caveats
+
+#### Write-Ahead Logging
+
+Because WASM does not support shared memory,
+[WAL](https://www.sqlite.org/wal.html) support is [limited](https://www.sqlite.org/wal.html#noshm).
+
+To work around this limitation, SQLite is compiled with
+[`SQLITE_DEFAULT_LOCKING_MODE=1`](https://www.sqlite.org/compile.html#default_locking_mode),
+making `EXCLUSIVE` the default locking mode.
+For non-WAL databases, `NORMAL` locking mode can be activated with
+[`PRAGMA locking_mode=NORMAL`](https://www.sqlite.org/pragma.html#pragma_locking_mode).
+
+Because connection pooling is incompatible with `EXCLUSIVE` locking mode,
+the `database/sql` driver defaults to `NORMAL` locking mode,
+and WAL databases are not supported.
+
+#### Open File Description Locks
+
+On Unix, this module uses [OFD locks](https://www.gnu.org/software/libc/manual/html_node/Open-File-Description-Locks.html)
+to synchronize access to database files.
+
+POSIX advisory locks, which SQLite uses, are [broken by design](https://www.sqlite.org/src/artifact/90c4fa?ln=1073-1161).
+OFD locks are fully compatible with process-associated POSIX advisory locks,
+and are supported on Linux, macOS and illumos.
+As a work around for other Unixes, you can use [`nolock=1`](https://www.sqlite.org/uri.html).
+
+### Roadmap
 
-Roadmap:
 - [x] build SQLite using `zig cc --target=wasm32-wasi`
 - [x] `:memory:` databases
 - [x] port [`test_demovfs.c`](https://www.sqlite.org/src/doc/trunk/src/test_demovfs.c) to Go
   - branch [`wasi`](https://github.com/ncruces/go-sqlite3/tree/wasi) uses `test_demovfs.c` directly
-- [x] design a simple, nice API, enough for simple use cases
+- [x] design a nice API, enough for simple use cases
 - [x] provide a simple `database/sql` driver
-- [x] file locking, compatible with SQLite on Windows/Unix
-- [ ] shared memory, compatible with SQLite on Windows/Unix
-  - needed for improved WAL mode
-- [ ] advanced features
-  - [ ] incremental BLOB I/O
+- [x] file locking, compatible with SQLite on macOS/Linux/Windows
+- [ ] advanced SQLite features
+  - [x] nested transactions
+  - [x] incremental BLOB I/O
   - [ ] online backup
+  - [ ] snapshots
   - [ ] session extension
-  - [ ] snapshot
+  - [ ] resumable bulk update
+  - [ ] shared cache mode
+  - [ ] unlock-notify
+- [ ] custom SQL functions
+- [ ] custom VFSes
+  - [ ] read-only VFS, wrapping an [`io.ReaderAt`](https://pkg.go.dev/io#ReaderAt)
+  - [ ] in-memory VFS, wrapping a [`bytes.Buffer`](https://pkg.go.dev/bytes#Buffer)
+  - [ ] cloud-based VFS, based on [Cloud Backed SQLite](https://sqlite.org/cloudsqlite/doc/trunk/www/index.wiki)
+  - [ ] custom VFS API
+  
+### Alternatives
+
+- [`modernc.org/sqlite`](https://pkg.go.dev/modernc.org/sqlite)
+- [`crawshaw.io/sqlite`](https://pkg.go.dev/crawshaw.io/sqlite)
+- [`github.com/mattn/go-sqlite3`](https://pkg.go.dev/github.com/mattn/go-sqlite3)
+- [`github.com/zombiezen/go-sqlite`](https://pkg.go.dev/github.com/zombiezen/go-sqlite)

api.go

@@ -17,7 +17,7 @@ func newConn(ctx context.Context, module api.Module) (_ *Conn, err error) {
 		return f
 	}
 
-	getPtr := func(name string) uint32 {
+	getVal := func(name string) uint32 {
 		global := module.ExportedGlobal(name)
 		if global == nil {
 			err = noGlobalErr + errorString(name)
@@ -30,9 +30,9 @@ func newConn(ctx context.Context, module api.Module) (_ *Conn, err error) {
 		ctx: ctx,
 		mem: memory{module},
 		api: sqliteAPI{
-			malloc:        getFun("malloc"),
 			free:          getFun("free"),
-			destructor:    uint64(getPtr("malloc_destructor")),
+			malloc:        getFun("malloc"),
+			destructor:    uint64(getVal("malloc_destructor")),
 			errcode:       getFun("sqlite3_errcode"),
 			errstr:        getFun("sqlite3_errstr"),
 			errmsg:        getFun("sqlite3_errmsg"),
@@ -62,9 +62,16 @@ func newConn(ctx context.Context, module api.Module) (_ *Conn, err error) {
 			columnText:    getFun("sqlite3_column_text"),
 			columnBlob:    getFun("sqlite3_column_blob"),
 			columnBytes:   getFun("sqlite3_column_bytes"),
+			autocommit:    getFun("sqlite3_get_autocommit"),
 			lastRowid:     getFun("sqlite3_last_insert_rowid"),
 			changes:       getFun("sqlite3_changes64"),
-			interrupt:     getFun("sqlite3_interrupt"),
+			blobOpen:      getFun("sqlite3_blob_open"),
+			blobClose:     getFun("sqlite3_blob_close"),
+			blobReopen:    getFun("sqlite3_blob_reopen"),
+			blobBytes:     getFun("sqlite3_blob_bytes"),
+			blobRead:      getFun("sqlite3_blob_read"),
+			blobWrite:     getFun("sqlite3_blob_write"),
+			interrupt:     getVal("sqlite3_interrupt_offset"),
 		},
 	}
 	if err != nil {
@@ -74,8 +81,8 @@ func newConn(ctx context.Context, module api.Module) (_ *Conn, err error) {
 }
 
 type sqliteAPI struct {
-	malloc        api.Function
 	free          api.Function
+	malloc        api.Function
 	destructor    uint64
 	errcode       api.Function
 	errstr        api.Function
@@ -106,7 +113,14 @@ type sqliteAPI struct {
 	columnText    api.Function
 	columnBlob    api.Function
 	columnBytes   api.Function
+	autocommit    api.Function
 	lastRowid     api.Function
 	changes       api.Function
-	interrupt     api.Function
+	blobOpen      api.Function
+	blobClose     api.Function
+	blobReopen    api.Function
+	blobBytes     api.Function
+	blobRead      api.Function
+	blobWrite     api.Function
+	interrupt     uint32
 }

blob.go

@@ -1,6 +1,158 @@
 package sqlite3
 
+import "io"
+
 // ZeroBlob represents a zero-filled, length n BLOB
 // that can be used as an argument to
-// [database.sql.DB.Exec] and similar methods.
+// [database/sql.DB.Exec] and similar methods.
 type ZeroBlob int64
+
+// Blob is a handle to an open BLOB.
+//
+// It implements [io.ReadWriteSeeker] for incremental BLOB I/O.
+//
+// https://www.sqlite.org/c3ref/blob.html
+type Blob struct {
+	c      *Conn
+	handle uint32
+	bytes  int64
+	offset int64
+}
+
+var _ io.ReadWriteSeeker = &Blob{}
+
+// OpenBlob opens a BLOB for incremental I/O.
+//
+// https://www.sqlite.org/c3ref/blob_open.html
+func (c *Conn) OpenBlob(db, table, column string, row int64, write bool) (*Blob, error) {
+	defer c.arena.reset()
+	blobPtr := c.arena.new(ptrlen)
+	dbPtr := c.arena.string(db)
+	tablePtr := c.arena.string(table)
+	columnPtr := c.arena.string(column)
+
+	var flags uint64
+	if write {
+		flags = 1
+	}
+
+	r := c.call(c.api.blobOpen, uint64(c.handle),
+		uint64(dbPtr), uint64(tablePtr), uint64(columnPtr),
+		uint64(row), flags, uint64(blobPtr))
+
+	if err := c.error(r[0]); err != nil {
+		return nil, err
+	}
+
+	blob := Blob{c: c}
+	blob.handle = c.mem.readUint32(blobPtr)
+	blob.bytes = int64(c.call(c.api.blobBytes, uint64(blob.handle))[0])
+	return &blob, nil
+}
+
+// Close closes a BLOB handle.
+//
+// It is safe to close a nil, zero or closed Blob.
+//
+// https://www.sqlite.org/c3ref/blob_close.html
+func (b *Blob) Close() error {
+	if b == nil || b.handle == 0 {
+		return nil
+	}
+
+	r := b.c.call(b.c.api.blobClose, uint64(b.handle))
+
+	b.handle = 0
+	return b.c.error(r[0])
+}
+
+// Size returns the size of the BLOB in bytes.
+//
+// https://www.sqlite.org/c3ref/blob_bytes.html
+func (b *Blob) Size() int64 {
+	return b.bytes
+}
+
+// Read implements the [io.Reader] interface.
+//
+// https://www.sqlite.org/c3ref/blob_read.html
+func (b *Blob) Read(p []byte) (n int, err error) {
+	if b.offset >= b.bytes {
+		return 0, io.EOF
+	}
+
+	want := int64(len(p))
+	avail := b.bytes - b.offset
+	if want > avail {
+		want = avail
+	}
+
+	ptr := b.c.new(uint64(want))
+	defer b.c.free(ptr)
+
+	r := b.c.call(b.c.api.blobRead, uint64(b.handle),
+		uint64(ptr), uint64(want), uint64(b.offset))
+	err = b.c.error(r[0])
+	if err != nil {
+		return 0, err
+	}
+
+	mem := b.c.mem.view(ptr, uint64(want))
+	copy(p, mem)
+	b.offset += want
+	if b.offset >= b.bytes {
+		err = io.EOF
+	}
+	return int(want), err
+}
+
+// Write implements the [io.Writer] interface.
+//
+// https://www.sqlite.org/c3ref/blob_write.html
+func (b *Blob) Write(p []byte) (n int, err error) {
+	offset := b.offset
+	if offset > b.bytes {
+		offset = b.bytes
+	}
+
+	ptr := b.c.newBytes(p)
+	defer b.c.free(ptr)
+
+	r := b.c.call(b.c.api.blobWrite, uint64(b.handle),
+		uint64(ptr), uint64(len(p)), uint64(offset))
+	err = b.c.error(r[0])
+	if err != nil {
+		return 0, err
+	}
+	b.offset += int64(len(p))
+	return len(p), nil
+}
+
+// Seek implements the [io.Seeker] interface.
+func (b *Blob) Seek(offset int64, whence int) (int64, error) {
+	switch whence {
+	default:
+		return 0, whenceErr
+	case io.SeekStart:
+		break
+	case io.SeekCurrent:
+		offset += b.offset
+	case io.SeekEnd:
+		offset += b.bytes
+	}
+	if offset < 0 {
+		return 0, offsetErr
+	}
+	b.offset = offset
+	return offset, nil
+}
+
+// Reopen moves a BLOB handle to a new row of the same database table.
+//
+// https://www.sqlite.org/c3ref/blob_reopen.html
+func (b *Blob) Reopen(row int64) error {
+	r := b.c.call(b.c.api.blobReopen, uint64(b.handle), uint64(row))
+	b.bytes = int64(b.c.call(b.c.api.blobBytes, uint64(b.handle))[0])
+	b.offset = 0
+	return b.c.error(r[0])
+}

compile.go

@@ -2,7 +2,9 @@ package sqlite3
 
 import (
 	"context"
+	"crypto/rand"
 	"os"
+	"runtime"
 	"strconv"
 	"sync"
 	"sync/atomic"
@@ -11,9 +13,14 @@ import (
 	"github.com/tetratelabs/wazero/api"
 )
 
-// Configure SQLite.
+// Configure SQLite WASM.
+//
+// Importing package embed initializes these
+// with an appropriate build of SQLite:
+//
+//	import _ "github.com/ncruces/go-sqlite3/embed"
 var (
-	Binary []byte // Binary to load.
+	Binary []byte // WASM binary to load.
 	Path   string // Path to load the binary from.
 )
 
@@ -34,7 +41,10 @@ func (s *sqlite3Runtime) instantiateModule(ctx context.Context) (api.Module, err
 	}
 
 	cfg := wazero.NewModuleConfig().
-		WithName("sqlite3-" + strconv.FormatUint(s.instances.Add(1), 10))
+		WithName("sqlite3-" + strconv.FormatUint(s.instances.Add(1), 10)).
+		WithSysWalltime().WithSysNanotime().WithSysNanosleep().
+		WithOsyield(runtime.Gosched).
+		WithRandSource(rand.Reader)
 	return s.runtime.InstantiateModule(ctx, s.compiled, cfg)
 }
 

conn.go

@@ -2,10 +2,19 @@ package sqlite3
 
 import (
 	"context"
+	"database/sql/driver"
+	"fmt"
 	"math"
+	"net/url"
+	"strings"
+	"sync/atomic"
+	"unsafe"
+
+	"github.com/tetratelabs/wazero/api"
 )
 
 // Conn is a database connection handle.
+// A Conn is not safe for concurrent use by multiple goroutines.
 //
 // https://www.sqlite.org/c3ref/sqlite3.html
 type Conn struct {
@@ -14,19 +23,23 @@ type Conn struct {
 	mem    memory
 	handle uint32
 
-	arena   arena
-	pending *Stmt
-	waiter  chan struct{}
-	done    <-chan struct{}
+	arena     arena
+	interrupt context.Context
+	waiter    chan struct{}
+	pending   *Stmt
 }
 
-// Open calls [OpenFlags] with [OPEN_READWRITE] and [OPEN_CREATE].
+// Open calls [OpenFlags] with [OPEN_READWRITE], [OPEN_CREATE] and [OPEN_URI].
 func Open(filename string) (conn *Conn, err error) {
-	return OpenFlags(filename, OPEN_READWRITE|OPEN_CREATE)
+	return OpenFlags(filename, OPEN_READWRITE|OPEN_CREATE|OPEN_URI)
 }
 
 // OpenFlags opens an SQLite database file as specified by the filename argument.
 //
+// If a URI filename is used, PRAGMA statements to execute can be specified using "_pragma":
+//
+//	sqlite3.Open("file:demo.db?_pragma=busy_timeout(10000)&_pragma=locking_mode(normal)")
+//
 // https://www.sqlite.org/c3ref/open.html
 func OpenFlags(filename string, flags OpenFlag) (conn *Conn, err error) {
 	ctx := context.Background()
@@ -50,15 +63,27 @@ func OpenFlags(filename string, flags OpenFlag) (conn *Conn, err error) {
 	connPtr := c.arena.new(ptrlen)
 	namePtr := c.arena.string(filename)
 
-	r, err := c.api.open.Call(c.ctx, uint64(namePtr), uint64(connPtr), uint64(flags), 0)
-	if err != nil {
-		panic(err)
-	}
+	r := c.call(c.api.open, uint64(namePtr), uint64(connPtr), uint64(flags), 0)
 
 	c.handle = c.mem.readUint32(connPtr)
 	if err := c.error(r[0]); err != nil {
 		return nil, err
 	}
+
+	if flags|OPEN_URI != 0 && strings.HasPrefix(filename, "file:") {
+		var pragmas strings.Builder
+		if _, after, ok := strings.Cut(filename, "?"); ok {
+			query, _ := url.ParseQuery(after)
+			for _, p := range query["_pragma"] {
+				pragmas.WriteString(`PRAGMA `)
+				pragmas.WriteString(p)
+				pragmas.WriteByte(';')
+			}
+		}
+		if err := c.Exec(pragmas.String()); err != nil {
+			return nil, fmt.Errorf("sqlite3: invalid _pragma: %w", err)
+		}
+	}
 	return c, nil
 }
 
@@ -68,7 +93,7 @@ func OpenFlags(filename string, flags OpenFlag) (conn *Conn, err error) {
 // open blob handles, and/or unfinished backup objects,
 // Close will leave the database connection open and return [BUSY].
 //
-// It is safe to close a nil, zero or closed connection.
+// It is safe to close a nil, zero or closed Conn.
 //
 // https://www.sqlite.org/c3ref/close.html
 func (c *Conn) Close() error {
@@ -76,13 +101,9 @@ func (c *Conn) Close() error {
 		return nil
 	}
 
-	c.SetInterrupt(nil)
-
-	r, err := c.api.close.Call(c.ctx, uint64(c.handle))
-	if err != nil {
-		panic(err)
-	}
+	c.SetInterrupt(context.Background())
 
+	r := c.call(c.api.close, uint64(c.handle))
 	if err := c.error(r[0]); err != nil {
 		return err
 	}
@@ -91,82 +112,33 @@ func (c *Conn) Close() error {
 	return c.mem.mod.Close(c.ctx)
 }
 
-// SetInterrupt interrupts a long-running query when done is closed.
-//
-// Subsequent uses of the connection will return [INTERRUPT]
-// until done is reset by another call to SetInterrupt.
-//
-// Typically, done is provided by [context.Context.Done]:
-//
-//	ctx, cancel := context.WithTimeout(context.TODO(), 100*time.Millisecond)
-//	conn.SetInterrupt(ctx.Done())
-//	defer cancel()
-//
-// https://www.sqlite.org/c3ref/interrupt.html
-func (c *Conn) SetInterrupt(done <-chan struct{}) (old <-chan struct{}) {
-	// Is a waiter running?
-	if c.waiter != nil {
-		c.waiter <- struct{}{} // Cancel the waiter.
-		<-c.waiter             // Wait for it to finish.
-		c.waiter = nil
-	}
-
-	// Finalize the uncompleted SQL statement.
-	if c.pending != nil {
-		c.pending.Close()
-		c.pending = nil
-	}
-
-	old = c.done
-	c.done = done
-	if done == nil {
-		return old
-	}
-
-	// Creating an uncompleted SQL statement prevents SQLite from ignoring
-	// an interrupt that comes before any other statements are started.
-	c.pending, _, _ = c.Prepare(`SELECT 1 UNION ALL SELECT 2`)
-	c.pending.Step()
-
-	waiter := make(chan struct{})
-	c.waiter = waiter
-	go func() {
-		select {
-		case <-waiter: // Waiter was cancelled.
-			break
-
-		case <-done: // Done was closed.
-
-			// This is safe to call from a goroutine
-			// because it doesn't touch the C stack.
-			_, err := c.api.interrupt.Call(c.ctx, uint64(c.handle))
-			if err != nil {
-				panic(err)
-			}
-
-			// Wait for the next call to SetInterrupt.
-			<-waiter
-		}
-
-		// Signal that the waiter has finished.
-		waiter <- struct{}{}
-	}()
-	return old
-}
-
 // Exec is a convenience function that allows an application to run
 // multiple statements of SQL without having to use a lot of code.
 //
 // https://www.sqlite.org/c3ref/exec.html
 func (c *Conn) Exec(sql string) error {
+	c.checkInterrupt()
 	defer c.arena.reset()
 	sqlPtr := c.arena.string(sql)
 
-	r, err := c.api.exec.Call(c.ctx, uint64(c.handle), uint64(sqlPtr), 0, 0, 0)
+	r := c.call(c.api.exec, uint64(c.handle), uint64(sqlPtr), 0, 0, 0)
+	return c.error(r[0])
+}
+
+// MustPrepare calls [Conn.Prepare] and panics on error,
+// a nil Stmt, or a non-empty tail.
+func (c *Conn) MustPrepare(sql string) *Stmt {
+	s, tail, err := c.PrepareFlags(sql, 0)
 	if err != nil {
 		panic(err)
 	}
-	return c.error(r[0])
+	if s == nil {
+		panic(emptyErr)
+	}
+	if !emptyStatement(tail) {
+		panic(tailErr)
+	}
+	return s
 }
 
 // Prepare calls [Conn.PrepareFlags] with no flags.
@@ -190,12 +162,9 @@ func (c *Conn) PrepareFlags(sql string, flags PrepareFlag) (stmt *Stmt, tail str
 	tailPtr := c.arena.new(ptrlen)
 	sqlPtr := c.arena.string(sql)
 
-	r, err := c.api.prepare.Call(c.ctx, uint64(c.handle),
+	r := c.call(c.api.prepare, uint64(c.handle),
 		uint64(sqlPtr), uint64(len(sql)+1), uint64(flags),
 		uint64(stmtPtr), uint64(tailPtr))
-	if err != nil {
-		panic(err)
-	}
 
 	stmt = &Stmt{c: c}
 	stmt.handle = c.mem.readUint32(stmtPtr)
@@ -211,16 +180,21 @@ func (c *Conn) PrepareFlags(sql string, flags PrepareFlag) (stmt *Stmt, tail str
 	return
 }
 
