wazero 1.0.

.github/workflows/go.yml

@@ -18,11 +18,27 @@ jobs:
       with:
         lfs: 'true'
 
-    - name: Set up Go
-      uses: actions/setup-go@v3
+    - name: Set up
+      uses: actions/setup-go@v4
       with:
         go-version: stable
-        cache: true
+
+    - name: Format
+      run: gofmt -s -w . && git diff --exit-code
+      if: matrix.os != 'windows-latest'
+
+    - name: Tidy
+      run: go mod tidy && git diff --exit-code
+
+    - name: Download
+      run: go mod download
+
+    - name: Verify
+      run: go mod verify
+
+    - name: Vet
+      run: go vet ./...
+      continue-on-error: true
 
     - name: Build
       run: go build -v ./...
@@ -34,8 +50,15 @@ jobs:
       run: go test -v -race ./...
       if: matrix.os == 'ubuntu-latest'
 
-    - name: Update coverage report
+    - name: Test BSD locks
+      run: go test -v -tags sqlite3_bsd ./...
+      if: matrix.os == 'macos-latest'
+
+    - name: Coverage report
       uses: ncruces/go-coverage-report@main
+      with:
+        chart: 'true'
+        amend: 'true'
       if: |
         matrix.os == 'ubuntu-latest' &&
         github.event_name == 'push'

README.md

@@ -20,7 +20,7 @@ embeds a build of SQLite into your application.
 
 This module replaces the SQLite [OS Interface](https://www.sqlite.org/vfs.html) (aka VFS)
 with a pure Go implementation.
-This has numerous benefits, but also comes with some caveats.
+This has numerous benefits, but also comes with some drawbacks.
 
 #### Write-Ahead Logging
 
@@ -39,21 +39,27 @@ To open WAL databases, or use `EXCLUSIVE` locking mode,
 disable connection pooling by calling
 [`db.SetMaxOpenConns(1)`](https://pkg.go.dev/database/sql#DB.SetMaxOpenConns).
 
-#### Open File Description Locks
+#### POSIX Advisory Locks
 
-On Unix, this module uses [OFD locks](https://www.gnu.org/software/libc/manual/html_node/Open-File-Description-Locks.html)
+POSIX advisory locks, which SQLite uses, are
+[broken by design](https://www.sqlite.org/src/artifact/90c4fa?ln=1073-1161).
+
+On Linux, macOS and illumos, 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.
+OFD locks are fully compatible with process-associated POSIX advisory locks.
 
-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).
+On BSD Unixes, this module uses
+[BSD locks](https://man.freebsd.org/cgi/man.cgi?query=flock&sektion=2).
+BSD locks may _not_ be compatible with process-associated POSIX advisory locks.
 
 #### Testing
 
 The pure Go VFS is stress tested by running an unmodified build of SQLite's
 [mptest](https://github.com/sqlite/sqlite/blob/master/mptest/mptest.c)
 on Linux, macOS and Windows.
+Performance is tested by running
+[speedtest1](https://github.com/sqlite/sqlite/blob/master/test/speedtest1.c).
 
 ### Roadmap
 
@@ -61,18 +67,14 @@ on Linux, macOS and Windows.
   - [x] nested transactions
   - [x] incremental BLOB I/O
   - [x] online backup
-  - [ ] snapshots
   - [ ] session extension
-  - [ ] resumable bulk update
-  - [ ] shared-cache mode
-  - [ ] unlock-notify
 - [ ] custom SQL functions
 - [ ] custom VFSes
+  - [ ] in-memory VFS
   - [ ] 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)

backup.go

@@ -33,7 +33,7 @@ func (src *Conn) Backup(srcDB, dstURI string) error {
 //
 // https://www.sqlite.org/backup.html
 func (dst *Conn) Restore(dstDB, srcURI string) error {
-	src, err := dst.openDB(srcURI, OPEN_READWRITE|OPEN_CREATE|OPEN_URI)
+	src, err := dst.openDB(srcURI, OPEN_READONLY|OPEN_URI)
 	if err != nil {
 		return err
 	}

conn.go

@@ -26,19 +26,23 @@ type Conn struct {
 	pending   *Stmt
 }
 
-// Open calls [OpenFlags] with [OPEN_READWRITE], [OPEN_CREATE] and [OPEN_URI].
+// Open calls [OpenFlags] with [OPEN_READWRITE], [OPEN_CREATE], [OPEN_URI] and [OPEN_NOFOLLOW].
 func Open(filename string) (*Conn, error) {
-	return newConn(filename, OPEN_READWRITE|OPEN_CREATE|OPEN_URI)
+	return newConn(filename, OPEN_READWRITE|OPEN_CREATE|OPEN_URI|OPEN_NOFOLLOW)
 }
 
 // OpenFlags opens an SQLite database file as specified by the filename argument.
 //
+// If none of the required flags is used, a combination of [OPEN_READWRITE] and [OPEN_CREATE] is used.
 // 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, error) {
+	if flags&(OPEN_READONLY|OPEN_READWRITE|OPEN_CREATE) == 0 {
+		flags |= OPEN_READWRITE | OPEN_CREATE
+	}
 	return newConn(filename, flags)
 }
 
@@ -69,6 +73,7 @@ func (c *Conn) openDB(filename string, flags OpenFlag) (uint32, error) {
 	connPtr := c.arena.new(ptrlen)
 	namePtr := c.arena.string(filename)
 
+	flags |= OPEN_EXRESCODE
 	r := c.call(c.api.open, uint64(namePtr), uint64(connPtr), uint64(flags), 0)
 
 	handle := c.mem.readUint32(connPtr)
@@ -100,7 +105,6 @@ func (c *Conn) openDB(filename string, flags OpenFlag) (uint32, error) {
 		}
 	}
 
-	c.call(c.api.timeCollation, uint64(handle))
 	return handle, nil
 }
 

const.go

@@ -7,6 +7,8 @@ const (
 	_ROW  = 100 /* sqlite3_step() has another row ready */
 	_DONE = 101 /* sqlite3_step() has finished executing */
 
+	_OK_SYMLINK = (_OK | (2 << 8)) /* internal use only */
+
 	_UTF8 = 1
 
 	_MAX_STRING   = 512 // Used for short strings: names, error messages…
@@ -225,3 +227,49 @@ const (
 	_SYNC_FULL     _SyncFlag = 0x00003
 	_SYNC_DATAONLY _SyncFlag = 0x00010
 )
+
+type _FcntlOpcode uint32
+
+const (
+	_FCNTL_LOCKSTATE             = 1
+	_FCNTL_GET_LOCKPROXYFILE     = 2
+	_FCNTL_SET_LOCKPROXYFILE     = 3
+	_FCNTL_LAST_ERRNO            = 4
+	_FCNTL_SIZE_HINT             = 5
+	_FCNTL_CHUNK_SIZE            = 6
+	_FCNTL_FILE_POINTER          = 7
+	_FCNTL_SYNC_OMITTED          = 8
+	_FCNTL_WIN32_AV_RETRY        = 9
+	_FCNTL_PERSIST_WAL           = 10
+	_FCNTL_OVERWRITE             = 11
+	_FCNTL_VFSNAME               = 12
+	_FCNTL_POWERSAFE_OVERWRITE   = 13
+	_FCNTL_PRAGMA                = 14
+	_FCNTL_BUSYHANDLER           = 15
+	_FCNTL_TEMPFILENAME          = 16
+	_FCNTL_MMAP_SIZE             = 18
+	_FCNTL_TRACE                 = 19
+	_FCNTL_HAS_MOVED             = 20
+	_FCNTL_SYNC                  = 21
+	_FCNTL_COMMIT_PHASETWO       = 22
+	_FCNTL_WIN32_SET_HANDLE      = 23
+	_FCNTL_WAL_BLOCK             = 24
+	_FCNTL_ZIPVFS                = 25
+	_FCNTL_RBU                   = 26
+	_FCNTL_VFS_POINTER           = 27
+	_FCNTL_JOURNAL_POINTER       = 28
+	_FCNTL_WIN32_GET_HANDLE      = 29
+	_FCNTL_PDB                   = 30
+	_FCNTL_BEGIN_ATOMIC_WRITE    = 31
+	_FCNTL_COMMIT_ATOMIC_WRITE   = 32
+	_FCNTL_ROLLBACK_ATOMIC_WRITE = 33
+	_FCNTL_LOCK_TIMEOUT          = 34
+	_FCNTL_DATA_VERSION          = 35
+	_FCNTL_SIZE_LIMIT            = 36
+	_FCNTL_CKPT_DONE             = 37
+	_FCNTL_RESERVE_BYTES         = 38
+	_FCNTL_CKPT_START            = 39
+	_FCNTL_EXTERNAL_READER       = 40
+	_FCNTL_CKSM_FILE             = 41
+	_FCNTL_RESET_CACHE           = 42
+)

driver/driver.go

@@ -44,7 +44,7 @@ func init() {
 type sqlite struct{}
 
 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)
+	c, err := sqlite3.Open(name)
 	if err != nil {
 		return nil, err
 	}
@@ -386,8 +386,7 @@ func (r rows) Next(dest []driver.Value) error {
 		case sqlite3.TEXT:
 			dest[i] = maybeTime(r.stmt.ColumnText(i))
 		case sqlite3.BLOB:
-			buf, _ := dest[i].([]byte)
-			dest[i] = r.stmt.ColumnBlob(i, buf)
+			dest[i] = r.stmt.ColumnRawBlob(i)
 		case sqlite3.NULL:
 			if buf, ok := dest[i].([]byte); ok {
 				dest[i] = buf[0:0]

driver/driver_test.go

@@ -308,7 +308,7 @@ func Test_QueryRow_blob_null(t *testing.T) {
 
 	want := [][]byte{nil, {0xca, 0xfe}, {0xba, 0xbe}, nil}
 	for i := 0; rows.Next(); i++ {
-		var buf []byte
+		var buf sql.RawBytes
 		err = rows.Scan(&buf)
 		if err != nil {
 			t.Fatal(err)

embed/README.md

@@ -1,14 +1,21 @@
 # Embeddable WASM build of SQLite
 
-This folder includes an embeddable WASM build of SQLite 3.41.0 for use with
+This folder includes an embeddable WASM build of SQLite 3.41.2 for use with
 [`github.com/ncruces/go-sqlite3`](https://pkg.go.dev/github.com/ncruces/go-sqlite3).
 
