F2FS.

Bumps [cross-platform-actions/action](https://github.com/cross-platform-actions/action) from 0.23.0 to 0.24.0.
- [Release notes](https://github.com/cross-platform-actions/action/releases)
- [Changelog](https://github.com/cross-platform-actions/action/blob/master/changelog.md)
- [Commits](https://github.com/cross-platform-actions/action/compare/v0.23.0...v0.24.0)

---
updated-dependencies:
- dependency-name: cross-platform-actions/action
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/bsd.sh

@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+set -euo pipefail
 
 echo 'set -euo pipefail' > test.sh
 

.github/workflows/cross.sh

@@ -17,7 +17,9 @@ echo aix           ; GOOS=aix       GOARCH=ppc64 go build .
 echo js            ; GOOS=js        GOARCH=wasm  go build .
 echo wasip1        ; GOOS=wasip1    GOARCH=wasm  go build .
 echo darwin-flock  ; GOOS=darwin    GOARCH=amd64 go build -tags sqlite3_flock .
+echo darwin-noshm  ; GOOS=darwin    GOARCH=amd64 go build -tags sqlite3_noshm .
 echo darwin-nosys  ; GOOS=darwin    GOARCH=amd64 go build -tags sqlite3_nosys .
+echo linux-noshm   ; GOOS=linux     GOARCH=amd64 go build -tags sqlite3_noshm .
 echo linux-nosys   ; GOOS=linux     GOARCH=amd64 go build -tags sqlite3_nosys .
 echo windows-nosys ; GOOS=windows   GOARCH=amd64 go build -tags sqlite3_nosys .
 echo freebsd-nosys ; GOOS=freebsd   GOARCH=amd64 go build -tags sqlite3_nosys .

.github/workflows/repro.sh

@@ -2,22 +2,22 @@
 set -euo pipefail
 
 if [[ "$OSTYPE" == "linux"* ]]; then
-  WASI_SDK="https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-21/wasi-sdk-21.0-linux.tar.gz"
+  WASI_SDK="https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-22/wasi-sdk-22.0-linux.tar.gz"
   BINARYEN="https://github.com/WebAssembly/binaryen/releases/download/version_117/binaryen-version_117-x86_64-linux.tar.gz"
 elif [[ "$OSTYPE" == "darwin"* ]]; then
-  WASI_SDK="https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-21/wasi-sdk-21.0-macos.tar.gz"
+  WASI_SDK="https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-22/wasi-sdk-22.0-macos.tar.gz"
   BINARYEN="https://github.com/WebAssembly/binaryen/releases/download/version_117/binaryen-version_117-x86_64-macos.tar.gz"
 elif [[ "$OSTYPE" == "msys" || "$OSTYPE" == "cygwin" ]]; then
-  WASI_SDK="https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-21/wasi-sdk-21.0.m-mingw.tar.gz"
+  WASI_SDK="https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-22/wasi-sdk-22.0.m-mingw.tar.gz"
   BINARYEN="https://github.com/WebAssembly/binaryen/releases/download/version_117/binaryen-version_117-x86_64-windows.tar.gz"
 fi
 
 # Download tools
-mkdir -p tools
+mkdir -p tools/
 [ -d "tools/wasi-sdk"* ]         || curl -#L "$WASI_SDK" | tar xzC tools &
 [ -d "tools/binaryen-version"* ] || curl -#L "$BINARYEN" | tar xzC tools &
 wait
 
 sqlite3/download.sh   # Download SQLite
-embed/build.sh        # Build WASM
+embed/build.sh        # Build Wasm
 git diff --exit-code  # Check diffs

.github/workflows/test.yml

@@ -47,6 +47,10 @@ jobs:
       run: go test -v -tags sqlite3_flock ./...
       if: matrix.os == 'macos-latest'
 
+    - name: Test no shared memory
+      run: go test -v -tags sqlite3_noshm ./...
+      if: matrix.os == 'ubuntu-latest'
+
     - name: Test no locks
       run: go test -v -tags sqlite3_nosys ./tests -run TestDB_nolock
 
@@ -76,7 +80,7 @@ jobs:
       run: .github/workflows/bsd.sh
 
     - name: Test
-      uses: cross-platform-actions/action@v0.23.0
+      uses: cross-platform-actions/action@v0.24.0
       with:
         operating_system: freebsd
         version: '14.0'

README.md

@@ -8,7 +8,7 @@ Go module `github.com/ncruces/go-sqlite3` is `cgo`-free [SQLite](https://sqlite.
 It provides a [`database/sql`](https://pkg.go.dev/database/sql) compatible driver,
 as well as direct access to most of the [C SQLite API](https://sqlite.org/cintro.html).
 
-It wraps a [WASM](https://webassembly.org/) build of SQLite, and uses [wazero](https://wazero.io/) as the runtime.\
+It wraps a [Wasm](https://webassembly.org/) build of SQLite, and uses [wazero](https://wazero.io/) as the runtime.\
 Go, wazero and [`x/sys`](https://pkg.go.dev/golang.org/x/sys) are the _only_ runtime dependencies.
 
 ### Packages
@@ -72,49 +72,10 @@ Go, wazero and [`x/sys`](https://pkg.go.dev/golang.org/x/sys) are the _only_ run
 ### Caveats
 
 This module replaces the SQLite [OS Interface](https://sqlite.org/vfs.html)
-(aka VFS) with a [pure Go](vfs/) implementation.
-This has benefits, but also comes with some drawbacks.
+(aka VFS) with a [pure Go](vfs/) implementation,
+which has advantages and disadvantages.
 
-#### Write-Ahead Logging
-
-Because WASM does not support shared memory,
-[WAL](https://sqlite.org/wal.html) support is [limited](https://sqlite.org/wal.html#noshm).
-
-To work around this limitation, SQLite is [patched](sqlite3/locking_mode.patch)
-to always use `EXCLUSIVE` locking mode for WAL databases.
-
-Because connection pooling is incompatible with `EXCLUSIVE` locking mode,
-to use the [`database/sql`](https://pkg.go.dev/database/sql) driver
-with WAL mode databases you should disable connection pooling by calling
-[`db.SetMaxOpenConns(1)`](https://pkg.go.dev/database/sql#DB.SetMaxOpenConns).
-
-#### File Locking
-
-POSIX advisory locks, which SQLite uses on Unix, are
-[broken by design](https://sqlite.org/src/artifact/2e8b12?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 POSIX advisory locks.
-
-On BSD Unixes, this module uses
-[BSD locks](https://man.freebsd.org/cgi/man.cgi?query=flock&sektion=2).
-On BSD Unixes, BSD locks are fully compatible with POSIX advisory locks.
-
-On Windows, this module uses `LockFileEx` and `UnlockFileEx`,
-like SQLite.
-
-On all other platforms, file locking is not supported, and you must use
-[`nolock=1`](https://sqlite.org/uri.html#urinolock)
-(or [`immutable=1`](https://sqlite.org/uri.html#uriimmutable))
-to open database files.
-You can use [`vfs.SupportsFileLocking`](https://pkg.go.dev/github.com/ncruces/go-sqlite3/vfs#SupportsFileLocking)
-to check if your platform supports file locking.
-
-To use the [`database/sql`](https://pkg.go.dev/database/sql) driver
-with `nolock=1` you must disable connection pooling by calling
-[`db.SetMaxOpenConns(1)`](https://pkg.go.dev/database/sql#DB.SetMaxOpenConns).
+Read more about the Go VFS design [here](vfs/README.md).
 
 ### Testing
 
@@ -122,7 +83,7 @@ This project aims for [high test coverage](https://github.com/ncruces/go-sqlite3
 It also benefits greatly from [SQLite's](https://sqlite.org/testing.html) and
 [wazero's](https://tetrate.io/blog/introducing-wazero-from-tetrate/#:~:text=Rock%2Dsolid%20test%20approach) thorough testing.
 
-The pure Go VFS is tested by running SQLite's
+The Go VFS is tested by running SQLite's
 [mptest](https://github.com/sqlite/sqlite/blob/master/mptest/mptest.c)
 on Linux, macOS, Windows and FreeBSD.
 
@@ -131,7 +92,7 @@ on Linux, macOS, Windows and FreeBSD.
 Perfomance of the [`database/sql`](https://pkg.go.dev/database/sql) driver is
 [competitive](https://github.com/cvilsmeier/go-sqlite-bench) with alternatives.
 
-The WASM and VFS layers are also tested by running SQLite's
+The Wasm and VFS layers are also tested by running SQLite's
 [speedtest1](https://github.com/sqlite/sqlite/blob/master/test/speedtest1.c).
 
 ### Alternatives

config.go

@@ -82,7 +82,7 @@ func (c *Conn) SetAuthorizer(cb func(action AuthorizerActionCode, name3rd, name4
 
 }
 
-func authorizerCallback(ctx context.Context, mod api.Module, pDB uint32, action AuthorizerActionCode, zName3rd, zName4th, zSchema, zNameInner uint32) AuthorizerReturnCode {
+func authorizerCallback(ctx context.Context, mod api.Module, pDB uint32, action AuthorizerActionCode, zName3rd, zName4th, zSchema, zNameInner uint32) (rc AuthorizerReturnCode) {
 	if c, ok := ctx.Value(connKey{}).(*Conn); ok && c.handle == pDB && c.authorizer != nil {
 		var name3rd, name4th, schema, nameInner string
 		if zName3rd != 0 {
@@ -97,7 +97,68 @@ func authorizerCallback(ctx context.Context, mod api.Module, pDB uint32, action
 		if zNameInner != 0 {
 			nameInner = util.ReadString(mod, zNameInner, _MAX_NAME)
 		}
-		return c.authorizer(action, name3rd, name4th, schema, nameInner)
+		rc = c.authorizer(action, name3rd, name4th, schema, nameInner)
 	}
-	return AUTH_OK
+	return rc
+}
+
+// WalCheckpoint checkpoints a WAL database.
+//
+// https://sqlite.org/c3ref/wal_checkpoint_v2.html
+func (c *Conn) WalCheckpoint(schema string, mode CheckpointMode) (nLog, nCkpt int, err error) {
+	defer c.arena.mark()()
+	nLogPtr := c.arena.new(ptrlen)
+	nCkptPtr := c.arena.new(ptrlen)
+	schemaPtr := c.arena.string(schema)
+	r := c.call("sqlite3_wal_checkpoint_v2",
+		uint64(c.handle), uint64(schemaPtr), uint64(mode),
+		uint64(nLogPtr), uint64(nCkptPtr))
+	nLog = int(int32(util.ReadUint32(c.mod, nLogPtr)))
+	nCkpt = int(int32(util.ReadUint32(c.mod, nCkptPtr)))
+	return nLog, nCkpt, c.error(r)
+}
+
+// WalAutoCheckpoint configures WAL auto-checkpoints.
+//
+// https://sqlite.org/c3ref/wal_autocheckpoint.html
+func (c *Conn) WalAutoCheckpoint(pages int) error {
+	r := c.call("sqlite3_wal_autocheckpoint", uint64(c.handle), uint64(pages))
+	return c.error(r)
+}
+
+// WalHook registers a callback function to be invoked
+// each time data is committed to a database in WAL mode.
+//
+// https://sqlite.org/c3ref/wal_hook.html
+func (c *Conn) WalHook(cb func(db *Conn, schema string, pages int) error) {
+	var enable uint64
+	if cb != nil {
+		enable = 1
+	}
+	c.call("sqlite3_wal_hook_go", uint64(c.handle), enable)
+	c.wal = cb
+}
+
+func walCallback(ctx context.Context, mod api.Module, _, pDB, zSchema uint32, pages int32) (rc uint32) {
+	if c, ok := ctx.Value(connKey{}).(*Conn); ok && c.handle == pDB && c.wal != nil {
+		schema := util.ReadString(mod, zSchema, _MAX_NAME)
+		err := c.wal(c, schema, int(pages))
+		_, rc = errorCode(err, ERROR)
+	}
+	return rc
+}
+
+// AutoVacuumPages registers a autovacuum compaction amount callback.
+//
+// https://sqlite.org/c3ref/autovacuum_pages.html
+func (c *Conn) AutoVacuumPages(cb func(schema string, dbPages, freePages, bytesPerPage uint) uint) error {
+	funcPtr := util.AddHandle(c.ctx, cb)
+	r := c.call("sqlite3_autovacuum_pages_go", uint64(c.handle), uint64(funcPtr))
+	return c.error(r)
+}
+
+func autoVacuumCallback(ctx context.Context, mod api.Module, pApp, zSchema, nDbPage, nFreePage, nBytePerPage uint32) uint32 {
+	fn := util.GetHandle(ctx, pApp).(func(schema string, dbPages, freePages, bytesPerPage uint) uint)
+	schema := util.ReadString(mod, zSchema, _MAX_NAME)
+	return uint32(fn(schema, uint(nDbPage), uint(nFreePage), uint(nBytePerPage)))
 }

conn.go

@@ -29,6 +29,7 @@ type Conn struct {
 	update     func(AuthorizerActionCode, string, string, int64)
 	commit     func() bool
 	rollback   func()
+	wal        func(*Conn, string, int) error
 	arena      arena
 
 	handle uint32
@@ -281,6 +282,12 @@ func (c *Conn) ReleaseMemory() error {
 	return c.error(r)
 }
 