+// GetAutocommit tests the connection for auto-commit mode.
+//
+// https://www.sqlite.org/c3ref/get_autocommit.html
+func (c *Conn) GetAutocommit() bool {
+	r := c.call(c.api.autocommit, uint64(c.handle))
+	return r[0] != 0
+}
+
 // LastInsertRowID returns the rowid of the most recent successful INSERT
 // on the database connection.
 //
 // https://www.sqlite.org/c3ref/last_insert_rowid.html
-func (c *Conn) LastInsertRowID() uint64 {
-	r, err := c.api.lastRowid.Call(c.ctx, uint64(c.handle))
-	if err != nil {
-		panic(err)
-	}
-	return r[0]
+func (c *Conn) LastInsertRowID() int64 {
+	r := c.call(c.api.lastRowid, uint64(c.handle))
+	return int64(r[0])
 }
 
 // Changes returns the number of rows modified, inserted or deleted
@@ -228,12 +202,100 @@ func (c *Conn) LastInsertRowID() uint64 {
 // on the database connection.
 //
 // https://www.sqlite.org/c3ref/changes.html
-func (c *Conn) Changes() uint64 {
-	r, err := c.api.changes.Call(c.ctx, uint64(c.handle))
-	if err != nil {
-		panic(err)
+func (c *Conn) Changes() int64 {
+	r := c.call(c.api.changes, uint64(c.handle))
+	return int64(r[0])
+}
+
+// SetInterrupt interrupts a long-running query when a context is done.
+//
+// Subsequent uses of the connection will return [INTERRUPT]
+// until the context is reset by another call to SetInterrupt.
+//
+// To associate a timeout with a connection:
+//
+//	ctx, cancel := context.WithTimeout(context.TODO(), 100*time.Millisecond)
+//	conn.SetInterrupt(ctx)
+//	defer cancel()
+//
+// SetInterrupt returns the old context assigned to the connection.
+//
+// https://www.sqlite.org/c3ref/interrupt.html
+func (c *Conn) SetInterrupt(ctx context.Context) (old context.Context) {
+	// Is a waiter running?
+	if c.waiter != nil {
+		c.waiter <- struct{}{} // Cancel the waiter.
+		<-c.waiter             // Wait for it to finish.
+		c.waiter = nil
 	}
-	return r[0]
+
+	old = c.interrupt
+	c.interrupt = ctx
+	if ctx == nil || ctx.Done() == nil {
+		// Finalize the uncompleted SQL statement.
+		if c.pending != nil {
+			c.pending.Close()
+			c.pending = nil
+		}
+		return old
+	}
+
+	// Creating an uncompleted SQL statement prevents SQLite from ignoring
+	// an interrupt that comes before any other statements are started.
+	if c.pending == nil {
+		c.pending = c.MustPrepare(`SELECT 1 UNION ALL SELECT 2`)
+		c.pending.Step()
+	} else {
+		c.pending.Reset()
+	}
+
+	// Don't create the goroutine if we're already interrupted.
+	// This happens frequently while restoring to a previously interrupted state.
+	if c.checkInterrupt() {
+		return old
+	}
+
+	waiter := make(chan struct{})
+	c.waiter = waiter
+	go func() {
+		select {
+		case <-waiter: // Waiter was cancelled.
+			break
+
+		case <-ctx.Done(): // Done was closed.
+			buf := c.mem.view(c.handle+c.api.interrupt, 4)
+			(*atomic.Uint32)(unsafe.Pointer(&buf[0])).Store(1)
+			// Wait for the next call to SetInterrupt.
+			<-waiter
+		}
+
+		// Signal that the waiter has finished.
+		waiter <- struct{}{}
+	}()
+	return old
+}
+
+func (c *Conn) checkInterrupt() bool {
+	if c.interrupt == nil || c.interrupt.Err() == nil {
+		return false
+	}
+	buf := c.mem.view(c.handle+c.api.interrupt, 4)
+	(*atomic.Uint32)(unsafe.Pointer(&buf[0])).Store(1)
+	return true
+}
+
+// Pragma executes a PRAGMA statement and returns any results.
+//
+// https://www.sqlite.org/pragma.html
+func (c *Conn) Pragma(str string) []string {
+	stmt := c.MustPrepare(`PRAGMA ` + str)
+	defer stmt.Close()
+
+	var pragmas []string
+	for stmt.Step() {
+		pragmas = append(pragmas, stmt.ColumnText(0))
+	}
+	return pragmas
 }
 
 func (c *Conn) error(rc uint64, sql ...string) error {
@@ -273,21 +335,26 @@ func (c *Conn) error(rc uint64, sql ...string) error {
 	return &err
 }
 
+func (c *Conn) call(fn api.Function, params ...uint64) []uint64 {
+	r, err := fn.Call(c.ctx, params...)
+	if err != nil {
+		panic(err)
+	}
+	return r
+}
+
 func (c *Conn) free(ptr uint32) {
 	if ptr == 0 {
 		return
 	}
-	_, err := c.api.free.Call(c.ctx, uint64(ptr))
-	if err != nil {
-		panic(err)
-	}
+	c.call(c.api.free, uint64(ptr))
 }
 
-func (c *Conn) new(size uint32) uint32 {
-	r, err := c.api.malloc.Call(c.ctx, uint64(size))
-	if err != nil {
-		panic(err)
+func (c *Conn) new(size uint64) uint32 {
+	if size > _MAX_ALLOCATION_SIZE {
+		panic(oomErr)
 	}
+	r := c.call(c.api.malloc, size)
 	ptr := uint32(r[0])
 	if ptr == 0 && size != 0 {
 		panic(oomErr)
@@ -299,22 +366,22 @@ func (c *Conn) newBytes(b []byte) uint32 {
 	if b == nil {
 		return 0
 	}
-	ptr := c.new(uint32(len(b)))
+	ptr := c.new(uint64(len(b)))
 	c.mem.writeBytes(ptr, b)
 	return ptr
 }
 
 func (c *Conn) newString(s string) uint32 {
-	ptr := c.new(uint32(len(s) + 1))
+	ptr := c.new(uint64(len(s) + 1))
 	c.mem.writeString(ptr, s)
 	return ptr
 }
 
-func (c *Conn) newArena(size uint32) arena {
+func (c *Conn) newArena(size uint64) arena {
 	return arena{
 		c:    c,
-		size: size,
 		base: c.new(size),
+		size: uint32(size),
 	}
 }
 
@@ -326,6 +393,15 @@ type arena struct {
 	ptrs []uint32
 }
 
+func (a *arena) free() {
+	if a.c == nil {
+		return
+	}
+	a.reset()
+	a.c.free(a.base)
+	a.c = nil
+}
+
 func (a *arena) reset() {
 	for _, ptr := range a.ptrs {
 		a.c.free(ptr)
@@ -334,10 +410,10 @@ func (a *arena) reset() {
 	a.next = 0
 }
 
-func (a *arena) new(size uint32) uint32 {
-	if a.next+size <= a.size {
+func (a *arena) new(size uint64) uint32 {
+	if size <= uint64(a.size-a.next) {
 		ptr := a.base + a.next
-		a.next += size
+		a.next += uint32(size)
 		return ptr
 	}
 	ptr := a.c.new(size)
@@ -346,7 +422,23 @@ func (a *arena) new(size uint32) uint32 {
 }
 
 func (a *arena) string(s string) uint32 {
-	ptr := a.new(uint32(len(s) + 1))
+	ptr := a.new(uint64(len(s) + 1))
 	a.c.mem.writeString(ptr, s)
 	return ptr
 }
+
+// DriverConn is implemented by the SQLite [database/sql] driver connection.
+//
+// It can be used to access advanced SQLite features like
+// [savepoints] and [incremental BLOB I/O].
+//
+// [savepoints]: https://www.sqlite.org/lang_savepoint.html
+// [incremental BLOB I/O]: https://www.sqlite.org/c3ref/blob_open.html
+type DriverConn interface {
+	driver.ConnBeginTx
+	driver.ExecerContext
+	driver.ConnPrepareContext
+
+	Savepoint() (release func(*error))
+	OpenBlob(db, table, column string, row int64, write bool) (*Blob, error)
+}

conn_test.go

@@ -6,6 +6,34 @@ import (
 	"testing"
 )
 
+func TestConn_error_OOM(t *testing.T) {
+	t.Parallel()
+
+	db, err := Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	defer func() { _ = recover() }()
+	db.error(uint64(NOMEM))
+	t.Error("want panic")
+}
+
+func TestConn_call_nil(t *testing.T) {
+	t.Parallel()
+
+	db, err := Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	defer func() { _ = recover() }()
+	db.call(db.api.free)
+	t.Error("want panic")
+}
+
 func TestConn_new(t *testing.T) {
 	t.Parallel()
 
@@ -15,9 +43,14 @@ func TestConn_new(t *testing.T) {
 	}
 	defer db.Close()
 
-	defer func() { _ = recover() }()
-	db.new(math.MaxUint32)
-	t.Error("want panic")
+	testOOM := func(size uint64) {
+		defer func() { _ = recover() }()
+		db.new(size)
+		t.Error("want panic")
+	}
+
+	testOOM(math.MaxUint32)
+	testOOM(_MAX_ALLOCATION_SIZE)
 }
 
 func TestConn_newArena(t *testing.T) {
@@ -30,7 +63,7 @@ func TestConn_newArena(t *testing.T) {
 	defer db.Close()
 
 	arena := db.newArena(16)
-	defer arena.reset()
+	defer arena.free()
 
 	const title = "Lorem ipsum"
 
@@ -50,6 +83,7 @@ func TestConn_newArena(t *testing.T) {
 	if got := db.mem.readString(ptr, math.MaxUint32); got != body {
 		t.Errorf("got %q, want %q", got, body)
 	}
+	arena.free()
 }
 
 func TestConn_newBytes(t *testing.T) {
@@ -73,7 +107,7 @@ func TestConn_newBytes(t *testing.T) {
 	}
 
 	want := buf
-	if got := db.mem.view(ptr, uint32(len(want))); !bytes.Equal(got, want) {
+	if got := db.mem.view(ptr, uint64(len(want))); !bytes.Equal(got, want) {
 		t.Errorf("got %q, want %q", got, want)
 	}
 }
@@ -99,7 +133,7 @@ func TestConn_newString(t *testing.T) {
 	}
 
 	want := str + "\000"
-	if got := db.mem.view(ptr, uint32(len(want))); string(got) != want {
+	if got := db.mem.view(ptr, uint64(len(want))); string(got) != want {
 		t.Errorf("got %q, want %q", got, want)
 	}
 }

const.go

@@ -12,6 +12,8 @@ const (
 	_MAX_STRING   = 512 // Used for short strings: names, error messages…
 	_MAX_PATHNAME = 512
 
+	_MAX_ALLOCATION_SIZE = 0x7ffffeff
+
 	ptrlen = 4
 )
 

driver/driver.go

@@ -1,4 +1,27 @@
 // Package driver provides a database/sql driver for SQLite.
+//
+// Importing package driver registers a [database/sql] driver named "sqlite3".
+// You may also need to import package embed.
+//
+//	import _ "github.com/ncruces/go-sqlite3/driver"
+//	import _ "github.com/ncruces/go-sqlite3/embed"
+//
+// The data source name for "sqlite3" databases can be a filename or a "file:" [URI].
+//
+// The [TRANSACTION] mode can be specified using "_txlock":
+//
+//	sql.Open("sqlite3", "file:demo.db?_txlock=immediate")
+//
+// [PRAGMA] statements can be specified using "_pragma":
+//
+//	sql.Open("sqlite3", "file:demo.db?_pragma=busy_timeout(10000)&_pragma=locking_mode(normal)")
+//
+// If no PRAGMAs are specifed, a busy timeout of 1 minute
+// and normal locking mode are used.
+//
+// [URI]: https://www.sqlite.org/uri.html
+// [PRAGMA]: https://www.sqlite.org/pragma.html
+// [TRANSACTION]: https://www.sqlite.org/lang_transaction.html#deferred_immediate_and_exclusive_transactions
 package driver
 
 import (
@@ -20,81 +43,65 @@ func init() {
 
 type sqlite struct{}
 
-func (sqlite) Open(name string) (driver.Conn, error) {
+func (sqlite) Open(name string) (_ driver.Conn, err error) {
 	c, err := sqlite3.OpenFlags(name, sqlite3.OPEN_READWRITE|sqlite3.OPEN_CREATE|sqlite3.OPEN_URI|sqlite3.OPEN_EXRESCODE)
 	if err != nil {
 		return nil, err
 	}
 
 	var txBegin string
-	var pragmas strings.Builder
-	if _, after, ok := strings.Cut(name, "?"); ok {
-		query, _ := url.ParseQuery(after)
+	var pragmas []string
+	if strings.HasPrefix(name, "file:") {
+		if _, after, ok := strings.Cut(name, "?"); ok {
+			query, _ := url.ParseQuery(after)
 
-		switch s := query.Get("_txlock"); s {
-		case "":
-			txBegin = "BEGIN"
-		case "deferred", "immediate", "exclusive":
-			txBegin = "BEGIN " + s
-		default:
-			return nil, fmt.Errorf("sqlite3: invalid _txlock: %s", s)
-		}
+			switch s := query.Get("_txlock"); s {
+			case "":
+				txBegin = "BEGIN"
+			case "deferred", "immediate", "exclusive":
+				txBegin = "BEGIN " + s
+			default:
+				c.Close()
+				return nil, fmt.Errorf("sqlite3: invalid _txlock: %s", s)
+			}
 
-		for _, p := range query["_pragma"] {
-			pragmas.WriteString(`PRAGMA `)
-			pragmas.WriteString(p)
-			pragmas.WriteByte(';')
+			pragmas = query["_pragma"]
 		}
 	}
-	if pragmas.Len() == 0 {
-		pragmas.WriteString(`PRAGMA locking_mode=normal;`)
-		pragmas.WriteString(`PRAGMA busy_timeout=60000;`)
+	if len(pragmas) == 0 {
+		err := c.Exec(`
+			PRAGMA busy_timeout=60000;
+			PRAGMA locking_mode=normal;
+		`)
+		if err != nil {
+			c.Close()
+			return nil, err
+		}
 	}
 
-	err = c.Exec(pragmas.String())
-	if err != nil {
-		return nil, fmt.Errorf("sqlite3: invalid _pragma: %w", err)
-	}
 	return conn{
 		conn:    c,
 		txBegin: txBegin,
-		pragmas: pragmas.String(),
 	}, nil
 }
 
 type conn struct {
-	conn       *sqlite3.Conn
-	pragmas    string
-	txBegin    string
-	txReadOnly bool
+	conn     *sqlite3.Conn
+	txBegin  string
+	txCommit string
 }
 
 var (
 	// Ensure these interfaces are implemented:
-	_ driver.Validator       = conn{}
-	_ driver.SessionResetter = conn{}
-	_ driver.ExecerContext   = conn{}
-	_ driver.ConnBeginTx     = conn{}
+	_ driver.ExecerContext = conn{}
+	_ driver.ConnBeginTx   = conn{}
+	_ sqlite3.DriverConn   = conn{}
 )
 
 func (c conn) Close() error {
 	return c.conn.Close()
 }
 
-func (c conn) IsValid() bool {
-	// Pool only normal locking mode connections.
-	stmt, _, err := c.conn.Prepare(`PRAGMA locking_mode`)
-	if err != nil {
-		return false
-	}
-	defer stmt.Close()
-	return stmt.Step() && stmt.ColumnText(0) == "normal"
-}
-
-func (c conn) ResetSession(ctx context.Context) error {
-	return c.conn.Exec(c.pragmas)
-}
-
 func (c conn) Begin() (driver.Tx, error) {
 	return c.BeginTx(context.Background(), driver.TxOptions{})
 }
@@ -108,13 +115,15 @@ func (c conn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, er
 	}
 
 	txBegin := c.txBegin
+	c.txCommit = `COMMIT`
 	if opts.ReadOnly {
+		c.txCommit = `
+			ROLLBACK;
+			PRAGMA query_only=` + c.conn.Pragma("query_only")[0]
 		txBegin = `
 			BEGIN deferred;
-			PRAGMA query_only=on;
-		`
+			PRAGMA query_only=on`
 	}
-	c.txReadOnly = opts.ReadOnly
 
 	err := c.conn.Exec(txBegin)
 	if err != nil {
@@ -124,10 +133,7 @@ func (c conn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, er
 }
 
 func (c conn) Commit() error {
-	if c.txReadOnly {
-		return c.Rollback()
-	}
-	err := c.conn.Exec(`COMMIT`)
+	err := c.conn.Exec(c.txCommit)
 	if err != nil {
 		c.Rollback()
 	}
@@ -159,14 +165,18 @@ func (c conn) Prepare(query string) (driver.Stmt, error) {
 	return stmt{s, c.conn}, nil
 }
 
+func (c conn) PrepareContext(_ context.Context, query string) (driver.Stmt, error) {
+	return c.Prepare(query)
+}
+
 func (c conn) ExecContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Result, error) {
 	if len(args) != 0 {
 		// Slow path.
 		return nil, driver.ErrSkip
 	}
 
-	ch := c.conn.SetInterrupt(ctx.Done())
-	defer c.conn.SetInterrupt(ch)
+	old := c.conn.SetInterrupt(ctx)
+	defer c.conn.SetInterrupt(old)
 
 	err := c.conn.Exec(query)
 	if err != nil {
@@ -174,11 +184,19 @@ func (c conn) ExecContext(ctx context.Context, query string, args []driver.Named
 	}
 
 	return result{
-		int64(c.conn.LastInsertRowID()),
-		int64(c.conn.Changes()),
+		c.conn.LastInsertRowID(),
+		c.conn.Changes(),
 	}, nil
 }
 
+func (c conn) Savepoint() (release func(*error)) {
+	return c.conn.Savepoint()
+}
+
+func (c conn) OpenBlob(db, table, column string, row int64, write bool) (*sqlite3.Blob, error) {
+	return c.conn.OpenBlob(db, table, column, row, write)
+}
+
 type stmt struct {
 	stmt *sqlite3.Stmt
 	conn *sqlite3.Conn
@@ -325,8 +343,8 @@ func (r rows) Columns() []string {
 }
 
 func (r rows) Next(dest []driver.Value) error {
-	ch := r.conn.SetInterrupt(r.ctx.Done())
-	defer r.conn.SetInterrupt(ch)
+	old := r.conn.SetInterrupt(r.ctx)
+	defer r.conn.SetInterrupt(old)
 
 	if !r.stmt.Step() {
 		if err := r.stmt.Err(); err != nil {
@@ -342,7 +360,7 @@ func (r rows) Next(dest []driver.Value) error {
 		case sqlite3.FLOAT:
 			dest[i] = r.stmt.ColumnFloat(i)
 		case sqlite3.TEXT:
-			dest[i] = maybeDate(r.stmt.ColumnText(i))
+			dest[i] = maybeTime(r.stmt.ColumnText(i))
 		case sqlite3.BLOB:
 			buf, _ := dest[i].([]byte)
 			dest[i] = r.stmt.ColumnBlob(i, buf)

driver/driver_test.go

@@ -15,6 +15,8 @@ import (
 )
 
 func Test_Open_dir(t *testing.T) {
+	t.Parallel()
+
 	db, err := sql.Open("sqlite3", ".")
 	if err != nil {
 		t.Fatal(err)
@@ -25,19 +27,14 @@ func Test_Open_dir(t *testing.T) {
 	if err == nil {
 		t.Fatal("want error")
 	}
-	var serr *sqlite3.Error
-	if !errors.As(err, &serr) {
-		t.Fatalf("got %T, want sqlite3.Error", err)
-	}
-	if rc := serr.Code(); rc != sqlite3.CANTOPEN {
-		t.Errorf("got %d, want sqlite3.CANTOPEN", rc)
-	}
-	if got := err.Error(); got != `sqlite3: unable to open database file` {
-		t.Error("got message: ", got)
+	if !errors.Is(err, sqlite3.CANTOPEN) {
+		t.Errorf("got %v, want sqlite3.CANTOPEN", err)
 	}
 }
 
 func Test_Open_pragma(t *testing.T) {
+	t.Parallel()
+
 	db, err := sql.Open("sqlite3", "file::memory:?_pragma=busy_timeout(1000)")
 	if err != nil {
 		t.Fatal(err)
@@ -55,6 +52,8 @@ func Test_Open_pragma(t *testing.T) {
 }
 
 func Test_Open_pragma_invalid(t *testing.T) {
+	t.Parallel()
+
 	db, err := sql.Open("sqlite3", "file::memory:?_pragma=busy_timeout+1000")
 	if err != nil {
 		t.Fatal(err)
@@ -73,13 +72,15 @@ func Test_Open_pragma_invalid(t *testing.T) {
 		t.Errorf("got %d, want sqlite3.ERROR", rc)
 	}
 	if got := err.Error(); got != `sqlite3: invalid _pragma: sqlite3: SQL logic error: near "1000": syntax error` {
-		t.Error("got message: ", got)
+		t.Error("got message:", got)
 	}
 }
 