 The following optional features are compiled in:
-- math functions
-- FTS3/4/5
-- JSON
-- R*Tree
-- GeoPoly
+- [math functions](https://www.sqlite.org/lang_mathfunc.html)
+- [FTS3/4](https://www.sqlite.org/fts3.html)/[5](https://www.sqlite.org/fts5.html)
+- [JSON](https://www.sqlite.org/json1.html)
+- [R*Tree](https://www.sqlite.org/rtree.html)
+- [GeoPoly](https://www.sqlite.org/geopoly.html)
+- [base64](https://github.com/sqlite/sqlite/blob/master/ext/misc/base64.c)
+- [decimal](https://github.com/sqlite/sqlite/blob/master/ext/misc/decimal.c)
+- [regexp](https://github.com/sqlite/sqlite/blob/master/ext/misc/regexp.c)
+- [series](https://github.com/sqlite/sqlite/blob/master/ext/misc/series.c)
+- [uint](https://github.com/sqlite/sqlite/blob/master/ext/misc/uint.c)
+- [uuid](https://github.com/sqlite/sqlite/blob/master/ext/misc/uuid.c)
+- [time](../sqlite3/time.c)
 
 See the [configuration options](../sqlite3/sqlite_cfg.h).
 

embed/build.sh

@@ -3,14 +3,13 @@ set -eo pipefail
 
 cd -P -- "$(dirname -- "$0")"
 
-# download SQLite
-../sqlite3/download.sh
-
 # build SQLite
-zig cc --target=wasm32-wasi -flto -g0 -Os \
-  -o sqlite3.wasm ../sqlite3/amalg.c \
+zig cc --target=wasm32-wasi -flto -g0 -O2 \
+  -o sqlite3.wasm ../sqlite3/main.c \
+	-I../sqlite3/ \
 	-mmutable-globals \
 	-mbulk-memory -mreference-types \
 	-mnontrapping-fptoint -msign-ext \
+	-mexec-model=reactor \
 	-D_HAVE_SQLITE_CONFIG_H \
 	$(awk '{print "-Wl,--export="$0}' exports.txt)

embed/exports.txt

@@ -40,11 +40,9 @@ sqlite3_blob_reopen
 sqlite3_get_autocommit
 sqlite3_last_insert_rowid
 sqlite3_changes64
-sqlite3_unlock_notify
 sqlite3_backup_init
 sqlite3_backup_step
 sqlite3_backup_finish
 sqlite3_backup_remaining
 sqlite3_backup_pagecount
-sqlite3_time_collation
 sqlite3_interrupt_offset

error.go

@@ -202,7 +202,6 @@ const (
 	noFuncErr   = errorString("sqlite3: could not find function: ")
 	binaryErr   = errorString("sqlite3: no SQLite binary embed/set/loaded")
 	timeErr     = errorString("sqlite3: invalid time value")
-	notImplErr  = errorString("sqlite3: not implemented")
 	whenceErr   = errorString("sqlite3: invalid whence")
 	offsetErr   = errorString("sqlite3: invalid offset")
 )

go.mod

@@ -4,7 +4,7 @@ go 1.19
 
 require (
 	github.com/ncruces/julianday v0.1.5
-	github.com/tetratelabs/wazero v1.0.0-rc.1
+	github.com/tetratelabs/wazero v1.0.0
 	golang.org/x/sync v0.1.0
 	golang.org/x/sys v0.6.0
 )

go.sum

@@ -1,7 +1,7 @@
 github.com/ncruces/julianday v0.1.5 h1:hDJ9ejiMp3DHsoZ5KW4c1lwfMjbARS7u/gbYcd0FBZk=
 github.com/ncruces/julianday v0.1.5/go.mod h1:Dusn2KvZrrovOMJuOt0TNXL6tB7U2E8kvza5fFc9G7g=
-github.com/tetratelabs/wazero v1.0.0-rc.1 h1:ytecMV5Ue0BwezjKh/cM5yv1Mo49ep2R2snSsQUyToc=
-github.com/tetratelabs/wazero v1.0.0-rc.1/go.mod h1:wYx2gNRg8/WihJfSDxA1TIL8H+GkfLYm+bIfbblu9VQ=
+github.com/tetratelabs/wazero v1.0.0 h1:sCE9+mjFex95Ki6hdqwvhyF25x5WslADjDKIFU5BXzI=
+github.com/tetratelabs/wazero v1.0.0/go.mod h1:wYx2gNRg8/WihJfSDxA1TIL8H+GkfLYm+bIfbblu9VQ=
 golang.org/x/sync v0.1.0 h1:wsuoTGHzEhffawBOhz5CYhcrV4IdKZbEyZjBMuTp12o=
 golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.6.0 h1:MVltZSvRTcU2ljQOhs94SXPftV6DCNnZViHeQps87pQ=

mem.go

@@ -25,6 +25,27 @@ func (m memory) view(ptr uint32, size uint64) []byte {
 	return buf
 }
 
+func (m memory) readUint8(ptr uint32) uint8 {
+	if ptr == 0 {
+		panic(nilErr)
+	}
+	v, ok := m.mod.Memory().ReadByte(ptr)
+	if !ok {
+		panic(rangeErr)
+	}
+	return v
+}
+
+func (m memory) writeUint8(ptr uint32, v uint8) {
+	if ptr == 0 {
+		panic(nilErr)
+	}
+	ok := m.mod.Memory().WriteByte(ptr, v)
+	if !ok {
+		panic(rangeErr)
+	}
+}
+
 func (m memory) readUint32(ptr uint32) uint32 {
 	if ptr == 0 {
 		panic(nilErr)
@@ -36,7 +57,7 @@ func (m memory) readUint32(ptr uint32) uint32 {
 	return v
 }
 
-func (m memory) writeUint32(ptr, v uint32) {
+func (m memory) writeUint32(ptr uint32, v uint32) {
 	if ptr == 0 {
 		panic(nilErr)
 	}

module.go

@@ -3,14 +3,10 @@ package sqlite3
 
 import (
 	"context"
-	"crypto/rand"
 	"io"
 	"math"
 	"os"
-	"runtime"
-	"strconv"
 	"sync"
-	"sync/atomic"
 
 	"github.com/tetratelabs/wazero"
 	"github.com/tetratelabs/wazero/api"
@@ -28,11 +24,10 @@ var (
 )
 
 var sqlite3 struct {
-	once      sync.Once
-	runtime   wazero.Runtime
-	compiled  wazero.CompiledModule
-	instances atomic.Uint64
-	err       error
+	once     sync.Once
+	runtime  wazero.Runtime
+	compiled wazero.CompiledModule
+	err      error
 }
 
 func instantiateModule() (*module, error) {
@@ -43,12 +38,7 @@ func instantiateModule() (*module, error) {
 		return nil, sqlite3.err
 	}
 
-	name := "sqlite3-" + strconv.FormatUint(sqlite3.instances.Add(1), 10)
-
-	cfg := wazero.NewModuleConfig().WithName(name).
-		WithSysWalltime().WithSysNanotime().WithSysNanosleep().
-		WithOsyield(runtime.Gosched).
-		WithRandSource(rand.Reader)
+	cfg := wazero.NewModuleConfig().WithStartFunctions("_initialize")
 
 	mod, err := sqlite3.runtime.InstantiateModule(ctx, sqlite3.compiled, cfg)
 	if err != nil {
@@ -155,7 +145,6 @@ func newModule(mod api.Module) (m *module, err error) {
 		backupFinish:    getFun("sqlite3_backup_finish"),
 		backupRemaining: getFun("sqlite3_backup_remaining"),
 		backupPageCount: getFun("sqlite3_backup_pagecount"),
-		timeCollation:   getFun("sqlite3_time_collation"),
 		interrupt:       getVal("sqlite3_interrupt_offset"),
 	}
 	if err != nil {
@@ -349,6 +338,5 @@ type sqliteAPI struct {
 	backupFinish    api.Function
 	backupRemaining api.Function
 	backupPageCount api.Function
-	timeCollation   api.Function
 	interrupt       uint32
 }

sqlite3/download.sh

@@ -3,11 +3,29 @@ set -eo pipefail
 
 cd -P -- "$(dirname -- "$0")"
 
-if [ ! -f "sqlite3.c" ]; then
-	url="https://sqlite.org/2023/sqlite-amalgamation-3410000.zip"
-	curl "$url" > sqlite.zip
-	unzip -d . sqlite.zip
-	mv sqlite-amalgamation-*/sqlite3* .
-	rm -rf sqlite-amalgamation-*
-	rm sqlite.zip
-fi
+curl -#OL "https://sqlite.org/2023/sqlite-amalgamation-3410200.zip"
+unzip -d . sqlite-amalgamation-*.zip
+mv sqlite-amalgamation-*/sqlite3* .
+rm -rf sqlite-amalgamation-*
+
+cd ext/
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.41.2/ext/misc/decimal.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.41.2/ext/misc/uint.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.41.2/ext/misc/uuid.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.41.2/ext/misc/base64.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.41.2/ext/misc/regexp.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.41.2/ext/misc/series.c"
+cd ~-
+
+cd ../tests/mptest/testdata/
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.41.2/mptest/mptest.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.41.2/mptest/config01.test"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.41.2/mptest/config02.test"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.41.2/mptest/crash01.test"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.41.2/mptest/crash02.subtest"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.41.2/mptest/multiwrite01.test"
+cd ~-
+
+cd ../tests/speedtest1/testdata/
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.41.2/test/speedtest1.c"
+cd ~-

sqlite3/ext/.gitignore

@@ -0,0 +1 @@
+*.c

sqlite3/format.sh

@@ -1,8 +1,5 @@
 #!/usr/bin/env bash
 cd -P -- "$(dirname -- "$0")"
 
-clang-format -i \
-	main.c \
-	os.c \
-	qsort.c \
-	amalg.c
+shopt -s extglob
+clang-format -i !(sqlite3*).@(c|h)

sqlite3/main.c

@@ -1,14 +1,33 @@
 #include <stdbool.h>
+#include <stddef.h>
 
-#include "sqlite3.h"
+#include "sqlite3.c"
+//
+#include "os.c"
+#include "qsort.c"
+//
+#include "ext/base64.c"
+#include "ext/decimal.c"
+#include "ext/regexp.c"
+#include "ext/series.c"
+#include "ext/uint.c"
+#include "ext/uuid.c"
+#include "time.c"
 
-int main() {
-  int rc = sqlite3_initialize();
-  if (rc != SQLITE_OK) return 1;
-}
-
-sqlite3_vfs *os_vfs();
+sqlite3_destructor_type malloc_destructor = &free;
+size_t sqlite3_interrupt_offset = offsetof(sqlite3, u1.isInterrupted);
 
 int sqlite3_os_init() {
   return sqlite3_vfs_register(os_vfs(), /*default=*/true);
 }
+
+__attribute__((constructor)) void premain() {
+  sqlite3_initialize();
+  sqlite3_auto_extension((void (*)(void))sqlite3_base_init);
+  sqlite3_auto_extension((void (*)(void))sqlite3_decimal_init);
+  sqlite3_auto_extension((void (*)(void))sqlite3_regexp_init);
+  sqlite3_auto_extension((void (*)(void))sqlite3_series_init);
+  sqlite3_auto_extension((void (*)(void))sqlite3_uint_init);
+  sqlite3_auto_extension((void (*)(void))sqlite3_uuid_init);
+  sqlite3_auto_extension((void (*)(void))sqlite3_time_init);
+}

sqlite3/os.c

@@ -2,7 +2,7 @@
 
 #include "sqlite3.h"
 
-int os_localtime(sqlite3_int64, struct tm *);
+int os_localtime(struct tm *, sqlite3_int64);
 
 int os_randomness(sqlite3_vfs *, int nByte, char *zOut);
 int os_sleep(sqlite3_vfs *, int microseconds);
@@ -18,36 +18,73 @@ int os_full_pathname(sqlite3_vfs *, const char *zName, int nOut, char *zOut);
 struct os_file {
   sqlite3_file base;
   int id;
-  int lock;
+  char lock;
+  char psow;
+  int lockTimeout;
 };
 