+// GetInterrupt gets the context set with [Conn.SetInterrupt],
+// or nil if none was set.
+func (c *Conn) GetInterrupt() context.Context {
+	return c.interrupt
+}
+
 // SetInterrupt interrupts a long-running query when a context is done.
 //
 // Subsequent uses of the connection will return [INTERRUPT]
@@ -325,13 +332,13 @@ func (c *Conn) checkInterrupt() {
 	}
 }
 
-func progressCallback(ctx context.Context, mod api.Module, pDB uint32) uint32 {
+func progressCallback(ctx context.Context, mod api.Module, pDB uint32) (interrupt uint32) {
 	if c, ok := ctx.Value(connKey{}).(*Conn); ok && c.handle == pDB && c.commit != nil {
 		if c.interrupt != nil && c.interrupt.Err() != nil {
-			return 1
+			interrupt = 1
 		}
 	}
-	return 0
+	return interrupt
 }
 
 // BusyTimeout sets a busy timeout.
@@ -359,28 +366,13 @@ func (c *Conn) BusyHandler(cb func(count int) (retry bool)) error {
 	return nil
 }
 
-func busyCallback(ctx context.Context, mod api.Module, pDB, count uint32) uint32 {
+func busyCallback(ctx context.Context, mod api.Module, pDB uint32, count int32) (retry uint32) {
 	if c, ok := ctx.Value(connKey{}).(*Conn); ok && c.handle == pDB && c.busy != nil {
-		if retry := c.busy(int(count)); retry {
-			return 1
+		if c.busy(int(count)) {
+			retry = 1
 		}
 	}
-	return 0
-}
-
-// Deprecated: executes a PRAGMA statement and returns results.
-func (c *Conn) Pragma(str string) ([]string, error) {
-	stmt, _, err := c.Prepare(`PRAGMA ` + str)
-	if err != nil {
-		return nil, err
-	}
-	defer stmt.Close()
-
-	var pragmas []string
-	for stmt.Step() {
-		pragmas = append(pragmas, stmt.ColumnText(0))
-	}
-	return pragmas, stmt.Close()
+	return retry
 }
 
 func (c *Conn) error(rc uint64, sql ...string) error {

const.go

@@ -256,41 +256,41 @@ const (
 type AuthorizerActionCode uint32
 
 const (
-	/************************************************ 3rd ************ 4th ***********/
-	CREATE_INDEX        AuthorizerActionCode = 1  /* Index Name      Table Name      */
-	CREATE_TABLE        AuthorizerActionCode = 2  /* Table Name      NULL            */
-	CREATE_TEMP_INDEX   AuthorizerActionCode = 3  /* Index Name      Table Name      */
-	CREATE_TEMP_TABLE   AuthorizerActionCode = 4  /* Table Name      NULL            */
-	CREATE_TEMP_TRIGGER AuthorizerActionCode = 5  /* Trigger Name    Table Name      */
-	CREATE_TEMP_VIEW    AuthorizerActionCode = 6  /* View Name       NULL            */
-	CREATE_TRIGGER      AuthorizerActionCode = 7  /* Trigger Name    Table Name      */
-	CREATE_VIEW         AuthorizerActionCode = 8  /* View Name       NULL            */
-	DELETE              AuthorizerActionCode = 9  /* Table Name      NULL            */
-	DROP_INDEX          AuthorizerActionCode = 10 /* Index Name      Table Name      */
-	DROP_TABLE          AuthorizerActionCode = 11 /* Table Name      NULL            */
-	DROP_TEMP_INDEX     AuthorizerActionCode = 12 /* Index Name      Table Name      */
-	DROP_TEMP_TABLE     AuthorizerActionCode = 13 /* Table Name      NULL            */
-	DROP_TEMP_TRIGGER   AuthorizerActionCode = 14 /* Trigger Name    Table Name      */
-	DROP_TEMP_VIEW      AuthorizerActionCode = 15 /* View Name       NULL            */
-	DROP_TRIGGER        AuthorizerActionCode = 16 /* Trigger Name    Table Name      */
-	DROP_VIEW           AuthorizerActionCode = 17 /* View Name       NULL            */
-	INSERT              AuthorizerActionCode = 18 /* Table Name      NULL            */
-	PRAGMA              AuthorizerActionCode = 19 /* Pragma Name     1st arg or NULL */
-	READ                AuthorizerActionCode = 20 /* Table Name      Column Name     */
-	SELECT              AuthorizerActionCode = 21 /* NULL            NULL            */
-	TRANSACTION         AuthorizerActionCode = 22 /* Operation       NULL            */
-	UPDATE              AuthorizerActionCode = 23 /* Table Name      Column Name     */
-	ATTACH              AuthorizerActionCode = 24 /* Filename        NULL            */
-	DETACH              AuthorizerActionCode = 25 /* Database Name   NULL            */
-	ALTER_TABLE         AuthorizerActionCode = 26 /* Database Name   Table Name      */
-	REINDEX             AuthorizerActionCode = 27 /* Index Name      NULL            */
-	ANALYZE             AuthorizerActionCode = 28 /* Table Name      NULL            */
-	CREATE_VTABLE       AuthorizerActionCode = 29 /* Table Name      Module Name     */
-	DROP_VTABLE         AuthorizerActionCode = 30 /* Table Name      Module Name     */
-	FUNCTION            AuthorizerActionCode = 31 /* NULL            Function Name   */
-	SAVEPOINT           AuthorizerActionCode = 32 /* Operation       Savepoint Name  */
-	COPY                AuthorizerActionCode = 0  /* No longer used */
-	RECURSIVE           AuthorizerActionCode = 33 /* NULL            NULL            */
+	/***************************************************** 3rd ************ 4th ***********/
+	AUTH_CREATE_INDEX        AuthorizerActionCode = 1  /* Index Name      Table Name      */
+	AUTH_CREATE_TABLE        AuthorizerActionCode = 2  /* Table Name      NULL            */
+	AUTH_CREATE_TEMP_INDEX   AuthorizerActionCode = 3  /* Index Name      Table Name      */
+	AUTH_CREATE_TEMP_TABLE   AuthorizerActionCode = 4  /* Table Name      NULL            */
+	AUTH_CREATE_TEMP_TRIGGER AuthorizerActionCode = 5  /* Trigger Name    Table Name      */
+	AUTH_CREATE_TEMP_VIEW    AuthorizerActionCode = 6  /* View Name       NULL            */
+	AUTH_CREATE_TRIGGER      AuthorizerActionCode = 7  /* Trigger Name    Table Name      */
+	AUTH_CREATE_VIEW         AuthorizerActionCode = 8  /* View Name       NULL            */
+	AUTH_DELETE              AuthorizerActionCode = 9  /* Table Name      NULL            */
+	AUTH_DROP_INDEX          AuthorizerActionCode = 10 /* Index Name      Table Name      */
+	AUTH_DROP_TABLE          AuthorizerActionCode = 11 /* Table Name      NULL            */
+	AUTH_DROP_TEMP_INDEX     AuthorizerActionCode = 12 /* Index Name      Table Name      */
+	AUTH_DROP_TEMP_TABLE     AuthorizerActionCode = 13 /* Table Name      NULL            */
+	AUTH_DROP_TEMP_TRIGGER   AuthorizerActionCode = 14 /* Trigger Name    Table Name      */
+	AUTH_DROP_TEMP_VIEW      AuthorizerActionCode = 15 /* View Name       NULL            */
+	AUTH_DROP_TRIGGER        AuthorizerActionCode = 16 /* Trigger Name    Table Name      */
+	AUTH_DROP_VIEW           AuthorizerActionCode = 17 /* View Name       NULL            */
+	AUTH_INSERT              AuthorizerActionCode = 18 /* Table Name      NULL            */
+	AUTH_PRAGMA              AuthorizerActionCode = 19 /* Pragma Name     1st arg or NULL */
+	AUTH_READ                AuthorizerActionCode = 20 /* Table Name      Column Name     */
+	AUTH_SELECT              AuthorizerActionCode = 21 /* NULL            NULL            */
+	AUTH_TRANSACTION         AuthorizerActionCode = 22 /* Operation       NULL            */
+	AUTH_UPDATE              AuthorizerActionCode = 23 /* Table Name      Column Name     */
+	AUTH_ATTACH              AuthorizerActionCode = 24 /* Filename        NULL            */
+	AUTH_DETACH              AuthorizerActionCode = 25 /* Database Name   NULL            */
+	AUTH_ALTER_TABLE         AuthorizerActionCode = 26 /* Database Name   Table Name      */
+	AUTH_REINDEX             AuthorizerActionCode = 27 /* Index Name      NULL            */
+	AUTH_ANALYZE             AuthorizerActionCode = 28 /* Table Name      NULL            */
+	AUTH_CREATE_VTABLE       AuthorizerActionCode = 29 /* Table Name      Module Name     */
+	AUTH_DROP_VTABLE         AuthorizerActionCode = 30 /* Table Name      Module Name     */
+	AUTH_FUNCTION            AuthorizerActionCode = 31 /* NULL            Function Name   */
+	AUTH_SAVEPOINT           AuthorizerActionCode = 32 /* Operation       Savepoint Name  */
+	AUTH_COPY                AuthorizerActionCode = 0  /* No longer used */
+	AUTH_RECURSIVE           AuthorizerActionCode = 33 /* NULL            NULL            */
 )
 
 // AuthorizerReturnCode are the integer codes
@@ -305,6 +305,18 @@ const (
 	AUTH_IGNORE AuthorizerReturnCode = 2 /* Don't allow access, but don't generate an error */
 )
 
+// CheckpointMode are all the checkpoint mode values.
+//
+// https://sqlite.org/c3ref/c_checkpoint_full.html
+type CheckpointMode uint32
+
+const (
+	CHECKPOINT_PASSIVE  CheckpointMode = 0 /* Do as much as possible w/o blocking */
+	CHECKPOINT_FULL     CheckpointMode = 1 /* Wait for writers, then checkpoint */
+	CHECKPOINT_RESTART  CheckpointMode = 2 /* Like FULL but wait for readers */
+	CHECKPOINT_TRUNCATE CheckpointMode = 3 /* Like RESTART but also truncate WAL */
+)
+
 // TxnState are the allowed return values from [Conn.TxnState].
 //
 // https://sqlite.org/c3ref/c_txn_none.html

driver/driver_test.go

@@ -153,7 +153,7 @@ func Test_BeginTx(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	_, err = tx1.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	_, err = tx1.Exec(`CREATE TABLE test (col)`)
 	if err == nil {
 		t.Error("want error")
 	}
@@ -310,7 +310,7 @@ func Test_time(t *testing.T) {
 
 			twosday := time.Date(2022, 2, 22, 22, 22, 22, 0, time.UTC)
 
-			_, err = db.Exec(`CREATE TABLE IF NOT EXISTS test (at DATETIME)`)
+			_, err = db.Exec(`CREATE TABLE test (at DATETIME)`)
 			if err != nil {
 				t.Fatal(err)
 			}

driver/json_test.go

@@ -18,7 +18,7 @@ func Example_json() {
 	defer db.Close()
 
 	_, err = db.Exec(`
-		CREATE TABLE IF NOT EXISTS orders (
+		CREATE TABLE orders (
 			cart_id INTEGER PRIMARY KEY,
 			user_id INTEGER NOT NULL,
 			cart    TEXT

driver/savepoint_test.go

@@ -16,7 +16,7 @@ func ExampleSavepoint() {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(`CREATE TABLE IF NOT EXISTS users (id INT, name VARCHAR(10))`)
+	_, err = db.Exec(`CREATE TABLE users (id INT, name VARCHAR(10))`)
 	if err != nil {
 		log.Fatal(err)
 	}

embed/README.md

@@ -1,6 +1,6 @@
-# Embeddable WASM build of SQLite
+# Embeddable Wasm build of SQLite
 
-This folder includes an embeddable WASM build of SQLite 3.45.1 for use with
+This folder includes an embeddable Wasm build of SQLite 3.45.3 for use with
 [`github.com/ncruces/go-sqlite3`](https://pkg.go.dev/github.com/ncruces/go-sqlite3).
 