 func Test_Open_txLock(t *testing.T) {
+	t.Parallel()
+
 	db, err := sql.Open("sqlite3", "file:"+
-		filepath.Join(t.TempDir(), "test.db")+
+		filepath.ToSlash(filepath.Join(t.TempDir(), "test.db"))+
 		"?_txlock=exclusive&_pragma=busy_timeout(0)")
 	if err != nil {
 		t.Fatal(err)
@@ -95,20 +96,13 @@ func Test_Open_txLock(t *testing.T) {
 	if err == nil {
 		t.Error("want error")
 	}
-	var serr *sqlite3.Error
-	if !errors.As(err, &serr) {
-		t.Fatalf("got %T, want sqlite3.Error", err)
-	}
-	if rc := serr.Code(); rc != sqlite3.BUSY {
-		t.Errorf("got %d, want sqlite3.BUSY", rc)
+	if !errors.Is(err, sqlite3.BUSY) {
+		t.Errorf("got %v, want sqlite3.BUSY", err)
 	}
 	var terr interface{ Temporary() bool }
 	if !errors.As(err, &terr) || !terr.Temporary() {
 		t.Error("not temporary", err)
 	}
-	if got := err.Error(); got != `sqlite3: database is locked` {
-		t.Error("got message: ", got)
-	}
 
 	err = tx1.Commit()
 	if err != nil {
@@ -117,6 +111,8 @@ func Test_Open_txLock(t *testing.T) {
 }
 
 func Test_Open_txLock_invalid(t *testing.T) {
+	t.Parallel()
+
 	db, err := sql.Open("sqlite3", "file::memory:?_txlock=xclusive")
 	if err != nil {
 		t.Fatal(err)
@@ -128,11 +124,13 @@ func Test_Open_txLock_invalid(t *testing.T) {
 		t.Fatal("want error")
 	}
 	if got := err.Error(); got != `sqlite3: invalid _txlock: xclusive` {
-		t.Error("got message: ", got)
+		t.Error("got message:", got)
 	}
 }
 
 func Test_BeginTx(t *testing.T) {
+	t.Parallel()
+
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
@@ -161,15 +159,8 @@ func Test_BeginTx(t *testing.T) {
 	if err == nil {
 		t.Error("want error")
 	}
-	var serr *sqlite3.Error
-	if !errors.As(err, &serr) {
-		t.Fatalf("got %T, want sqlite3.Error", err)
-	}
-	if rc := serr.Code(); rc != sqlite3.READONLY {
-		t.Errorf("got %d, want sqlite3.READONLY", rc)
-	}
-	if got := err.Error(); got != `sqlite3: attempt to write a readonly database` {
-		t.Error("got message: ", got)
+	if !errors.Is(err, sqlite3.READONLY) {
+		t.Errorf("got %v, want sqlite3.READONLY", err)
 	}
 
 	err = tx2.Commit()
@@ -184,6 +175,8 @@ func Test_BeginTx(t *testing.T) {
 }
 
 func Test_Prepare(t *testing.T) {
+	t.Parallel()
+
 	db, err := sql.Open("sqlite3", ":memory:")
 	if err != nil {
 		t.Fatal(err)
@@ -208,7 +201,7 @@ func Test_Prepare(t *testing.T) {
 		t.Errorf("got %d, want sqlite3.ERROR", rc)
 	}
 	if got := err.Error(); got != `sqlite3: SQL logic error: incomplete input` {
-		t.Error("got message: ", got)
+		t.Error("got message:", got)
 	}
 
 	_, err = db.Prepare(`SELECT 1; SELECT`)
@@ -222,7 +215,7 @@ func Test_Prepare(t *testing.T) {
 		t.Errorf("got %d, want sqlite3.ERROR", rc)
 	}
 	if got := err.Error(); got != `sqlite3: SQL logic error: incomplete input` {
-		t.Error("got message: ", got)
+		t.Error("got message:", got)
 	}
 
 	_, err = db.Prepare(`SELECT 1; SELECT 2`)
@@ -232,6 +225,8 @@ func Test_Prepare(t *testing.T) {
 }
 
 func Test_QueryRow_named(t *testing.T) {
+	t.Parallel()
+
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
@@ -282,6 +277,8 @@ func Test_QueryRow_named(t *testing.T) {
 }
 
 func Test_QueryRow_blob_null(t *testing.T) {
+	t.Parallel()
+
 	db, err := sql.Open("sqlite3", ":memory:")
 	if err != nil {
 		t.Fatal(err)
@@ -310,39 +307,3 @@ func Test_QueryRow_blob_null(t *testing.T) {
 		}
 	}
 }
-
-func Test_ZeroBlob(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-
-	db, err := sql.Open("sqlite3", ":memory:")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer db.Close()
-
-	conn, err := db.Conn(ctx)
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer conn.Close()
-
-	_, err = conn.ExecContext(ctx, `CREATE TABLE IF NOT EXISTS test (col)`)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	_, err = conn.ExecContext(ctx, `INSERT INTO test(col) VALUES(?)`, sqlite3.ZeroBlob(4))
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	var got []byte
-	err = conn.QueryRowContext(ctx, `SELECT col FROM test`).Scan(&got)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if string(got) != "\x00\x00\x00\x00" {
-		t.Errorf(`got %q, want "\x00\x00\x00\x00"`, got)
-	}
-}

driver/example_test.go

@@ -31,7 +31,8 @@ func Example() {
 	defer db.Close()
 	defer os.Remove("./recordings.db")
 
-	err = createAlbumsTable()
+	// Create a table with some data in it.
+	err = albumsSetup()
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -58,14 +59,13 @@ func Example() {
 		log.Fatal(err)
 	}
 	fmt.Printf("ID of added album: %v\n", albID)
-
 	// Output:
 	// Albums found: [{1 Blue Train John Coltrane 56.99} {2 Giant Steps John Coltrane 63.99}]
 	// Album found: {2 Giant Steps John Coltrane 63.99}
 	// ID of added album: 5
 }
 
-func createAlbumsTable() error {
+func albumsSetup() error {
 	_, err := db.Exec(`
 		DROP TABLE IF EXISTS album;
 		CREATE TABLE album (

driver/time.go

@@ -8,8 +8,8 @@ import (
 // Convert a string in [time.RFC3339Nano] format into a [time.Time]
 // if it roundtrips back to the same string.
 // This way times can be persisted to, and recovered from, the database,
-// but if a string is needed, [database.sql] will recover the same string.
-func maybeDate(text string) driver.Value {
+// but if a string is needed, [database/sql] will recover the same string.
+func maybeTime(text string) driver.Value {
 	// Weed out (some) values that can't possibly be
 	// [time.RFC3339Nano] timestamps.
 	if len(text) < len("2006-01-02T15:04:05Z") {

driver/time_test.go

@@ -5,7 +5,8 @@ import (
 	"time"
 )
 
-func Fuzz_maybeDate(f *testing.F) {
+// This checks that any string can be recovered as the same string.
+func Fuzz_maybeTime_1(f *testing.F) {
 	f.Add("")
 	f.Add(" ")
 	f.Add("SQLite")
@@ -21,7 +22,7 @@ func Fuzz_maybeDate(f *testing.F) {
 	f.Add("Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.")
 
 	f.Fuzz(func(t *testing.T, str string) {
-		value := maybeDate(str)
+		value := maybeTime(str)
 
 		switch v := value.(type) {
 		case time.Time:
@@ -44,3 +45,56 @@ func Fuzz_maybeDate(f *testing.F) {
 		}
 	})
 }
+
+// This checks that any [time.Time] can be recovered as a [time.Time],
+// with nanosecond accuracy, and preserving any timezone offset.
+func Fuzz_maybeTime_2(f *testing.F) {
+	f.Add(0, 0)
+	f.Add(0, 1)
+	f.Add(0, -1)
+	f.Add(0, 999_999_999)
+	f.Add(0, 1_000_000_000)
+	f.Add(7956915742, 222_222_222)    // twosday
+	f.Add(639095955742, 222_222_222)  // twosday, year 22222AD
+	f.Add(-763421161058, 222_222_222) // twosday, year 22222BC
+
+	checkTime := func(t *testing.T, date time.Time) {
+		value := maybeTime(date.Format(time.RFC3339Nano))
+
+		switch v := value.(type) {
+		case time.Time:
+			// Make sure times round-trip to the same time:
+			if !v.Equal(date) {
+				t.Fatalf("did not round-trip: %v", date)
+			}
+			// Make with the same zone offset:
+			_, off1 := v.Zone()
+			_, off2 := date.Zone()
+			if off1 != off2 {
+				t.Fatalf("did not round-trip: %v", date)
+			}
+		case string:
+			t.Fatalf("was not recovered: %v", date)
+		default:
+			t.Fatalf("invalid type %T: %v", v, date)
+		}
+	}
+
+	f.Fuzz(func(t *testing.T, sec, nsec int) {
+		// Reduce the search space.
+		if 1e12 < sec || sec < -1e12 {
+			// Dates before 29000BC and after 33000AD; I think we're safe.
+			return
+		}
+		if 0 < nsec || nsec > 1e10 {
+			// Out of range nsec: [time.Time.Unix] handles these.
+			return
+		}
+
+		unix := time.Unix(int64(sec), int64(nsec))
+		checkTime(t, unix)
+		checkTime(t, unix.UTC())
+		checkTime(t, unix.In(time.FixedZone("", -8*3600)))
+		checkTime(t, unix.In(time.FixedZone("", +8*3600)))
+	})
+}

driver_test.go

@@ -0,0 +1,74 @@
+package sqlite3_test
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"log"
+	"os"
+
+	"github.com/ncruces/go-sqlite3"
+	_ "github.com/ncruces/go-sqlite3/driver"
+	_ "github.com/ncruces/go-sqlite3/embed"
+)
+
+var db *sql.DB
+
+func ExampleDriverConn() {
+	var err error
+	db, err = sql.Open("sqlite3", "demo.db")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer db.Close()
+	defer os.Remove("demo.db")
+
+	ctx := context.Background()
+
+	conn, err := db.Conn(ctx)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer conn.Close()
+
+	_, err = conn.ExecContext(ctx, `CREATE TABLE IF NOT EXISTS test (col)`)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	res, err := conn.ExecContext(ctx, `INSERT INTO test VALUES (?)`, sqlite3.ZeroBlob(11))
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	id, err := res.LastInsertId()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	err = conn.Raw(func(driverConn any) error {
+		conn := driverConn.(sqlite3.DriverConn)
+		defer conn.Savepoint()(&err)
+
+		blob, err := conn.OpenBlob("main", "test", "col", id, true)
+		if err != nil {
+			return err
+		}
+		defer blob.Close()
+
+		_, err = fmt.Fprint(blob, "Hello BLOB!")
+		return err
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	var msg string
+	err = conn.QueryRowContext(ctx, `SELECT col FROM test`).Scan(&msg)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(msg)
+	// Output:
+	// Hello BLOB!
+}

embed/build.sh

@@ -8,13 +8,13 @@ cd -P -- "$(dirname -- "$0")"
 
 # build SQLite
 zig cc --target=wasm32-wasi -flto -g0 -Os \
-  -o sqlite3.wasm ../sqlite3/*.c \
+  -o sqlite3.wasm ../sqlite3/amalg.c \
 	-mmutable-globals \
 	-mbulk-memory -mreference-types \
 	-mnontrapping-fptoint -msign-ext \
 	-D_HAVE_SQLITE_CONFIG_H \
-	-Wl,--export=malloc \
 	-Wl,--export=free \
+	-Wl,--export=malloc \
 	-Wl,--export=malloc_destructor \
 	-Wl,--export=sqlite3_errcode \
 	-Wl,--export=sqlite3_errstr \
@@ -45,6 +45,19 @@ zig cc --target=wasm32-wasi -flto -g0 -Os \
 	-Wl,--export=sqlite3_column_text \
 	-Wl,--export=sqlite3_column_blob \
 	-Wl,--export=sqlite3_column_bytes \
+	-Wl,--export=sqlite3_blob_open \
+	-Wl,--export=sqlite3_blob_close \
+	-Wl,--export=sqlite3_blob_bytes \
+	-Wl,--export=sqlite3_blob_read \
+	-Wl,--export=sqlite3_blob_write \
+	-Wl,--export=sqlite3_blob_reopen \
+	-Wl,--export=sqlite3_get_autocommit \
 	-Wl,--export=sqlite3_last_insert_rowid \
 	-Wl,--export=sqlite3_changes64 \
-	-Wl,--export=sqlite3_interrupt \
+	-Wl,--export=sqlite3_unlock_notify \
+	-Wl,--export=sqlite3_backup_init \
+	-Wl,--export=sqlite3_backup_step \
+	-Wl,--export=sqlite3_backup_finish \
+	-Wl,--export=sqlite3_backup_remaining \
+	-Wl,--export=sqlite3_backup_pagecount \
+	-Wl,--export=sqlite3_interrupt_offset \

embed/init.go

@@ -1,5 +1,10 @@
 // Package embed embeds SQLite into your application.
 //
+// Importing package embed initializes the [sqlite3.Binary] variable
+// with an appropriate build of SQLite:
+//
+//	import _ "github.com/ncruces/go-sqlite3/embed"
+//
 // You can obtain this build of SQLite from:
 // https://github.com/ncruces/go-sqlite3/tree/main/embed
 package embed

error.go

@@ -50,29 +50,162 @@ func (e *Error) Error() string {
 	return b.String()
 }
 
+// Is tests whether this error matches a given [ErrorCode] or [ExtendedErrorCode].
+//
+// It makes it possible to do:
+//
+//	if errors.Is(err, sqlite3.BUSY) {
+//		// ... handle BUSY
+//	}
+func (e *Error) Is(err error) bool {
+	switch c := err.(type) {
+	case ErrorCode:
+		return c == e.Code()
+	case ExtendedErrorCode:
+		return c == e.ExtendedCode()
+	}
+	return false
+}
+
 // Temporary returns true for [BUSY] errors.
 func (e *Error) Temporary() bool {
 	return e.Code() == BUSY
 }
 
+// Timeout returns true for [BUSY_TIMEOUT] errors.
+func (e *Error) Timeout() bool {
+	return e.ExtendedCode() == BUSY_TIMEOUT
+}
+
 // SQL returns the SQL starting at the token that triggered a syntax error.
 func (e *Error) SQL() string {
 	return e.sql
 }
 
+// Error implements the error interface.
+func (e ErrorCode) Error() string {
+	switch e {
+	case _OK:
+		return "sqlite3: not an error"
+	case _ROW:
+		return "sqlite3: another row available"
+	case _DONE:
+		return "sqlite3: no more rows available"
+
+	case ERROR:
+		return "sqlite3: SQL logic error"
+	case INTERNAL:
+		break
+	case PERM:
+		return "sqlite3: access permission denied"
+	case ABORT:
+		return "sqlite3: query aborted"
+	case BUSY:
+		return "sqlite3: database is locked"
+	case LOCKED:
+		return "sqlite3: database table is locked"
+	case NOMEM:
+		return "sqlite3: out of memory"
+	case READONLY:
+		return "sqlite3: attempt to write a readonly database"
+	case INTERRUPT:
+		return "sqlite3: interrupted"
+	case IOERR:
+		return "sqlite3: disk I/O error"
+	case CORRUPT:
+		return "sqlite3: database disk image is malformed"
+	case NOTFOUND:
+		return "sqlite3: unknown operation"
+	case FULL:
+		return "sqlite3: database or disk is full"
+	case CANTOPEN:
+		return "sqlite3: unable to open database file"
+	case PROTOCOL:
+		return "sqlite3: locking protocol"
+	case FORMAT:
+		break
+	case SCHEMA:
+		return "sqlite3: database schema has changed"
+	case TOOBIG:
+		return "sqlite3: string or blob too big"
+	case CONSTRAINT:
+		return "sqlite3: constraint failed"
+	case MISMATCH:
+		return "sqlite3: datatype mismatch"
+	case MISUSE:
+		return "sqlite3: bad parameter or other API misuse"
+	case NOLFS:
+		break
+	case AUTH:
+		return "sqlite3: authorization denied"
+	case EMPTY:
+		break
+	case RANGE:
+		return "sqlite3: column index out of range"
+	case NOTADB:
+		return "sqlite3: file is not a database"
+	case NOTICE:
+		return "sqlite3: notification message"
+	case WARNING:
+		return "sqlite3: warning message"
+	}
+	return "sqlite3: unknown error"
+}
+
+// Temporary returns true for [BUSY] errors.
+func (e ErrorCode) Temporary() bool {
+	return e == BUSY
+}
+
+// Error implements the error interface.
+func (e ExtendedErrorCode) Error() string {
+	switch x := ErrorCode(e); {
+	case e == ABORT_ROLLBACK:
+		return "sqlite3: abort due to ROLLBACK"
+	case x < _ROW:
+		return x.Error()
+	case e == _ROW:
+		return "sqlite3: another row available"
+	case e == _DONE:
+		return "sqlite3: no more rows available"
+	}
+	return "sqlite3: unknown error"
+}
+
+// Is tests whether this error matches a given [ErrorCode].
+func (e ExtendedErrorCode) Is(err error) bool {
+	c, ok := err.(ErrorCode)
+	return ok && c == ErrorCode(e)
+}
+
+// Temporary returns true for [BUSY] errors.
+func (e ExtendedErrorCode) Temporary() bool {
+	return ErrorCode(e) == BUSY
+}
+
+// Timeout returns true for [BUSY_TIMEOUT] errors.
+func (e ExtendedErrorCode) Timeout() bool {
+	return e == BUSY_TIMEOUT
+}
+
 type errorString string
 
 func (e errorString) Error() string { return string(e) }
 
 const (
-	binaryErr   = errorString("sqlite3: no SQLite binary embed/set/loaded")
 	nilErr      = errorString("sqlite3: invalid memory address or null pointer dereference")
 	oomErr      = errorString("sqlite3: out of memory")
 	rangeErr    = errorString("sqlite3: index out of range")
 	noNulErr    = errorString("sqlite3: missing NUL terminator")
 	noGlobalErr = errorString("sqlite3: could not find global: ")
 	noFuncErr   = errorString("sqlite3: could not find function: ")
+	binaryErr   = errorString("sqlite3: no SQLite binary embed/set/loaded")
 	timeErr     = errorString("sqlite3: invalid time value")
+	emptyErr    = errorString("sqlite3: empty statement")
+	tailErr     = errorString("sqlite3: non-empty tail")
+	notImplErr  = errorString("sqlite3: not implemented")
+	whenceErr   = errorString("sqlite3: invalid whence")
+	offsetErr   = errorString("sqlite3: invalid offset")
 )
 
 func assertErr() errorString {

error_test.go

@@ -1,26 +1,157 @@
 package sqlite3
 
 import (
+	"context"
+	"errors"
 	"strings"
 	"testing"
 )
 
-func TestError(t *testing.T) {
-	err := Error{code: 0x8080}
-	if rc := err.Code(); rc != 0x80 {
-		t.Errorf("got %#x, want 0x80", rc)
-	}
-	if rc := err.ExtendedCode(); rc != 0x8080 {
-		t.Errorf("got %#x, want 0x8080", rc)
-	}
-	if s := err.Error(); s != "sqlite3: 32896" {
+func Test_assertErr(t *testing.T) {
+	err := assertErr()
+	if s := err.Error(); !strings.HasPrefix(s, "sqlite3: assertion failed") || !strings.HasSuffix(s, "error_test.go:11)") {
 		t.Errorf("got %q", s)
 	}
 }
 