+static_assert(offsetof(struct os_file, id) == 4, "Unexpected offset");
+static_assert(offsetof(struct os_file, lock) == 8, "Unexpected offset");
+static_assert(offsetof(struct os_file, psow) == 9, "Unexpected offset");
+static_assert(offsetof(struct os_file, lockTimeout) == 12, "Unexpected offset");
+
 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_file_control(sqlite3_file *, 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);
+int os_lock(sqlite3_file *, int eLock);
+int os_unlock(sqlite3_file *, int eLock);
+int os_check_reserved_lock(sqlite3_file *, 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) {
+static int os_file_control_w(sqlite3_file *file, int op, void *pArg) {
+  struct os_file *pFile = (struct os_file *)file;
+  switch (op) {
+    case SQLITE_FCNTL_VFSNAME: {
+      *(char **)pArg = sqlite3_mprintf("%s", "os");
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_LOCKSTATE: {
+      *(int *)pArg = pFile->lock;
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_LOCK_TIMEOUT: {
+      int iOld = pFile->lockTimeout;
+      pFile->lockTimeout = *(int *)pArg;
+      *(int *)pArg = iOld;
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_POWERSAFE_OVERWRITE: {
+      if (*(int *)pArg < 0) {
+        *(int *)pArg = pFile->psow;
+      } else {
+        pFile->psow = *(int *)pArg;
+      }
+      return SQLITE_OK;
+    }
+    case SQLITE_FCNTL_SIZE_HINT:
+    case SQLITE_FCNTL_HAS_MOVED:
+      return os_file_control(file, op, pArg);
+  }
+  // Consider also implementing these opcodes (in use by SQLite):
+  //  SQLITE_FCNTL_BUSYHANDLER
+  //  SQLITE_FCNTL_COMMIT_PHASETWO
+  //  SQLITE_FCNTL_PDB
+  //  SQLITE_FCNTL_PRAGMA
+  //  SQLITE_FCNTL_SYNC
   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_sector_size(sqlite3_file *file) {
+  return SQLITE_DEFAULT_SECTOR_SIZE;
+}
+
+static int os_device_characteristics(sqlite3_file *file) {
+  struct os_file *pFile = (struct os_file *)file;
+  return pFile->psow ? SQLITE_IOCAP_POWERSAFE_OVERWRITE : 0;
 }
 
 static int os_open_w(sqlite3_vfs *vfs, sqlite3_filename zName,
@@ -63,12 +100,23 @@ static int os_open_w(sqlite3_vfs *vfs, sqlite3_filename zName,
       .xLock = os_lock,
       .xUnlock = os_unlock,
       .xCheckReservedLock = os_check_reserved_lock,
-      .xFileControl = no_file_control,
-      .xDeviceCharacteristics = no_device_characteristics,
+      .xFileControl = os_file_control_w,
+      .xSectorSize = os_sector_size,
+      .xDeviceCharacteristics = os_device_characteristics,
   };
+  memset(file, 0, sizeof(struct os_file));
   int rc = os_open(vfs, zName, file, flags, pOutFlags);
-  file->pMethods = (char)rc == SQLITE_OK ? &os_io : NULL;
-  return rc;
+  if (rc) {
+    return rc;
+  }
+
+  struct os_file *pFile = (struct os_file *)file;
+  pFile->base.pMethods = &os_io;
+  if (flags & SQLITE_OPEN_MAIN_DB) {
+    pFile->psow =
+        sqlite3_uri_boolean(zName, "psow", SQLITE_POWERSAFE_OVERWRITE);
+  }
+  return SQLITE_OK;
 }
 
 sqlite3_vfs *os_vfs() {
@@ -90,3 +138,7 @@ sqlite3_vfs *os_vfs() {
   };
   return &os_vfs;
 }
+
+int localtime_s(struct tm *const pTm, time_t const *const pTime) {
+  return os_localtime(pTm, (sqlite3_int64)*pTime);
+}

sqlite3/time.c

@@ -4,15 +4,18 @@
 
 static int time_collation(void *pArg, int nKey1, const void *pKey1, int nKey2,
                           const void *pKey2) {
-  // If keys are of different length, and both terminated by a Z,
-  // ignore the Z for collation purposes.
-  if (nKey1 && nKey2 && nKey1 != nKey2) {
-    const char *pK1 = (const char *)pKey1;
-    const char *pK2 = (const char *)pKey2;
-    if (pK1[nKey1 - 1] == 'Z' && pK2[nKey2 - 1] == 'Z') {
-      nKey1--;
-      nKey2--;
-    }
+  // Remove a Z suffix if one key is no longer than the other.
+  // A Z suffix collates before any character but after the empty string.
+  // This avoids making different keys equal.
+  const int nK1 = nKey1;
+  const int nK2 = nKey2;
+  const char *pK1 = (const char *)pKey1;
+  const char *pK2 = (const char *)pKey2;
+  if (nK1 && nK1 <= nK2 && pK1[nK1 - 1] == 'Z') {
+    nKey1--;
+  }
+  if (nK2 && nK2 <= nK1 && pK2[nK2 - 1] == 'Z') {
+    nKey2--;
   }
 
   int n = nKey1 < nKey2 ? nKey1 : nKey2;
@@ -23,6 +26,7 @@ static int time_collation(void *pArg, int nKey1, const void *pKey1, int nKey2,
   return rc;
 }
 
-int sqlite3_time_collation(sqlite3 *db) {
-  return sqlite3_create_collation(db, "TIME", SQLITE_UTF8, 0, time_collation);
+int sqlite3_time_init(sqlite3 *db, char **pzErrMsg,
+                      const sqlite3_api_routines *pApi) {
+  return sqlite3_create_collation(db, "time", SQLITE_UTF8, 0, time_collation);
 }

stmt.go

@@ -334,21 +334,7 @@ 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 := s.c.call(s.c.api.columnText,
-		uint64(s.handle), uint64(col))
-
-	ptr := uint32(r[0])
-	if ptr == 0 {
-		r = s.c.call(s.c.api.errcode, uint64(s.c.handle))
-		s.err = s.c.error(r[0])
-		return ""
-	}
-
-	r = s.c.call(s.c.api.columnBytes,
-		uint64(s.handle), uint64(col))
-
-	mem := s.c.mem.view(ptr, r[0])
-	return string(mem)
+	return string(s.ColumnRawText(col))
 }
 
 // ColumnBlob appends to buf and returns
@@ -357,6 +343,39 @@ func (s *Stmt) ColumnText(col int) string {
 //
 // https://www.sqlite.org/c3ref/column_blob.html
 func (s *Stmt) ColumnBlob(col int, buf []byte) []byte {
+	return append(buf, s.ColumnRawBlob(col)...)
+}
+
+// ColumnRawText returns the value of the result column as a []byte.
+// The []byte is owned by SQLite and may be invalidated by
+// subsequent calls to [Stmt] methods.
+// The leftmost column of the result set has the index 0.
+//
+// https://www.sqlite.org/c3ref/column_blob.html
+func (s *Stmt) ColumnRawText(col int) []byte {
+	r := s.c.call(s.c.api.columnText,
+		uint64(s.handle), uint64(col))
+
+	ptr := uint32(r[0])
+	if ptr == 0 {
+		r = s.c.call(s.c.api.errcode, uint64(s.c.handle))
+		s.err = s.c.error(r[0])
+		return nil
+	}
+
+	r = s.c.call(s.c.api.columnBytes,
+		uint64(s.handle), uint64(col))
+
+	return s.c.mem.view(ptr, r[0])
+}
+
+// ColumnRawBlob returns the value of the result column as a []byte.
+// The []byte is owned by SQLite and may be invalidated by
+// subsequent calls to [Stmt] methods.
+// The leftmost column of the result set has the index 0.
+//
+// https://www.sqlite.org/c3ref/column_blob.html
+func (s *Stmt) ColumnRawBlob(col int) []byte {
 	r := s.c.call(s.c.api.columnBlob,
 		uint64(s.handle), uint64(col))
 
@@ -364,14 +383,13 @@ func (s *Stmt) ColumnBlob(col int, buf []byte) []byte {
 	if ptr == 0 {
 		r = s.c.call(s.c.api.errcode, uint64(s.c.handle))
 		s.err = s.c.error(r[0])
-		return buf[0:0]
+		return nil
 	}
 
 	r = s.c.call(s.c.api.columnBytes,
 		uint64(s.handle), uint64(col))
 
-	mem := s.c.mem.view(ptr, r[0])
-	return append(buf[0:0], mem...)
+	return s.c.mem.view(ptr, r[0])
 }
 
 // Return true if stmt is an empty SQL statement.

tests/bradfitz/sql_test.go

@@ -126,7 +126,7 @@ func testTxQuery(t params) {
 		if r.Err() != nil {
 			t.Fatal(err)
 		}
-		t.Fatal("expected one rows")
+		t.Fatal("expected one row")
 	}
 
 	var name string

tests/conn_test.go

@@ -13,7 +13,7 @@ import (
 func TestConn_Open_dir(t *testing.T) {
 	t.Parallel()
 
-	_, err := sqlite3.Open(".")
+	_, err := sqlite3.OpenFlags(".", 0)
 	if err == nil {
 		t.Fatal("want error")
 	}

tests/ext_test.go

@@ -0,0 +1,77 @@
+package tests
+
+import (
+	"testing"
+
+	"github.com/ncruces/go-sqlite3"
+)
+
+func Test_base64(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	// base64
+	stmt, _, err := db.Prepare(`SELECT base64('TWFueSBoYW5kcyBtYWtlIGxpZ2h0IHdvcmsu')`)
+	if err != nil {
+		t.Error(err)
+	}
+	defer stmt.Close()
+
+	if !stmt.Step() {
+		t.Fatal("expected one row")
+	}
+	if got := stmt.ColumnText(0); got != "Many hands make light work." {
+		t.Errorf("got %q", got)
+	}
+}
+
+func Test_decimal(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	stmt, _, err := db.Prepare(`SELECT decimal_add(decimal('0.1'), decimal('0.2')) = decimal('0.3')`)
+	if err != nil {
+		t.Error(err)
+	}
+	defer stmt.Close()
+
+	if !stmt.Step() {
+		t.Fatal("expected one row")
+	}
+	if !stmt.ColumnBool(0) {
+		t.Error("want true")
+	}
+}
+
+func Test_uint(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	stmt, _, err := db.Prepare(`SELECT 'z2' < 'z11' COLLATE UINT`)
+	if err != nil {
+		t.Error(err)
+	}
+	defer stmt.Close()
+
+	if !stmt.Step() {
+		t.Fatal("expected one row")
+	}
+	if !stmt.ColumnBool(0) {
+		t.Error("want true")
+	}
+}

tests/mptest/mptest_test.go

@@ -99,11 +99,12 @@ func Test_config01(t *testing.T) {
 	ctx, vfs := vfsContext(newContext(t))
 	name := filepath.Join(t.TempDir(), "test.db")
 	cfg := config(ctx).WithArgs("mptest", name, "config01.test")
-	_, err := rt.InstantiateModule(ctx, module, cfg)
+	mod, err := rt.InstantiateModule(ctx, module, cfg)
 	if err != nil {
 		t.Error(err)
 	}
 	vfs.Close()
+	mod.Close(ctx)
 }
 
 func Test_config02(t *testing.T) {
@@ -117,11 +118,12 @@ func Test_config02(t *testing.T) {
 	ctx, vfs := vfsContext(newContext(t))
 	name := filepath.Join(t.TempDir(), "test.db")
 	cfg := config(ctx).WithArgs("mptest", name, "config02.test")
-	_, err := rt.InstantiateModule(ctx, module, cfg)
+	mod, err := rt.InstantiateModule(ctx, module, cfg)
 	if err != nil {
 		t.Error(err)
 	}
 	vfs.Close()
+	mod.Close(ctx)
 }
 
 func Test_crash01(t *testing.T) {
@@ -132,11 +134,12 @@ func Test_crash01(t *testing.T) {
 	ctx, vfs := vfsContext(newContext(t))
 	name := filepath.Join(t.TempDir(), "test.db")
 	cfg := config(ctx).WithArgs("mptest", name, "crash01.test")
-	_, err := rt.InstantiateModule(ctx, module, cfg)
+	mod, err := rt.InstantiateModule(ctx, module, cfg)
 	if err != nil {
 		t.Error(err)
 	}
 	vfs.Close()
+	mod.Close(ctx)
 }
 
 func Test_multiwrite01(t *testing.T) {
@@ -147,11 +150,12 @@ func Test_multiwrite01(t *testing.T) {
 	ctx, vfs := vfsContext(newContext(t))
 	name := filepath.Join(t.TempDir(), "test.db")
 	cfg := config(ctx).WithArgs("mptest", name, "multiwrite01.test")
-	_, err := rt.InstantiateModule(ctx, module, cfg)
+	mod, err := rt.InstantiateModule(ctx, module, cfg)
 	if err != nil {
 		t.Error(err)
 	}
 	vfs.Close()
+	mod.Close(ctx)
 }
 
 func newContext(t *testing.T) context.Context {

tests/mptest/testdata/build.sh

@@ -3,18 +3,9 @@ set -eo pipefail
 
 cd -P -- "$(dirname -- "$0")"
 