 The following optional features are compiled in:

embed/build.sh

@@ -5,7 +5,7 @@ cd -P -- "$(dirname -- "$0")"
 
 ROOT=../
 BINARYEN="$ROOT/tools/binaryen-version_117/bin"
-WASI_SDK="$ROOT/tools/wasi-sdk-21.0/bin"
+WASI_SDK="$ROOT/tools/wasi-sdk-22.0/bin"
 
 "$WASI_SDK/clang" --target=wasm32-wasi -std=c17 -flto -g0 -O2 \
   -Wall -Wextra -Wno-unused-parameter \

embed/exports.txt

@@ -1,7 +1,9 @@
+aligned_alloc
 free
 malloc
 malloc_destructor
 sqlite3_anycollseq_init
+sqlite3_autovacuum_pages_go
 sqlite3_backup_finish
 sqlite3_backup_init
 sqlite3_backup_pagecount
@@ -114,4 +116,7 @@ sqlite3_vtab_in_first
 sqlite3_vtab_in_next
 sqlite3_vtab_nochange
 sqlite3_vtab_on_conflict
-sqlite3_vtab_rhs_value
+sqlite3_vtab_rhs_value
+sqlite3_wal_autocheckpoint
+sqlite3_wal_checkpoint_v2
+sqlite3_wal_hook_go

example_test.go

@@ -16,7 +16,7 @@ func Example() {
 		log.Fatal(err)
 	}
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS users (id INT, name VARCHAR(10))`)
+	err = db.Exec(`CREATE TABLE users (id INT, name VARCHAR(10))`)
 	if err != nil {
 		log.Fatal(err)
 	}

ext/blobio/blob_test.go

@@ -27,7 +27,7 @@ func Example() {
 	}
 	defer db.Close()
 
-	_, err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	_, err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -79,8 +79,8 @@ func Test_readblob(t *testing.T) {
 	}
 
 	err = db.Exec(`
-		CREATE TABLE IF NOT EXISTS test1 (col);
-		CREATE TABLE IF NOT EXISTS test2 (col);
+		CREATE TABLE test1 (col);
+		CREATE TABLE test2 (col);
 		INSERT INTO test1 VALUES (x'cafe');
 		INSERT INTO test2 VALUES (x'babe');
 	`)
@@ -139,8 +139,8 @@ func Test_openblob(t *testing.T) {
 	}
 
 	err = db.Exec(`
-		CREATE TABLE IF NOT EXISTS test1 (col);
-		CREATE TABLE IF NOT EXISTS test2 (col);
+		CREATE TABLE test1 (col);
+		CREATE TABLE test2 (col);
 		INSERT INTO test1 VALUES (x'cafe');
 		INSERT INTO test2 VALUES (x'babe');
 	`)

ext/csv/csv_test.go

@@ -20,7 +20,7 @@ func Example() {
 	csv.Register(db)
 
 	err = db.Exec(`
-		CREATE VIRTUAL TABLE IF NOT EXISTS eurofxref USING csv(
+		CREATE VIRTUAL TABLE eurofxref USING csv(
 			filename = 'testdata/eurofxref.csv',
 			header   = YES,
 			columns  = 42,

ext/fileio/coro.go

@@ -0,0 +1,68 @@
+package fileio
+
+import (
+	"fmt"
+
+	"github.com/ncruces/go-sqlite3/internal/util"
+)
+
+// Adapted from: https://research.swtch.com/coro
+
+const errCoroCanceled = util.ErrorString("coroutine canceled")
+
+func coroNew[In, Out any](f func(In, func(Out) In) Out) (resume func(In) (Out, bool), cancel func()) {
+	type msg[T any] struct {
+		panic any
+		val   T
+	}
+
+	cin := make(chan msg[In])
+	cout := make(chan msg[Out])
+	running := true
+	resume = func(in In) (out Out, ok bool) {
+		if !running {
+			return
+		}
+		cin <- msg[In]{val: in}
+		m := <-cout
+		if m.panic != nil {
+			panic(m.panic)
+		}
+		return m.val, running
+	}
+	cancel = func() {
+		if !running {
+			return
+		}
+		e := fmt.Errorf("%w", errCoroCanceled)
+		cin <- msg[In]{panic: e}
+		m := <-cout
+		if m.panic != nil && m.panic != e {
+			panic(m.panic)
+		}
+	}
+	yield := func(out Out) In {
+		cout <- msg[Out]{val: out}
+		m := <-cin
+		if m.panic != nil {
+			panic(m.panic)
+		}
+		return m.val
+	}
+	go func() {
+		defer func() {
+			if running {
+				running = false
+				cout <- msg[Out]{panic: recover()}
+			}
+		}()
+		var out Out
+		m := <-cin
+		if m.panic == nil {
+			out = f(m.val, yield)
+		}
+		running = false
+		cout <- msg[Out]{val: out}
+	}()
+	return resume, cancel
+}

ext/fileio/fsdir.go

@@ -53,12 +53,12 @@ func (d fsdir) Open() (sqlite3.VTabCursor, error) {
 
 type cursor struct {
 	fsdir
-	curr  entry
-	next  chan entry
-	done  chan struct{}
-	base  string
-	rowID int64
-	eof   bool
+	base   string
+	resume func(struct{}) (entry, bool)
+	cancel func()
+	curr   entry
+	eof    bool
+	rowID  int64
 }
 
 type entry struct {
@@ -68,12 +68,8 @@ type entry struct {
 }
 
 func (c *cursor) Close() error {
-	if c.done != nil {
-		close(c.done)
-		s := <-c.next
-		c.done = nil
-		c.next = nil
-		return s.err
+	if c.cancel != nil {
+		c.cancel()
 	}
 	return nil
 }
@@ -96,16 +92,25 @@ func (c *cursor) Filter(idxNum int, idxStr string, arg ...sqlite3.Value) error {
 		c.base = base
 	}
 
-	c.rowID = 0
+	c.resume, c.cancel = coroNew(func(_ struct{}, yield func(entry) struct{}) entry {
+		walkDir := func(path string, d fs.DirEntry, err error) error {
+			yield(entry{d, err, path})
+			return nil
+		}
+		if c.fsys != nil {
+			fs.WalkDir(c.fsys, root, walkDir)
+		} else {
+			filepath.WalkDir(root, walkDir)
+		}
+		return entry{}
+	})
 	c.eof = false
-	c.next = make(chan entry)
-	c.done = make(chan struct{})
-	go c.WalkDir(root)
+	c.rowID = 0
 	return c.Next()
 }
 
 func (c *cursor) Next() error {
-	curr, ok := <-c.next
+	curr, ok := c.resume(struct{}{})
 	c.curr = curr
 	c.eof = !ok
 	c.rowID++
@@ -165,22 +170,3 @@ func (c *cursor) Column(ctx *sqlite3.Context, n int) error {
 	}
 	return nil
 }
-
-func (c *cursor) WalkDir(path string) {
-	defer close(c.next)
-
-	if c.fsys != nil {
-		fs.WalkDir(c.fsys, path, c.WalkDirFunc)
-	} else {
-		filepath.WalkDir(path, c.WalkDirFunc)
-	}
-}
-
-func (c *cursor) WalkDirFunc(path string, d fs.DirEntry, err error) error {
-	select {
-	case <-c.done:
-		return fs.SkipAll
-	case c.next <- entry{d, err, path}:
-		return nil
-	}
-}

ext/fileio/fsdir_test.go

@@ -28,7 +28,7 @@ func Test_fsdir(t *testing.T) {
 			}
 			defer db.Close()
 
-			rows, err := db.Query(`SELECT * FROM fsdir('.', '.') LIMIT 4`)
+			rows, err := db.Query(`SELECT * FROM fsdir('.', '.')`)
 			if err != nil {
 				t.Fatal(err)
 			}

ext/stats/stats_test.go

@@ -20,7 +20,7 @@ func TestRegister_variance(t *testing.T) {
 
 	stats.Register(db)
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS data (x)`)
+	err = db.Exec(`CREATE TABLE data (x)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -92,7 +92,7 @@ func TestRegister_covariance(t *testing.T) {
 
 	stats.Register(db)
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS data (y, x)`)
+	err = db.Exec(`CREATE TABLE data (y, x)`)
 	if err != nil {
 		t.Fatal(err)
 	}

ext/unicode/unicode_test.go

@@ -81,7 +81,7 @@ func TestRegister_collation(t *testing.T) {
 
 	Register(db)
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS words (word VARCHAR(10))`)
+	err = db.Exec(`CREATE TABLE words (word VARCHAR(10))`)
 	if err != nil {
 		t.Fatal(err)
 	}

func_test.go

@@ -18,7 +18,7 @@ func ExampleConn_CreateCollation() {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS words (word VARCHAR(10))`)
+	err = db.Exec(`CREATE TABLE words (word VARCHAR(10))`)
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -66,7 +66,7 @@ func ExampleConn_CreateFunction() {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS words (word VARCHAR(10))`)
+	err = db.Exec(`CREATE TABLE words (word VARCHAR(10))`)
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -111,7 +111,7 @@ func ExampleContext_SetAuxData() {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS words (word VARCHAR(10))`)
+	err = db.Exec(`CREATE TABLE words (word VARCHAR(10))`)
 	if err != nil {
 		log.Fatal(err)
 	}

func_win_test.go

@@ -16,7 +16,7 @@ func ExampleConn_CreateWindowFunction() {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS words (word VARCHAR(10))`)
+	err = db.Exec(`CREATE TABLE words (word VARCHAR(10))`)
 	if err != nil {
 		log.Fatal(err)
 	}

go.mod

@@ -5,10 +5,10 @@ go 1.21
 require (
 	github.com/ncruces/julianday v1.0.0
 	github.com/psanford/httpreadat v0.1.0
-	github.com/tetratelabs/wazero v1.7.0
-	golang.org/x/crypto v0.21.0
-	golang.org/x/sync v0.6.0
-	golang.org/x/sys v0.18.0
+	github.com/tetratelabs/wazero v1.7.1
+	golang.org/x/crypto v0.22.0
+	golang.org/x/sync v0.7.0
+	golang.org/x/sys v0.19.0
 	golang.org/x/text v0.14.0
 )
 

go.sum

@@ -2,13 +2,13 @@ github.com/ncruces/julianday v1.0.0 h1:fH0OKwa7NWvniGQtxdJRxAgkBMolni2BjDHaWTxqt
 github.com/ncruces/julianday v1.0.0/go.mod h1:Dusn2KvZrrovOMJuOt0TNXL6tB7U2E8kvza5fFc9G7g=
 github.com/psanford/httpreadat v0.1.0 h1:VleW1HS2zO7/4c7c7zNl33fO6oYACSagjJIyMIwZLUE=
 github.com/psanford/httpreadat v0.1.0/go.mod h1:Zg7P+TlBm3bYbyHTKv/EdtSJZn3qwbPwpfZ/I9GKCRE=
-github.com/tetratelabs/wazero v1.7.0 h1:jg5qPydno59wqjpGrHph81lbtHzTrWzwwtD4cD88+hQ=
-github.com/tetratelabs/wazero v1.7.0/go.mod h1:ytl6Zuh20R/eROuyDaGPkp82O9C/DJfXAwJfQ3X6/7Y=
-golang.org/x/crypto v0.21.0 h1:X31++rzVUdKhX5sWmSOFZxx8UW/ldWx55cbf08iNAMA=
-golang.org/x/crypto v0.21.0/go.mod h1:0BP7YvVV9gBbVKyeTG0Gyn+gZm94bibOW5BjDEYAOMs=
-golang.org/x/sync v0.6.0 h1:5BMeUDZ7vkXGfEr1x9B4bRcTH4lpkTkpdh0T/J+qjbQ=
-golang.org/x/sync v0.6.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
-golang.org/x/sys v0.18.0 h1:DBdB3niSjOA/O0blCZBqDefyWNYveAYMNF1Wum0DYQ4=
-golang.org/x/sys v0.18.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+github.com/tetratelabs/wazero v1.7.1 h1:QtSfd6KLc41DIMpDYlJdoMc6k7QTN246DM2+n2Y/Dx8=
+github.com/tetratelabs/wazero v1.7.1/go.mod h1:ytl6Zuh20R/eROuyDaGPkp82O9C/DJfXAwJfQ3X6/7Y=
+golang.org/x/crypto v0.22.0 h1:g1v0xeRhjcugydODzvb3mEM9SQ0HGp9s/nh3COQ/C30=
+golang.org/x/crypto v0.22.0/go.mod h1:vr6Su+7cTlO45qkww3VDJlzDn0ctJvRgYbC2NvXHt+M=
+golang.org/x/sync v0.7.0 h1:YsImfSBoP9QPYL0xyKJPq0gcaJdG3rInoqxTWbfQu9M=
+golang.org/x/sync v0.7.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/sys v0.19.0 h1:q5f1RH2jigJ1MoAWp2KTp3gm5zAGFUTarQZ5U386+4o=
+golang.org/x/sys v0.19.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
 golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=

go.work.sum

@@ -1,4 +1,8 @@
+golang.org/x/mod v0.8.0 h1:LUYupSeNrTNCGzR/hVBk2NHZO4hXcVaW1k4Qx7rjPx8=
 golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
+golang.org/x/net v0.21.0 h1:AQyQV4dYCvJ7vGmJyKki9+PBdyvhkSd8EIx/qb0AYv4=
 golang.org/x/net v0.21.0/go.mod h1:bIjVDfnllIU7BJ2DNgfnXvpSvtn8VRwhlsaeUTyUS44=
-golang.org/x/term v0.18.0/go.mod h1:ILwASektA3OnRv7amZ1xhE/KTR+u50pbXfZ03+6Nx58=
+golang.org/x/term v0.19.0 h1:+ThwsDv+tYfnJFhF4L8jITxu1tdTWRTZpdsWgEgjL6Q=
+golang.org/x/term v0.19.0/go.mod h1:2CuTdWZ7KHSQwUzKva0cbMg6q2DMI3Mmxp+gKJbskEk=
+golang.org/x/tools v0.6.0 h1:BOw41kyTf3PuCW1pVQf8+Cyg8pMlkYB1oo9iJ6D/lKM=
 golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=

gormlite/go.mod

@@ -3,14 +3,14 @@ module github.com/ncruces/go-sqlite3/gormlite
 go 1.21
 
 require (
-	github.com/ncruces/go-sqlite3 v0.12.2
-	gorm.io/gorm v1.25.7
+	github.com/ncruces/go-sqlite3 v0.13.0
+	gorm.io/gorm v1.25.9
 )
 
 require (
 	github.com/jinzhu/inflection v1.0.0 // indirect
 	github.com/jinzhu/now v1.1.5 // indirect
 	github.com/ncruces/julianday v1.0.0 // indirect
-	github.com/tetratelabs/wazero v1.7.0-pre.1 // indirect
-	golang.org/x/sys v0.18.0 // indirect
+	github.com/tetratelabs/wazero v1.7.0 // indirect
+	golang.org/x/sys v0.19.0 // indirect
 )