-func Test_assertErr(t *testing.T) {
-	err := assertErr()
-	if s := err.Error(); !strings.HasPrefix(s, "sqlite3: assertion failed") || !strings.HasSuffix(s, "error_test.go:22)") {
+func TestError(t *testing.T) {
+	t.Parallel()
+
+	err := Error{code: 0x8080}
+	if rc := err.Code(); rc != 0x80 {
+		t.Errorf("got %#x, want 0x80", rc)
+	}
+	if !errors.Is(&err, ErrorCode(0x80)) {
+		t.Errorf("want true")
+	}
+	if rc := err.ExtendedCode(); rc != 0x8080 {
+		t.Errorf("got %#x, want 0x8080", rc)
+	}
+	if !errors.Is(&err, ExtendedErrorCode(0x8080)) {
+		t.Errorf("want true")
+	}
+	if s := err.Error(); s != "sqlite3: 32896" {
 		t.Errorf("got %q", s)
 	}
+	if !errors.Is(err.ExtendedCode(), ErrorCode(0x80)) {
+		t.Errorf("want true")
+	}
+}
+
+func TestError_Temporary(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		code uint64
+		want bool
+	}{
+		{"ERROR", uint64(ERROR), false},
+		{"BUSY", uint64(BUSY), true},
+		{"BUSY_RECOVERY", uint64(BUSY_RECOVERY), true},
+		{"BUSY_SNAPSHOT", uint64(BUSY_SNAPSHOT), true},
+		{"BUSY_TIMEOUT", uint64(BUSY_TIMEOUT), true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			{
+				err := &Error{code: tt.code}
+				if got := err.Temporary(); got != tt.want {
+					t.Errorf("Error.Temporary(%d) = %v, want %v", tt.code, got, tt.want)
+				}
+			}
+			{
+				err := ErrorCode(tt.code)
+				if got := err.Temporary(); got != tt.want {
+					t.Errorf("ErrorCode.Temporary(%d) = %v, want %v", tt.code, got, tt.want)
+				}
+			}
+			{
+				err := ExtendedErrorCode(tt.code)
+				if got := err.Temporary(); got != tt.want {
+					t.Errorf("ExtendedErrorCode.Temporary(%d) = %v, want %v", tt.code, got, tt.want)
+				}
+			}
+		})
+	}
+}
+
+func TestError_Timeout(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name string
+		code uint64
+		want bool
+	}{
+		{"ERROR", uint64(ERROR), false},
+		{"BUSY", uint64(BUSY), false},
+		{"BUSY_RECOVERY", uint64(BUSY_RECOVERY), false},
+		{"BUSY_SNAPSHOT", uint64(BUSY_SNAPSHOT), false},
+		{"BUSY_TIMEOUT", uint64(BUSY_TIMEOUT), true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			{
+				err := &Error{code: tt.code}
+				if got := err.Timeout(); got != tt.want {
+					t.Errorf("Error.Timeout(%d) = %v, want %v", tt.code, got, tt.want)
+				}
+			}
+			{
+				err := ExtendedErrorCode(tt.code)
+				if got := err.Timeout(); got != tt.want {
+					t.Errorf("Error.Timeout(%d) = %v, want %v", tt.code, got, tt.want)
+				}
+			}
+		})
+	}
+}
+
+func Test_ErrorCode_Error(t *testing.T) {
+	t.Parallel()
+
+	db, err := Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	// Test all error codes.
+	for i := 0; i == int(ErrorCode(i)); i++ {
+		want := "sqlite3: "
+		r, _ := db.api.errstr.Call(context.TODO(), uint64(i))
+		if r != nil {
+			want += db.mem.readString(uint32(r[0]), _MAX_STRING)
+		}
+
+		got := ErrorCode(i).Error()
+		if got != want {
+			t.Fatalf("got %q, want %q, with %d", got, want, i)
+		}
+	}
+}
+
+func Test_ExtendedErrorCode_Error(t *testing.T) {
+	t.Parallel()
+
+	db, err := Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	// Test all extended error codes.
+	for i := 0; i == int(ExtendedErrorCode(i)); i++ {
+		want := "sqlite3: "
+		r, _ := db.api.errstr.Call(context.TODO(), uint64(i))
+		if r != nil {
+			want += db.mem.readString(uint32(r[0]), _MAX_STRING)
+		}
+
+		got := ExtendedErrorCode(i).Error()
+		if got != want {
+			t.Fatalf("got %q, want %q, with %d", got, want, i)
+		}
+	}
 }

example_test.go

@@ -21,15 +21,12 @@ func Example() {
 		log.Fatal(err)
 	}
 
-	err = db.Exec(`INSERT INTO users(id, name) VALUES(0, 'go'), (1, 'zig'), (2, 'whatever')`)
+	err = db.Exec(`INSERT INTO users (id, name) VALUES (0, 'go'), (1, 'zig'), (2, 'whatever')`)
 	if err != nil {
 		log.Fatal(err)
 	}
 
-	stmt, _, err := db.Prepare(`SELECT id, name FROM users`)
-	if err != nil {
-		log.Fatal(err)
-	}
+	stmt := db.MustPrepare(`SELECT id, name FROM users`)
 
 	for stmt.Step() {
 		fmt.Println(stmt.ColumnInt(0), stmt.ColumnText(1))
@@ -47,7 +44,6 @@ func Example() {
 	if err != nil {
 		log.Fatal(err)
 	}
-
 	// Output:
 	// 0 go
 	// 1 zig

mem.go

@@ -11,11 +11,14 @@ type memory struct {
 	mod api.Module
 }
 
-func (m memory) view(ptr, size uint32) []byte {
+func (m memory) view(ptr uint32, size uint64) []byte {
 	if ptr == 0 {
 		panic(nilErr)
 	}
-	buf, ok := m.mod.Memory().Read(ptr, size)
+	if size > math.MaxUint32 {
+		panic(rangeErr)
+	}
+	buf, ok := m.mod.Memory().Read(ptr, uint32(size))
 	if !ok {
 		panic(rangeErr)
 	}
@@ -100,12 +103,12 @@ func (m memory) readString(ptr, maxlen uint32) string {
 }
 
 func (m memory) writeBytes(ptr uint32, b []byte) {
-	buf := m.view(ptr, uint32(len(b)))
+	buf := m.view(ptr, uint64(len(b)))
 	copy(buf, b)
 }
 
 func (m memory) writeString(ptr uint32, s string) {
-	buf := m.view(ptr, uint32(len(s)+1))
+	buf := m.view(ptr, uint64(len(s)+1))
 	buf[len(s)] = 0
 	copy(buf, s)
 }

mem_test.go

@@ -19,6 +19,13 @@ func Test_memory_view_range(t *testing.T) {
 	t.Error("want panic")
 }
 
+func Test_memory_view_overflow(t *testing.T) {
+	defer func() { _ = recover() }()
+	mem := newMemory(128)
+	mem.view(1, math.MaxInt64)
+	t.Error("want panic")
+}
+
 func Test_memory_readUint32_nil(t *testing.T) {
 	defer func() { _ = recover() }()
 	mem := newMemory(128)

sqlite3/amalg.c

@@ -0,0 +1,9 @@
+#include <stddef.h>
+
+#include "main.c"
+#include "os.c"
+#include "qsort.c"
+#include "sqlite3.c"
+
+sqlite3_destructor_type malloc_destructor = &free;
+size_t sqlite3_interrupt_offset = offsetof(sqlite3, u1.isInterrupted);

sqlite3/download.sh

@@ -4,7 +4,7 @@ set -eo pipefail
 cd -P -- "$(dirname -- "$0")"
 
 if [ ! -f "sqlite3.c" ]; then
-	url="https://www.sqlite.org/2022/sqlite-amalgamation-3400100.zip"
+	url="https://sqlite.org/2023/sqlite-amalgamation-3410000.zip"
 	curl "$url" > sqlite.zip
 	unzip -d . sqlite.zip
 	mv sqlite-amalgamation-*/sqlite3* .

sqlite3/format.sh

@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+cd -P -- "$(dirname -- "$0")"
+
+clang-format -i \
+	main.c \
+	os.c \
+	qsort.c \
+	amalg.c

sqlite3/main.c

@@ -1,6 +1,4 @@
 #include <stdbool.h>
-#include <stdlib.h>
-#include <time.h>
 
 #include "sqlite3.h"
 
@@ -9,94 +7,8 @@ int main() {
   if (rc != SQLITE_OK) return 1;
 }
 
-int go_localtime(sqlite3_int64, struct tm *);
-
-int go_randomness(sqlite3_vfs *, int nByte, char *zOut);
-int go_sleep(sqlite3_vfs *, int microseconds);
-int go_current_time(sqlite3_vfs *, double *);
-int go_current_time_64(sqlite3_vfs *, sqlite3_int64 *);
-
-int go_open(sqlite3_vfs *, sqlite3_filename zName, sqlite3_file *, int flags,
-            int *pOutFlags);
-int go_delete(sqlite3_vfs *, const char *zName, int syncDir);
-int go_access(sqlite3_vfs *, const char *zName, int flags, int *pResOut);
-int go_full_pathname(sqlite3_vfs *, const char *zName, int nOut, char *zOut);
-
-struct go_file {
-  sqlite3_file base;
-  int id;
-  int eLock;
-};
-
-int go_close(sqlite3_file *);
-int go_read(sqlite3_file *, void *, int iAmt, sqlite3_int64 iOfst);
-int go_write(sqlite3_file *, const void *, int iAmt, sqlite3_int64 iOfst);
-int go_truncate(sqlite3_file *, sqlite3_int64 size);
-int go_sync(sqlite3_file *, int flags);
-int go_file_size(sqlite3_file *, sqlite3_int64 *pSize);
-int go_file_control(sqlite3_file *pFile, int op, void *pArg);
-
-int go_lock(sqlite3_file *pFile, int eLock);
-int go_unlock(sqlite3_file *pFile, int eLock);
-int go_check_reserved_lock(sqlite3_file *pFile, int *pResOut);
-
-static int no_lock(sqlite3_file *pFile, int eLock) { return SQLITE_OK; }
-static int no_unlock(sqlite3_file *pFile, int eLock) { return SQLITE_OK; }
-static int no_check_reserved_lock(sqlite3_file *pFile, int *pResOut) {
-  *pResOut = 0;
-  return SQLITE_OK;
-}
-
-static int no_file_control(sqlite3_file *pFile, int op, void *pArg) {
-  return SQLITE_NOTFOUND;
-}
-static int no_sector_size(sqlite3_file *pFile) { return 0; }
-static int no_device_characteristics(sqlite3_file *pFile) { return 0; }
-
-int localtime_s(struct tm *const pTm, time_t const *const pTime) {
-  return go_localtime((sqlite3_int64)*pTime, pTm);
-}
-
-static int go_open_c(sqlite3_vfs *vfs, sqlite3_filename zName,
-                     sqlite3_file *file, int flags, int *pOutFlags) {
-  static const sqlite3_io_methods go_io = {
-      .iVersion = 1,
-      .xClose = go_close,
-      .xRead = go_read,
-      .xWrite = go_write,
-      .xTruncate = go_truncate,
-      .xSync = go_sync,
-      .xFileSize = go_file_size,
-      .xLock = go_lock,
-      .xUnlock = go_unlock,
-      .xCheckReservedLock = go_check_reserved_lock,
-      .xFileControl = no_file_control,
-      .xSectorSize = no_sector_size,
-      .xDeviceCharacteristics = no_device_characteristics,
-  };
-  int rc = go_open(vfs, zName, file, flags, pOutFlags);
-  file->pMethods = (char)rc == SQLITE_OK ? &go_io : NULL;
-  return rc;
-}
+sqlite3_vfs *os_vfs();
 
 int sqlite3_os_init() {
-  static sqlite3_vfs go_vfs = {
-      .iVersion = 2,
-      .szOsFile = sizeof(struct go_file),
-      .mxPathname = 512,
-      .zName = "go",
-
-      .xOpen = go_open_c,
-      .xDelete = go_delete,
-      .xAccess = go_access,
-      .xFullPathname = go_full_pathname,
-
-      .xRandomness = go_randomness,
-      .xSleep = go_sleep,
-      .xCurrentTime = go_current_time,
-      .xCurrentTimeInt64 = go_current_time_64,
-  };
-  return sqlite3_vfs_register(&go_vfs, /*default=*/true);
+  return sqlite3_vfs_register(os_vfs(), /*default=*/true);
 }
-
-sqlite3_destructor_type malloc_destructor = &free;

sqlite3/os.c

@@ -0,0 +1,92 @@
+#include <time.h>
+
+#include "sqlite3.h"
+
+int os_localtime(sqlite3_int64, struct tm *);
+
+int os_randomness(sqlite3_vfs *, int nByte, char *zOut);
+int os_sleep(sqlite3_vfs *, int microseconds);
+int os_current_time(sqlite3_vfs *, double *);
+int os_current_time_64(sqlite3_vfs *, sqlite3_int64 *);
+
+int os_open(sqlite3_vfs *, sqlite3_filename zName, sqlite3_file *, int flags,
+            int *pOutFlags);
+int os_delete(sqlite3_vfs *, const char *zName, int syncDir);
+int os_access(sqlite3_vfs *, const char *zName, int flags, int *pResOut);
+int os_full_pathname(sqlite3_vfs *, const char *zName, int nOut, char *zOut);
+
+struct os_file {
+  sqlite3_file base;
+  int id;
+  int lock;
+};
+
+int os_close(sqlite3_file *);
+int os_read(sqlite3_file *, void *, int iAmt, sqlite3_int64 iOfst);
+int os_write(sqlite3_file *, const void *, int iAmt, sqlite3_int64 iOfst);
+int os_truncate(sqlite3_file *, sqlite3_int64 size);
+int os_sync(sqlite3_file *, int flags);
+int os_file_size(sqlite3_file *, sqlite3_int64 *pSize);
+int os_file_control(sqlite3_file *pFile, int op, void *pArg);
+
+int os_lock(sqlite3_file *pFile, int eLock);
+int os_unlock(sqlite3_file *pFile, int eLock);
+int os_check_reserved_lock(sqlite3_file *pFile, int *pResOut);
+
+static int no_lock(sqlite3_file *pFile, int eLock) { return SQLITE_OK; }
+static int no_unlock(sqlite3_file *pFile, int eLock) { return SQLITE_OK; }
+static int no_check_reserved_lock(sqlite3_file *pFile, int *pResOut) {
+  *pResOut = 0;
+  return SQLITE_OK;
+}
+
+static int no_file_control(sqlite3_file *pFile, int op, void *pArg) {
+  return SQLITE_NOTFOUND;
+}
+static int no_sector_size(sqlite3_file *pFile) { return 0; }
+static int no_device_characteristics(sqlite3_file *pFile) { return 0; }
+
+int localtime_s(struct tm *const pTm, time_t const *const pTime) {
+  return os_localtime((sqlite3_int64)*pTime, pTm);
+}
+
+static int os_open_w(sqlite3_vfs *vfs, sqlite3_filename zName,
+                     sqlite3_file *file, int flags, int *pOutFlags) {
+  static const sqlite3_io_methods os_io = {
+      .iVersion = 1,
+      .xClose = os_close,
+      .xRead = os_read,
+      .xWrite = os_write,
+      .xTruncate = os_truncate,
+      .xSync = os_sync,
+      .xFileSize = os_file_size,
+      .xLock = os_lock,
+      .xUnlock = os_unlock,
+      .xCheckReservedLock = os_check_reserved_lock,
+      .xFileControl = no_file_control,
+      .xDeviceCharacteristics = no_device_characteristics,
+  };
+  int rc = os_open(vfs, zName, file, flags, pOutFlags);
+  file->pMethods = (char)rc == SQLITE_OK ? &os_io : NULL;
+  return rc;
+}
+
+sqlite3_vfs *os_vfs() {
+  static sqlite3_vfs os_vfs = {
+      .iVersion = 2,
+      .szOsFile = sizeof(struct os_file),
+      .mxPathname = 512,
+      .zName = "os",
+
+      .xOpen = os_open_w,
+      .xDelete = os_delete,
+      .xAccess = os_access,
+      .xFullPathname = os_full_pathname,
+
+      .xRandomness = os_randomness,
+      .xSleep = os_sleep,
+      .xCurrentTime = os_current_time,
+      .xCurrentTimeInt64 = os_current_time_64,
+  };
+  return &os_vfs;
+}

sqlite3/qsort.c

@@ -0,0 +1,14 @@
+#include <stddef.h>
+
+void qsort_r(void *, size_t, size_t,
+             int (*)(const void *, const void *, void *), void *);
+
+typedef int (*cmpfun)(const void *, const void *);
+
+static int wrapper_cmp(const void *v1, const void *v2, void *cmp) {
+  return ((cmpfun)cmp)(v1, v2);
+}
+
+void qsort(void *base, size_t nel, size_t width, cmpfun cmp) {
+  qsort_r(base, nel, width, wrapper_cmp, cmp);
+}

sqlite3/sqlite_cfg.h

@@ -28,18 +28,33 @@
 #define SQLITE_OMIT_AUTOINIT
 #define SQLITE_USE_ALLOCA
 
+// Because WASM does not support shared memory,
+// SQLite disables it for WASM builds.
+// We set the default locking mode to EXCLUSIVE instead.
+// https://www.sqlite.org/wal.html#noshm
+#undef SQLITE_OMIT_WAL
+#define SQLITE_DEFAULT_LOCKING_MODE 1
+
 // Recommended Extensions
 
-// #define SQLITE_ENABLE_MATH_FUNCTIONS 1
-// #define SQLITE_ENABLE_FTS3 1
-// #define SQLITE_ENABLE_FTS3_PARENTHESIS 1
-// #define SQLITE_ENABLE_FTS4 1
-// #define SQLITE_ENABLE_FTS5 1
-// #define SQLITE_ENABLE_RTREE 1
-// #define SQLITE_ENABLE_GEOPOLY 1
+#define SQLITE_ENABLE_MATH_FUNCTIONS 1
+#define SQLITE_ENABLE_JSON1 1
+#define SQLITE_ENABLE_FTS3 1
+#define SQLITE_ENABLE_FTS3_PARENTHESIS 1
+#define SQLITE_ENABLE_FTS4 1
+#define SQLITE_ENABLE_FTS5 1
+#define SQLITE_ENABLE_RTREE 1
+#define SQLITE_ENABLE_GEOPOLY 1
 
-// Need this to access WAL databases without the use of shared memory.
-#define SQLITE_DEFAULT_LOCKING_MODE 1
+// Snapshot
+// #define SQLITE_ENABLE_SNAPSHOT 1
+
+// Session Extension
+// #define SQLITE_ENABLE_SESSION 1
+// #define SQLITE_ENABLE_PREUPDATE_HOOK 1
+
+// Resumable Bulk Update Extension
+// #define SQLITE_ENABLE_RBU 1
 
 // Implemented in Go.
 int localtime_s(struct tm *const pTm, time_t const *const pTime);

stmt.go

@@ -16,7 +16,7 @@ type Stmt struct {
 
 // Close destroys the prepared statement object.
 //
-// It is safe to close a nil, zero or closed prepared statement.
+// It is safe to close a nil, zero or closed Stmt.
 //
 // https://www.sqlite.org/c3ref/finalize.html
 func (s *Stmt) Close() error {
@@ -24,10 +24,7 @@ func (s *Stmt) Close() error {
 		return nil
 	}
 
-	r, err := s.c.api.finalize.Call(s.c.ctx, uint64(s.handle))
-	if err != nil {
-		panic(err)
-	}
+	r := s.c.call(s.c.api.finalize, uint64(s.handle))
 
 	s.handle = 0
 	return s.c.error(r[0])
@@ -37,10 +34,7 @@ func (s *Stmt) Close() error {
 //
 // https://www.sqlite.org/c3ref/reset.html
 func (s *Stmt) Reset() error {
-	r, err := s.c.api.reset.Call(s.c.ctx, uint64(s.handle))
-	if err != nil {
-		panic(err)
-	}
+	r := s.c.call(s.c.api.reset, uint64(s.handle))
 	s.err = nil
 	return s.c.error(r[0])
 }
@@ -49,10 +43,7 @@ func (s *Stmt) Reset() error {
 //
 // https://www.sqlite.org/c3ref/clear_bindings.html
 func (s *Stmt) ClearBindings() error {
-	r, err := s.c.api.clearBindings.Call(s.c.ctx, uint64(s.handle))
-	if err != nil {
-		panic(err)
-	}
+	r := s.c.call(s.c.api.clearBindings, uint64(s.handle))
 	return s.c.error(r[0])
 }
 
@@ -66,10 +57,8 @@ func (s *Stmt) ClearBindings() error {
 //
 // https://www.sqlite.org/c3ref/step.html
 func (s *Stmt) Step() bool {
-	r, err := s.c.api.step.Call(s.c.ctx, uint64(s.handle))
-	if err != nil {
-		panic(err)
-	}
+	s.c.checkInterrupt()
+	r := s.c.call(s.c.api.step, uint64(s.handle))
 	if r[0] == _ROW {
 		return true
 	}
@@ -101,11 +90,8 @@ func (s *Stmt) Exec() error {
 //
 // https://www.sqlite.org/c3ref/bind_parameter_count.html
 func (s *Stmt) BindCount() int {
-	r, err := s.c.api.bindCount.Call(s.c.ctx,
+	r := s.c.call(s.c.api.bindCount,
 		uint64(s.handle))
-	if err != nil {
-		panic(err)
-	}
 	return int(r[0])
 }
 
@@ -116,11 +102,8 @@ func (s *Stmt) BindCount() int {
 func (s *Stmt) BindIndex(name string) int {
 	defer s.c.arena.reset()
 	namePtr := s.c.arena.string(name)
-	r, err := s.c.api.bindIndex.Call(s.c.ctx,
+	r := s.c.call(s.c.api.bindIndex,
 		uint64(s.handle), uint64(namePtr))
-	if err != nil {
-		panic(err)
-	}
 	return int(r[0])
 }
 