-if [ ! -f "mptest.c" ]; then
-	curl -sOL	"https://github.com/sqlite/sqlite/raw/master/mptest/mptest.c"
-	curl -sOL "https://github.com/sqlite/sqlite/raw/master/mptest/config01.test"
-  curl -sOL "https://github.com/sqlite/sqlite/raw/master/mptest/config02.test"
-  curl -sOL "https://github.com/sqlite/sqlite/raw/master/mptest/crash01.test"
-  curl -sOL "https://github.com/sqlite/sqlite/raw/master/mptest/crash02.subtest"
-  curl -sOL "https://github.com/sqlite/sqlite/raw/master/mptest/multiwrite01.test"
-fi
-
-zig cc --target=wasm32-wasi -flto -g0 -Os \
-  -o mptest.wasm main.c test.c \
-	-I../../../sqlite3 \
+zig cc --target=wasm32-wasi -flto -g0 -O2 \
+  -o mptest.wasm main.c \
+	-I../../../sqlite3/ \
 	-mmutable-globals \
 	-mbulk-memory -mreference-types \
 	-mnontrapping-fptoint -msign-ext \

tests/mptest/testdata/main.c

@@ -1,22 +1,23 @@
 #include <stdbool.h>
 #include <stddef.h>
 
+#include "sqlite3.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);
 
-void __attribute__((constructor)) premain() { sqlite3_initialize(); }
-
-int sqlite3_enable_load_extension(sqlite3 *db, int onoff) { return SQLITE_OK; }
-
-void *sqlite3_trace(sqlite3 *db, void (*xTrace)(void *, const char *),
-                    void *pArg) {
-  return NULL;
-}
-
 int sqlite3_os_init() {
   return sqlite3_vfs_register(os_vfs(), /*default=*/true);
-}
+}
+
+__attribute__((constructor)) void premain() { sqlite3_initialize(); }
+
+static int dont_unlink(const char *pathname) { return 0; }
+#define sqlite3_enable_load_extension(...)
+#define sqlite3_trace(...)
+#define unlink dont_unlink
+#undef UNUSED_PARAMETER
+#include "mptest.c"

tests/mptest/testdata/mptest.wasm

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:3960b873a7dab969a66f7859d491cec0dd4e6c0c9f83eab449fb15ec5ebdfd8f
-size 1077281
+oid sha256:f81ce390812d944d1fa9b2cc607a3629febab0bc0e4473dad3170134509c1751
+size 1630826

tests/mptest/testdata/test.c

@@ -1,5 +0,0 @@
-#define unlink dont_unlink
-
-#include "mptest.c"
-
-int dont_unlink(const char *pathname) { return 0; }

tests/speedtest1/speedtest1_test.go

@@ -0,0 +1,92 @@
+package speedtest1
+
+import (
+	"bytes"
+	"context"
+	"crypto/rand"
+	"io"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strconv"
+	"strings"
+	"testing"
+
+	_ "embed"
+	_ "unsafe"
+
+	"github.com/tetratelabs/wazero"
+	"github.com/tetratelabs/wazero/imports/wasi_snapshot_preview1"
+
+	_ "github.com/ncruces/go-sqlite3"
+)
+
+//go:embed testdata/speedtest1.wasm
+var binary []byte
+
+//go:linkname vfsNewEnvModuleBuilder github.com/ncruces/go-sqlite3.vfsNewEnvModuleBuilder
+func vfsNewEnvModuleBuilder(r wazero.Runtime) wazero.HostModuleBuilder
+
+//go:linkname vfsContext github.com/ncruces/go-sqlite3.vfsContext
+func vfsContext(ctx context.Context) (context.Context, io.Closer)
+
+var (
+	rt      wazero.Runtime
+	module  wazero.CompiledModule
+	output  bytes.Buffer
+	options []string
+)
+
+func init() {
+	ctx := context.TODO()
+
+	rt = wazero.NewRuntime(ctx)
+	wasi_snapshot_preview1.MustInstantiate(ctx, rt)
+	env := vfsNewEnvModuleBuilder(rt)
+	_, err := env.Instantiate(ctx)
+	if err != nil {
+		panic(err)
+	}
+
+	module, err = rt.CompileModule(ctx, binary)
+	if err != nil {
+		panic(err)
+	}
+}
+
+func TestMain(m *testing.M) {
+	i := 1
+	options = append(options, "speedtest1")
+	for _, arg := range os.Args[1:] {
+		if strings.HasPrefix(arg, "-test.") {
+			os.Args[i] = arg
+			i++
+		} else {
+			options = append(options, arg)
+		}
+	}
+	os.Args = os.Args[:i]
+
+	code := m.Run()
+	io.Copy(os.Stderr, &output)
+	os.Exit(code)
+}
+
+func Benchmark_speedtest1(b *testing.B) {
+	output.Reset()
+	ctx, vfs := vfsContext(context.Background())
+	name := filepath.Join(b.TempDir(), "test.db")
+	args := append(options, "--size", strconv.Itoa(b.N), name)
+	cfg := wazero.NewModuleConfig().
+		WithArgs(args...).WithName("speedtest1").
+		WithStdout(&output).WithStderr(&output).
+		WithSysWalltime().WithSysNanotime().WithSysNanosleep().
+		WithOsyield(runtime.Gosched).
+		WithRandSource(rand.Reader)
+	mod, err := rt.InstantiateModule(ctx, module, cfg)
+	if err != nil {
+		b.Error(err)
+	}
+	vfs.Close()
+	mod.Close(ctx)
+}

tests/speedtest1/testdata/.gitattributes

@@ -0,0 +1 @@
+speedtest1.wasm filter=lfs diff=lfs merge=lfs -text

tests/speedtest1/testdata/.gitignore

@@ -0,0 +1 @@
+speedtest1.c

tests/speedtest1/testdata/build.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+set -eo pipefail
+
+cd -P -- "$(dirname -- "$0")"
+
+zig cc --target=wasm32-wasi -flto -g0 -O2 \
+  -o speedtest1.wasm main.c \
+	-I../../../sqlite3/ \
+	-mmutable-globals \
+	-mbulk-memory -mreference-types \
+	-mnontrapping-fptoint -msign-ext \
+	-D_HAVE_SQLITE_CONFIG_H

tests/speedtest1/testdata/main.c

@@ -1,11 +1,17 @@
+#include <stdbool.h>
 #include <stddef.h>
 
-#include "main.c"
+#include "sqlite3.c"
+//
 #include "os.c"
 #include "qsort.c"
-#include "time.c"
-
-#include "sqlite3.c"
 
 sqlite3_destructor_type malloc_destructor = &free;
-size_t sqlite3_interrupt_offset = offsetof(sqlite3, u1.isInterrupted);
+size_t sqlite3_interrupt_offset = offsetof(sqlite3, u1.isInterrupted);
+
+int sqlite3_os_init() {
+  return sqlite3_vfs_register(os_vfs(), /*default=*/true);
+}
+
+#define randomFunc(args...) randomFunc2(args)
+#include "speedtest1.c"

tests/speedtest1/testdata/speedtest1.wasm

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:0e02a26b86832a4703cd2a86c98ff8041d9d889b865a61f324b512a15d2d361e
+size 1676129

vfs.go

@@ -14,19 +14,11 @@ import (
 	"github.com/ncruces/julianday"
 	"github.com/tetratelabs/wazero"
 	"github.com/tetratelabs/wazero/api"
-	"github.com/tetratelabs/wazero/sys"
 )
 
 func vfsInstantiate(ctx context.Context, r wazero.Runtime) {
-	wasi := r.NewHostModuleBuilder("wasi_snapshot_preview1")
-	wasi.NewFunctionBuilder().WithFunc(vfsExit).Export("proc_exit")
-	_, err := wasi.Instantiate(ctx)
-	if err != nil {
-		panic(err)
-	}
-
 	env := vfsNewEnvModuleBuilder(r)
-	_, err = env.Instantiate(ctx)
+	_, err := env.Instantiate(ctx)
 	if err != nil {
 		panic(err)
 	}
@@ -34,25 +26,25 @@ func vfsInstantiate(ctx context.Context, r wazero.Runtime) {
 
 func vfsNewEnvModuleBuilder(r wazero.Runtime) wazero.HostModuleBuilder {
 	env := r.NewHostModuleBuilder("env")
-	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")
+	vfsRegisterFuncT(env, "os_localtime", vfsLocaltime)
+	vfsRegisterFunc3(env, "os_randomness", vfsRandomness)
+	vfsRegisterFunc2(env, "os_sleep", vfsSleep)
+	vfsRegisterFunc2(env, "os_current_time", vfsCurrentTime)
+	vfsRegisterFunc2(env, "os_current_time_64", vfsCurrentTime64)
+	vfsRegisterFunc4(env, "os_full_pathname", vfsFullPathname)
+	vfsRegisterFunc3(env, "os_delete", vfsDelete)
+	vfsRegisterFunc4(env, "os_access", vfsAccess)
+	vfsRegisterFunc5(env, "os_open", vfsOpen)
+	vfsRegisterFunc1(env, "os_close", vfsClose)
+	vfsRegisterFuncRW(env, "os_read", vfsRead)
+	vfsRegisterFuncRW(env, "os_write", vfsWrite)
+	vfsRegisterFuncT(env, "os_truncate", vfsTruncate)
+	vfsRegisterFunc2(env, "os_sync", vfsSync)
+	vfsRegisterFunc2(env, "os_file_size", vfsFileSize)
+	vfsRegisterFunc2(env, "os_lock", vfsLock)
+	vfsRegisterFunc2(env, "os_unlock", vfsUnlock)
+	vfsRegisterFunc2(env, "os_check_reserved_lock", vfsCheckReservedLock)
+	vfsRegisterFunc3(env, "os_file_control", vfsFileControl)
 	return env
 }
 
@@ -87,14 +79,7 @@ func (vfs *vfsState) Close() error {
 	return nil
 }
 
-func vfsExit(ctx context.Context, mod api.Module, exitCode uint32) {
-	// Ensure other callers see the exit code.
-	_ = mod.CloseWithExitCode(ctx, exitCode)
-	// Prevent any code from executing after this function.
-	panic(sys.NewExitError(mod.Name(), exitCode))
-}
-
-func vfsLocaltime(ctx context.Context, mod api.Module, t uint64, pTm uint32) uint32 {
+func vfsLocaltime(ctx context.Context, mod api.Module, pTm uint32, t uint64) uint32 {
 	tm := time.Unix(int64(t), 0)
 	var isdst int
 	if tm.IsDST() {
@@ -121,7 +106,7 @@ func vfsRandomness(ctx context.Context, mod api.Module, pVfs, nByte, zByte uint3
 	return uint32(n)
 }
 
-func vfsSleep(ctx context.Context, pVfs, nMicro uint32) uint32 {
+func vfsSleep(ctx context.Context, mod api.Module, pVfs, nMicro uint32) uint32 {
 	time.Sleep(time.Duration(nMicro) * time.Microsecond)
 	return _OK
 }
@@ -143,22 +128,26 @@ func vfsFullPathname(ctx context.Context, mod api.Module, pVfs, zRelative, nFull
 	rel := memory{mod}.readString(zRelative, _MAX_PATHNAME)
 	abs, err := filepath.Abs(rel)
 	if err != nil {
-		return uint32(IOERR)
+		return uint32(CANTOPEN_FULLPATH)
 	}
 