gormlite/go.sum

@@ -2,15 +2,15 @@ github.com/jinzhu/inflection v1.0.0 h1:K317FqzuhWc8YvSVlFMCCUb36O/S9MCKRDI7QkRKD
 github.com/jinzhu/inflection v1.0.0/go.mod h1:h+uFLlag+Qp1Va5pdKtLDYj+kHp5pxUVkryuEj+Srlc=
 github.com/jinzhu/now v1.1.5 h1:/o9tlHleP7gOFmsnYNz3RGnqzefHA47wQpKrrdTIwXQ=
 github.com/jinzhu/now v1.1.5/go.mod h1:d3SSVoowX0Lcu0IBviAWJpolVfI5UJVZZ7cO71lE/z8=
-github.com/ncruces/go-sqlite3 v0.12.2 h1:NO8lFyFTA6aUtDWviQX2Rzqi1RX3X52peWq/MLgV1Gc=
-github.com/ncruces/go-sqlite3 v0.12.2/go.mod h1:+8dWcBxb2Yar4EcCwav1a21MpKZbztwOYBLSRYt9bMY=
+github.com/ncruces/go-sqlite3 v0.13.0 h1:+N1VHVLnrCJasyXdAKQL9MNTKC3wHZa8pLMUuP8wb3k=
+github.com/ncruces/go-sqlite3 v0.13.0/go.mod h1:y9zPUI+C42V9xuuJeN+tGhpOjr4gUHz2Pi2RLFVEdZg=
 github.com/ncruces/julianday v1.0.0 h1:fH0OKwa7NWvniGQtxdJRxAgkBMolni2BjDHaWTxqt7M=
 github.com/ncruces/julianday v1.0.0/go.mod h1:Dusn2KvZrrovOMJuOt0TNXL6tB7U2E8kvza5fFc9G7g=
-github.com/tetratelabs/wazero v1.7.0-pre.1 h1:mOcomS6m5tz4gZgUaocVm0o64uDPPAmErJJmiOVLHvw=
-github.com/tetratelabs/wazero v1.7.0-pre.1/go.mod h1:ytl6Zuh20R/eROuyDaGPkp82O9C/DJfXAwJfQ3X6/7Y=
-golang.org/x/sys v0.18.0 h1:DBdB3niSjOA/O0blCZBqDefyWNYveAYMNF1Wum0DYQ4=
-golang.org/x/sys v0.18.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+github.com/tetratelabs/wazero v1.7.0 h1:jg5qPydno59wqjpGrHph81lbtHzTrWzwwtD4cD88+hQ=
+github.com/tetratelabs/wazero v1.7.0/go.mod h1:ytl6Zuh20R/eROuyDaGPkp82O9C/DJfXAwJfQ3X6/7Y=
+golang.org/x/sys v0.19.0 h1:q5f1RH2jigJ1MoAWp2KTp3gm5zAGFUTarQZ5U386+4o=
+golang.org/x/sys v0.19.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
 golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
-gorm.io/gorm v1.25.7 h1:VsD6acwRjz2zFxGO50gPO6AkNs7KKnvfzUjHQhZDz/A=
-gorm.io/gorm v1.25.7/go.mod h1:hbnx/Oo0ChWMn1BIhpy1oYozzpM15i4YPuHDmfYtwg8=
+gorm.io/gorm v1.25.9 h1:wct0gxZIELDk8+ZqF/MVnHLkA1rvYlBWUMv2EdsK1g8=
+gorm.io/gorm v1.25.9/go.mod h1:hbnx/Oo0ChWMn1BIhpy1oYozzpM15i4YPuHDmfYtwg8=

gormlite/migrator.go

@@ -334,7 +334,7 @@ type _Index struct {
 // GetIndexes return Indexes []gorm.Index and execErr error,
 // See the [doc]
 //
-// [doc]: https://www.sqlite.org/pragma.html#pragma_index_list
+// [doc]: https://sqlite.org/pragma.html#pragma_index_list
 func (m _Migrator) GetIndexes(value interface{}) ([]gorm.Index, error) {
 	indexes := make([]gorm.Index, 0)
 	err := m.RunWithValue(value, func(stmt *gorm.Statement) error {

gormlite/test.sh

@@ -7,7 +7,7 @@ rm -rf gorm/ tests/
 go work use -r .
 go test
 
-git clone --branch v1.25.7 --filter=blob:none https://github.com/go-gorm/gorm.git
+git clone --branch v1.25.9 --filter=blob:none https://github.com/go-gorm/gorm.git
 mv gorm/tests tests
 rm -rf gorm/
 

internal/util/alloc.go

@@ -0,0 +1,71 @@
+//go:build unix
+
+package util
+
+import (
+	"math"
+
+	"github.com/tetratelabs/wazero/experimental"
+	"golang.org/x/sys/unix"
+)
+
+func mmappedAllocator(cap, max uint64) experimental.LinearMemory {
+	// Round up to the page size.
+	rnd := uint64(unix.Getpagesize() - 1)
+	max = (max + rnd) &^ rnd
+	cap = (cap + rnd) &^ rnd
+
+	if max > math.MaxInt {
+		// This ensures int(max) overflows to a negative value,
+		// and unix.Mmap returns EINVAL.
+		max = math.MaxUint64
+	}
+	// Reserve max bytes of address space, to ensure we won't need to move it.
+	// A protected, private, anonymous mapping should not commit memory.
+	b, err := unix.Mmap(-1, 0, int(max), unix.PROT_NONE, unix.MAP_PRIVATE|unix.MAP_ANON)
+	if err != nil {
+		panic(err)
+	}
+	// Commit the initial cap bytes of memory.
+	err = unix.Mprotect(b[:cap], unix.PROT_READ|unix.PROT_WRITE)
+	if err != nil {
+		unix.Munmap(b)
+		panic(err)
+	}
+	return &mmappedMemory{buf: b[:cap]}
+}
+
+// The slice covers the entire mmapped memory:
+//   - len(buf) is the already committed memory,
+//   - cap(buf) is the reserved address space.
+type mmappedMemory struct {
+	buf []byte
+}
+
+func (m *mmappedMemory) Reallocate(size uint64) []byte {
+	if com := uint64(len(m.buf)); com < size {
+		// Round up to the page size.
+		rnd := uint64(unix.Getpagesize() - 1)
+		new := (size + rnd) &^ rnd
+
+		// Commit additional memory up to new bytes.
+		err := unix.Mprotect(m.buf[com:new], unix.PROT_READ|unix.PROT_WRITE)
+		if err != nil {
+			panic(err)
+		}
+
+		// Update committed memory.
+		m.buf = m.buf[:new]
+	}
+	// Limit returned capacity because bytes beyond
+	// len(m.buf) have not yet been committed.
+	return m.buf[:size:len(m.buf)]
+}
+
+func (m *mmappedMemory) Free() {
+	err := unix.Munmap(m.buf[:cap(m.buf)])
+	if err != nil {
+		panic(err)
+	}
+	m.buf = nil
+}

internal/util/handle.go

@@ -3,21 +3,11 @@ package util
 import (
 	"context"
 	"io"
-
-	"github.com/tetratelabs/wazero/experimental"
 )
 
-type handleKey struct{}
 type handleState struct {
 	handles []any
-	empty   int
-}
-
-func NewContext(ctx context.Context) context.Context {
-	state := new(handleState)
-	ctx = experimental.WithCloseNotifier(ctx, state)
-	ctx = context.WithValue(ctx, handleKey{}, state)
-	return ctx
+	holes   int
 }
 
 func (s *handleState) CloseNotify(ctx context.Context, exitCode uint32) {
@@ -27,14 +17,14 @@ func (s *handleState) CloseNotify(ctx context.Context, exitCode uint32) {
 		}
 	}
 	s.handles = nil
-	s.empty = 0
+	s.holes = 0
 }
 
 func GetHandle(ctx context.Context, id uint32) any {
 	if id == 0 {
 		return nil
 	}
-	s := ctx.Value(handleKey{}).(*handleState)
+	s := ctx.Value(moduleKey{}).(*moduleState)
 	return s.handles[^id]
 }
 
@@ -42,10 +32,10 @@ func DelHandle(ctx context.Context, id uint32) error {
 	if id == 0 {
 		return nil
 	}
-	s := ctx.Value(handleKey{}).(*handleState)
+	s := ctx.Value(moduleKey{}).(*moduleState)
 	a := s.handles[^id]
 	s.handles[^id] = nil
-	s.empty++
+	s.holes++
 	if c, ok := a.(io.Closer); ok {
 		return c.Close()
 	}
@@ -56,13 +46,13 @@ func AddHandle(ctx context.Context, a any) (id uint32) {
 	if a == nil {
 		panic(NilErr)
 	}
-	s := ctx.Value(handleKey{}).(*handleState)
+	s := ctx.Value(moduleKey{}).(*moduleState)
 
 	// Find an empty slot.
-	if s.empty > cap(s.handles)-len(s.handles) {
+	if s.holes > cap(s.handles)-len(s.handles) {
 		for id, h := range s.handles {
 			if h == nil {
-				s.empty--
+				s.holes--
 				s.handles[id] = a
 				return ^uint32(id)
 			}

internal/util/mmap.go

@@ -0,0 +1,106 @@
+//go:build (darwin || linux || illumos) && (amd64 || arm64 || riscv64) && !sqlite3_flock && !sqlite3_noshm && !sqlite3_nosys
+
+package util
+
+import (
+	"context"
+	"os"
+	"unsafe"
+
+	"github.com/tetratelabs/wazero/api"
+	"github.com/tetratelabs/wazero/experimental"
+	"golang.org/x/sys/unix"
+)
+
+type mmapState struct {
+	regions []*MappedRegion
+	enabled bool
+}
+
+func (s *mmapState) init(ctx context.Context, enabled bool) context.Context {
+	if s.enabled = enabled; enabled {
+		return experimental.WithMemoryAllocator(ctx,
+			experimental.MemoryAllocatorFunc(mmappedAllocator))
+	}
+	return ctx
+}
+
+func CanMap(ctx context.Context) bool {
+	s := ctx.Value(moduleKey{}).(*moduleState)
+	return s.mmapState.enabled
+}
+
+func (s *mmapState) new(ctx context.Context, mod api.Module, size int32) *MappedRegion {
+	// Find unused region.
+	for _, r := range s.regions {
+		if !r.used && r.size == size {
+			return r
+		}
+	}
+
+	// Allocate page aligned memmory.
+	alloc := mod.ExportedFunction("aligned_alloc")
+	stack := [2]uint64{
+		uint64(unix.Getpagesize()),
+		uint64(size),
+	}
+	if err := alloc.CallWithStack(ctx, stack[:]); err != nil {
+		panic(err)
+	}
+	if stack[0] == 0 {
+		panic(OOMErr)
+	}
+
+	// Save the newly allocated region.
+	ptr := uint32(stack[0])
+	buf := View(mod, ptr, uint64(size))
+	addr := uintptr(unsafe.Pointer(&buf[0]))
+	s.regions = append(s.regions, &MappedRegion{
+		Ptr:  ptr,
+		addr: addr,
+		size: size,
+	})
+	return s.regions[len(s.regions)-1]
+}
+
+type MappedRegion struct {
+	addr uintptr
+	Ptr  uint32
+	size int32
+	used bool
+}
+
+func MapRegion(ctx context.Context, mod api.Module, f *os.File, offset int64, size int32, prot int) (*MappedRegion, error) {
+	s := ctx.Value(moduleKey{}).(*moduleState)
+	r := s.new(ctx, mod, size)
+	err := r.mmap(f, offset, prot)
+	if err != nil {
+		return nil, err
+	}
+	return r, nil
+}
+
+func (r *MappedRegion) Unmap() error {
+	// We can't munmap the region, otherwise it could be remaped.
+	// Instead, convert it to a protected, private, anonymous mapping.
+	// If successful, it can be reused for a subsequent mmap.
+	_, err := mmap(r.addr, uintptr(r.size),
+		unix.PROT_NONE, unix.MAP_PRIVATE|unix.MAP_ANON|unix.MAP_FIXED,
+		-1, 0)
+	r.used = err != nil
+	return err
+}
+
+func (r *MappedRegion) mmap(f *os.File, offset int64, prot int) error {
+	_, err := mmap(r.addr, uintptr(r.size),
+		prot, unix.MAP_SHARED|unix.MAP_FIXED,
+		int(f.Fd()), offset)
+	r.used = err == nil
+	return err
+}
+
+// We need the low level mmap for MAP_FIXED to work.
+// Bind the syscall version hoping that it is more stable.
+
+//go:linkname mmap syscall.mmap
+func mmap(addr, length uintptr, prot, flag, fd int, pos int64) (*byte, error)

internal/util/mmap_other.go

@@ -0,0 +1,15 @@
+//go:build !(darwin || linux || illumos) || !(amd64 || arm64 || riscv64) || sqlite3_flock || sqlite3_noshm || sqlite3_nosys
+
+package util
+
+import "context"
+
+type mmapState struct{}
+
+func (s *mmapState) init(ctx context.Context, _ bool) context.Context {
+	return ctx
+}
+
+func CanMap(ctx context.Context) bool {
+	return false
+}

internal/util/module.go

@@ -0,0 +1,21 @@
+package util
+
+import (
+	"context"
+
+	"github.com/tetratelabs/wazero/experimental"
+)
+
+type moduleKey struct{}
+type moduleState struct {
+	handleState
+	mmapState
+}
+
+func NewContext(ctx context.Context, mappableMemory bool) context.Context {
+	state := new(moduleState)
+	ctx = context.WithValue(ctx, moduleKey{}, state)
+	ctx = experimental.WithCloseNotifier(ctx, state)
+	ctx = state.mmapState.init(ctx, mappableMemory)
+	return ctx
+}

sqlite.go

@@ -15,14 +15,14 @@ import (
 	"github.com/tetratelabs/wazero/api"
 )
 
-// Configure SQLite WASM.
+// Configure SQLite Wasm.
 //
-// Importing package embed initializes these
+// Importing package embed initializes [Binary]
 // with an appropriate build of SQLite:
 //
 //	import _ "github.com/ncruces/go-sqlite3/embed"
 var (
-	Binary []byte // WASM binary to load.
+	Binary []byte // Wasm binary to load.
 	Path   string // Path to load the binary from.
 