@@ -129,11 +112,8 @@ func (s *Stmt) BindIndex(name string) int {
 //
 // https://www.sqlite.org/c3ref/bind_parameter_name.html
 func (s *Stmt) BindName(param int) string {
-	r, err := s.c.api.bindName.Call(s.c.ctx,
+	r := s.c.call(s.c.api.bindName,
 		uint64(s.handle), uint64(param))
-	if err != nil {
-		panic(err)
-	}
 
 	ptr := uint32(r[0])
 	if ptr == 0 {
@@ -168,11 +148,8 @@ func (s *Stmt) BindInt(param int, value int) error {
 //
 // https://www.sqlite.org/c3ref/bind_blob.html
 func (s *Stmt) BindInt64(param int, value int64) error {
-	r, err := s.c.api.bindInteger.Call(s.c.ctx,
+	r := s.c.call(s.c.api.bindInteger,
 		uint64(s.handle), uint64(param), uint64(value))
-	if err != nil {
-		panic(err)
-	}
 	return s.c.error(r[0])
 }
 
@@ -181,11 +158,8 @@ func (s *Stmt) BindInt64(param int, value int64) error {
 //
 // https://www.sqlite.org/c3ref/bind_blob.html
 func (s *Stmt) BindFloat(param int, value float64) error {
-	r, err := s.c.api.bindFloat.Call(s.c.ctx,
+	r := s.c.call(s.c.api.bindFloat,
 		uint64(s.handle), uint64(param), math.Float64bits(value))
-	if err != nil {
-		panic(err)
-	}
 	return s.c.error(r[0])
 }
 
@@ -195,13 +169,10 @@ func (s *Stmt) BindFloat(param int, value float64) error {
 // https://www.sqlite.org/c3ref/bind_blob.html
 func (s *Stmt) BindText(param int, value string) error {
 	ptr := s.c.newString(value)
-	r, err := s.c.api.bindText.Call(s.c.ctx,
+	r := s.c.call(s.c.api.bindText,
 		uint64(s.handle), uint64(param),
 		uint64(ptr), uint64(len(value)),
 		s.c.api.destructor, _UTF8)
-	if err != nil {
-		panic(err)
-	}
 	return s.c.error(r[0])
 }
 
@@ -212,13 +183,10 @@ func (s *Stmt) BindText(param int, value string) error {
 // https://www.sqlite.org/c3ref/bind_blob.html
 func (s *Stmt) BindBlob(param int, value []byte) error {
 	ptr := s.c.newBytes(value)
-	r, err := s.c.api.bindBlob.Call(s.c.ctx,
+	r := s.c.call(s.c.api.bindBlob,
 		uint64(s.handle), uint64(param),
 		uint64(ptr), uint64(len(value)),
 		s.c.api.destructor)
-	if err != nil {
-		panic(err)
-	}
 	return s.c.error(r[0])
 }
 
@@ -227,11 +195,8 @@ func (s *Stmt) BindBlob(param int, value []byte) error {
 //
 // https://www.sqlite.org/c3ref/bind_blob.html
 func (s *Stmt) BindZeroBlob(param int, n int64) error {
-	r, err := s.c.api.bindZeroBlob.Call(s.c.ctx,
+	r := s.c.call(s.c.api.bindZeroBlob,
 		uint64(s.handle), uint64(param), uint64(n))
-	if err != nil {
-		panic(err)
-	}
 	return s.c.error(r[0])
 }
 
@@ -240,11 +205,8 @@ func (s *Stmt) BindZeroBlob(param int, n int64) error {
 //
 // https://www.sqlite.org/c3ref/bind_blob.html
 func (s *Stmt) BindNull(param int) error {
-	r, err := s.c.api.bindNull.Call(s.c.ctx,
+	r := s.c.call(s.c.api.bindNull,
 		uint64(s.handle), uint64(param))
-	if err != nil {
-		panic(err)
-	}
 	return s.c.error(r[0])
 }
 
@@ -270,11 +232,8 @@ func (s *Stmt) BindTime(param int, value time.Time, format TimeFormat) error {
 //
 // https://www.sqlite.org/c3ref/column_count.html
 func (s *Stmt) ColumnCount() int {
-	r, err := s.c.api.columnCount.Call(s.c.ctx,
+	r := s.c.call(s.c.api.columnCount,
 		uint64(s.handle))
-	if err != nil {
-		panic(err)
-	}
 	return int(r[0])
 }
 
@@ -283,11 +242,8 @@ func (s *Stmt) ColumnCount() int {
 //
 // https://www.sqlite.org/c3ref/column_name.html
 func (s *Stmt) ColumnName(col int) string {
-	r, err := s.c.api.columnName.Call(s.c.ctx,
+	r := s.c.call(s.c.api.columnName,
 		uint64(s.handle), uint64(col))
-	if err != nil {
-		panic(err)
-	}
 
 	ptr := uint32(r[0])
 	if ptr == 0 {
@@ -301,11 +257,8 @@ func (s *Stmt) ColumnName(col int) string {
 //
 // https://www.sqlite.org/c3ref/column_blob.html
 func (s *Stmt) ColumnType(col int) Datatype {
-	r, err := s.c.api.columnType.Call(s.c.ctx,
+	r := s.c.call(s.c.api.columnType,
 		uint64(s.handle), uint64(col))
-	if err != nil {
-		panic(err)
-	}
 	return Datatype(r[0])
 }
 
@@ -336,11 +289,8 @@ func (s *Stmt) ColumnInt(col int) int {
 //
 // https://www.sqlite.org/c3ref/column_blob.html
 func (s *Stmt) ColumnInt64(col int) int64 {
-	r, err := s.c.api.columnInteger.Call(s.c.ctx,
+	r := s.c.call(s.c.api.columnInteger,
 		uint64(s.handle), uint64(col))
-	if err != nil {
-		panic(err)
-	}
 	return int64(r[0])
 }
 
@@ -349,11 +299,8 @@ func (s *Stmt) ColumnInt64(col int) int64 {
 //
 // https://www.sqlite.org/c3ref/column_blob.html
 func (s *Stmt) ColumnFloat(col int) float64 {
-	r, err := s.c.api.columnFloat.Call(s.c.ctx,
+	r := s.c.call(s.c.api.columnFloat,
 		uint64(s.handle), uint64(col))
-	if err != nil {
-		panic(err)
-	}
 	return math.Float64frombits(r[0])
 }
 
@@ -387,29 +334,20 @@ func (s *Stmt) ColumnTime(col int, format TimeFormat) time.Time {
 //
 // https://www.sqlite.org/c3ref/column_blob.html
 func (s *Stmt) ColumnText(col int) string {
-	r, err := s.c.api.columnText.Call(s.c.ctx,
+	r := s.c.call(s.c.api.columnText,
 		uint64(s.handle), uint64(col))
-	if err != nil {
-		panic(err)
-	}
 
 	ptr := uint32(r[0])
 	if ptr == 0 {
-		r, err = s.c.api.errcode.Call(s.c.ctx, uint64(s.handle))
-		if err != nil {
-			panic(err)
-		}
+		r = s.c.call(s.c.api.errcode, uint64(s.handle))
 		s.err = s.c.error(r[0])
 		return ""
 	}
 
-	r, err = s.c.api.columnBytes.Call(s.c.ctx,
+	r = s.c.call(s.c.api.columnBytes,
 		uint64(s.handle), uint64(col))
-	if err != nil {
-		panic(err)
-	}
 
-	mem := s.c.mem.view(ptr, uint32(r[0]))
+	mem := s.c.mem.view(ptr, r[0])
 	return string(mem)
 }
 
@@ -419,28 +357,34 @@ func (s *Stmt) ColumnText(col int) string {
 //
 // https://www.sqlite.org/c3ref/column_blob.html
 func (s *Stmt) ColumnBlob(col int, buf []byte) []byte {
-	r, err := s.c.api.columnBlob.Call(s.c.ctx,
+	r := s.c.call(s.c.api.columnBlob,
 		uint64(s.handle), uint64(col))
-	if err != nil {
-		panic(err)
-	}
 
 	ptr := uint32(r[0])
 	if ptr == 0 {
-		r, err = s.c.api.errcode.Call(s.c.ctx, uint64(s.handle))
-		if err != nil {
-			panic(err)
-		}
+		r = s.c.call(s.c.api.errcode, uint64(s.handle))
 		s.err = s.c.error(r[0])
 		return buf[0:0]
 	}
 
-	r, err = s.c.api.columnBytes.Call(s.c.ctx,
+	r = s.c.call(s.c.api.columnBytes,
 		uint64(s.handle), uint64(col))
-	if err != nil {
-		panic(err)
-	}
 
-	mem := s.c.mem.view(ptr, uint32(r[0]))
+	mem := s.c.mem.view(ptr, r[0])
 	return append(buf[0:0], mem...)
 }
+
+// Return true if stmt is an empty SQL statement.
+// This is used as an optimization.
+// It's OK to always return false here.
+func emptyStatement(stmt string) bool {
+	for _, b := range []byte(stmt) {
+		switch b {
+		case ' ', '\n', '\r', '\t', '\v', '\f':
+		case ';':
+		default:
+			return false
+		}
+	}
+	return true
+}

tests/blob_test.go

@@ -0,0 +1,297 @@
+package tests
+
+import (
+	"bytes"
+	"crypto/rand"
+	"errors"
+	"fmt"
+	"io"
+	"testing"
+
+	"github.com/ncruces/go-sqlite3"
+	_ "github.com/ncruces/go-sqlite3/embed"
+)
+
+func TestBlob(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = db.Exec(`INSERT INTO test VALUES (zeroblob(1024))`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	blob, err := db.OpenBlob("main", "test", "col", db.LastInsertRowID(), true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer blob.Close()
+
+	size := blob.Size()
+	if size != 1024 {
+		t.Errorf("got %d, want 1024", size)
+	}
+
+	var data [1280]byte
+	_, err = rand.Read(data[:])
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = io.Copy(blob, bytes.NewReader(data[:size/2]))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = io.Copy(blob, bytes.NewReader(data[:]))
+	if !errors.Is(err, sqlite3.ERROR) {
+		t.Fatal("want error")
+	}
+
+	_, err = io.Copy(blob, bytes.NewReader(data[size/2:size]))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = blob.Seek(size/4, io.SeekStart)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if got, err := io.ReadAll(blob); err != nil {
+		t.Fatal(err)
+	} else if !bytes.Equal(got, data[size/4:size]) {
+		t.Errorf("got %q, want %q", got, data[size/4:size])
+	}
+
+	if n, err := blob.Read(make([]byte, 1)); n != 0 || err != io.EOF {
+		t.Errorf("got (%d, %v), want (0, EOF)", n, err)
+	}
+
+	if err := blob.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := db.Close(); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestBlob_invalid(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = db.Exec(`INSERT INTO test VALUES (zeroblob(1024))`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = db.OpenBlob("", "test", "col", db.LastInsertRowID(), false)
+	if !errors.Is(err, sqlite3.ERROR) {
+		t.Fatal("want error")
+	}
+}
+
+func TestBlob_Write_readonly(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = db.Exec(`INSERT INTO test VALUES (zeroblob(1024))`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	blob, err := db.OpenBlob("main", "test", "col", db.LastInsertRowID(), false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer blob.Close()
+
+	_, err = blob.Write([]byte("data"))
+	if !errors.Is(err, sqlite3.READONLY) {
+		t.Fatal("want error")
+	}
+}
+
+func TestBlob_Read_expired(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = db.Exec(`INSERT INTO test VALUES (zeroblob(1024))`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	blob, err := db.OpenBlob("main", "test", "col", db.LastInsertRowID(), false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer blob.Close()
+
+	err = db.Exec(`DELETE FROM test`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = io.ReadAll(blob)
+	if !errors.Is(err, sqlite3.ABORT) {
+		t.Fatal("want error", err)
+	}
+}
+
+func TestBlob_Seek(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = db.Exec(`INSERT INTO test VALUES (zeroblob(1024))`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	blob, err := db.OpenBlob("main", "test", "col", db.LastInsertRowID(), true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer blob.Close()
+
+	_, err = blob.Seek(0, 10)
+	if err == nil {
+		t.Fatal("want error")
+	}
+
+	_, err = blob.Seek(-1, io.SeekCurrent)
+	if err == nil {
+		t.Fatal("want error")
+	}
+
+	n, err := blob.Seek(1, io.SeekEnd)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if n != blob.Size()+1 {
+		t.Errorf("got %d, want %d", n, blob.Size())
+	}
+
+	_, err = blob.Write([]byte("data"))
+	if !errors.Is(err, sqlite3.ERROR) {
+		t.Fatal("want error")
+	}
+}
+
+func TestBlob_Reopen(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var rowids []int64
+	for i := 0; i < 100; i++ {
+		err = db.Exec(`INSERT INTO test VALUES (zeroblob(10))`)
+		if err != nil {
+			t.Fatal(err)
+		}
+		rowids = append(rowids, db.LastInsertRowID())
+	}
+
+	var blob *sqlite3.Blob
+
+	for i, rowid := range rowids {
+		if i > 0 {
+			err = blob.Reopen(rowid)
+		} else {
+			blob, err = db.OpenBlob("main", "test", "col", rowid, true)
+		}
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		_, err = fmt.Fprintf(blob, "blob %d\n", i)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+	if err := blob.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	for i, rowid := range rowids {
+		if i > 0 {
+			err = blob.Reopen(rowid)
+		} else {
+			blob, err = db.OpenBlob("main", "test", "col", rowid, false)
+		}
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		var got int
+		_, err = fmt.Fscanf(blob, "blob %d\n", &got)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if got != i {
+			t.Errorf("got %d, want %d", got, i)
+		}
+	}
+	if err := blob.Close(); err != nil {
+		t.Fatal(err)
+	}
+}

tests/bradfitz/sql_test.go

@@ -41,7 +41,9 @@ func (t params) mustExec(sql string, args ...interface{}) sql.Result {
 }
 
 func (sqliteDB) RunTest(t *testing.T, fn func(params)) {
-	db, err := sql.Open("sqlite3", filepath.Join(t.TempDir(), "foo.db"))
+	db, err := sql.Open("sqlite3", "file:"+
+		filepath.Join(t.TempDir(), "foo.db")+
+		"?_pragma=busy_timeout(10000)&_pragma=locking_mode(normal)&_pragma=synchronous(off)")
 	if err != nil {
 		t.Fatalf("foo.db open fail: %v", err)
 	}
@@ -104,7 +106,7 @@ func testTxQuery(t params) {
 	}
 	defer tx.Rollback()
 
-	_, err = t.DB.Exec("create table " + TablePrefix + "foo (id integer primary key, name varchar(50))")
+	_, err = tx.Exec("create table " + TablePrefix + "foo (id integer primary key, name varchar(50))")
 	if err != nil {
 		t.Logf("cannot drop table "+TablePrefix+"foo: %s", err)
 	}

tests/conn_test.go

@@ -17,15 +17,8 @@ func TestConn_Open_dir(t *testing.T) {
 	if err == nil {
 		t.Fatal("want error")
 	}
-	var serr *sqlite3.Error
-	if !errors.As(err, &serr) {
-		t.Fatalf("got %T, want sqlite3.Error", err)
-	}
-	if rc := serr.Code(); rc != sqlite3.CANTOPEN {
-		t.Errorf("got %d, want sqlite3.CANTOPEN", rc)
-	}
-	if got := err.Error(); got != `sqlite3: unable to open database file` {
-		t.Error("got message: ", got)
+	if !errors.Is(err, sqlite3.CANTOPEN) {
+		t.Errorf("got %v, want sqlite3.CANTOPEN", err)
 	}
 }
 
@@ -53,23 +46,21 @@ func TestConn_Close_BUSY(t *testing.T) {
 	if err == nil {
 		t.Fatal("want error")
 	}
-	var serr *sqlite3.Error
-	if !errors.As(err, &serr) {
-		t.Fatalf("got %T, want sqlite3.Error", err)
-	}
-	if rc := serr.Code(); rc != sqlite3.BUSY {
-		t.Errorf("got %d, want sqlite3.BUSY", rc)
+	if !errors.Is(err, sqlite3.BUSY) {
+		t.Errorf("got %v, want sqlite3.BUSY", err)
 	}
 	var terr interface{ Temporary() bool }
 	if !errors.As(err, &terr) || !terr.Temporary() {
 		t.Error("not temporary", err)
 	}
 	if got := err.Error(); got != `sqlite3: database is locked: unable to close due to unfinalized statements or unfinished backups` {
-		t.Error("got message: ", got)
+		t.Error("got message:", got)
 	}
 }
 
 func TestConn_SetInterrupt(t *testing.T) {
+	t.Parallel()
+
 	db, err := sqlite3.Open(":memory:")
 	if err != nil {
 		t.Fatal(err)
@@ -77,7 +68,7 @@ func TestConn_SetInterrupt(t *testing.T) {
 	defer db.Close()
 
 	ctx, cancel := context.WithCancel(context.Background())
-	db.SetInterrupt(ctx.Done())
+	db.SetInterrupt(ctx)
 
 	// Interrupt doesn't interrupt this.
 	err = db.Exec(`SELECT 1`)
@@ -85,7 +76,7 @@ func TestConn_SetInterrupt(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	db.SetInterrupt(nil)
+	db.SetInterrupt(context.Background())
 
 	stmt, _, err := db.Prepare(`
 		WITH RECURSIVE
@@ -103,40 +94,24 @@ func TestConn_SetInterrupt(t *testing.T) {
 	}
 	defer stmt.Close()
 
+	db.SetInterrupt(ctx)
 	cancel()
-	db.SetInterrupt(ctx.Done())
-
-	var serr *sqlite3.Error
 
 	// Interrupting works.
 	err = stmt.Exec()
-	if err != nil {
-		if !errors.As(err, &serr) {
-			t.Fatalf("got %T, want sqlite3.Error", err)
-		}
-		if rc := serr.Code(); rc != sqlite3.INTERRUPT {
-			t.Errorf("got %d, want sqlite3.INTERRUPT", rc)
-		}
-		if got := err.Error(); got != `sqlite3: interrupted` {
-			t.Error("got message: ", got)
-		}
+	if !errors.Is(err, sqlite3.INTERRUPT) {
+		t.Errorf("got %v, want sqlite3.INTERRUPT", err)
 	}
 
 	// Interrupting sticks.
 	err = db.Exec(`SELECT 1`)
-	if err != nil {
-		if !errors.As(err, &serr) {
-			t.Fatalf("got %T, want sqlite3.Error", err)
-		}
-		if rc := serr.Code(); rc != sqlite3.INTERRUPT {
-			t.Errorf("got %d, want sqlite3.INTERRUPT", rc)
-		}
-		if got := err.Error(); got != `sqlite3: interrupted` {
-			t.Error("got message: ", got)
-		}
+	if !errors.Is(err, sqlite3.INTERRUPT) {
+		t.Errorf("got %v, want sqlite3.INTERRUPT", err)
 	}
 
-	db.SetInterrupt(nil)
+	ctx, cancel = context.WithCancel(context.Background())
+	defer cancel()
+	db.SetInterrupt(ctx)
 
 	// Interrupting can be cleared.
 	err = db.Exec(`SELECT 1`)
@@ -207,7 +182,7 @@ func TestConn_Prepare_invalid(t *testing.T) {
 		t.Errorf("got %d, want sqlite3.ERROR", rc)
 	}
 	if got := err.Error(); got != `sqlite3: SQL logic error: incomplete input` {
-		t.Error("got message: ", got)
+		t.Error("got message:", got)
 	}
 