-	// Consider either using [filepath.EvalSymlinks] to canonicalize the path (as the Unix VFS does).
-	// 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 := uint64(len(abs) + 1)
 	if size > uint64(nFull) {
 		return uint32(CANTOPEN_FULLPATH)
 	}
 	mem := memory{mod}.view(zFull, size)
-
 	mem[len(abs)] = 0
 	copy(mem, abs)
-	return _OK
+
+	if fi, err := os.Lstat(abs); err == nil {
+		if fi.Mode()&fs.ModeSymlink != 0 {
+			return _OK_SYMLINK
+		}
+		return _OK
+	} else if errors.Is(err, fs.ErrNotExist) {
+		return _OK
+	}
+	return uint32(CANTOPEN_FULLPATH)
 }
 
 func vfsDelete(ctx context.Context, mod api.Module, pVfs, zPath, syncDir uint32) uint32 {
@@ -186,11 +175,30 @@ func vfsDelete(ctx context.Context, mod api.Module, pVfs, zPath, syncDir uint32)
 
 func vfsAccess(ctx context.Context, mod api.Module, pVfs, zPath uint32, flags _AccessFlag, pResOut uint32) uint32 {
 	path := memory{mod}.readString(zPath, _MAX_PATHNAME)
-	ok, rc := vfsOS.Access(path, flags)
+	err := vfsOS.Access(path, flags)
+
 	var res uint32
-	if ok {
-		res = 1
+	var rc xErrorCode
+	if flags == _ACCESS_EXISTS {
+		switch {
+		case err == nil:
+			res = 1
+		case errors.Is(err, fs.ErrNotExist):
+			res = 0
+		default:
+			rc = IOERR_ACCESS
+		}
+	} else {
+		switch {
+		case err == nil:
+			res = 1
+		case errors.Is(err, fs.ErrPermission):
+			res = 0
+		default:
+			rc = IOERR_ACCESS
+		}
 	}
+
 	memory{mod}.writeUint32(pResOut, res)
 	return uint32(rc)
 }
@@ -301,14 +309,110 @@ func vfsFileSize(ctx context.Context, mod api.Module, pFile, pSize uint32) uint3
 	return _OK
 }
 
-func vfsFileControl(ctx context.Context, pFile, op, pArg uint32) uint32 {
-	// SQLite calls vfsFileControl with these opcodes:
-	//  SQLITE_FCNTL_SIZE_HINT
-	//  SQLITE_FCNTL_PRAGMA
-	//  SQLITE_FCNTL_BUSYHANDLER
-	//  SQLITE_FCNTL_HAS_MOVED
-	//  SQLITE_FCNTL_SYNC
-	//  SQLITE_FCNTL_COMMIT_PHASETWO
-	//  SQLITE_FCNTL_PDB
+func vfsFileControl(ctx context.Context, mod api.Module, pFile uint32, op _FcntlOpcode, pArg uint32) uint32 {
+	switch op {
+	case _FCNTL_SIZE_HINT:
+		return vfsSizeHint(ctx, mod, pFile, pArg)
+	case _FCNTL_HAS_MOVED:
+		return vfsFileMoved(ctx, mod, pFile, pArg)
+	}
 	return uint32(NOTFOUND)
 }
+
+func vfsSizeHint(ctx context.Context, mod api.Module, pFile, pArg uint32) uint32 {
+	file := vfsFile.GetOS(ctx, mod, pFile)
+	size := memory{mod}.readUint64(pArg)
+	err := vfsOS.Allocate(file, int64(size))
+	if err != nil {
+		return uint32(IOERR_TRUNCATE)
+	}
+	return _OK
+}
+
+func vfsFileMoved(ctx context.Context, mod api.Module, pFile, pResOut uint32) uint32 {
+	file := vfsFile.GetOS(ctx, mod, pFile)
+	fi, err := file.Stat()
+	if err != nil {
+		return uint32(IOERR_FSTAT)
+	}
+	pi, err := os.Stat(file.Name())
+	if err != nil && !errors.Is(err, fs.ErrNotExist) {
+		return uint32(IOERR_FSTAT)
+	}
+	var res uint32
+	if !os.SameFile(fi, pi) {
+		res = 1
+	}
+	memory{mod}.writeUint32(pResOut, res)
+	return _OK
+}
+
+func vfsRegisterFunc1(mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ uint32) uint32) {
+	mod.NewFunctionBuilder().
+		WithGoModuleFunction(api.GoModuleFunc(
+			func(ctx context.Context, mod api.Module, stack []uint64) {
+				stack[0] = uint64(fn(ctx, mod, uint32(stack[0])))
+			}),
+			[]api.ValueType{api.ValueTypeI32}, []api.ValueType{api.ValueTypeI32}).
+		Export(name)
+}
+
+func vfsRegisterFunc2[T0, T1 ~uint32](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0, _ T1) uint32) {
+	mod.NewFunctionBuilder().
+		WithGoModuleFunction(api.GoModuleFunc(
+			func(ctx context.Context, mod api.Module, stack []uint64) {
+				stack[0] = uint64(fn(ctx, mod, T0(stack[0]), T1(stack[1])))
+			}),
+			[]api.ValueType{api.ValueTypeI32, api.ValueTypeI32}, []api.ValueType{api.ValueTypeI32}).
+		Export(name)
+}
+
+func vfsRegisterFunc3[T0, T1, T2 ~uint32](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0, _ T1, _ T2) uint32) {
+	mod.NewFunctionBuilder().
+		WithGoModuleFunction(api.GoModuleFunc(
+			func(ctx context.Context, mod api.Module, stack []uint64) {
+				stack[0] = uint64(fn(ctx, mod, T0(stack[0]), T1(stack[1]), T2(stack[2])))
+			}),
+			[]api.ValueType{api.ValueTypeI32, api.ValueTypeI32, api.ValueTypeI32}, []api.ValueType{api.ValueTypeI32}).
+		Export(name)
+}
+
+func vfsRegisterFunc4[T0, T1, T2, T3 ~uint32](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0, _ T1, _ T2, _ T3) uint32) {
+	mod.NewFunctionBuilder().
+		WithGoModuleFunction(api.GoModuleFunc(
+			func(ctx context.Context, mod api.Module, stack []uint64) {
+				stack[0] = uint64(fn(ctx, mod, T0(stack[0]), T1(stack[1]), T2(stack[2]), T3(stack[3])))
+			}),
+			[]api.ValueType{api.ValueTypeI32, api.ValueTypeI32, api.ValueTypeI32, api.ValueTypeI32}, []api.ValueType{api.ValueTypeI32}).
+		Export(name)
+}
+
+func vfsRegisterFunc5[T0, T1, T2, T3, T4 ~uint32](mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ T0, _ T1, _ T2, _ T3, _ T4) uint32) {
+	mod.NewFunctionBuilder().
+		WithGoModuleFunction(api.GoModuleFunc(
+			func(ctx context.Context, mod api.Module, stack []uint64) {
+				stack[0] = uint64(fn(ctx, mod, T0(stack[0]), T1(stack[1]), T2(stack[2]), T3(stack[3]), T4(stack[4])))
+			}),
+			[]api.ValueType{api.ValueTypeI32, api.ValueTypeI32, api.ValueTypeI32, api.ValueTypeI32, api.ValueTypeI32}, []api.ValueType{api.ValueTypeI32}).
+		Export(name)
+}
+
+func vfsRegisterFuncRW(mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _, _, _ uint32, _ uint64) uint32) {
+	mod.NewFunctionBuilder().
+		WithGoModuleFunction(api.GoModuleFunc(
+			func(ctx context.Context, mod api.Module, stack []uint64) {
+				stack[0] = uint64(fn(ctx, mod, uint32(stack[0]), uint32(stack[1]), uint32(stack[2]), stack[3]))
+			}),
+			[]api.ValueType{api.ValueTypeI32, api.ValueTypeI32, api.ValueTypeI32, api.ValueTypeI64}, []api.ValueType{api.ValueTypeI32}).
+		Export(name)
+}
+
+func vfsRegisterFuncT(mod wazero.HostModuleBuilder, name string, fn func(ctx context.Context, mod api.Module, _ uint32, _ uint64) uint32) {
+	mod.NewFunctionBuilder().
+		WithGoModuleFunction(api.GoModuleFunc(
+			func(ctx context.Context, mod api.Module, stack []uint64) {
+				stack[0] = uint64(fn(ctx, mod, uint32(stack[0]), stack[1]))
+			}),
+			[]api.ValueType{api.ValueTypeI32, api.ValueTypeI64}, []api.ValueType{api.ValueTypeI32}).
+		Export(name)
+}

vfs_file.go

@@ -3,10 +3,18 @@ package sqlite3
 import (
 	"context"
 	"os"
+	"time"
 
 	"github.com/tetratelabs/wazero/api"
 )
 
+const (
+	// These need to match the offsets asserted in os.c
+	vfsFileIDOffset          = 4
+	vfsFileLockOffset        = 8
+	vfsFileLockTimeoutOffset = 12
+)
+
 func (vfsFileMethods) NewID(ctx context.Context, file *os.File) uint32 {
 	vfs := ctx.Value(vfsKey{}).(*vfsState)
 
@@ -26,13 +34,12 @@ func (vfsFileMethods) NewID(ctx context.Context, file *os.File) uint32 {
 func (vfsFileMethods) Open(ctx context.Context, mod api.Module, pFile uint32, file *os.File) {
 	mem := memory{mod}
 	id := vfsFile.NewID(ctx, file)
-	mem.writeUint32(pFile+ptrlen, id)
-	mem.writeUint32(pFile+2*ptrlen, _NO_LOCK)
+	mem.writeUint32(pFile+vfsFileIDOffset, id)
 }
 
 func (vfsFileMethods) Close(ctx context.Context, mod api.Module, pFile uint32) error {
 	mem := memory{mod}
-	id := mem.readUint32(pFile + ptrlen)
+	id := mem.readUint32(pFile + vfsFileIDOffset)
 	vfs := ctx.Value(vfsKey{}).(*vfsState)
 	file := vfs.files[id]
 	vfs.files[id] = nil
@@ -41,17 +48,22 @@ func (vfsFileMethods) Close(ctx context.Context, mod api.Module, pFile uint32) e
 
 func (vfsFileMethods) GetOS(ctx context.Context, mod api.Module, pFile uint32) *os.File {
 	mem := memory{mod}
-	id := mem.readUint32(pFile + ptrlen)
+	id := mem.readUint32(pFile + vfsFileIDOffset)
 	vfs := ctx.Value(vfsKey{}).(*vfsState)
 	return vfs.files[id]
 }
 
 func (vfsFileMethods) GetLock(ctx context.Context, mod api.Module, pFile uint32) vfsLockState {
 	mem := memory{mod}
-	return vfsLockState(mem.readUint32(pFile + 2*ptrlen))
+	return vfsLockState(mem.readUint8(pFile + vfsFileLockOffset))
 }
 
 func (vfsFileMethods) SetLock(ctx context.Context, mod api.Module, pFile uint32, lock vfsLockState) {
 	mem := memory{mod}
-	mem.writeUint32(pFile+2*ptrlen, uint32(lock))
+	mem.writeUint8(pFile+vfsFileLockOffset, uint8(lock))
+}
+
+func (vfsFileMethods) GetLockTimeout(ctx context.Context, mod api.Module, pFile uint32) time.Duration {
+	mem := memory{mod}
+	return time.Duration(mem.readUint32(pFile+vfsFileLockTimeoutOffset)) * time.Millisecond
 }

vfs_lock.go

@@ -3,6 +3,7 @@ package sqlite3
 import (
 	"context"
 	"os"
+	"time"
 