 	RuntimeConfig wazero.RuntimeConfig
@@ -85,10 +85,10 @@ func instantiateSQLite() (sqlt *sqlite, err error) {
 	}
 
 	sqlt = new(sqlite)
-	sqlt.ctx = util.NewContext(context.Background())
+	sqlt.ctx = util.NewContext(context.Background(), vfs.SupportsSharedMemory)
 
 	sqlt.mod, err = instance.runtime.InstantiateModule(sqlt.ctx,
-		instance.compiled, wazero.NewModuleConfig())
+		instance.compiled, wazero.NewModuleConfig().WithName(""))
 	if err != nil {
 		return nil, err
 	}
@@ -99,8 +99,8 @@ func instantiateSQLite() (sqlt *sqlite, err error) {
 	}
 
 	sqlt.freer = util.ReadUint32(sqlt.mod, uint32(global.Get()))
-	if err != nil {
-		return nil, err
+	if sqlt.freer == 0 {
+		return nil, util.BadBinaryErr
 	}
 	return sqlt, nil
 }
@@ -274,7 +274,7 @@ func (a *arena) new(size uint64) uint32 {
 }
 
 func (a *arena) bytes(b []byte) uint32 {
-	if b == nil {
+	if (*[0]byte)(b) == nil {
 		return 0
 	}
 	ptr := a.new(uint64(len(b)))
@@ -294,6 +294,8 @@ func exportCallbacks(env wazero.HostModuleBuilder) wazero.HostModuleBuilder {
 	util.ExportFuncII(env, "go_commit_hook", commitCallback)
 	util.ExportFuncVI(env, "go_rollback_hook", rollbackCallback)
 	util.ExportFuncVIIIIJ(env, "go_update_hook", updateCallback)
+	util.ExportFuncIIIII(env, "go_wal_hook", walCallback)
+	util.ExportFuncIIIIII(env, "go_autovacuum_pages", autoVacuumCallback)
 	util.ExportFuncIIIIIII(env, "go_authorizer", authorizerCallback)
 	util.ExportFuncVIII(env, "go_log", logCallback)
 	util.ExportFuncVI(env, "go_destroy", destroyCallback)

sqlite3/download.sh

@@ -12,25 +12,25 @@ cat *.patch | patch --no-backup-if-mismatch
 
 mkdir -p ext/
 cd ext/
-curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.2/ext/misc/anycollseq.c"
-curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.2/ext/misc/base64.c"
-curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.2/ext/misc/decimal.c"
-curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.2/ext/misc/ieee754.c"
-curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.2/ext/misc/regexp.c"
-curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.2/ext/misc/series.c"
-curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.2/ext/misc/uint.c"
-curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.2/ext/misc/uuid.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.3/ext/misc/anycollseq.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.3/ext/misc/base64.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.3/ext/misc/decimal.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.3/ext/misc/ieee754.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.3/ext/misc/regexp.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.3/ext/misc/series.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.3/ext/misc/uint.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.3/ext/misc/uuid.c"
 cd ~-
 
 cd ../vfs/tests/mptest/testdata/
-curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.2/mptest/mptest.c"
-curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.2/mptest/config01.test"
-curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.2/mptest/config02.test"
-curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.2/mptest/crash01.test"
-curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.2/mptest/crash02.subtest"
-curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.2/mptest/multiwrite01.test"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.3/mptest/mptest.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.3/mptest/config01.test"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.3/mptest/config02.test"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.3/mptest/crash01.test"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.3/mptest/crash02.subtest"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.3/mptest/multiwrite01.test"
 cd ~-
 
 cd ../vfs/tests/speedtest1/testdata/
-curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.2/test/speedtest1.c"
+curl -#OL "https://github.com/sqlite/sqlite/raw/version-3.45.3/test/speedtest1.c"
 cd ~-

sqlite3/hooks.c

@@ -8,12 +8,16 @@ int go_busy_handler(void *, int);
 int go_commit_hook(void *);
 void go_rollback_hook(void *);
 void go_update_hook(void *, int, char const *, char const *, sqlite3_int64);
+int go_wal_hook(void *, sqlite3 *, const char *, int);
 
 int go_authorizer(void *, int, const char *, const char *, const char *,
                   const char *);
 
 void go_log(void *, int, const char *);
 
+unsigned int go_autovacuum_pages(void *, const char *, unsigned int,
+                                 unsigned int, unsigned int);
+
 void sqlite3_progress_handler_go(sqlite3 *db, int n) {
   sqlite3_progress_handler(db, n, go_progress_handler, /*arg=*/db);
 }
@@ -34,6 +38,10 @@ void sqlite3_update_hook_go(sqlite3 *db, bool enable) {
   sqlite3_update_hook(db, enable ? go_update_hook : NULL, /*arg=*/db);
 }
 
+void sqlite3_wal_hook_go(sqlite3 *db, bool enable) {
+  sqlite3_wal_hook(db, enable ? go_wal_hook : NULL, /*arg=*/NULL);
+}
+
 int sqlite3_set_authorizer_go(sqlite3 *db, bool enable) {
   return sqlite3_set_authorizer(db, enable ? go_authorizer : NULL, /*arg=*/db);
 }
@@ -41,4 +49,10 @@ int sqlite3_set_authorizer_go(sqlite3 *db, bool enable) {
 int sqlite3_config_log_go(bool enable) {
   return sqlite3_config(SQLITE_CONFIG_LOG, enable ? go_log : NULL,
                         /*arg=*/NULL);
+}
+
+int sqlite3_autovacuum_pages_go(sqlite3 *db, go_handle app) {
+  int rc = sqlite3_autovacuum_pages(db, go_autovacuum_pages, app, go_destroy);
+  if (rc) go_destroy(app);
+  return rc;
 }

sqlite3/sqlite_cfg.h

@@ -57,8 +57,8 @@
 #define SQLITE_ENABLE_ATOMIC_WRITE
 #define SQLITE_ENABLE_BATCH_ATOMIC_WRITE
 
-// Because WASM does not support shared memory,
-// SQLite disables WAL for WASM builds.
+// Because Wasm does not support shared memory,
+// SQLite disables WAL for Wasm builds.
 // We patch SQLite to use exclusive locking mode instead.
 // https://sqlite.org/wal.html#noshm
 #undef SQLITE_OMIT_WAL

sqlite3/vfs.c

@@ -5,15 +5,15 @@
 #include "include.h"
 #include "sqlite3.h"
 
-int go_localtime(struct tm *, sqlite3_int64);
 int go_vfs_find(const char *zVfsName);
+int go_localtime(struct tm *, sqlite3_int64);
 
 int go_randomness(sqlite3_vfs *, int nByte, char *zOut);
 int go_sleep(sqlite3_vfs *, int microseconds);
 int go_current_time_64(sqlite3_vfs *, sqlite3_int64 *);
 
 int go_open(sqlite3_vfs *, sqlite3_filename zName, sqlite3_file *, int flags,
-            int *pOutFlags);
+            int *pOutFlags, int *pOutVFS);
 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);
@@ -32,29 +32,55 @@ int go_lock(sqlite3_file *, int eLock);
 int go_unlock(sqlite3_file *, int eLock);
 int go_check_reserved_lock(sqlite3_file *, int *pResOut);
 
+int go_shm_map(sqlite3_file *, int iPg, int pgsz, int, void volatile **);
+int go_shm_lock(sqlite3_file *, int offset, int n, int flags);
+int go_shm_unmap(sqlite3_file *, int deleteFlag);
+void go_shm_barrier(sqlite3_file *);
+
 static int go_open_wrapper(sqlite3_vfs *vfs, sqlite3_filename zName,
                            sqlite3_file *file, int flags, int *pOutFlags) {
-  static const sqlite3_io_methods os_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 = go_file_control,
-      .xSectorSize = go_sector_size,
-      .xDeviceCharacteristics = go_device_characteristics,
-  };
+  static const sqlite3_io_methods go_io[2] = {
+      {
+          .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 = go_file_control,
+          .xSectorSize = go_sector_size,
+          .xDeviceCharacteristics = go_device_characteristics,
+      },
+      {
+          .iVersion = 2,
+          .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 = go_file_control,
+          .xSectorSize = go_sector_size,
+          .xDeviceCharacteristics = go_device_characteristics,
+          .xShmMap = go_shm_map,
+          .xShmLock = go_shm_lock,
+          .xShmBarrier = go_shm_barrier,
+          .xShmUnmap = go_shm_unmap,
+      }};
+  int vfsID = 0;
   memset(file, 0, vfs->szOsFile);
-  int rc = go_open(vfs, zName, file, flags, pOutFlags);
+  int rc = go_open(vfs, zName, file, flags, pOutFlags, &vfsID);
   if (rc) {
     return rc;
   }
-  file->pMethods = &os_io;
+  file->pMethods = &go_io[vfsID];
   return SQLITE_OK;
 }
 

stmt.go

@@ -120,7 +120,7 @@ func (s *Stmt) Status(op StmtStatus, reset bool) int {
 	}
 	r := s.c.call("sqlite3_stmt_status", uint64(s.handle),
 		uint64(op), i)
-	return int(r)
+	return int(int32(r))
 }
 
 // ClearBindings resets all bindings on the prepared statement.
@@ -137,7 +137,7 @@ func (s *Stmt) ClearBindings() error {
 func (s *Stmt) BindCount() int {
 	r := s.c.call("sqlite3_bind_parameter_count",
 		uint64(s.handle))
-	return int(r)
+	return int(int32(r))
 }
 
 // BindIndex returns the index of a parameter in the prepared statement
@@ -149,7 +149,7 @@ func (s *Stmt) BindIndex(name string) int {
 	namePtr := s.c.arena.string(name)
 	r := s.c.call("sqlite3_bind_parameter_index",
 		uint64(s.handle), uint64(namePtr))
-	return int(r)
+	return int(int32(r))
 }
 
 // BindName returns the name of a parameter in the prepared statement.
@@ -357,7 +357,7 @@ func (s *Stmt) BindValue(param int, value Value) error {
 func (s *Stmt) ColumnCount() int {
 	r := s.c.call("sqlite3_column_count",
 		uint64(s.handle))
-	return int(r)
+	return int(int32(r))
 }
 
 // ColumnName returns the name of the result column.
@@ -553,6 +553,14 @@ func (s *Stmt) ColumnValue(col int) Value {
 	}
 }
 
+// Columns populates result columns into the provided slice.
+// The slice must have [Stmt.ColumnCount] length.
+//
+// [INTEGER] columns will be retrieved as int64 values,
+// [FLOAT] as float64, [NULL] as nil,
+// [TEXT] as string, and [BLOB] as []byte.
+// Any []byte are owned by SQLite and may be invalidated by
+// subsequent calls to [Stmt] methods.
 func (s *Stmt) Columns(dest []any) error {
 	defer s.c.arena.mark()()
 	count := uint64(len(dest))

tests/backup_test.go

@@ -20,7 +20,7 @@ func TestBackup(t *testing.T) {
 		}
 		defer db.Close()
 
-		err = db.Exec(`CREATE TABLE IF NOT EXISTS users (id INT, name VARCHAR(10))`)
+		err = db.Exec(`CREATE TABLE users (id INT, name VARCHAR(10))`)
 		if err != nil {
 			t.Fatal(err)
 		}

tests/blob_test.go

@@ -22,7 +22,7 @@ func TestBlob(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -97,7 +97,7 @@ func TestBlob_large(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -158,7 +158,7 @@ func TestBlob_overflow(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -217,7 +217,7 @@ func TestBlob_invalid(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -242,7 +242,7 @@ func TestBlob_Write_readonly(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -273,7 +273,7 @@ func TestBlob_Read_expired(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -309,7 +309,7 @@ func TestBlob_Seek(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -358,7 +358,7 @@ func TestBlob_Reopen(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}

tests/conn_test.go

@@ -6,12 +6,12 @@ import (
 	"math"
 	"os"
 	"path/filepath"
-	"reflect"
 	"strings"
 	"testing"
 
 	"github.com/ncruces/go-sqlite3"
 	_ "github.com/ncruces/go-sqlite3/embed"
+	_ "github.com/ncruces/go-sqlite3/vfs/memdb"
 )
 
 func TestConn_Open_dir(t *testing.T) {
@@ -111,41 +111,6 @@ func TestConn_Close_BUSY(t *testing.T) {
 	}
 }
 