 	_, _, err = db.Prepare(`SELECT * FRM sqlite_schema`)
@@ -221,9 +196,65 @@ func TestConn_Prepare_invalid(t *testing.T) {
 		t.Errorf("got %d, want sqlite3.ERROR", rc)
 	}
 	if got := serr.SQL(); got != `FRM sqlite_schema` {
-		t.Error("got SQL: ", got)
+		t.Error("got SQL:", got)
 	}
 	if got := serr.Error(); got != `sqlite3: SQL logic error: near "FRM": syntax error` {
-		t.Error("got message: ", got)
+		t.Error("got message:", got)
 	}
 }
+
+func TestConn_MustPrepare_empty(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	defer func() { _ = recover() }()
+	_ = db.MustPrepare(``)
+	t.Error("want panic")
+}
+
+func TestConn_MustPrepare_tail(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	defer func() { _ = recover() }()
+	_ = db.MustPrepare(`SELECT 1; -- HERE`)
+	t.Error("want panic")
+}
+
+func TestConn_MustPrepare_invalid(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	defer func() { _ = recover() }()
+	_ = db.MustPrepare(`SELECT`)
+	t.Error("want panic")
+}
+
+func TestConn_Pragma(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	defer func() { _ = recover() }()
+	_ = db.Pragma("encoding=''")
+	t.Error("want panic")
+}

tests/db_test.go

@@ -30,7 +30,7 @@ func testDB(t *testing.T, name string) {
 		t.Fatal(err)
 	}
 
-	err = db.Exec(`INSERT INTO users(id, name) VALUES(0, 'go'), (1, 'zig'), (2, 'whatever')`)
+	err = db.Exec(`INSERT INTO users (id, name) VALUES (0, 'go'), (1, 'zig'), (2, 'whatever')`)
 	if err != nil {
 		t.Fatal(err)
 	}

tests/driver_test.go

@@ -34,7 +34,7 @@ func TestDriver(t *testing.T) {
 	}
 
 	res, err := conn.ExecContext(ctx,
-		`INSERT INTO users(id, name) VALUES(0, 'go'), (1, 'zig'), (2, 'whatever')`)
+		`INSERT INTO users (id, name) VALUES (0, 'go'), (1, 'zig'), (2, 'whatever')`)
 	if err != nil {
 		t.Fatal(err)
 	}

tests/parallel/parallel_test.go

@@ -1,7 +1,6 @@
 package tests
 
 import (
-	"errors"
 	"io"
 	"os"
 	"os/exec"
@@ -16,13 +15,13 @@ import (
 
 func TestParallel(t *testing.T) {
 	name := filepath.Join(t.TempDir(), "test.db")
-	testParallel(t, name, 100)
+	testParallel(t, name, 1000)
 	testIntegrity(t, name)
 }
 
 func TestMultiProcess(t *testing.T) {
 	if testing.Short() {
-		t.Skip()
+		t.Skip("skipping in short mode")
 	}
 
 	name := filepath.Join(t.TempDir(), "test.db")
@@ -46,10 +45,6 @@ func TestMultiProcess(t *testing.T) {
 	testParallel(t, name, 1000)
 	if err := cmd.Wait(); err != nil {
 		t.Error(err)
-		var eerr *exec.ExitError
-		if errors.As(err, &eerr) {
-			t.Error(eerr.Stderr)
-		}
 	}
 	testIntegrity(t, name)
 }
@@ -72,8 +67,10 @@ func testParallel(t *testing.T, name string, n int) {
 		defer db.Close()
 
 		err = db.Exec(`
-			PRAGMA locking_mode = NORMAL;
-			PRAGMA busy_timeout = 10000;
+			PRAGMA busy_timeout=10000;
+			PRAGMA synchronous=off;
+			PRAGMA locking_mode=normal;
+			PRAGMA journal_mode=truncate;
 		`)
 		if err != nil {
 			return err
@@ -84,7 +81,7 @@ func testParallel(t *testing.T, name string, n int) {
 			return err
 		}
 
-		err = db.Exec(`INSERT INTO users(id, name) VALUES(0, 'go'), (1, 'zig'), (2, 'whatever')`)
+		err = db.Exec(`INSERT INTO users (id, name) VALUES (0, 'go'), (1, 'zig'), (2, 'whatever')`)
 		if err != nil {
 			return err
 		}
@@ -100,8 +97,8 @@ func testParallel(t *testing.T, name string, n int) {
 		defer db.Close()
 
 		err = db.Exec(`
-			PRAGMA locking_mode = NORMAL;
-			PRAGMA busy_timeout = 10000;
+			PRAGMA busy_timeout=10000;
+			PRAGMA locking_mode=normal;
 		`)
 		if err != nil {
 			return err
@@ -148,7 +145,7 @@ func testParallel(t *testing.T, name string, n int) {
 	}
 	err = group.Wait()
 	if err != nil {
-		t.Fatal(err)
+		t.Error(err)
 	}
 }
 

tests/stmt_test.go

@@ -22,7 +22,7 @@ func TestStmt(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	stmt, _, err := db.Prepare(`INSERT INTO test(col) VALUES(?)`)
+	stmt, _, err := db.Prepare(`INSERT INTO test VALUES (?)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -400,7 +400,7 @@ func TestStmt_BindName(t *testing.T) {
 	}
 }
 
-func TestStmt_Time(t *testing.T) {
+func TestStmt_ColumnTime(t *testing.T) {
 	t.Parallel()
 
 	db, err := sqlite3.Open(":memory:")
@@ -430,23 +430,23 @@ func TestStmt_Time(t *testing.T) {
 	}
 
 	if now := time.Now(); stmt.Step() {
-		if got := stmt.ColumnTime(0, sqlite3.TimeFormatAuto); !reference.Equal(got) {
+		if got := stmt.ColumnTime(0, sqlite3.TimeFormatAuto); !got.Equal(reference) {
 			t.Errorf("got %v, want %v", got, reference)
 		}
-		if got := stmt.ColumnTime(1, sqlite3.TimeFormatAuto); !reference.Equal(got) {
+		if got := stmt.ColumnTime(1, sqlite3.TimeFormatAuto); !got.Equal(reference) {
 			t.Errorf("got %v, want %v", got, reference)
 		}
-		if got := stmt.ColumnTime(2, sqlite3.TimeFormatAuto); reference.Sub(got) > time.Millisecond {
+		if got := stmt.ColumnTime(2, sqlite3.TimeFormatAuto); got.Sub(reference).Abs() > time.Millisecond {
 			t.Errorf("got %v, want %v", got, reference)
 		}
 
-		if got := stmt.ColumnTime(3, sqlite3.TimeFormatAuto); now.Sub(got) > time.Second {
+		if got := stmt.ColumnTime(3, sqlite3.TimeFormatAuto); got.Sub(now).Abs() > time.Second {
 			t.Errorf("got %v, want %v", got, now)
 		}
-		if got := stmt.ColumnTime(4, sqlite3.TimeFormatAuto); now.Sub(got) > time.Second {
+		if got := stmt.ColumnTime(4, sqlite3.TimeFormatAuto); got.Sub(now).Abs() > time.Second {
 			t.Errorf("got %v, want %v", got, now)
 		}
-		if got := stmt.ColumnTime(5, sqlite3.TimeFormatAuto); now.Sub(got) > time.Millisecond {
+		if got := stmt.ColumnTime(5, sqlite3.TimeFormatAuto); got.Sub(now).Abs() > time.Second/10 {
 			t.Errorf("got %v, want %v", got, now)
 		}
 

tests/tx_test.go

@@ -0,0 +1,504 @@
+package tests
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/ncruces/go-sqlite3"
+)
+
+func TestConn_Transaction_exec(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	errFailed := errors.New("failed")
+
+	count := func() int {
+		stmt, _, err := db.Prepare(`SELECT count(*) FROM test`)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if stmt.Step() {
+			return stmt.ColumnInt(0)
+		}
+		t.Fatal(stmt.Err())
+		return 0
+	}
+
+	insert := func(succeed bool) (err error) {
+		tx := db.Begin()
+		defer tx.End(&err)
+
+		err = db.Exec(`INSERT INTO test VALUES ('hello')`)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if succeed {
+			return nil
+		}
+		return errFailed
+	}
+
+	err = insert(true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := count(); got != 1 {
+		t.Errorf("got %d, want 1", got)
+	}
+
+	err = insert(true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := count(); got != 2 {
+		t.Errorf("got %d, want 2", got)
+	}
+
+	err = insert(false)
+	if err != errFailed {
+		t.Errorf("got %v, want errFailed", err)
+	}
+	if got := count(); got != 2 {
+		t.Errorf("got %d, want 2", got)
+	}
+}
+
+func TestConn_Transaction_panic(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = db.Exec(`INSERT INTO test VALUES ('one');`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	panics := func() (err error) {
+		tx := db.Begin()
+		defer tx.End(&err)
+
+		err = db.Exec(`INSERT INTO test VALUES ('hello')`)
+		if err != nil {
+			return err
+		}
+
+		panic("omg!")
+	}
+
+	defer func() {
+		p := recover()
+		if p != "omg!" {
+			t.Errorf("got %v, want panic", p)
+		}
+
+		stmt, _, err := db.Prepare(`SELECT count(*) FROM test`)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if stmt.Step() {
+			got := stmt.ColumnInt(0)
+			if got != 1 {
+				t.Errorf("got %d, want 1", got)
+			}
+			return
+		}
+		t.Fatal(stmt.Err())
+	}()
+
+	err = panics()
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func TestConn_Transaction_interrupt(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	tx, err := db.BeginImmediate()
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = db.Exec(`INSERT INTO test VALUES (1)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	tx.End(&err)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	db.SetInterrupt(ctx)
+
+	tx, err = db.BeginExclusive()
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = db.Exec(`INSERT INTO test VALUES (2)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	cancel()
+	_, err = db.BeginImmediate()
+	if !errors.Is(err, sqlite3.INTERRUPT) {
+		t.Errorf("got %v, want sqlite3.INTERRUPT", err)
+	}
+
+	err = db.Exec(`INSERT INTO test VALUES (3)`)
+	if !errors.Is(err, sqlite3.INTERRUPT) {
+		t.Errorf("got %v, want sqlite3.INTERRUPT", err)
+	}
+
+	var nilErr error
+	tx.End(&nilErr)
+	if !errors.Is(nilErr, sqlite3.INTERRUPT) {
+		t.Errorf("got %v, want sqlite3.INTERRUPT", nilErr)
+	}
+
+	db.SetInterrupt(context.Background())
+	stmt, _, err := db.Prepare(`SELECT count(*) FROM test`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stmt.Close()
+
+	if stmt.Step() {
+		got := stmt.ColumnInt(0)
+		if got != 1 {
+			t.Errorf("got %d, want 1", got)
+		}
+	}
+	err = stmt.Err()
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func TestConn_Transaction_rollback(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	tx := db.Begin()
+	err = db.Exec(`INSERT INTO test VALUES (1)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = db.Exec(`COMMIT`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	tx.End(&err)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	stmt, _, err := db.Prepare(`SELECT count(*) FROM test`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stmt.Close()
+
+	if stmt.Step() {
+		got := stmt.ColumnInt(0)
+		if got != 1 {
+			t.Errorf("got %d, want 1", got)
+		}
+	}
+	err = stmt.Err()
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func TestConn_Savepoint_exec(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	errFailed := errors.New("failed")
+
+	count := func() int {
+		stmt, _, err := db.Prepare(`SELECT count(*) FROM test`)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if stmt.Step() {
+			return stmt.ColumnInt(0)
+		}
+		t.Fatal(stmt.Err())
+		return 0
+	}
+
+	insert := func(succeed bool) (err error) {
+		defer db.Savepoint()(&err)
+
+		err = db.Exec(`INSERT INTO test VALUES ('hello')`)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if succeed {
+			return nil
+		}
+		return errFailed
+	}
+
+	err = insert(true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := count(); got != 1 {
+		t.Errorf("got %d, want 1", got)
+	}
+
+	err = insert(true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := count(); got != 2 {
+		t.Errorf("got %d, want 2", got)
+	}
+
+	err = insert(false)
+	if err != errFailed {
+		t.Errorf("got %v, want errFailed", err)
+	}
+	if got := count(); got != 2 {
+		t.Errorf("got %d, want 2", got)
+	}
+}
+
+func TestConn_Savepoint_panic(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = db.Exec(`INSERT INTO test VALUES ('one');`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	panics := func() (err error) {
+		defer db.Savepoint()(&err)
+
+		err = db.Exec(`INSERT INTO test VALUES ('hello')`)
+		if err != nil {
+			return err
+		}
+
+		panic("omg!")
+	}
+
+	defer func() {
+		p := recover()
+		if p != "omg!" {
+			t.Errorf("got %v, want panic", p)
+		}
+
+		stmt, _, err := db.Prepare(`SELECT count(*) FROM test`)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if stmt.Step() {
+			got := stmt.ColumnInt(0)
+			if got != 1 {
+				t.Errorf("got %d, want 1", got)
+			}
+			return
+		}
+		t.Fatal(stmt.Err())
+	}()
+
+	err = panics()
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func TestConn_Savepoint_interrupt(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	release := db.Savepoint()
+	err = db.Exec(`INSERT INTO test VALUES (1)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	release(&err)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	db.SetInterrupt(ctx)
+
+	release1 := db.Savepoint()
+	err = db.Exec(`INSERT INTO test VALUES (2)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	release2 := db.Savepoint()
+	err = db.Exec(`INSERT INTO test VALUES (3)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	cancel()
+	db.Savepoint()(&err)
+	if !errors.Is(err, sqlite3.INTERRUPT) {
+		t.Errorf("got %v, want sqlite3.INTERRUPT", err)
+	}
+
+	err = db.Exec(`INSERT INTO test VALUES (4)`)
+	if !errors.Is(err, sqlite3.INTERRUPT) {
+		t.Errorf("got %v, want sqlite3.INTERRUPT", err)
+	}
+
+	err = context.Canceled
+	release2(&err)
+	if err != context.Canceled {
+		t.Fatal(err)
+	}
+
+	var nilErr error
+	release1(&nilErr)
+	if !errors.Is(nilErr, sqlite3.INTERRUPT) {
+		t.Errorf("got %v, want sqlite3.INTERRUPT", nilErr)
+	}
+
+	db.SetInterrupt(context.Background())
+	stmt, _, err := db.Prepare(`SELECT count(*) FROM test`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stmt.Close()
+
+	if stmt.Step() {
+		got := stmt.ColumnInt(0)
+		if got != 1 {
+			t.Errorf("got %d, want 1", got)
+		}
+	}
+	err = stmt.Err()
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func TestConn_Savepoint_rollback(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	release := db.Savepoint()
+	err = db.Exec(`INSERT INTO test VALUES (1)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = db.Exec(`COMMIT`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	release(&err)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	stmt, _, err := db.Prepare(`SELECT count(*) FROM test`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stmt.Close()
+
+	if stmt.Step() {
+		got := stmt.ColumnInt(0)
+		if got != 1 {
+			t.Errorf("got %d, want 1", got)
+		}
+	}
+	err = stmt.Err()
+	if err != nil {
+		t.Error(err)
+	}
+}

time.go

@@ -11,6 +11,9 @@ import (
 
 // TimeFormat specifies how to encode/decode time values.
 //
+// See the documentation for the [TimeFormatDefault] constant
+// for formats recognized by SQLite.
+//
 // https://www.sqlite.org/lang_datefunc.html
 type TimeFormat string
 
@@ -57,11 +60,23 @@ const (
 // Encode encodes a time value using this format.
 //
 // [TimeFormatDefault] and [TimeFormatAuto] encode using [time.RFC3339Nano],
-// with nanosecond accuracy, and preserving timezone.
+// with nanosecond accuracy, and preserving any timezone offset.
 //
-// Formats that don't record the timezone
+// This is the format used by the database/sql driver:
+// [database/sql.Row.Scan] is able to decode as [time.Time]
+// values encoded with [time.RFC3339Nano].
+//
+// Time values encoded with [time.RFC3339Nano] cannot be sorted as strings
+// to produce a time-ordered sequence.
+// Use [TimeFormat7] for time-ordered encoding.
+//
+// Formats [TimeFormat1] through [TimeFormat10]
 // convert time values to UTC before encoding.
 //
+// Returns a string for the text formats,
+// a float64 for [TimeFormatJulianDay] and [TimeFormatUnixFrac],
+// or an int64 for the other numeric formats.
+//
 // https://www.sqlite.org/lang_datefunc.html
 func (f TimeFormat) Encode(t time.Time) any {
 	switch f {
@@ -81,11 +96,13 @@ func (f TimeFormat) Encode(t time.Time) any {
 	// Special formats
 	case TimeFormatDefault, TimeFormatAuto:
 		f = time.RFC3339Nano
-	}
 	// SQLite assumes UTC if unspecified.
-	if !strings.Contains(string(f), "MST") &&
-		!strings.Contains(string(f), "Z07") &&
-		!strings.Contains(string(f), "-07") {
+	case
+		TimeFormat1, TimeFormat2,
+		TimeFormat3, TimeFormat4,
+		TimeFormat5, TimeFormat6,
+		TimeFormat7, TimeFormat8,
+		TimeFormat9, TimeFormat10:
 		t = t.UTC()
 	}
 	return t.Format(string(f))
@@ -93,8 +110,23 @@ func (f TimeFormat) Encode(t time.Time) any {
 
 // Decode decodes a time value using this format.
 //
-// Decoding of SQLite recognized formats is lenient:
-// timezones and fractional seconds are always optional.
+// The time value can be a string, an int64, or a float64.
+//
+// Formats [TimeFormat8] through [TimeFormat10]
+// (and [TimeFormat8TZ] through [TimeFormat10TZ])
+// assume a date of 2000-01-01.
+//
+// The timezone indicator and fractional seconds are always optional
+// for formats [TimeFormat2] through [TimeFormat10]
+// (and [TimeFormat2TZ] through [TimeFormat10TZ]).
+//
+// [TimeFormatAuto] implements (and extends) the SQLite auto modifier.
+// Julian day numbers are safe to use for historical dates,
+// from 4712BC through 9999AD.
+// Unix timestamps (expressed in seconds, milliseconds, microseconds, or nanoseconds),
+// are safe to use for current events, from 1980 through at least 2260.
+// Unix timestamps before 1980 may be misinterpreted as julian day numbers,
+// or have the wrong time unit.
 //
 // https://www.sqlite.org/lang_datefunc.html
 func (f TimeFormat) Decode(v any) (time.Time, error) {
@@ -263,14 +295,7 @@ func (f TimeFormat) Decode(v any) (time.Time, error) {
 		if !ok {
 			return time.Time{}, timeErr
 		}
-		f := string(f)
-		f = strings.TrimSuffix(f, "Z07:00")
-		f = strings.TrimSuffix(f, ".000")
-		t, err := time.Parse(f+"Z07:00", s)
-		if err != nil {
-			t, err = time.Parse(f, s)
-		}
-		return t, err
+		return f.parseRelaxed(s)
 
 	case
 		TimeFormat8, TimeFormat8TZ,
@@ -280,13 +305,7 @@ func (f TimeFormat) Decode(v any) (time.Time, error) {
 		if !ok {
 			return time.Time{}, timeErr
 		}
-		f := string(f)
-		f = strings.TrimSuffix(f, "Z07:00")
-		f = strings.TrimSuffix(f, ".000")
-		t, err := time.Parse(f+"Z07:00", s)
-		if err != nil {
-			t, err = time.Parse(f, s)
-		}
+		t, err := f.parseRelaxed(s)
 		return t.AddDate(2000, 0, 0), err
 
 	default:
@@ -294,10 +313,20 @@ func (f TimeFormat) Decode(v any) (time.Time, error) {
 		if !ok {
 			return time.Time{}, timeErr
 		}
-		f := string(f)
 		if f == "" {
 			f = time.RFC3339Nano
 		}
-		return time.Parse(f, s)
+		return time.Parse(string(f), s)
 	}
 }
+
+func (f TimeFormat) parseRelaxed(s string) (time.Time, error) {
+	fs := string(f)
+	fs = strings.TrimSuffix(fs, "Z07:00")
+	fs = strings.TrimSuffix(fs, ".000")
+	t, err := time.Parse(fs+"Z07:00", s)
+	if err != nil {
+		return time.Parse(fs, s)
+	}
+	return t, nil
+}