 	"github.com/tetratelabs/wazero/api"
 )
@@ -56,13 +57,14 @@ const (
 type vfsLockState uint32
 
 func vfsLock(ctx context.Context, mod api.Module, pFile uint32, eLock vfsLockState) uint32 {
-	// Argument check. SQLite never explicitly requests a pendig lock.
+	// Argument check. SQLite never explicitly requests a pending lock.
 	if eLock != _SHARED_LOCK && eLock != _RESERVED_LOCK && eLock != _EXCLUSIVE_LOCK {
 		panic(assertErr())
 	}
 
 	file := vfsFile.GetOS(ctx, mod, pFile)
 	cLock := vfsFile.GetLock(ctx, mod, pFile)
+	timeout := vfsFile.GetLockTimeout(ctx, mod, pFile)
 
 	switch {
 	case cLock < _NO_LOCK || cLock > _EXCLUSIVE_LOCK:
@@ -87,11 +89,7 @@ func vfsLock(ctx context.Context, mod api.Module, pFile uint32, eLock vfsLockSta
 		if cLock != _NO_LOCK {
 			panic(assertErr())
 		}
-		// 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 {
+		if rc := vfsOS.GetSharedLock(file, timeout); rc != _OK {
 			return uint32(rc)
 		}
 		vfsFile.SetLock(ctx, mod, pFile, _SHARED_LOCK)
@@ -102,7 +100,7 @@ func vfsLock(ctx context.Context, mod api.Module, pFile uint32, eLock vfsLockSta
 		if cLock != _SHARED_LOCK {
 			panic(assertErr())
 		}
-		if rc := vfsOS.GetReservedLock(file); rc != _OK {
+		if rc := vfsOS.GetReservedLock(file, timeout); rc != _OK {
 			return uint32(rc)
 		}
 		vfsFile.SetLock(ctx, mod, pFile, _RESERVED_LOCK)
@@ -114,13 +112,13 @@ func vfsLock(ctx context.Context, mod api.Module, pFile uint32, eLock vfsLockSta
 			panic(assertErr())
 		}
 		// A PENDING lock is needed before acquiring an EXCLUSIVE lock.
-		if cLock == _RESERVED_LOCK {
+		if cLock < _PENDING_LOCK {
 			if rc := vfsOS.GetPendingLock(file); rc != _OK {
 				return uint32(rc)
 			}
 			vfsFile.SetLock(ctx, mod, pFile, _PENDING_LOCK)
 		}
-		if rc := vfsOS.GetExclusiveLock(file); rc != _OK {
+		if rc := vfsOS.GetExclusiveLock(file, timeout); rc != _OK {
 			return uint32(rc)
 		}
 		vfsFile.SetLock(ctx, mod, pFile, _EXCLUSIVE_LOCK)
@@ -169,15 +167,22 @@ func vfsUnlock(ctx context.Context, mod api.Module, pFile uint32, eLock vfsLockS
 }
 
 func vfsCheckReservedLock(ctx context.Context, mod api.Module, pFile, pResOut uint32) uint32 {
+	file := vfsFile.GetOS(ctx, mod, pFile)
 	cLock := vfsFile.GetLock(ctx, mod, pFile)
 
-	if cLock > _SHARED_LOCK {
+	// Connection state check.
+	if cLock < _NO_LOCK || cLock > _EXCLUSIVE_LOCK {
 		panic(assertErr())
 	}
 
-	file := vfsFile.GetOS(ctx, mod, pFile)
+	var locked bool
+	var rc xErrorCode
+	if cLock >= _RESERVED_LOCK {
+		locked = true
+	} else {
+		locked, rc = vfsOS.CheckReservedLock(file)
+	}
 
-	locked, rc := vfsOS.CheckReservedLock(file)
 	var res uint32
 	if locked {
 		res = 1
@@ -186,27 +191,17 @@ func vfsCheckReservedLock(ctx context.Context, mod api.Module, pFile, pResOut ui
 	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 {
+func (vfsOSMethods) GetReservedLock(file *os.File, timeout time.Duration) xErrorCode {
 	// Acquire the RESERVED lock.
-	return vfsOS.writeLock(file, _RESERVED_BYTE, 1)
+	return vfsOS.writeLock(file, _RESERVED_BYTE, 1, timeout)
 }
 
 func (vfsOSMethods) GetPendingLock(file *os.File) xErrorCode {
 	// Acquire the PENDING lock.
-	return vfsOS.writeLock(file, _PENDING_BYTE, 1)
+	return vfsOS.writeLock(file, _PENDING_BYTE, 1, 0)
 }
 
 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

@@ -10,7 +10,7 @@ import (
 
 func Test_vfsLock(t *testing.T) {
 	switch runtime.GOOS {
-	case "linux", "darwin", "illumos", "windows":
+	case "linux", "darwin", "windows":
 		break
 	default:
 		t.Skip("OS lacks OFD locks")
@@ -51,6 +51,13 @@ func Test_vfsLock(t *testing.T) {
 	if got := mem.readUint32(pOutput); got != 0 {
 		t.Error("file was locked")
 	}
+	rc = vfsCheckReservedLock(ctx, mem.mod, pFile2, pOutput)
+	if rc != _OK {
+		t.Fatal("returned", rc)
+	}
+	if got := mem.readUint32(pOutput); got != 0 {
+		t.Error("file was locked")
+	}
 
 	rc = vfsLock(ctx, mem.mod, pFile2, _SHARED_LOCK)
 	if rc != _OK {
@@ -64,6 +71,13 @@ func Test_vfsLock(t *testing.T) {
 	if got := mem.readUint32(pOutput); got != 0 {
 		t.Error("file was locked")
 	}
+	rc = vfsCheckReservedLock(ctx, mem.mod, pFile2, pOutput)
+	if rc != _OK {
+		t.Fatal("returned", rc)
+	}
+	if got := mem.readUint32(pOutput); got != 0 {
+		t.Error("file was locked")
+	}
 
 	rc = vfsLock(ctx, mem.mod, pFile2, _RESERVED_LOCK)
 	if rc != _OK {
@@ -81,6 +95,13 @@ func Test_vfsLock(t *testing.T) {
 	if got := mem.readUint32(pOutput); got == 0 {
 		t.Error("file wasn't locked")
 	}
+	rc = vfsCheckReservedLock(ctx, mem.mod, pFile2, pOutput)
+	if rc != _OK {
+		t.Fatal("returned", rc)
+	}
+	if got := mem.readUint32(pOutput); got == 0 {
+		t.Error("file wasn't locked")
+	}
 
 	rc = vfsLock(ctx, mem.mod, pFile2, _EXCLUSIVE_LOCK)
 	if rc != _OK {
@@ -94,6 +115,13 @@ func Test_vfsLock(t *testing.T) {
 	if got := mem.readUint32(pOutput); got == 0 {
 		t.Error("file wasn't locked")
 	}
+	rc = vfsCheckReservedLock(ctx, mem.mod, pFile2, pOutput)
+	if rc != _OK {
+		t.Fatal("returned", rc)
+	}
+	if got := mem.readUint32(pOutput); got == 0 {
+		t.Error("file wasn't locked")
+	}
 
 	rc = vfsLock(ctx, mem.mod, pFile1, _SHARED_LOCK)
 	if rc == _OK {
@@ -107,6 +135,13 @@ func Test_vfsLock(t *testing.T) {
 	if got := mem.readUint32(pOutput); got == 0 {
 		t.Error("file wasn't locked")
 	}
+	rc = vfsCheckReservedLock(ctx, mem.mod, pFile2, pOutput)
+	if rc != _OK {
+		t.Fatal("returned", rc)
+	}
+	if got := mem.readUint32(pOutput); got == 0 {
+		t.Error("file wasn't locked")
+	}
 
 	rc = vfsUnlock(ctx, mem.mod, pFile2, _SHARED_LOCK)
 	if rc != _OK {
@@ -120,6 +155,13 @@ func Test_vfsLock(t *testing.T) {
 	if got := mem.readUint32(pOutput); got != 0 {
 		t.Error("file was locked")
 	}
+	rc = vfsCheckReservedLock(ctx, mem.mod, pFile2, pOutput)
+	if rc != _OK {
+		t.Fatal("returned", rc)
+	}
+	if got := mem.readUint32(pOutput); got != 0 {
+		t.Error("file was locked")
+	}
 
 	rc = vfsLock(ctx, mem.mod, pFile1, _SHARED_LOCK)
 	if rc != _OK {

vfs_os_bsd.go

@@ -0,0 +1,56 @@
+//go:build freebsd || openbsd || netbsd || dragonfly || (darwin && sqlite3_bsd)
+
+package sqlite3
+
+import (
+	"os"
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+func (vfsOSMethods) unlock(file *os.File, start, len int64) xErrorCode {
+	if start == 0 && len == 0 {
+		err := unix.Flock(int(file.Fd()), unix.LOCK_UN)
+		if err != nil {
+			return IOERR_UNLOCK
+		}
+	}
+	return _OK
+}
+
+func (vfsOSMethods) lock(file *os.File, how int, timeout time.Duration, def xErrorCode) xErrorCode {
+	var err error
+	for {
+		err = unix.Flock(int(file.Fd()), how)
+		if errno, _ := err.(unix.Errno); errno != unix.EAGAIN {
+			break
+		}
+		if timeout < time.Millisecond {
+			break
+		}
+		timeout -= time.Millisecond
+		time.Sleep(time.Millisecond)
+	}
+	return vfsOS.lockErrorCode(err, def)
+}
+
+func (vfsOSMethods) readLock(file *os.File, start, len int64, timeout time.Duration) xErrorCode {
+	return vfsOS.lock(file, unix.LOCK_SH|unix.LOCK_NB, timeout, IOERR_RDLOCK)
+}
+
+func (vfsOSMethods) writeLock(file *os.File, start, len int64, timeout time.Duration) xErrorCode {
+	return vfsOS.lock(file, unix.LOCK_EX|unix.LOCK_NB, timeout, IOERR_LOCK)
+}
+
+func (vfsOSMethods) checkLock(file *os.File, start, len int64) (bool, xErrorCode) {
+	lock := unix.Flock_t{
+		Type:  unix.F_RDLCK,
+		Start: start,
+		Len:   len,
+	}
+	if unix.FcntlFlock(file.Fd(), unix.F_GETLK, &lock) != nil {
+		return false, IOERR_CHECKRESERVEDLOCK
+	}
+	return lock.Type != unix.F_UNLCK, _OK
+}