-func TestConn_Pragma(t *testing.T) {
-	t.Parallel()
-
-	db, err := sqlite3.Open("file::memory:?_pragma=busy_timeout(1000)")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer db.Close()
-
-	got, err := db.Pragma("busy_timeout")
-	if err != nil {
-		t.Fatal(err)
-	}
-	want := []string{"1000"}
-
-	if !reflect.DeepEqual(got, want) {
-		t.Errorf("got %v, want %v", got, want)
-	}
-
-	var serr *sqlite3.Error
-	_, err = db.Pragma("+")
-	if err == nil {
-		t.Error("want: error")
-	}
-	if !errors.As(err, &serr) {
-		t.Fatalf("got %T, want sqlite3.Error", err)
-	}
-	if rc := serr.Code(); rc != sqlite3.ERROR {
-		t.Errorf("got %d, want sqlite3.ERROR", rc)
-	}
-	if got := err.Error(); got != `sqlite3: SQL logic error: near "+": syntax error` {
-		t.Error("got message:", got)
-	}
-}
-
 func TestConn_SetInterrupt(t *testing.T) {
 	t.Parallel()
 
@@ -485,3 +450,35 @@ func TestConn_DBName(t *testing.T) {
 		t.Errorf("got %s", name)
 	}
 }
+
+func TestConn_AutoVacuumPages(t *testing.T) {
+	t.Parallel()
+
+	db, err := sqlite3.Open("file:test.db?vfs=memdb&_pragma=auto_vacuum(FULL)")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.AutoVacuumPages(func(schema string, dbPages, freePages, bytesPerPage uint) uint {
+		return freePages
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = db.Exec(`CREATE TABLE test (col)`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = db.Exec(`INSERT INTO test VALUES (zeroblob(1024*1024))`)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = db.Exec(`DROP TABLE test`)
+	if err != nil {
+		t.Fatal(err)
+	}
+}

tests/driver_test.go

@@ -27,7 +27,7 @@ func TestDriver(t *testing.T) {
 	defer conn.Close()
 
 	res, err := conn.ExecContext(ctx,
-		`CREATE TABLE IF NOT EXISTS users (id INT, name VARCHAR(10))`)
+		`CREATE TABLE users (id INT, name VARCHAR(10))`)
 	if err != nil {
 		t.Fatal(err)
 	}

tests/func_test.go

@@ -196,7 +196,7 @@ func TestAnyCollationNeeded(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS users (id INT, name VARCHAR(10))`)
+	err = db.Exec(`CREATE TABLE users (id INT, name VARCHAR(10))`)
 	if err != nil {
 		t.Fatal(err)
 	}

tests/json_test.go

@@ -31,7 +31,7 @@ func TestJSON(t *testing.T) {
 	}
 	defer conn.Close()
 
-	_, err = conn.ExecContext(ctx, `CREATE TABLE IF NOT EXISTS test (col)`)
+	_, err = conn.ExecContext(ctx, `CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}

tests/parallel/parallel_test.go

@@ -12,9 +12,16 @@ import (
 
 	"github.com/ncruces/go-sqlite3"
 	_ "github.com/ncruces/go-sqlite3/embed"
+	"github.com/ncruces/go-sqlite3/vfs"
 	"github.com/ncruces/go-sqlite3/vfs/memdb"
+	"github.com/tetratelabs/wazero"
 )
 
+func TestMain(m *testing.M) {
+	sqlite3.RuntimeConfig = wazero.NewRuntimeConfig().WithMemoryLimitPages(1024)
+	os.Exit(m.Run())
+}
+
 func TestParallel(t *testing.T) {
 	var iter int
 	if testing.Short() {
@@ -32,6 +39,20 @@ func TestParallel(t *testing.T) {
 	testIntegrity(t, name)
 }
 
+func TestWAL(t *testing.T) {
+	if !vfs.SupportsSharedMemory {
+		t.Skip("skipping without shared memory")
+	}
+
+	name := "file:" +
+		filepath.Join(t.TempDir(), "test.db") +
+		"?_pragma=busy_timeout(10000)" +
+		"&_pragma=journal_mode(wal)" +
+		"&_pragma=synchronous(off)"
+	testParallel(t, name, 1000)
+	testIntegrity(t, name)
+}
+
 func TestMemory(t *testing.T) {
 	var iter int
 	if testing.Short() {

tests/stmt_test.go

@@ -19,7 +19,7 @@ func TestStmt(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}

tests/testdata/f2fs.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+cd -P -- "$(dirname -- "$0")"
+ROOT=../../
+
+if mountpoint -q f2fs/; then
+  sudo umount f2fs/
+fi
+
+mkdir -p f2fs/
+gunzip -c f2fs.img.gz > f2fs.img
+sudo mount -nv -o loop f2fs.img f2fs/
+mkdir -p f2fs/tmp/
+
+go test -c "$ROOT/tests" -coverpkg github.com/ncruces/go-sqlite3/...
+TMPDIR=f2fs/tmp/ ./tests.test -test.v -test.short -test.coverprofile cover.out
+go tool cover -html cover.out
+
+sudo umount f2fs/
+rm -r f2fs/ f2fs.img cover.out *.test

tests/time_test.go

@@ -146,8 +146,7 @@ func TestTimeFormat_Scanner(t *testing.T) {
 	}
 	defer conn.Close()
 
-	_, err = conn.ExecContext(ctx,
-		`CREATE TABLE IF NOT EXISTS test (col)`)
+	_, err = conn.ExecContext(ctx, `CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -178,7 +177,7 @@ func TestDB_timeCollation(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS times (tstamp COLLATE TIME)`)
+	err = db.Exec(`CREATE TABLE times (tstamp COLLATE TIME)`)
 	if err != nil {
 		t.Fatal(err)
 	}

tests/txn_test.go

@@ -22,7 +22,7 @@ func TestConn_Transaction_exec(t *testing.T) {
 	db.CommitHook(func() bool { return true })
 	db.UpdateHook(func(sqlite3.AuthorizerActionCode, string, string, int64) {})
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -95,7 +95,7 @@ func TestConn_Transaction_panic(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -153,7 +153,7 @@ func TestConn_Transaction_interrupt(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -255,7 +255,7 @@ func TestConn_Transaction_rollback(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -301,7 +301,7 @@ func TestConn_Savepoint_exec(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -369,7 +369,7 @@ func TestConn_Savepoint_panic(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -426,7 +426,7 @@ func TestConn_Savepoint_interrupt(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -506,7 +506,7 @@ func TestConn_Savepoint_rollback(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS test (col)`)
+	err = db.Exec(`CREATE TABLE test (col)`)
 	if err != nil {
 		t.Fatal(err)
 	}

tests/wal_test.go

@@ -0,0 +1,96 @@
+package tests
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/ncruces/go-sqlite3"
+	"github.com/ncruces/go-sqlite3/vfs"
+)
+
+func TestWAL_enter_exit(t *testing.T) {
+	t.Parallel()
+
+	file := filepath.Join(t.TempDir(), "test.db")
+
+	db, err := sqlite3.Open(file)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.Exec(`
+		CREATE TABLE test (col);
+		PRAGMA journal_mode=WAL;
+		SELECT * FROM test;
+		PRAGMA journal_mode=DELETE;
+		SELECT * FROM test;
+		PRAGMA journal_mode=WAL;
+		SELECT * FROM test;
+	`)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestWAL_readonly(t *testing.T) {
+	if !vfs.SupportsSharedMemory {
+		t.Skip("skipping without shared memory")
+	}
+
+	t.Parallel()
+
+	tmp := filepath.Join(t.TempDir(), "test.db")
+	err := os.WriteFile(tmp, waldb, 0666)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	db, err := sqlite3.OpenFlags(tmp, sqlite3.OPEN_READONLY)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	stmt, _, err := db.Prepare(`SELECT * FROM sqlite_master`)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stmt.Close()
+
+	if stmt.Step() {
+		t.Error("want no rows")
+	}
+}
+
+func TestConn_WalCheckpoint(t *testing.T) {
+	t.Parallel()
+
+	file := filepath.Join(t.TempDir(), "test.db")
+
+	db, err := sqlite3.Open(file)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	err = db.WalAutoCheckpoint(1000)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	db.WalHook(func(db *sqlite3.Conn, schema string, pages int) error {
+		log, ckpt, err := db.WalCheckpoint(schema, sqlite3.CHECKPOINT_FULL)
+		t.Log(log, ckpt, err)
+		return err
+	})
+
+	err = db.Exec(`
+		PRAGMA journal_mode=WAL;
+		CREATE TABLE test (col);
+	`)
+	if err != nil {
+		t.Fatal(err)
+	}
+}

txn.go

@@ -230,9 +230,6 @@ func (c *Conn) TxnState(schema string) TxnState {
 	return TxnState(r)
 }
 
-// Deprecated: renamed for consistency with [Conn.TxnState].
-type Tx = Txn
-
 // CommitHook registers a callback function to be invoked
 // whenever a transaction is committed.
 // Return true to allow the commit operation to continue normally.
@@ -260,7 +257,7 @@ func (c *Conn) RollbackHook(cb func()) {
 	c.rollback = cb
 }
 
-// RollbackHook registers a callback function to be invoked
+// UpdateHook registers a callback function to be invoked
 // whenever a row is updated, inserted or deleted in a rowid table.
 //
 // https://sqlite.org/c3ref/update_hook.html
@@ -273,13 +270,13 @@ func (c *Conn) UpdateHook(cb func(action AuthorizerActionCode, schema, table str
 	c.update = cb
 }
 
-func commitCallback(ctx context.Context, mod api.Module, pDB uint32) uint32 {
+func commitCallback(ctx context.Context, mod api.Module, pDB uint32) (rollback uint32) {
 	if c, ok := ctx.Value(connKey{}).(*Conn); ok && c.handle == pDB && c.commit != nil {
-		if ok := c.commit(); !ok {
-			return 1
+		if !c.commit() {
+			rollback = 1
 		}
 	}
-	return 0
+	return rollback
 }
 
 func rollbackCallback(ctx context.Context, mod api.Module, pDB uint32) {

util/fsutil/mode.go

@@ -1,3 +1,4 @@
+// Package fsutil implements filesystem utility functions.
 package fsutil
 
 import (

util/ioutil/seek.go

@@ -8,8 +8,8 @@ import (
 // SeekingReaderAt implements [io.ReaderAt]
 // through an underlying [io.ReadSeeker].
 type SeekingReaderAt struct {
-	l sync.Mutex
 	r io.ReadSeeker
+	l sync.Mutex
 }
 
 // NewSeekingReaderAt creates a new SeekingReaderAt.

vfs/README.md

@@ -2,6 +2,79 @@
 
 This package implements the SQLite [OS Interface](https://sqlite.org/vfs.html) (aka VFS).
 
-It replaces the default SQLite VFS with a pure Go implementation.
+It replaces the default SQLite VFS with a **pure Go** implementation.
 
-It also exposes interfaces that should allow you to implement your own custom VFSes.
+It also exposes [interfaces](https://pkg.go.dev/github.com/ncruces/go-sqlite3/vfs#VFS)
+that should allow you to implement your own custom VFSes.
+
+Since it is a from scratch reimplementation,
+there are naturally some ways it deviates from the original.
+
+The main differences are [file locking](#file-locking) and [WAL mode](write-ahead-logging) support.
+
+### File Locking
+
+POSIX advisory locks, which SQLite uses on Unix, are
+[broken by design](https://sqlite.org/src/artifact/2e8b12?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 POSIX advisory locks.
+
+On BSD Unixes, this module uses
+[BSD locks](https://man.freebsd.org/cgi/man.cgi?query=flock&sektion=2).
+On BSD Unixes, BSD locks are fully compatible with POSIX advisory locks.
+However, concurrency is reduced with BSD locks
+(`BEGIN IMMEDIATE` behaves the same as `BEGIN EXCLUSIVE`). 
+
+On Windows, this module uses `LockFileEx` and `UnlockFileEx`,
+like SQLite.
+
+On all other platforms, file locking is not supported, and you must use
+[`nolock=1`](https://sqlite.org/uri.html#urinolock)
+(or [`immutable=1`](https://sqlite.org/uri.html#uriimmutable))
+to open database files.
+
+To use the [`database/sql`](https://pkg.go.dev/database/sql) driver
+with `nolock=1` you must disable connection pooling by calling
+[`db.SetMaxOpenConns(1)`](https://pkg.go.dev/database/sql#DB.SetMaxOpenConns).
+
+You can use [`vfs.SupportsFileLocking`](https://pkg.go.dev/github.com/ncruces/go-sqlite3/vfs#SupportsFileLocking)
+to check if your platform supports file locking.
+
+### Write-Ahead Logging
+
+On 64-bit Linux, macOS and illumos, this module uses `mmap` to implement
+[shared-memory for the WAL-index](https://sqlite.org/wal.html#implementation_of_shared_memory_for_the_wal_index),
+like SQLite.
+
+To allow `mmap` to work, each connection needs to reserve up to 4GB of address space.\
+To limit the amount of address space each connection needs,
+use [`WithMemoryLimitPages`](../tests/parallel/parallel_test.go#L21).
+
+On all other platforms, [WAL](https://sqlite.org/wal.html) support is
+[limited](https://sqlite.org/wal.html#noshm).
+
+To work around this limitation, SQLite is [patched](sqlite3/locking_mode.patch)
+to automatically use `EXCLUSIVE` locking mode for WAL databases on such platforms.
+
+To use the [`database/sql`](https://pkg.go.dev/database/sql) driver
+with `EXCLUSIVE` locking mode you should disable connection pooling by calling
+[`db.SetMaxOpenConns(1)`](https://pkg.go.dev/database/sql#DB.SetMaxOpenConns).
+
+You can use [`vfs.SupportsSharedMemory`](https://pkg.go.dev/github.com/ncruces/go-sqlite3/vfs#SupportsSharedMemory)
+to check if your platform supports shared memory.
+
+### Batch-Atomic Write
+
+On 64-bit Linux, this module supports [batch-atomic writes](https://sqlite.org/cgi/src/technote/714)
+on the F2FS filesystem.
+
+### Build tags
+
+The VFS can be customized with a few build tags:
+- `sqlite3_flock` forces the use of BSD locks; it can be used on macOS to test the BSD locking implementation.
+- `sqlite3_nosys` prevents importing [`x/sys`](https://pkg.go.dev/golang.org/x/sys);
+  disables locking _and_ shared memory on all platforms.
+- `sqlite3_noshm` disables shared memory on all platforms.