tx.go

@@ -0,0 +1,177 @@
+package sqlite3
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"runtime"
+)
+
+type Tx struct {
+	c *Conn
+}
+
+// Begin starts a deferred transaction.
+//
+// https://www.sqlite.org/lang_transaction.html
+func (c *Conn) Begin() Tx {
+	err := c.Exec(`BEGIN DEFERRED`)
+	if err != nil && !errors.Is(err, INTERRUPT) {
+		panic(err)
+	}
+	return Tx{c}
+}
+
+// BeginImmediate starts an immediate transaction.
+//
+// https://www.sqlite.org/lang_transaction.html
+func (c *Conn) BeginImmediate() (Tx, error) {
+	err := c.Exec(`BEGIN IMMEDIATE`)
+	if err != nil {
+		return Tx{}, err
+	}
+	return Tx{c}, nil
+}
+
+// BeginExclusive starts an exclusive transaction.
+//
+// https://www.sqlite.org/lang_transaction.html
+func (c *Conn) BeginExclusive() (Tx, error) {
+	err := c.Exec(`BEGIN EXCLUSIVE`)
+	if err != nil {
+		return Tx{}, err
+	}
+	return Tx{c}, nil
+}
+
+// End calls either [Tx.Commit] or [Tx.Rollback]
+// depending on whether *error points to a nil or non-nil error.
+//
+// This is meant to be deferred:
+//
+//	func doWork(conn *sqlite3.Conn) (err error) {
+//		tx := conn.Begin()
+//		defer tx.End(&err)
+//
+//		// ... do work in the transaction
+//	}
+//
+// https://www.sqlite.org/lang_transaction.html
+func (tx Tx) End(errp *error) {
+	recovered := recover()
+	if recovered != nil {
+		defer panic(recovered)
+	}
+
+	if tx.c.GetAutocommit() {
+		// There is nothing to commit/rollback.
+		return
+	}
+
+	if *errp == nil && recovered == nil {
+		// Success path.
+		*errp = tx.Commit()
+		if *errp == nil {
+			return
+		}
+		// Possible interrupt, fall through to the error path.
+	}
+
+	// Error path.
+	err := tx.Rollback()
+	if err != nil {
+		panic(err)
+	}
+}
+
+// Commit commits the transaction.
+//
+// https://www.sqlite.org/lang_transaction.html
+func (tx Tx) Commit() error {
+	return tx.c.Exec(`COMMIT`)
+}
+
+// Rollback rollsback the transaction.
+//
+// https://www.sqlite.org/lang_transaction.html
+func (tx Tx) Rollback() error {
+	// ROLLBACK even if the connection has been interrupted.
+	old := tx.c.SetInterrupt(context.Background())
+	defer tx.c.SetInterrupt(old)
+	return tx.c.Exec(`ROLLBACK`)
+}
+
+// Savepoint creates a named SQLite transaction using SAVEPOINT.
+//
+// On success Savepoint returns a release func that will call either
+// RELEASE or ROLLBACK depending on whether the parameter *error
+// points to a nil or non-nil error.
+//
+// This is meant to be deferred:
+//
+//	func doWork(conn *sqlite3.Conn) (err error) {
+//		defer conn.Savepoint()(&err)
+//
+//		// ... do work in the transaction
+//	}
+//
+// https://www.sqlite.org/lang_savepoint.html
+func (c *Conn) Savepoint() (release func(*error)) {
+	name := "sqlite3.Savepoint" // names can be reused
+	var pc [1]uintptr
+	if n := runtime.Callers(2, pc[:]); n > 0 {
+		frames := runtime.CallersFrames(pc[:n])
+		frame, _ := frames.Next()
+		if frame.Function != "" {
+			name = frame.Function
+		}
+	}
+
+	err := c.Exec(fmt.Sprintf("SAVEPOINT %q;", name))
+	if err != nil {
+		if errors.Is(err, INTERRUPT) {
+			return func(errp *error) {
+				if *errp == nil {
+					*errp = err
+				}
+			}
+		}
+		panic(err)
+	}
+
+	return func(errp *error) {
+		recovered := recover()
+		if recovered != nil {
+			defer panic(recovered)
+		}
+
+		if c.GetAutocommit() {
+			// There is nothing to commit/rollback.
+			return
+		}
+
+		if *errp == nil && recovered == nil {
+			// Success path.
+			// RELEASE the savepoint successfully.
+			*errp = c.Exec(fmt.Sprintf("RELEASE %q;", name))
+			if *errp == nil {
+				return
+			}
+			// Possible interrupt, fall through to the error path.
+		}
+
+		// Error path.
+		// Always ROLLBACK even if the connection has been interrupted.
+		old := c.SetInterrupt(context.Background())
+		defer c.SetInterrupt(old)
+
+		err := c.Exec(fmt.Sprintf("ROLLBACK TO %q;", name))
+		if err != nil {
+			panic(err)
+		}
+		err = c.Exec(fmt.Sprintf("RELEASE %q;", name))
+		if err != nil {
+			panic(err)
+		}
+	}
+}

util.go

@@ -1,16 +0,0 @@
-package sqlite3
-
-// Return true if stmt is an empty SQL statement.
-// This is used as an optimization.
-// It's OK to always return false here.
-func emptyStatement(stmt string) bool {
-	for _, b := range []byte(stmt) {
-		switch b {
-		case ' ', '\n', '\r', '\t', '\v', '\f':
-		case ';':
-		default:
-			return false
-		}
-	}
-	return true
-}

vfs.go

@@ -27,31 +27,35 @@ func vfsInstantiate(ctx context.Context, r wazero.Runtime) {
 	}
 
 	env := r.NewHostModuleBuilder("env")
-	env.NewFunctionBuilder().WithFunc(vfsLocaltime).Export("go_localtime")
-	env.NewFunctionBuilder().WithFunc(vfsRandomness).Export("go_randomness")
-	env.NewFunctionBuilder().WithFunc(vfsSleep).Export("go_sleep")
-	env.NewFunctionBuilder().WithFunc(vfsCurrentTime).Export("go_current_time")
-	env.NewFunctionBuilder().WithFunc(vfsCurrentTime64).Export("go_current_time_64")
-	env.NewFunctionBuilder().WithFunc(vfsFullPathname).Export("go_full_pathname")
-	env.NewFunctionBuilder().WithFunc(vfsDelete).Export("go_delete")
-	env.NewFunctionBuilder().WithFunc(vfsAccess).Export("go_access")
-	env.NewFunctionBuilder().WithFunc(vfsOpen).Export("go_open")
-	env.NewFunctionBuilder().WithFunc(vfsClose).Export("go_close")
-	env.NewFunctionBuilder().WithFunc(vfsRead).Export("go_read")
-	env.NewFunctionBuilder().WithFunc(vfsWrite).Export("go_write")
-	env.NewFunctionBuilder().WithFunc(vfsTruncate).Export("go_truncate")
-	env.NewFunctionBuilder().WithFunc(vfsSync).Export("go_sync")
-	env.NewFunctionBuilder().WithFunc(vfsFileSize).Export("go_file_size")
-	env.NewFunctionBuilder().WithFunc(vfsLock).Export("go_lock")
-	env.NewFunctionBuilder().WithFunc(vfsUnlock).Export("go_unlock")
-	env.NewFunctionBuilder().WithFunc(vfsCheckReservedLock).Export("go_check_reserved_lock")
-	env.NewFunctionBuilder().WithFunc(vfsFileControl).Export("go_file_control")
+	env.NewFunctionBuilder().WithFunc(vfsLocaltime).Export("os_localtime")
+	env.NewFunctionBuilder().WithFunc(vfsRandomness).Export("os_randomness")
+	env.NewFunctionBuilder().WithFunc(vfsSleep).Export("os_sleep")
+	env.NewFunctionBuilder().WithFunc(vfsCurrentTime).Export("os_current_time")
+	env.NewFunctionBuilder().WithFunc(vfsCurrentTime64).Export("os_current_time_64")
+	env.NewFunctionBuilder().WithFunc(vfsFullPathname).Export("os_full_pathname")
+	env.NewFunctionBuilder().WithFunc(vfsDelete).Export("os_delete")
+	env.NewFunctionBuilder().WithFunc(vfsAccess).Export("os_access")
+	env.NewFunctionBuilder().WithFunc(vfsOpen).Export("os_open")
+	env.NewFunctionBuilder().WithFunc(vfsClose).Export("os_close")
+	env.NewFunctionBuilder().WithFunc(vfsRead).Export("os_read")
+	env.NewFunctionBuilder().WithFunc(vfsWrite).Export("os_write")
+	env.NewFunctionBuilder().WithFunc(vfsTruncate).Export("os_truncate")
+	env.NewFunctionBuilder().WithFunc(vfsSync).Export("os_sync")
+	env.NewFunctionBuilder().WithFunc(vfsFileSize).Export("os_file_size")
+	env.NewFunctionBuilder().WithFunc(vfsLock).Export("os_lock")
+	env.NewFunctionBuilder().WithFunc(vfsUnlock).Export("os_unlock")
+	env.NewFunctionBuilder().WithFunc(vfsCheckReservedLock).Export("os_check_reserved_lock")
+	env.NewFunctionBuilder().WithFunc(vfsFileControl).Export("os_file_control")
 	_, err = env.Instantiate(ctx)
 	if err != nil {
 		panic(err)
 	}
 }
 
+type vfsOSMethods bool
+
+const vfsOS vfsOSMethods = false
+
 func vfsExit(ctx context.Context, mod api.Module, exitCode uint32) {
 	// Ensure other callers see the exit code.
 	_ = mod.CloseWithExitCode(ctx, exitCode)
@@ -81,7 +85,7 @@ func vfsLocaltime(ctx context.Context, mod api.Module, t uint64, pTm uint32) uin
 }
 
 func vfsRandomness(ctx context.Context, mod api.Module, pVfs, nByte, zByte uint32) uint32 {
-	mem := memory{mod}.view(zByte, nByte)
+	mem := memory{mod}.view(zByte, uint64(nByte))
 	n, _ := rand.Reader.Read(mem)
 	return uint32(n)
 }
@@ -115,8 +119,8 @@ func vfsFullPathname(ctx context.Context, mod api.Module, pVfs, zRelative, nFull
 	// Or using [os.Readlink] to resolve a symbolic link (as the Unix VFS did).
 	// This might be buggy on Windows (the Windows VFS doesn't try).
 
-	size := uint32(len(abs) + 1)
-	if size > nFull {
+	size := uint64(len(abs) + 1)
+	if size > uint64(nFull) {
 		return uint32(CANTOPEN_FULLPATH)
 	}
 	mem := memory{mod}.view(zFull, size)
@@ -220,17 +224,10 @@ func vfsOpen(ctx context.Context, mod api.Module, pVfs, zName, pFile uint32, fla
 	}
 
 	if flags&OPEN_DELETEONCLOSE != 0 {
-		deleteOnClose(file)
+		vfsOS.DeleteOnClose(file)
 	}
 
-	info, err := file.Stat()
-	if err != nil {
-		return uint32(CANTOPEN)
-	}
-	if info.IsDir() {
-		return uint32(CANTOPEN_ISDIR)
-	}
-	id := vfsGetOpenFileID(file, info)
+	id := vfsGetFileID(file)
 	vfsFilePtr{mod, pFile}.SetID(id).SetLock(_NO_LOCK)
 
 	if pOutFlags != 0 {
@@ -241,7 +238,7 @@ func vfsOpen(ctx context.Context, mod api.Module, pVfs, zName, pFile uint32, fla
 
 func vfsClose(ctx context.Context, mod api.Module, pFile uint32) uint32 {
 	id := vfsFilePtr{mod, pFile}.ID()
-	err := vfsReleaseOpenFile(id)
+	err := vfsCloseFile(id)
 	if err != nil {
 		return uint32(IOERR_CLOSE)
 	}
@@ -249,7 +246,7 @@ func vfsClose(ctx context.Context, mod api.Module, pFile uint32) uint32 {
 }
 
 func vfsRead(ctx context.Context, mod api.Module, pFile, zBuf, iAmt uint32, iOfst uint64) uint32 {
-	buf := memory{mod}.view(zBuf, iAmt)
+	buf := memory{mod}.view(zBuf, uint64(iAmt))
 
 	file := vfsFilePtr{mod, pFile}.OSFile()
 	n, err := file.ReadAt(buf, int64(iOfst))
@@ -266,7 +263,7 @@ func vfsRead(ctx context.Context, mod api.Module, pFile, zBuf, iAmt uint32, iOfs
 }
 
 func vfsWrite(ctx context.Context, mod api.Module, pFile, zBuf, iAmt uint32, iOfst uint64) uint32 {
-	buf := memory{mod}.view(zBuf, iAmt)
+	buf := memory{mod}.view(zBuf, uint64(iAmt))
 
 	file := vfsFilePtr{mod, pFile}.OSFile()
 	_, err := file.WriteAt(buf, int64(iOfst))

vfs_files.go

@@ -7,66 +7,35 @@ import (
 	"github.com/tetratelabs/wazero/api"
 )
 
-type vfsOpenFile struct {
-	file   *os.File
-	info   os.FileInfo
-	nref   int
-	locker vfsFileLocker
-}
-
 var (
-	vfsOpenFiles    []*vfsOpenFile
+	vfsOpenFiles    []*os.File
 	vfsOpenFilesMtx sync.Mutex
 )
 
-func vfsGetOpenFileID(file *os.File, info os.FileInfo) uint32 {
+func vfsGetFileID(file *os.File) uint32 {
 	vfsOpenFilesMtx.Lock()
 	defer vfsOpenFilesMtx.Unlock()
 
-	// Reuse an already opened file.
-	for id, of := range vfsOpenFiles {
-		if of == nil {
-			continue
-		}
-		if os.SameFile(info, of.info) {
-			of.nref++
-			_ = file.Close()
-			return uint32(id)
-		}
-	}
-
-	of := &vfsOpenFile{
-		file:   file,
-		info:   info,
-		nref:   1,
-		locker: vfsFileLocker{file: file},
-	}
-
 	// Find an empty slot.
 	for id, ptr := range vfsOpenFiles {
 		if ptr == nil {
-			vfsOpenFiles[id] = of
+			vfsOpenFiles[id] = file
 			return uint32(id)
 		}
 	}
 
 	// Add a new slot.
-	id := len(vfsOpenFiles)
-	vfsOpenFiles = append(vfsOpenFiles, of)
-	return uint32(id)
+	vfsOpenFiles = append(vfsOpenFiles, file)
+	return uint32(len(vfsOpenFiles) - 1)
 }
 
-func vfsReleaseOpenFile(id uint32) error {
+func vfsCloseFile(id uint32) error {
 	vfsOpenFilesMtx.Lock()
 	defer vfsOpenFilesMtx.Unlock()
 
-	of := vfsOpenFiles[id]
-	if of.nref--; of.nref > 0 {
-		return nil
-	}
-	err := of.file.Close()
+	file := vfsOpenFiles[id]
 	vfsOpenFiles[id] = nil
-	return err
+	return file.Close()
 }
 
 type vfsFilePtr struct {
@@ -78,14 +47,7 @@ func (p vfsFilePtr) OSFile() *os.File {
 	id := p.ID()
 	vfsOpenFilesMtx.Lock()
 	defer vfsOpenFilesMtx.Unlock()
-	return vfsOpenFiles[id].file
-}
-
-func (p vfsFilePtr) Locker() *vfsFileLocker {
-	id := p.ID()
-	vfsOpenFilesMtx.Lock()
-	defer vfsOpenFilesMtx.Unlock()
-	return &vfsOpenFiles[id].locker
+	return vfsOpenFiles[id]
 }
 
 func (p vfsFilePtr) ID() uint32 {

vfs_lock.go

@@ -3,7 +3,6 @@ package sqlite3
 import (
 	"context"
 	"os"
-	"sync"
 
 	"github.com/tetratelabs/wazero/api"
 )
@@ -56,13 +55,6 @@ const (
 
 type vfsLockState uint32
 
-type vfsFileLocker struct {
-	sync.Mutex
-	file   *os.File
-	state  vfsLockState
-	shared int
-}
-
 func vfsLock(ctx context.Context, mod api.Module, pFile uint32, eLock vfsLockState) uint32 {
 	// Argument check. SQLite never explicitly requests a pendig lock.
 	if eLock != _SHARED_LOCK && eLock != _RESERVED_LOCK && eLock != _EXCLUSIVE_LOCK {
@@ -70,6 +62,7 @@ func vfsLock(ctx context.Context, mod api.Module, pFile uint32, eLock vfsLockSta
 	}
 
 	ptr := vfsFilePtr{mod, pFile}
+	file := ptr.OSFile()
 	cLock := ptr.Lock()
 
 	switch {
@@ -89,93 +82,49 @@ func vfsLock(ctx context.Context, mod api.Module, pFile uint32, eLock vfsLockSta
 		return _OK
 	}
 
-	fLock := ptr.Locker()
-	fLock.Lock()
-	defer fLock.Unlock()
-
-	// File state check.
-	switch {
-	case fLock.state < _NO_LOCK || fLock.state > _EXCLUSIVE_LOCK:
-		panic(assertErr())
-	case fLock.state == _NO_LOCK && fLock.shared != 0:
-		panic(assertErr())
-	case fLock.state == _EXCLUSIVE_LOCK && fLock.shared != 1:
-		panic(assertErr())
-	case fLock.state != _NO_LOCK && fLock.shared <= 0:
-		panic(assertErr())
-	case fLock.state < cLock:
-		panic(assertErr())
-	}
-
-	// If some other connection has a lock that precludes the requested lock, return BUSY.
-	if cLock != fLock.state && (eLock > _SHARED_LOCK || fLock.state >= _PENDING_LOCK) {
-		return uint32(BUSY)
-	}
-
 	switch eLock {
 	case _SHARED_LOCK:
-		// Test the PENDING lock before acquiring a new SHARED lock.
-		if locked, _ := fLock.CheckPending(); locked {
-			return uint32(BUSY)
-		}
-
-		// If some other connection has a SHARED or RESERVED lock,
-		// increment the reference count and return OK.
-		if fLock.state == _SHARED_LOCK || fLock.state == _RESERVED_LOCK {
-			ptr.SetLock(_SHARED_LOCK)
-			fLock.shared++
-			return _OK
-		}
-
 		// Must be unlocked to get SHARED.
-		if fLock.state != _NO_LOCK {
+		if cLock != _NO_LOCK {
 			panic(assertErr())
 		}
-		if rc := fLock.GetShared(); rc != _OK {
+		// Test the PENDING lock before acquiring a new SHARED lock.
+		if locked, _ := vfsOS.CheckPendingLock(file); locked {
+			return uint32(BUSY)
+		}
+		if rc := vfsOS.GetSharedLock(file); rc != _OK {
 			return uint32(rc)
 		}
 		ptr.SetLock(_SHARED_LOCK)
-		fLock.state = _SHARED_LOCK
-		fLock.shared = 1
 		return _OK
 
 	case _RESERVED_LOCK:
 		// Must be SHARED to get RESERVED.
-		if fLock.state != _SHARED_LOCK {
+		if cLock != _SHARED_LOCK {
 			panic(assertErr())
 		}
-		if rc := fLock.GetReserved(); rc != _OK {
+		if rc := vfsOS.GetReservedLock(file); rc != _OK {
 			return uint32(rc)
 		}
 		ptr.SetLock(_RESERVED_LOCK)
-		fLock.state = _RESERVED_LOCK
 		return _OK
 
 	case _EXCLUSIVE_LOCK:
-		// Must be SHARED, PENDING or RESERVED to get EXCLUSIVE.
-		if fLock.state <= _NO_LOCK || fLock.state >= _EXCLUSIVE_LOCK {
+		// Must be SHARED, RESERVED or PENDING to get EXCLUSIVE.
+		if cLock <= _NO_LOCK || cLock >= _EXCLUSIVE_LOCK {
 			panic(assertErr())
 		}
-
 		// A PENDING lock is needed before acquiring an EXCLUSIVE lock.
-		if fLock.state == _RESERVED_LOCK {
-			if rc := fLock.GetPending(); rc != _OK {
+		if cLock == _RESERVED_LOCK {
+			if rc := vfsOS.GetPendingLock(file); rc != _OK {
 				return uint32(rc)
 			}
 			ptr.SetLock(_PENDING_LOCK)
-			fLock.state = _PENDING_LOCK
 		}
-
-		// We are trying for an EXCLUSIVE lock but another connection is still holding a shared lock.
-		if fLock.shared > 1 {
-			return uint32(BUSY)
-		}
-
-		if rc := fLock.GetExclusive(); rc != _OK {
+		if rc := vfsOS.GetExclusiveLock(file); rc != _OK {
 			return uint32(rc)
 		}
 		ptr.SetLock(_EXCLUSIVE_LOCK)
-		fLock.state = _EXCLUSIVE_LOCK
 		return _OK
 
 	default:
@@ -190,6 +139,7 @@ func vfsUnlock(ctx context.Context, mod api.Module, pFile uint32, eLock vfsLockS
 	}
 
 	ptr := vfsFilePtr{mod, pFile}
+	file := ptr.OSFile()
 	cLock := ptr.Lock()
 
 	// Connection state check.
@@ -202,51 +152,22 @@ func vfsUnlock(ctx context.Context, mod api.Module, pFile uint32, eLock vfsLockS
 		return _OK
 	}
 
-	fLock := ptr.Locker()
-	fLock.Lock()
-	defer fLock.Unlock()
-
-	// File state check.
-	switch {
-	case fLock.state <= _NO_LOCK || fLock.state > _EXCLUSIVE_LOCK:
-		panic(assertErr())
-	case fLock.state == _EXCLUSIVE_LOCK && fLock.shared != 1:
-		panic(assertErr())
-	case fLock.shared <= 0:
-		panic(assertErr())
-	case fLock.state < cLock:
-		panic(assertErr())
-	}
-
-	if cLock > _SHARED_LOCK {
-		// The connection must own the lock to release it.
-		if cLock != fLock.state {
-			panic(assertErr())
+	switch eLock {
+	case _SHARED_LOCK:
+		if rc := vfsOS.DowngradeLock(file, cLock); rc != _OK {
+			return uint32(rc)
 		}
-		if eLock == _SHARED_LOCK {
-			if rc := fLock.Downgrade(); rc != _OK {
-				return uint32(rc)
-			}
-			ptr.SetLock(_SHARED_LOCK)
-			fLock.state = _SHARED_LOCK
-			return _OK
-		}
-	}
+		ptr.SetLock(_SHARED_LOCK)
+		return _OK
 