vfs_os_darwin.go

@@ -0,0 +1,106 @@
+//go:build !sqlite3_bsd
+
+package sqlite3
+
+import (
+	"io"
+	"os"
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+const (
+	// https://github.com/apple/darwin-xnu/blob/main/bsd/sys/fcntl.h
+	_F_OFD_SETLK         = 90
+	_F_OFD_SETLKW        = 91
+	_F_OFD_GETLK         = 92
+	_F_OFD_SETLKWTIMEOUT = 93
+)
+
+type flocktimeout_t struct {
+	fl      unix.Flock_t
+	timeout unix.Timespec
+}
+
+func (vfsOSMethods) Sync(file *os.File, fullsync, dataonly bool) error {
+	if fullsync {
+		return file.Sync()
+	}
+	return unix.Fsync(int(file.Fd()))
+}
+
+func (vfsOSMethods) Allocate(file *os.File, size int64) error {
+	off, err := file.Seek(0, io.SeekEnd)
+	if err != nil {
+		return err
+	}
+	if size <= off {
+		return nil
+	}
+
+	// https://stackoverflow.com/a/11497568/867786
+	store := unix.Fstore_t{
+		Flags:   unix.F_ALLOCATECONTIG,
+		Posmode: unix.F_PEOFPOSMODE,
+		Offset:  0,
+		Length:  size,
+	}
+
+	// Try to get a continous chunk of disk space.
+	err = unix.FcntlFstore(file.Fd(), unix.F_PREALLOCATE, &store)
+	if err != nil {
+		// OK, perhaps we are too fragmented, allocate non-continuous.
+		store.Flags = unix.F_ALLOCATEALL
+		unix.FcntlFstore(file.Fd(), unix.F_PREALLOCATE, &store)
+	}
+	return file.Truncate(size)
+}
+
+func (vfsOSMethods) unlock(file *os.File, start, len int64) xErrorCode {
+	err := unix.FcntlFlock(file.Fd(), _F_OFD_SETLK, &unix.Flock_t{
+		Type:  unix.F_UNLCK,
+		Start: start,
+		Len:   len,
+	})
+	if err != nil {
+		return IOERR_UNLOCK
+	}
+	return _OK
+}
+
+func (vfsOSMethods) lock(file *os.File, typ int16, start, len int64, timeout time.Duration, def xErrorCode) xErrorCode {
+	lock := flocktimeout_t{fl: unix.Flock_t{
+		Type:  typ,
+		Start: start,
+		Len:   len,
+	}}
+	var err error
+	if timeout == 0 {
+		err = unix.FcntlFlock(file.Fd(), _F_OFD_SETLK, &lock.fl)
+	} else {
+		lock.timeout = unix.NsecToTimespec(int64(timeout / time.Nanosecond))
+		err = unix.FcntlFlock(file.Fd(), _F_OFD_SETLKWTIMEOUT, &lock.fl)
+	}
+	return vfsOS.lockErrorCode(err, def)
+}
+
+func (vfsOSMethods) readLock(file *os.File, start, len int64, timeout time.Duration) xErrorCode {
+	return vfsOS.lock(file, unix.F_RDLCK, start, len, timeout, IOERR_RDLOCK)
+}
+
+func (vfsOSMethods) writeLock(file *os.File, start, len int64, timeout time.Duration) xErrorCode {
+	return vfsOS.lock(file, unix.F_WRLCK, start, len, timeout, IOERR_LOCK)
+}
+
+func (vfsOSMethods) checkLock(file *os.File, start, len int64) (bool, xErrorCode) {
+	lock := unix.Flock_t{
+		Type:  unix.F_RDLCK,
+		Start: start,
+		Len:   len,
+	}
+	if unix.FcntlFlock(file.Fd(), _F_OFD_GETLK, &lock) != nil {
+		return false, IOERR_CHECKRESERVEDLOCK
+	}
+	return lock.Type != unix.F_UNLCK, _OK
+}

vfs_os_linux.go

@@ -0,0 +1,25 @@
+package sqlite3
+
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+func (vfsOSMethods) Sync(file *os.File, fullsync, dataonly bool) error {
+	if dataonly {
+		_, _, err := unix.Syscall(unix.SYS_FDATASYNC, file.Fd(), 0, 0)
+		if err != 0 {
+			return err
+		}
+		return nil
+	}
+	return file.Sync()
+}
+
+func (vfsOSMethods) Allocate(file *os.File, size int64) error {
+	if size == 0 {
+		return nil
+	}
+	return unix.Fallocate(int(file.Fd()), 0, 0, size)
+}

vfs_os_ofd.go

@@ -0,0 +1,63 @@
+//go:build linux || illumos
+
+package sqlite3
+
+import (
+	"os"
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+func (vfsOSMethods) unlock(file *os.File, start, len int64) xErrorCode {
+	err := unix.FcntlFlock(file.Fd(), unix.F_OFD_SETLK, &unix.Flock_t{
+		Type:  unix.F_UNLCK,
+		Start: start,
+		Len:   len,
+	})
+	if err != nil {
+		return IOERR_UNLOCK
+	}
+	return _OK
+}
+
+func (vfsOSMethods) lock(file *os.File, typ int16, start, len int64, timeout time.Duration, def xErrorCode) xErrorCode {
+	lock := unix.Flock_t{
+		Type:  typ,
+		Start: start,
+		Len:   len,
+	}
+	var err error
+	for {
+		err = unix.FcntlFlock(file.Fd(), unix.F_OFD_SETLK, &lock)
+		if errno, _ := err.(unix.Errno); errno != unix.EAGAIN {
+			break
+		}
+		if timeout < time.Millisecond {
+			break
+		}
+		timeout -= time.Millisecond
+		time.Sleep(time.Millisecond)
+	}
+	return vfsOS.lockErrorCode(err, def)
+}
+
+func (vfsOSMethods) readLock(file *os.File, start, len int64, timeout time.Duration) xErrorCode {
+	return vfsOS.lock(file, unix.F_RDLCK, start, len, timeout, IOERR_RDLOCK)
+}
+
+func (vfsOSMethods) writeLock(file *os.File, start, len int64, timeout time.Duration) xErrorCode {
+	return vfsOS.lock(file, unix.F_WRLCK, start, len, timeout, IOERR_LOCK)
+}
+
+func (vfsOSMethods) checkLock(file *os.File, start, len int64) (bool, xErrorCode) {
+	lock := unix.Flock_t{
+		Type:  unix.F_RDLCK,
+		Start: start,
+		Len:   len,
+	}
+	if unix.FcntlFlock(file.Fd(), unix.F_OFD_GETLK, &lock) != nil {
+		return false, IOERR_CHECKRESERVEDLOCK
+	}
+	return lock.Type != unix.F_UNLCK, _OK
+}

vfs_os_other.go

@@ -0,0 +1,23 @@
+//go:build !linux && (!darwin || sqlite3_bsd)
+
+package sqlite3
+
+import (
+	"io"
+	"os"
+)
+
+func (vfsOSMethods) Sync(file *os.File, fullsync, dataonly bool) error {
+	return file.Sync()
+}
+
+func (vfsOSMethods) Allocate(file *os.File, size int64) error {
+	off, err := file.Seek(0, io.SeekEnd)
+	if err != nil {
+		return err
+	}
+	if size <= off {
+		return nil
+	}
+	return file.Truncate(size)
+}

vfs_os_unix.go

@@ -0,0 +1,87 @@
+//go:build unix
+
+package sqlite3
+
+import (
+	"io/fs"
+	"os"
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+func (vfsOSMethods) OpenFile(name string, flag int, perm fs.FileMode) (*os.File, error) {
+	return os.OpenFile(name, flag, perm)
+}
+
+func (vfsOSMethods) Access(path string, flags _AccessFlag) error {
+	var access uint32 // unix.F_OK
+	switch flags {
+	case _ACCESS_READWRITE:
+		access = unix.R_OK | unix.W_OK
+	case _ACCESS_READ:
+		access = unix.R_OK
+	}
+	return unix.Access(path, access)
+}
+
+func (vfsOSMethods) GetSharedLock(file *os.File, timeout time.Duration) xErrorCode {
+	// Test the PENDING lock before acquiring a new SHARED lock.
+	if pending, _ := vfsOS.checkLock(file, _PENDING_BYTE, 1); pending {
+		return xErrorCode(BUSY)
+	}
+	// Acquire the SHARED lock.
+	return vfsOS.readLock(file, _SHARED_FIRST, _SHARED_SIZE, timeout)
+}
+
+func (vfsOSMethods) GetExclusiveLock(file *os.File, timeout time.Duration) xErrorCode {
+	if timeout == 0 {
+		timeout = time.Millisecond
+	}
+
+	// Acquire the EXCLUSIVE lock.
+	return vfsOS.writeLock(file, _SHARED_FIRST, _SHARED_SIZE, timeout)
+}
+
+func (vfsOSMethods) DowngradeLock(file *os.File, state vfsLockState) xErrorCode {
+	if state >= _EXCLUSIVE_LOCK {
+		// Downgrade to a SHARED lock.
+		if rc := vfsOS.readLock(file, _SHARED_FIRST, _SHARED_SIZE, 0); 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
+			// protocol. If this happens, return IOERR_RDLOCK. Returning
+			// BUSY would confuse the upper layer.
+			return IOERR_RDLOCK
+		}
+	}
+	// Release the PENDING and RESERVED locks.
+	return vfsOS.unlock(file, _PENDING_BYTE, 2)
+}
+
+func (vfsOSMethods) ReleaseLock(file *os.File, _ vfsLockState) xErrorCode {
+	// Release all locks.
+	return vfsOS.unlock(file, 0, 0)
+}
+
+func (vfsOSMethods) lockErrorCode(err error, def xErrorCode) xErrorCode {
+	if err == nil {
+		return _OK
+	}
+	if errno, ok := err.(unix.Errno); ok {
+		switch errno {
+		case
+			unix.EACCES,
+			unix.EAGAIN,
+			unix.EBUSY,
+			unix.EINTR,
+			unix.ENOLCK,
+			unix.EDEADLK,
+			unix.ETIMEDOUT:
+			return xErrorCode(BUSY)
+		case unix.EPERM:
+			return xErrorCode(PERM)
+		}
+	}
+	return def
+}

vfs_os_windows.go

@@ -1,10 +1,10 @@
 package sqlite3
 
 import (
-	"errors"
 	"io/fs"
 	"os"
 	"syscall"
+	"time"
 
 	"golang.org/x/sys/windows"
 )
@@ -25,56 +25,56 @@ func (vfsOSMethods) OpenFile(name string, flag int, perm fs.FileMode) (*os.File,
 	return os.NewFile(uintptr(r), name), nil
 }
 
-func (vfsOSMethods) Sync(file *os.File, fullsync, dataonly bool) error {
-	return file.Sync()
-}
-
-func (vfsOSMethods) Access(path string, flags _AccessFlag) (bool, xErrorCode) {
+func (vfsOSMethods) Access(path string, flags _AccessFlag) error {
 	fi, err := os.Stat(path)
-
-	switch {
-	case flags == _ACCESS_EXISTS:
-		switch {
-		case err == nil:
-			return true, _OK
-		case errors.Is(err, fs.ErrNotExist):
-			return false, _OK
-		default:
-			return false, IOERR_ACCESS
-		}
-
-	case err == nil:
-		var want fs.FileMode = syscall.S_IRUSR
-		if flags == _ACCESS_READWRITE {
-			want |= syscall.S_IWUSR
-		}
-		if fi.IsDir() {
-			want |= syscall.S_IXUSR
-		}
-		if fi.Mode()&want == want {
-			return true, _OK
-		} else {
-			return false, _OK
-		}
-
-	case errors.Is(err, fs.ErrPermission):
-		return false, _OK
-
-	default:
-		return false, IOERR_ACCESS
+	if err != nil {
+		return err
 	}
+	if flags == _ACCESS_EXISTS {
+		return nil
+	}
+
+	var want fs.FileMode = windows.S_IRUSR
+	if flags == _ACCESS_READWRITE {
+		want |= windows.S_IWUSR
+	}
+	if fi.IsDir() {
+		want |= windows.S_IXUSR
+	}
+	if fi.Mode()&want != want {
+		return fs.ErrPermission
+	}
+	return nil
 }
 
-func (vfsOSMethods) GetExclusiveLock(file *os.File) xErrorCode {
+func (vfsOSMethods) GetSharedLock(file *os.File, timeout time.Duration) xErrorCode {
+	// Acquire the PENDING lock temporarily before acquiring a new SHARED lock.
+	rc := vfsOS.readLock(file, _PENDING_BYTE, 1, timeout)
+
+	if rc == _OK {
+		// Acquire the SHARED lock.
+		rc = vfsOS.readLock(file, _SHARED_FIRST, _SHARED_SIZE, 0)
+
+		// Release the PENDING lock.
+		vfsOS.unlock(file, _PENDING_BYTE, 1)
+	}
+	return rc
+}
+
+func (vfsOSMethods) GetExclusiveLock(file *os.File, timeout time.Duration) xErrorCode {
+	if timeout == 0 {
+		timeout = time.Millisecond
+	}
+
 	// Release the SHARED lock.
 	vfsOS.unlock(file, _SHARED_FIRST, _SHARED_SIZE)
 