vfs/const.go

@@ -37,6 +37,10 @@ const (
 	_IOERR_CHECKRESERVEDLOCK _ErrorCode = util.IOERR_CHECKRESERVEDLOCK
 	_IOERR_LOCK              _ErrorCode = util.IOERR_LOCK
 	_IOERR_CLOSE             _ErrorCode = util.IOERR_CLOSE
+	_IOERR_SHMOPEN           _ErrorCode = util.IOERR_SHMOPEN
+	_IOERR_SHMSIZE           _ErrorCode = util.IOERR_SHMSIZE
+	_IOERR_SHMLOCK           _ErrorCode = util.IOERR_SHMLOCK
+	_IOERR_SHMMAP            _ErrorCode = util.IOERR_SHMMAP
 	_IOERR_SEEK              _ErrorCode = util.IOERR_SEEK
 	_IOERR_DELETE_NOENT      _ErrorCode = util.IOERR_DELETE_NOENT
 	_IOERR_BEGIN_ATOMIC      _ErrorCode = util.IOERR_BEGIN_ATOMIC
@@ -44,6 +48,7 @@ const (
 	_IOERR_ROLLBACK_ATOMIC   _ErrorCode = util.IOERR_ROLLBACK_ATOMIC
 	_CANTOPEN_FULLPATH       _ErrorCode = util.CANTOPEN_FULLPATH
 	_CANTOPEN_ISDIR          _ErrorCode = util.CANTOPEN_ISDIR
+	_READONLY_CANTINIT       _ErrorCode = util.READONLY_CANTINIT
 	_OK_SYMLINK              _ErrorCode = util.OK_SYMLINK
 )
 
@@ -213,3 +218,13 @@ const (
 	_FCNTL_CKSM_FILE             _FcntlOpcode = 41
 	_FCNTL_RESET_CACHE           _FcntlOpcode = 42
 )
+
+// https://sqlite.org/c3ref/c_shm_exclusive.html
+type _ShmFlag uint32
+
+const (
+	_SHM_UNLOCK    _ShmFlag = 1
+	_SHM_LOCK      _ShmFlag = 2
+	_SHM_SHARED    _ShmFlag = 4
+	_SHM_EXCLUSIVE _ShmFlag = 8
+)

vfs/file.go

@@ -1,6 +1,7 @@
 package vfs
 
 import (
+	"context"
 	"errors"
 	"io"
 	"io/fs"
@@ -11,6 +12,7 @@ import (
 	"syscall"
 
 	"github.com/ncruces/go-sqlite3/util/osutil"
+	"github.com/tetratelabs/wazero/api"
 )
 
 type vfsOS struct{}
@@ -125,6 +127,7 @@ func (vfsOS) OpenParams(name string, flags OpenFlag, params url.Values) (File, O
 
 type vfsFile struct {
 	*os.File
+	shm      vfsShm
 	lock     LockLevel
 	readOnly bool
 	keepWAL  bool
@@ -141,6 +144,11 @@ var (
 	_ FilePowersafeOverwrite = &vfsFile{}
 )
 
+func (f *vfsFile) Close() error {
+	f.shm.Close()
+	return f.File.Close()
+}
+
 func (f *vfsFile) Sync(flags SyncFlag) error {
 	dataonly := (flags & SYNC_DATAONLY) != 0
 	fullsync := (flags & 0x0f) == SYNC_FULL
@@ -173,10 +181,14 @@ func (*vfsFile) SectorSize() int {
 }
 
 func (f *vfsFile) DeviceCharacteristics() DeviceCharacteristic {
-	if f.psow {
-		return IOCAP_POWERSAFE_OVERWRITE
+	var res DeviceCharacteristic
+	if osBatchAtomic(f.File) {
+		res |= IOCAP_BATCH_ATOMIC
 	}
-	return 0
+	if f.psow {
+		res |= IOCAP_POWERSAFE_OVERWRITE
+	}
+	return res
 }
 
 func (f *vfsFile) SizeHint(size int64) error {
@@ -203,3 +215,9 @@ func (f *vfsFile) PowersafeOverwrite() bool        { return f.psow }
 func (f *vfsFile) PersistentWAL() bool             { return f.keepWAL }
 func (f *vfsFile) SetPowersafeOverwrite(psow bool) { f.psow = psow }
 func (f *vfsFile) SetPersistentWAL(keepWAL bool)   { f.keepWAL = keepWAL }
+
+type fileShm interface {
+	shmMap(context.Context, api.Module, int32, int32, bool) (uint32, error)
+	shmLock(int32, int32, _ShmFlag) error
+	shmUnmap(bool)
+}

vfs/lock.go

@@ -1,7 +1,17 @@
+//go:build (linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && !sqlite3_nosys
+
 package vfs
 
 import "github.com/ncruces/go-sqlite3/internal/util"
 
+// SupportsFileLocking is false on platforms that do not support file locking.
+// To open a database file on those platforms,
+// you need to use the [nolock] or [immutable] URI parameters.
+//
+// [nolock]: https://sqlite.org/uri.html#urinolock
+// [immutable]: https://sqlite.org/uri.html#uriimmutable
+const SupportsFileLocking = true
+
 const (
 	_PENDING_BYTE  = 0x40000000
 	_RESERVED_BYTE = (_PENDING_BYTE + 1)
@@ -107,11 +117,9 @@ func (f *vfsFile) Unlock(lock LockLevel) error {
 
 	switch lock {
 	case LOCK_SHARED:
-		if rc := osDowngradeLock(f.File, f.lock); rc != _OK {
-			return rc
-		}
+		rc := osDowngradeLock(f.File, f.lock)
 		f.lock = LOCK_SHARED
-		return nil
+		return rc
 
 	case LOCK_NONE:
 		rc := osReleaseLock(f.File, f.lock)

vfs/lock_other.go

@@ -0,0 +1,23 @@
+//go:build !(linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) || sqlite3_nosys
+
+package vfs
+
+// SupportsFileLocking is false on platforms that do not support file locking.
+// To open a database file on those platforms,
+// you need to use the [nolock] or [immutable] URI parameters.
+//
+// [nolock]: https://sqlite.org/uri.html#urinolock
+// [immutable]: https://sqlite.org/uri.html#uriimmutable
+const SupportsFileLocking = false
+
+func (f *vfsFile) Lock(LockLevel) error {
+	return _IOERR_LOCK
+}
+
+func (f *vfsFile) Unlock(LockLevel) error {
+	return _IOERR_UNLOCK
+}
+
+func (f *vfsFile) CheckReservedLock() (bool, error) {
+	return false, _IOERR_CHECKRESERVEDLOCK
+}

vfs/lock_test.go

@@ -33,7 +33,7 @@ func Test_vfsLock(t *testing.T) {
 		pOutput = 32
 	)
 	mod := wazerotest.NewModule(wazerotest.NewMemory(wazerotest.PageSize))
-	ctx := util.NewContext(context.TODO())
+	ctx := util.NewContext(context.TODO(), false)
 
 	vfsFileRegister(ctx, mod, pFile1, &vfsFile{File: file1})
 	vfsFileRegister(ctx, mod, pFile2, &vfsFile{File: file2})

vfs/memdb/memdb_test.go

@@ -21,7 +21,7 @@ func Test_wal(t *testing.T) {
 	}
 	defer db.Close()
 
-	err = db.Exec(`CREATE TABLE IF NOT EXISTS users (id INT, name VARCHAR(10))`)
+	err = db.Exec(`CREATE TABLE users (id INT, name VARCHAR(10))`)
 	if err != nil {
 		t.Fatal(err)
 	}

vfs/os_bsd.go

@@ -31,15 +31,3 @@ func osReadLock(file *os.File, _ /*start*/, _ /*len*/ int64, _ /*timeout*/ time.
 func osWriteLock(file *os.File, _ /*start*/, _ /*len*/ int64, _ /*timeout*/ time.Duration) _ErrorCode {
 	return osLock(file, unix.LOCK_EX|unix.LOCK_NB, _IOERR_LOCK)
 }
-
-func osCheckLock(file *os.File, start, len int64) (bool, _ErrorCode) {
-	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

@@ -14,7 +14,6 @@ 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
 )
 
@@ -94,15 +93,3 @@ func osReadLock(file *os.File, start, len int64, timeout time.Duration) _ErrorCo
 func osWriteLock(file *os.File, start, len int64, timeout time.Duration) _ErrorCode {
 	return osLock(file, unix.F_WRLCK, start, len, timeout, _IOERR_LOCK)
 }
-
-func osCheckLock(file *os.File, start, len int64) (bool, _ErrorCode) {
-	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_f2fs_linux.go

@@ -0,0 +1,34 @@
+//go:build (amd64 || arm64 || riscv64) && !sqlite3_nosys
+
+package vfs
+
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+const (
+	_F2FS_IOC_START_ATOMIC_WRITE  = 62721
+	_F2FS_IOC_COMMIT_ATOMIC_WRITE = 62722
+	_F2FS_IOC_ABORT_ATOMIC_WRITE  = 62725
+	_F2FS_IOC_GET_FEATURES        = 2147808524
+	_F2FS_FEATURE_ATOMIC_WRITE    = 4
+)
+
+func osBatchAtomic(file *os.File) bool {
+	flags, err := unix.IoctlGetInt(int(file.Fd()), _F2FS_IOC_GET_FEATURES)
+	return err == nil && flags&_F2FS_FEATURE_ATOMIC_WRITE != 0
+}
+
+func (f *vfsFile) BeginAtomicWrite() error {
+	return unix.IoctlSetInt(int(f.Fd()), _F2FS_IOC_START_ATOMIC_WRITE, 0)
+}
+
+func (f *vfsFile) CommitAtomicWrite() error {
+	return unix.IoctlSetInt(int(f.Fd()), _F2FS_IOC_COMMIT_ATOMIC_WRITE, 0)
+}
+
+func (f *vfsFile) RollbackAtomicWrite() error {
+	return unix.IoctlSetInt(int(f.Fd()), _F2FS_IOC_ABORT_ATOMIC_WRITE, 0)
+}

vfs/os_linux.go

@@ -8,15 +8,9 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-func osSync(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 osSync(file *os.File, _ /*fullsync*/, _ /*dataonly*/ bool) error {
+	// SQLite trusts Linux's fdatasync for all fsync's.
+	return unix.Fdatasync(int(file.Fd()))
 }
 
 func osAllocate(file *os.File, size int64) error {

vfs/os_nolock.go

@@ -1,41 +0,0 @@
-//go:build !(linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) || sqlite3_nosys
-
-package vfs
-
-import "os"
-
-// SupportsFileLocking is false on platforms that do not support file locking.
-// To open a database file in one such platform,
-// you need to use the [nolock] or [immutable] URI parameters.
-//
-// [nolock]: https://sqlite.org/uri.html#urinolock
-// [immutable]: https://sqlite.org/uri.html#uriimmutable
-const SupportsFileLocking = false
-
-func osGetSharedLock(_ *os.File) _ErrorCode {
-	return _IOERR_RDLOCK
-}
-
-func osGetReservedLock(_ *os.File) _ErrorCode {
-	return _IOERR_LOCK
-}
-
-func osGetPendingLock(_ *os.File, _ bool) _ErrorCode {
-	return _IOERR_LOCK
-}
-
-func osGetExclusiveLock(_ *os.File, _ bool) _ErrorCode {
-	return _IOERR_LOCK
-}
-
-func osDowngradeLock(_ *os.File, _ LockLevel) _ErrorCode {
-	return _IOERR_RDLOCK
-}
-
-func osReleaseLock(_ *os.File, _ LockLevel) _ErrorCode {
-	return _IOERR_UNLOCK
-}
-
-func osCheckReservedLock(_ *os.File) (bool, _ErrorCode) {
-	return false, _IOERR_CHECKRESERVEDLOCK
-}

vfs/os_ofd.go

@@ -3,6 +3,7 @@
 package vfs
 
 import (
+	"math/rand"
 	"os"
 	"time"
 