-	// If we get here, make sure we're dropping all locks.
-	if eLock != _NO_LOCK {
-		panic(assertErr())
-	}
-
-	// Release the connection lock and decrement the shared lock counter.
-	// Release the file lock only when all connections have released the lock.
-	ptr.SetLock(_NO_LOCK)
-	if fLock.shared--; fLock.shared == 0 {
-		rc := fLock.Release()
-		fLock.state = _NO_LOCK
+	case _NO_LOCK:
+		rc := vfsOS.ReleaseLock(file, cLock)
+		ptr.SetLock(_NO_LOCK)
 		return uint32(rc)
+
+	default:
+		panic(assertErr())
 	}
-	return _OK
 }
 
 func vfsCheckReservedLock(ctx context.Context, mod api.Module, pFile, pResOut uint32) uint32 {
@@ -257,16 +178,9 @@ func vfsCheckReservedLock(ctx context.Context, mod api.Module, pFile, pResOut ui
 		panic(assertErr())
 	}
 
-	fLock := ptr.Locker()
-	fLock.Lock()
-	defer fLock.Unlock()
+	file := ptr.OSFile()
 
-	if fLock.state >= _RESERVED_LOCK {
-		memory{mod}.writeUint32(pResOut, 1)
-		return _OK
-	}
-
-	locked, rc := fLock.CheckReserved()
+	locked, rc := vfsOS.CheckReservedLock(file)
 	var res uint32
 	if locked {
 		res = 1
@@ -274,3 +188,28 @@ func vfsCheckReservedLock(ctx context.Context, mod api.Module, pFile, pResOut ui
 	memory{mod}.writeUint32(pResOut, res)
 	return uint32(rc)
 }
+
+func (vfsOSMethods) GetSharedLock(file *os.File) xErrorCode {
+	// Acquire the SHARED lock.
+	return vfsOS.readLock(file, _SHARED_FIRST, _SHARED_SIZE)
+}
+
+func (vfsOSMethods) GetReservedLock(file *os.File) xErrorCode {
+	// Acquire the RESERVED lock.
+	return vfsOS.writeLock(file, _RESERVED_BYTE, 1)
+}
+
+func (vfsOSMethods) GetPendingLock(file *os.File) xErrorCode {
+	// Acquire the PENDING lock.
+	return vfsOS.writeLock(file, _PENDING_BYTE, 1)
+}
+
+func (vfsOSMethods) CheckReservedLock(file *os.File) (bool, xErrorCode) {
+	// Test the RESERVED lock.
+	return vfsOS.checkLock(file, _RESERVED_BYTE, 1)
+}
+
+func (vfsOSMethods) CheckPendingLock(file *os.File) (bool, xErrorCode) {
+	// Test the PENDING lock.
+	return vfsOS.checkLock(file, _PENDING_BYTE, 1)
+}

vfs_lock_test.go

@@ -9,12 +9,11 @@ import (
 )
 
 func Test_vfsLock(t *testing.T) {
-	// Other OSes lack open file descriptors locks.
 	switch runtime.GOOS {
 	case "linux", "darwin", "illumos", "windows":
-		//
+		break
 	default:
-		t.Skip()
+		t.Skip("OS lacks OFD locks")
 	}
 
 	name := filepath.Join(t.TempDir(), "test.db")
@@ -33,26 +32,14 @@ func Test_vfsLock(t *testing.T) {
 	}
 	defer file2.Close()
 
-	// Bypass open file reuse.
-	vfsOpenFiles = append(vfsOpenFiles, &vfsOpenFile{
-		file:   file1,
-		nref:   1,
-		locker: vfsFileLocker{file: file1},
-	}, &vfsOpenFile{
-		file:   file2,
-		nref:   1,
-		locker: vfsFileLocker{file: file2},
-	})
-
-	mem := newMemory(128)
-	mem.writeUint32(4+4, 0)
-	mem.writeUint32(16+4, 1)
-
 	const (
 		pFile1  = 4
 		pFile2  = 16
 		pOutput = 32
 	)
+	mem := newMemory(128)
+	vfsFilePtr{mem.mod, pFile1}.SetID(vfsGetFileID(file1)).SetLock(_NO_LOCK)
+	vfsFilePtr{mem.mod, pFile2}.SetID(vfsGetFileID(file2)).SetLock(_NO_LOCK)
 
 	rc := vfsCheckReservedLock(context.TODO(), mem.mod, pFile1, pOutput)
 	if rc != _OK {
@@ -110,11 +97,27 @@ func Test_vfsLock(t *testing.T) {
 		t.Fatal("returned", rc)
 	}
 
+	rc = vfsCheckReservedLock(context.TODO(), mem.mod, pFile1, pOutput)
+	if rc != _OK {
+		t.Fatal("returned", rc)
+	}
+	if got := mem.readUint32(pOutput); got == 0 {
+		t.Error("file wasn't locked")
+	}
+
 	rc = vfsUnlock(context.TODO(), mem.mod, pFile2, _SHARED_LOCK)
 	if rc != _OK {
 		t.Fatal("returned", rc)
 	}
 
+	rc = vfsCheckReservedLock(context.TODO(), mem.mod, pFile1, pOutput)
+	if rc != _OK {
+		t.Fatal("returned", rc)
+	}
+	if got := mem.readUint32(pOutput); got != 0 {
+		t.Error("file was locked")
+	}
+
 	rc = vfsLock(context.TODO(), mem.mod, pFile1, _SHARED_LOCK)
 	if rc != _OK {
 		t.Fatal("returned", rc)

vfs_unix.go

@@ -8,34 +8,19 @@ import (
 	"syscall"
 )
 
-func deleteOnClose(f *os.File) {
-	_ = os.Remove(f.Name())
+func (vfsOSMethods) DeleteOnClose(file *os.File) {
+	_ = os.Remove(file.Name())
 }
 
-func (l *vfsFileLocker) GetShared() xErrorCode {
-	// Acquire the SHARED lock.
-	return l.readLock(_SHARED_FIRST, _SHARED_SIZE)
-}
-
-func (l *vfsFileLocker) GetReserved() xErrorCode {
-	// Acquire the RESERVED lock.
-	return l.writeLock(_RESERVED_BYTE, 1)
-}
-
-func (l *vfsFileLocker) GetPending() xErrorCode {
-	// Acquire the PENDING lock.
-	return l.writeLock(_PENDING_BYTE, 1)
-}
-
-func (l *vfsFileLocker) GetExclusive() xErrorCode {
+func (vfsOSMethods) GetExclusiveLock(file *os.File) xErrorCode {
 	// Acquire the EXCLUSIVE lock.
-	return l.writeLock(_SHARED_FIRST, _SHARED_SIZE)
+	return vfsOS.writeLock(file, _SHARED_FIRST, _SHARED_SIZE)
 }
 
-func (l *vfsFileLocker) Downgrade() xErrorCode {
-	if l.state >= _EXCLUSIVE_LOCK {
+func (vfsOSMethods) DowngradeLock(file *os.File, state vfsLockState) xErrorCode {
+	if state >= _EXCLUSIVE_LOCK {
 		// Downgrade to a SHARED lock.
-		if rc := l.readLock(_SHARED_FIRST, _SHARED_SIZE); rc != _OK {
+		if rc := vfsOS.readLock(file, _SHARED_FIRST, _SHARED_SIZE); rc != _OK {
 			// In theory, the downgrade to a SHARED cannot fail because another
 			// process is holding an incompatible lock. If it does, this
 			// indicates that the other process is not following the locking
@@ -45,26 +30,16 @@ func (l *vfsFileLocker) Downgrade() xErrorCode {
 		}
 	}
 	// Release the PENDING and RESERVED locks.
-	return l.unlock(_PENDING_BYTE, 2)
+	return vfsOS.unlock(file, _PENDING_BYTE, 2)
 }
 
-func (l *vfsFileLocker) Release() xErrorCode {
+func (vfsOSMethods) ReleaseLock(file *os.File, _ vfsLockState) xErrorCode {
 	// Release all locks.
-	return l.unlock(0, 0)
+	return vfsOS.unlock(file, 0, 0)
 }
 
-func (l *vfsFileLocker) CheckReserved() (bool, xErrorCode) {
-	// Test the RESERVED lock.
-	return l.checkLock(_RESERVED_BYTE, 1)
-}
-
-func (l *vfsFileLocker) CheckPending() (bool, xErrorCode) {
-	// Test the PENDING lock.
-	return l.checkLock(_PENDING_BYTE, 1)
-}
-
-func (l *vfsFileLocker) unlock(start, len int64) xErrorCode {
-	err := l.fcntlSetLock(&syscall.Flock_t{
+func (vfsOSMethods) unlock(file *os.File, start, len int64) xErrorCode {
+	err := vfsOS.fcntlSetLock(file, &syscall.Flock_t{
 		Type:  syscall.F_UNLCK,
 		Start: start,
 		Len:   len,
@@ -75,67 +50,71 @@ func (l *vfsFileLocker) unlock(start, len int64) xErrorCode {
 	return _OK
 }
 
-func (l *vfsFileLocker) readLock(start, len int64) xErrorCode {
-	return l.errorCode(l.fcntlSetLock(&syscall.Flock_t{
+func (vfsOSMethods) readLock(file *os.File, start, len int64) xErrorCode {
+	return vfsOS.lockErrorCode(vfsOS.fcntlSetLock(file, &syscall.Flock_t{
 		Type:  syscall.F_RDLCK,
 		Start: start,
 		Len:   len,
 	}), IOERR_RDLOCK)
 }
 
-func (l *vfsFileLocker) writeLock(start, len int64) xErrorCode {
-	return l.errorCode(l.fcntlSetLock(&syscall.Flock_t{
+func (vfsOSMethods) writeLock(file *os.File, start, len int64) xErrorCode {
+	return vfsOS.lockErrorCode(vfsOS.fcntlSetLock(file, &syscall.Flock_t{
 		Type:  syscall.F_WRLCK,
 		Start: start,
 		Len:   len,
 	}), IOERR_LOCK)
 }
 
-func (l *vfsFileLocker) checkLock(start, len int64) (bool, xErrorCode) {
+func (vfsOSMethods) checkLock(file *os.File, start, len int64) (bool, xErrorCode) {
 	lock := syscall.Flock_t{
 		Type:  syscall.F_RDLCK,
 		Start: start,
 		Len:   len,
 	}
-	if l.fcntlGetLock(&lock) != nil {
+	if vfsOS.fcntlGetLock(file, &lock) != nil {
 		return false, IOERR_CHECKRESERVEDLOCK
 	}
 	return lock.Type != syscall.F_UNLCK, _OK
 }
 
-func (l *vfsFileLocker) fcntlGetLock(lock *syscall.Flock_t) error {
-	F_GETLK := syscall.F_GETLK
+func (vfsOSMethods) fcntlGetLock(file *os.File, lock *syscall.Flock_t) error {
+	var F_OFD_GETLK int
 	switch runtime.GOOS {
 	case "linux":
 		// https://github.com/torvalds/linux/blob/master/include/uapi/asm-generic/fcntl.h
-		F_GETLK = 36 // F_OFD_GETLK
+		F_OFD_GETLK = 36 // F_OFD_GETLK
 	case "darwin":
 		// https://github.com/apple/darwin-xnu/blob/main/bsd/sys/fcntl.h
-		F_GETLK = 92 // F_OFD_GETLK
+		F_OFD_GETLK = 92 // F_OFD_GETLK
 	case "illumos":
 		// https://github.com/illumos/illumos-gate/blob/master/usr/src/uts/common/sys/fcntl.h
-		F_GETLK = 47 // F_OFD_GETLK
+		F_OFD_GETLK = 47 // F_OFD_GETLK
+	default:
+		return notImplErr
 	}
-	return syscall.FcntlFlock(l.file.Fd(), F_GETLK, lock)
+	return syscall.FcntlFlock(file.Fd(), F_OFD_GETLK, lock)
 }
 
-func (l *vfsFileLocker) fcntlSetLock(lock *syscall.Flock_t) error {
-	F_SETLK := syscall.F_SETLK
+func (vfsOSMethods) fcntlSetLock(file *os.File, lock *syscall.Flock_t) error {
+	var F_OFD_SETLK int
 	switch runtime.GOOS {
 	case "linux":
 		// https://github.com/torvalds/linux/blob/master/include/uapi/asm-generic/fcntl.h
-		F_SETLK = 37 // F_OFD_SETLK
+		F_OFD_SETLK = 37 // F_OFD_SETLK
 	case "darwin":
 		// https://github.com/apple/darwin-xnu/blob/main/bsd/sys/fcntl.h
-		F_SETLK = 90 // F_OFD_SETLK
+		F_OFD_SETLK = 90 // F_OFD_SETLK
 	case "illumos":
 		// https://github.com/illumos/illumos-gate/blob/master/usr/src/uts/common/sys/fcntl.h
-		F_SETLK = 48 // F_OFD_SETLK
+		F_OFD_SETLK = 48 // F_OFD_SETLK
+	default:
+		return notImplErr
 	}
-	return syscall.FcntlFlock(l.file.Fd(), F_SETLK, lock)
+	return syscall.FcntlFlock(file.Fd(), F_OFD_SETLK, lock)
 }
 
-func (*vfsFileLocker) errorCode(err error, def xErrorCode) xErrorCode {
+func (vfsOSMethods) lockErrorCode(err error, def xErrorCode) xErrorCode {
 	if err == nil {
 		return _OK
 	}

vfs_windows.go

@@ -7,44 +7,29 @@ import (
 	"golang.org/x/sys/windows"
 )
 
-func deleteOnClose(f *os.File) {}
+func (vfsOSMethods) DeleteOnClose(file *os.File) {}
 
-func (l *vfsFileLocker) GetShared() xErrorCode {
-	// Acquire the SHARED lock.
-	return l.readLock(_SHARED_FIRST, _SHARED_SIZE)
-}
-
-func (l *vfsFileLocker) GetReserved() xErrorCode {
-	// Acquire the RESERVED lock.
-	return l.writeLock(_RESERVED_BYTE, 1)
-}
-
-func (l *vfsFileLocker) GetPending() xErrorCode {
-	// Acquire the PENDING lock.
-	return l.writeLock(_PENDING_BYTE, 1)
-}
-
-func (l *vfsFileLocker) GetExclusive() xErrorCode {
+func (vfsOSMethods) GetExclusiveLock(file *os.File) xErrorCode {
 	// Release the SHARED lock.
-	l.unlock(_SHARED_FIRST, _SHARED_SIZE)
+	vfsOS.unlock(file, _SHARED_FIRST, _SHARED_SIZE)
 
 	// Acquire the EXCLUSIVE lock.
-	rc := l.writeLock(_SHARED_FIRST, _SHARED_SIZE)
+	rc := vfsOS.writeLock(file, _SHARED_FIRST, _SHARED_SIZE)
 
 	// Reacquire the SHARED lock.
 	if rc != _OK {
-		l.readLock(_SHARED_FIRST, _SHARED_SIZE)
+		vfsOS.readLock(file, _SHARED_FIRST, _SHARED_SIZE)
 	}
 	return rc
 }
 
-func (l *vfsFileLocker) Downgrade() xErrorCode {
-	if l.state >= _EXCLUSIVE_LOCK {
+func (vfsOSMethods) DowngradeLock(file *os.File, state vfsLockState) xErrorCode {
+	if state >= _EXCLUSIVE_LOCK {
 		// Release the SHARED lock.
-		l.unlock(_SHARED_FIRST, _SHARED_SIZE)
+		vfsOS.unlock(file, _SHARED_FIRST, _SHARED_SIZE)
 
 		// Reacquire the SHARED lock.
-		if rc := l.readLock(_SHARED_FIRST, _SHARED_SIZE); rc != _OK {
+		if rc := vfsOS.readLock(file, _SHARED_FIRST, _SHARED_SIZE); rc != _OK {
 			// This should never happen.
 			// We should always be able to reacquire the read lock.
 			return IOERR_RDLOCK
@@ -52,49 +37,31 @@ func (l *vfsFileLocker) Downgrade() xErrorCode {
 	}
 
 	// Release the PENDING and RESERVED locks.
-	if l.state >= _RESERVED_LOCK {
-		l.unlock(_RESERVED_BYTE, 1)
+	if state >= _RESERVED_LOCK {
+		vfsOS.unlock(file, _RESERVED_BYTE, 1)
 	}
-	if l.state >= _PENDING_LOCK {
-		l.unlock(_PENDING_BYTE, 1)
+	if state >= _PENDING_LOCK {
+		vfsOS.unlock(file, _PENDING_BYTE, 1)
 	}
 	return _OK
 }
 
-func (l *vfsFileLocker) Release() xErrorCode {
+func (vfsOSMethods) ReleaseLock(file *os.File, state vfsLockState) xErrorCode {
 	// Release all locks.
-	if l.state >= _RESERVED_LOCK {
-		l.unlock(_RESERVED_BYTE, 1)
+	if state >= _RESERVED_LOCK {
+		vfsOS.unlock(file, _RESERVED_BYTE, 1)
 	}
-	if l.state >= _SHARED_LOCK {
-		l.unlock(_SHARED_FIRST, _SHARED_SIZE)
+	if state >= _SHARED_LOCK {
+		vfsOS.unlock(file, _SHARED_FIRST, _SHARED_SIZE)
 	}
-	if l.state >= _PENDING_LOCK {
-		l.unlock(_PENDING_BYTE, 1)
+	if state >= _PENDING_LOCK {
+		vfsOS.unlock(file, _PENDING_BYTE, 1)
 	}
 	return _OK
 }
 
-func (l *vfsFileLocker) CheckReserved() (bool, xErrorCode) {
-	// Test the RESERVED lock.
-	rc := l.readLock(_RESERVED_BYTE, 1)
-	if rc == _OK {
-		l.unlock(_RESERVED_BYTE, 1)
-	}
-	return rc != _OK, _OK
-}
-
-func (l *vfsFileLocker) CheckPending() (bool, xErrorCode) {
-	// Test the PENDING lock.
-	rc := l.readLock(_PENDING_BYTE, 1)
-	if rc == _OK {
-		l.unlock(_PENDING_BYTE, 1)
-	}
-	return rc != _OK, _OK
-}
-
-func (l *vfsFileLocker) unlock(start, len uint32) xErrorCode {
-	err := windows.UnlockFileEx(windows.Handle(l.file.Fd()),
+func (vfsOSMethods) unlock(file *os.File, start, len uint32) xErrorCode {
+	err := windows.UnlockFileEx(windows.Handle(file.Fd()),
 		0, len, 0, &windows.Overlapped{Offset: start})
 	if err != nil {
 		return IOERR_UNLOCK
@@ -102,21 +69,29 @@ func (l *vfsFileLocker) unlock(start, len uint32) xErrorCode {
 	return _OK
 }
 
-func (l *vfsFileLocker) readLock(start, len uint32) xErrorCode {
-	return l.errorCode(windows.LockFileEx(windows.Handle(l.file.Fd()),
+func (vfsOSMethods) readLock(file *os.File, start, len uint32) xErrorCode {
+	return vfsOS.lockErrorCode(windows.LockFileEx(windows.Handle(file.Fd()),
 		windows.LOCKFILE_FAIL_IMMEDIATELY,
 		0, len, 0, &windows.Overlapped{Offset: start}),
 		IOERR_RDLOCK)
 }
 
-func (l *vfsFileLocker) writeLock(start, len uint32) xErrorCode {
-	return l.errorCode(windows.LockFileEx(windows.Handle(l.file.Fd()),
+func (vfsOSMethods) writeLock(file *os.File, start, len uint32) xErrorCode {
+	return vfsOS.lockErrorCode(windows.LockFileEx(windows.Handle(file.Fd()),
 		windows.LOCKFILE_FAIL_IMMEDIATELY|windows.LOCKFILE_EXCLUSIVE_LOCK,
 		0, len, 0, &windows.Overlapped{Offset: start}),
 		IOERR_LOCK)
 }
 
-func (*vfsFileLocker) errorCode(err error, def xErrorCode) xErrorCode {
+func (vfsOSMethods) checkLock(file *os.File, start, len uint32) (bool, xErrorCode) {
+	rc := vfsOS.readLock(file, start, len)
+	if rc == _OK {
+		vfsOS.unlock(file, start, len)
+	}
+	return rc != _OK, _OK
+}
+
+func (vfsOSMethods) lockErrorCode(err error, def xErrorCode) xErrorCode {
 	if err == nil {
 		return _OK
 	}