 	// Acquire the EXCLUSIVE lock.
-	rc := vfsOS.writeLock(file, _SHARED_FIRST, _SHARED_SIZE)
+	rc := vfsOS.writeLock(file, _SHARED_FIRST, _SHARED_SIZE, timeout)
 
-	// Reacquire the SHARED lock.
 	if rc != _OK {
-		vfsOS.readLock(file, _SHARED_FIRST, _SHARED_SIZE)
+		// Reacquire the SHARED lock.
+		vfsOS.readLock(file, _SHARED_FIRST, _SHARED_SIZE, 0)
 	}
 	return rc
 }
@@ -85,7 +85,7 @@ func (vfsOSMethods) DowngradeLock(file *os.File, state vfsLockState) xErrorCode
 		vfsOS.unlock(file, _SHARED_FIRST, _SHARED_SIZE)
 
 		// Reacquire the SHARED lock.
-		if rc := vfsOS.readLock(file, _SHARED_FIRST, _SHARED_SIZE); rc != _OK {
+		if rc := vfsOS.readLock(file, _SHARED_FIRST, _SHARED_SIZE, 0); rc != _OK {
 			// This should never happen.
 			// We should always be able to reacquire the read lock.
 			return IOERR_RDLOCK
@@ -128,38 +128,59 @@ func (vfsOSMethods) unlock(file *os.File, start, len uint32) xErrorCode {
 	return _OK
 }
 
-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 (vfsOSMethods) lock(file *os.File, flags, start, len uint32, timeout time.Duration, def xErrorCode) xErrorCode {
+	var err error
+	for {
+		err = windows.LockFileEx(windows.Handle(file.Fd()), flags,
+			0, len, 0, &windows.Overlapped{Offset: start})
+		if errno, _ := err.(windows.Errno); errno != windows.ERROR_LOCK_VIOLATION {
+			break
+		}
+		if timeout < time.Millisecond {
+			break
+		}
+		timeout -= time.Millisecond
+		time.Sleep(time.Millisecond)
+	}
+	return vfsOS.lockErrorCode(err, def)
 }
 
-func (vfsOSMethods) writeLock(file *os.File, start, len uint32) xErrorCode {
-	return vfsOS.lockErrorCode(windows.LockFileEx(windows.Handle(file.Fd()),
+func (vfsOSMethods) readLock(file *os.File, start, len uint32, timeout time.Duration) xErrorCode {
+	return vfsOS.lock(file,
+		windows.LOCKFILE_FAIL_IMMEDIATELY,
+		start, len, timeout, IOERR_RDLOCK)
+}
+
+func (vfsOSMethods) writeLock(file *os.File, start, len uint32, timeout time.Duration) xErrorCode {
+	return vfsOS.lock(file,
 		windows.LOCKFILE_FAIL_IMMEDIATELY|windows.LOCKFILE_EXCLUSIVE_LOCK,
-		0, len, 0, &windows.Overlapped{Offset: start}),
-		IOERR_LOCK)
+		start, len, timeout, IOERR_LOCK)
 }
 
 func (vfsOSMethods) checkLock(file *os.File, start, len uint32) (bool, xErrorCode) {
-	rc := vfsOS.readLock(file, start, len)
+	rc := vfsOS.lock(file,
+		windows.LOCKFILE_FAIL_IMMEDIATELY,
+		start, len, 0, IOERR_CHECKRESERVEDLOCK)
+	if rc == xErrorCode(BUSY) {
+		return true, _OK
+	}
 	if rc == _OK {
 		vfsOS.unlock(file, start, len)
 	}
-	return rc != _OK, _OK
+	return false, rc
 }
 
 func (vfsOSMethods) lockErrorCode(err error, def xErrorCode) xErrorCode {
 	if err == nil {
 		return _OK
 	}
-	if errno, ok := err.(syscall.Errno); ok {
+	if errno, ok := err.(windows.Errno); ok {
 		// https://devblogs.microsoft.com/oldnewthing/20140905-00/?p=63
 		switch errno {
 		case
 			windows.ERROR_LOCK_VIOLATION,
-			windows.ERROR_IO_PENDING:
+			windows.ERROR_IO_PENDING,
+			windows.ERROR_OPERATION_ABORTED:
 			return xErrorCode(BUSY)
 		}
 	}

vfs_test.go

@@ -14,19 +14,11 @@ import (
 	"github.com/ncruces/julianday"
 )
 
-func Test_vfsExit(t *testing.T) {
-	mem := newMemory(128)
-	ctx := context.TODO()
-	defer func() { _ = recover() }()
-	vfsExit(ctx, mem.mod, 1)
-	t.Error("want panic")
-}
-
 func Test_vfsLocaltime(t *testing.T) {
 	mem := newMemory(128)
 	ctx := context.TODO()
 
-	rc := vfsLocaltime(ctx, mem.mod, 0, 4)
+	rc := vfsLocaltime(ctx, mem.mod, 4, 0)
 	if rc != 0 {
 		t.Fatal("returned", rc)
 	}
@@ -60,8 +52,9 @@ func Test_vfsLocaltime(t *testing.T) {
 
 func Test_vfsRandomness(t *testing.T) {
 	mem := newMemory(128)
+	ctx := context.TODO()
 
-	rc := vfsRandomness(context.TODO(), mem.mod, 0, 16, 4)
+	rc := vfsRandomness(ctx, mem.mod, 0, 16, 4)
 	if rc != 16 {
 		t.Fatal("returned", rc)
 	}
@@ -73,10 +66,11 @@ func Test_vfsRandomness(t *testing.T) {
 }
 
 func Test_vfsSleep(t *testing.T) {
+	mem := newMemory(128)
 	ctx := context.TODO()
 
 	now := time.Now()
-	rc := vfsSleep(ctx, 0, 123456)
+	rc := vfsSleep(ctx, mem.mod, 0, 123456)
 	if rc != 0 {
 		t.Fatal("returned", rc)
 	}

vfs_unix.go

@@ -1,170 +0,0 @@
-//go:build unix
-
-package sqlite3
-
-import (
-	"io/fs"
-	"os"
-	"runtime"
-
-	"golang.org/x/sys/unix"
-)
-
-func (vfsOSMethods) OpenFile(name string, flag int, perm fs.FileMode) (*os.File, error) {
-	return os.OpenFile(name, flag, perm)
-}
-
-func (vfsOSMethods) Access(path string, flags _AccessFlag) (bool, xErrorCode) {
-	var access uint32 = unix.F_OK
-	switch flags {
-	case _ACCESS_READWRITE:
-		access = unix.R_OK | unix.W_OK
-	case _ACCESS_READ:
-		access = unix.R_OK
-	}
-
-	err := unix.Access(path, access)
-	if err == nil {
-		return true, _OK
-	}
-	return false, _OK
-}
-
-func (vfsOSMethods) Sync(file *os.File, fullsync, dataonly bool) error {
-	if runtime.GOOS == "darwin" && !fullsync {
-		return unix.Fsync(int(file.Fd()))
-	}
-	if runtime.GOOS == "linux" && dataonly {
-		//lint:ignore SA1019 OK on linux
-		_, _, err := unix.Syscall(unix.SYS_FDATASYNC, file.Fd(), 0, 0)
-		if err != 0 {
-			return err
-		}
-		return nil
-	}
-	return file.Sync()
-}
-
-func (vfsOSMethods) GetExclusiveLock(file *os.File) xErrorCode {
-	// Acquire the EXCLUSIVE lock.
-	return vfsOS.writeLock(file, _SHARED_FIRST, _SHARED_SIZE)
-}
-
-func (vfsOSMethods) DowngradeLock(file *os.File, state vfsLockState) xErrorCode {
-	if state >= _EXCLUSIVE_LOCK {
-		// Downgrade to a SHARED lock.
-		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
-			// protocol. If this happens, return IOERR_RDLOCK. Returning
-			// BUSY would confuse the upper layer.
-			return IOERR_RDLOCK
-		}
-	}
-	// Release the PENDING and RESERVED locks.
-	return vfsOS.unlock(file, _PENDING_BYTE, 2)
-}
-
-func (vfsOSMethods) ReleaseLock(file *os.File, _ vfsLockState) xErrorCode {
-	// Release all locks.
-	return vfsOS.unlock(file, 0, 0)
-}
-
-func (vfsOSMethods) unlock(file *os.File, start, len int64) xErrorCode {
-	err := vfsOS.fcntlSetLock(file, &unix.Flock_t{
-		Type:  unix.F_UNLCK,
-		Start: start,
-		Len:   len,
-	})
-	if err != nil {
-		return IOERR_UNLOCK
-	}
-	return _OK
-}
-
-func (vfsOSMethods) readLock(file *os.File, start, len int64) xErrorCode {
-	return vfsOS.lockErrorCode(vfsOS.fcntlSetLock(file, &unix.Flock_t{
-		Type:  unix.F_RDLCK,
-		Start: start,
-		Len:   len,
-	}), IOERR_RDLOCK)
-}
-
-func (vfsOSMethods) writeLock(file *os.File, start, len int64) xErrorCode {
-	return vfsOS.lockErrorCode(vfsOS.fcntlSetLock(file, &unix.Flock_t{
-		Type:  unix.F_WRLCK,
-		Start: start,
-		Len:   len,
-	}), IOERR_LOCK)
-}
-
-func (vfsOSMethods) checkLock(file *os.File, start, len int64) (bool, xErrorCode) {
-	lock := unix.Flock_t{
-		Type:  unix.F_RDLCK,
-		Start: start,
-		Len:   len,
-	}
-	if vfsOS.fcntlGetLock(file, &lock) != nil {
-		return false, IOERR_CHECKRESERVEDLOCK
-	}
-	return lock.Type != unix.F_UNLCK, _OK
-}
-
-func (vfsOSMethods) fcntlGetLock(file *os.File, lock *unix.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_OFD_GETLK = 36
-	case "darwin":
-		// https://github.com/apple/darwin-xnu/blob/main/bsd/sys/fcntl.h
-		F_OFD_GETLK = 92
-	case "illumos":
-		// https://github.com/illumos/illumos-gate/blob/master/usr/src/uts/common/sys/fcntl.h
-		F_OFD_GETLK = 47
-	default:
-		return notImplErr
-	}
-	return unix.FcntlFlock(file.Fd(), F_OFD_GETLK, lock)
-}
-
-func (vfsOSMethods) fcntlSetLock(file *os.File, lock *unix.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_OFD_SETLK = 37
-	case "darwin":
-		// https://github.com/apple/darwin-xnu/blob/main/bsd/sys/fcntl.h
-		F_OFD_SETLK = 90
-	case "illumos":
-		// https://github.com/illumos/illumos-gate/blob/master/usr/src/uts/common/sys/fcntl.h
-		F_OFD_SETLK = 48
-	default:
-		return notImplErr
-	}
-	return unix.FcntlFlock(file.Fd(), F_OFD_SETLK, lock)
-}
-
-func (vfsOSMethods) lockErrorCode(err error, def xErrorCode) xErrorCode {
-	if err == nil {
-		return _OK
-	}
-	if errno, ok := err.(unix.Errno); ok {
-		switch errno {
-		case
-			unix.EACCES,
-			unix.EAGAIN,
-			unix.EBUSY,
-			unix.EINTR,
-			unix.ENOLCK,
-			unix.EDEADLK,
-			unix.ETIMEDOUT:
-			return xErrorCode(BUSY)
-		case unix.EPERM:
-			return xErrorCode(PERM)
-		}
-	}
-	return def
-}