@@ -40,10 +41,10 @@ func osLock(file *os.File, typ int16, start, len int64, timeout time.Duration, d
 			if errno, _ := err.(unix.Errno); errno != unix.EAGAIN {
 				break
 			}
-			if timeout <= 0 || timeout < time.Since(before) {
+			if timeout < time.Since(before) {
 				break
 			}
-			osSleep(time.Millisecond)
+			osSleep(time.Duration(rand.Int63n(int64(time.Millisecond))))
 		}
 	}
 	return osLockErrorCode(err, def)
@@ -56,15 +57,3 @@ func osReadLock(file *os.File, start, len int64, timeout time.Duration) _ErrorCo
 func osWriteLock(file *os.File, start, len int64, timeout time.Duration) _ErrorCode {
 	return osLock(file, unix.F_WRLCK, start, len, timeout, _IOERR_LOCK)
 }
-
-func osCheckLock(file *os.File, start, len int64) (bool, _ErrorCode) {
-	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_std_atomic.go

@@ -0,0 +1,9 @@
+//go:build !linux || !(amd64 || arm64 || riscv64) || sqlite3_nosys
+
+package vfs
+
+import "os"
+
+func osBatchAtomic(*os.File) bool {
+	return false
+}

vfs/os_unix_lock.go

@@ -9,17 +9,9 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-// SupportsFileLocking is false on platforms that do not support file locking.
-// To open a database file in one such platform,
-// you need to use the [nolock] or [immutable] URI parameters.
-//
-// [nolock]: https://sqlite.org/uri.html#urinolock
-// [immutable]: https://sqlite.org/uri.html#uriimmutable
-const SupportsFileLocking = true
-
 func osGetSharedLock(file *os.File) _ErrorCode {
 	// Test the PENDING lock before acquiring a new SHARED lock.
-	if pending, _ := osCheckLock(file, _PENDING_BYTE, 1); pending {
+	if lock, _ := osGetLock(file, _PENDING_BYTE, 1); lock == unix.F_WRLCK {
 		return _BUSY
 	}
 	// Acquire the SHARED lock.
@@ -72,7 +64,20 @@ func osReleaseLock(file *os.File, _ LockLevel) _ErrorCode {
 
 func osCheckReservedLock(file *os.File) (bool, _ErrorCode) {
 	// Test the RESERVED lock.
-	return osCheckLock(file, _RESERVED_BYTE, 1)
+	lock, rc := osGetLock(file, _RESERVED_BYTE, 1)
+	return lock == unix.F_WRLCK, rc
+}
+
+func osGetLock(file *os.File, start, len int64) (int16, _ErrorCode) {
+	lock := unix.Flock_t{
+		Type:  unix.F_WRLCK,
+		Start: start,
+		Len:   len,
+	}
+	if unix.FcntlFlock(file.Fd(), unix.F_GETLK, &lock) != nil {
+		return 0, _IOERR_CHECKRESERVEDLOCK
+	}
+	return lock.Type, _OK
 }
 
 func osLockErrorCode(err error, def _ErrorCode) _ErrorCode {

vfs/os_windows.go

@@ -3,24 +3,16 @@
 package vfs
 
 import (
+	"math/rand"
 	"os"
 	"time"
 
 	"golang.org/x/sys/windows"
 )
 
-// SupportsFileLocking is false on platforms that do not support file locking.
-// To open a database file in one such platform,
-// you need to use the [nolock] or [immutable] URI parameters.
-//
-// [nolock]: https://sqlite.org/uri.html#urinolock
-// [immutable]: https://sqlite.org/uri.html#uriimmutable
-const SupportsFileLocking = true
-
 func osGetSharedLock(file *os.File) _ErrorCode {
 	// Acquire the PENDING lock temporarily before acquiring a new SHARED lock.
 	rc := osReadLock(file, _PENDING_BYTE, 1, 0)
-
 	if rc == _OK {
 		// Acquire the SHARED lock.
 		rc = osReadLock(file, _SHARED_FIRST, _SHARED_SIZE, 0)
@@ -104,7 +96,15 @@ func osReleaseLock(file *os.File, state LockLevel) _ErrorCode {
 
 func osCheckReservedLock(file *os.File) (bool, _ErrorCode) {
 	// Test the RESERVED lock.
-	return osCheckLock(file, _RESERVED_BYTE, 1)
+	rc := osLock(file, 0, _RESERVED_BYTE, 1, 0, _IOERR_CHECKRESERVEDLOCK)
+	if rc == _BUSY {
+		return true, _OK
+	}
+	if rc == _OK {
+		// Release the RESERVED lock.
+		osUnlock(file, _RESERVED_BYTE, 1)
+	}
+	return false, rc
 }
 
 func osUnlock(file *os.File, start, len uint32) _ErrorCode {
@@ -133,10 +133,10 @@ func osLock(file *os.File, flags, start, len uint32, timeout time.Duration, def
 			if errno, _ := err.(windows.Errno); errno != windows.ERROR_LOCK_VIOLATION {
 				break
 			}
-			if timeout <= 0 || timeout < time.Since(before) {
+			if timeout < time.Since(before) {
 				break
 			}
-			osSleep(time.Millisecond)
+			osSleep(time.Duration(rand.Int63n(int64(time.Millisecond))))
 		}
 	}
 	return osLockErrorCode(err, def)
@@ -155,17 +155,6 @@ func osWriteLock(file *os.File, start, len uint32, timeout time.Duration) _Error
 	return osLock(file, windows.LOCKFILE_EXCLUSIVE_LOCK, start, len, timeout, _IOERR_LOCK)
 }
 
-func osCheckLock(file *os.File, start, len uint32) (bool, _ErrorCode) {
-	rc := osLock(file, 0, start, len, 0, _IOERR_CHECKRESERVEDLOCK)
-	if rc == _BUSY {
-		return true, _OK
-	}
-	if rc == _OK {
-		osUnlock(file, start, len)
-	}
-	return false, rc
-}
-
 func osLockErrorCode(err error, def _ErrorCode) _ErrorCode {
 	if err == nil {
 		return _OK

vfs/shm.go

@@ -0,0 +1,151 @@
+//go:build (darwin || linux || illumos) && (amd64 || arm64 || riscv64) && !sqlite3_flock && !sqlite3_noshm && !sqlite3_nosys
+
+package vfs
+
+import (
+	"context"
+	"io"
+	"os"
+
+	"github.com/ncruces/go-sqlite3/internal/util"
+	"github.com/tetratelabs/wazero/api"
+	"golang.org/x/sys/unix"
+)
+
+// SupportsSharedMemory is true on platforms that support shared memory.
+// To enable shared memory support on those platforms,
+// you need to set the appropriate [wazero.RuntimeConfig];
+// otherwise, [EXCLUSIVE locking mode] is activated automatically
+// to use [WAL without shared-memory].
+//
+// [WAL without shared-memory]: https://sqlite.org/wal.html#noshm
+// [EXCLUSIVE locking mode]: https://sqlite.org/pragma.html#pragma_locking_mode
+const SupportsSharedMemory = true
+
+type vfsShm struct {
+	*os.File
+	regions []*util.MappedRegion
+}
+
+const (
+	_SHM_NLOCK = 8
+	_SHM_BASE  = 120
+	_SHM_DMS   = _SHM_BASE + _SHM_NLOCK
+)
+
+func (f *vfsFile) shmMap(ctx context.Context, mod api.Module, id, size int32, extend bool) (uint32, error) {
+	// Ensure size is a multiple of the OS page size.
+	if int(size)&(unix.Getpagesize()-1) != 0 {
+		return 0, _IOERR_SHMMAP
+	}
+
+	if f.shm.File == nil {
+		var flag int
+		if f.readOnly {
+			flag = unix.O_RDONLY
+		} else {
+			flag = unix.O_RDWR
+		}
+		s, err := os.OpenFile(f.Name()+"-shm",
+			flag|unix.O_CREAT|unix.O_NOFOLLOW, 0666)
+		if err != nil {
+			return 0, _CANTOPEN
+		}
+		f.shm.File = s
+	}
+
+	// Dead man's switch.
+	if lock, rc := osGetLock(f.shm.File, _SHM_DMS, 1); rc != _OK {
+		return 0, _IOERR_LOCK
+	} else if lock == unix.F_WRLCK {
+		return 0, _BUSY
+	} else if lock == unix.F_UNLCK {
+		if f.readOnly {
+			return 0, _READONLY_CANTINIT
+		}
+		if rc := osWriteLock(f.shm.File, _SHM_DMS, 1, 0); rc != _OK {
+			return 0, rc
+		}
+		if err := f.shm.Truncate(0); err != nil {
+			return 0, _IOERR_SHMOPEN
+		}
+	}
+	if rc := osReadLock(f.shm.File, _SHM_DMS, 1, 0); rc != _OK {
+		return 0, rc
+	}
+
+	// Check if file is big enough.
+	s, err := f.shm.Seek(0, io.SeekEnd)
+	if err != nil {
+		return 0, _IOERR_SHMSIZE
+	}
+	if n := (int64(id) + 1) * int64(size); n > s {
+		if !extend {
+			return 0, nil
+		}
+		err := osAllocate(f.shm.File, n)
+		if err != nil {
+			return 0, _IOERR_SHMSIZE
+		}
+	}
+
+	var prot int
+	if f.readOnly {
+		prot = unix.PROT_READ
+	} else {
+		prot = unix.PROT_READ | unix.PROT_WRITE
+	}
+	r, err := util.MapRegion(ctx, mod, f.shm.File, int64(id)*int64(size), size, prot)
+	if err != nil {
+		return 0, err
+	}
+	f.shm.regions = append(f.shm.regions, r)
+	return r.Ptr, nil
+}
+
+func (f *vfsFile) shmLock(offset, n int32, flags _ShmFlag) error {
+	// Argument check.
+	if n <= 0 || offset < 0 || offset+n > _SHM_NLOCK {
+		panic(util.AssertErr())
+	}
+	switch flags {
+	case
+		_SHM_LOCK | _SHM_SHARED,
+		_SHM_LOCK | _SHM_EXCLUSIVE,
+		_SHM_UNLOCK | _SHM_SHARED,
+		_SHM_UNLOCK | _SHM_EXCLUSIVE:
+		//
+	default:
+		panic(util.AssertErr())
+	}
+	if n != 1 && flags&_SHM_EXCLUSIVE == 0 {
+		panic(util.AssertErr())
+	}
+
+	switch {
+	case flags&_SHM_UNLOCK != 0:
+		return osUnlock(f.shm.File, _SHM_BASE+int64(offset), int64(n))
+	case flags&_SHM_SHARED != 0:
+		return osReadLock(f.shm.File, _SHM_BASE+int64(offset), int64(n), 0)
+	case flags&_SHM_EXCLUSIVE != 0:
+		return osWriteLock(f.shm.File, _SHM_BASE+int64(offset), int64(n), 0)
+	default:
+		panic(util.AssertErr())
+	}
+}
+
+func (f *vfsFile) shmUnmap(delete bool) {
+	// Unmap regions.
+	for _, r := range f.shm.regions {
+		r.Unmap()
+	}
+	clear(f.shm.regions)
+	f.shm.regions = f.shm.regions[:0]
+
+	// Close the file.
+	if delete && f.shm.File != nil {
+		os.Remove(f.shm.Name())
+	}
+	f.shm.Close()
+	f.shm.File = nil
+}

vfs/shm_other.go

@@ -0,0 +1,17 @@
+//go:build !(darwin || linux || illumos) || !(amd64 || arm64 || riscv64) || sqlite3_flock || sqlite3_noshm || sqlite3_nosys
+
+package vfs
+
+// SupportsSharedMemory is true on platforms that support shared memory.
+// To enable shared memory support on those platforms,
+// you need to set the appropriate [wazero.RuntimeConfig];
+// otherwise, [EXCLUSIVE locking mode] is activated automatically
+// to use [WAL without shared-memory].
+//
+// [WAL without shared-memory]: https://sqlite.org/wal.html#noshm
+// [EXCLUSIVE locking mode]: https://sqlite.org/pragma.html#pragma_locking_mode
+const SupportsSharedMemory = false
+
+type vfsShm struct{}
+
+func (vfsShm) Close() error { return nil }

vfs/tests/mptest/mptest_test.go

@@ -19,7 +19,7 @@ import (
 
 	"github.com/ncruces/go-sqlite3/internal/util"
 	"github.com/ncruces/go-sqlite3/vfs"
-	_ "github.com/ncruces/go-sqlite3/vfs/memdb"
+	"github.com/ncruces/go-sqlite3/vfs/memdb"
 	"github.com/tetratelabs/wazero"
 	"github.com/tetratelabs/wazero/api"
 	"github.com/tetratelabs/wazero/imports/wasi_snapshot_preview1"
@@ -92,7 +92,7 @@ func system(ctx context.Context, mod api.Module, ptr uint32) uint32 {
 
 	cfg := config(ctx).WithArgs(args...)
 	go func() {
-		ctx := util.NewContext(ctx)
+		ctx := util.NewContext(ctx, true)
 		mod, _ := rt.InstantiateModule(ctx, module, cfg)
 		mod.Close(ctx)
 	}()
@@ -100,7 +100,7 @@ func system(ctx context.Context, mod api.Module, ptr uint32) uint32 {
 }
 
 func Test_config01(t *testing.T) {
-	ctx := util.NewContext(newContext(t))
+	ctx := util.NewContext(newContext(t), false)
 	name := filepath.Join(t.TempDir(), "test.db")
 	cfg := config(ctx).WithArgs("mptest", name, "config01.test")
 	mod, err := rt.InstantiateModule(ctx, module, cfg)
@@ -118,7 +118,7 @@ func Test_config02(t *testing.T) {
 		t.Skip("skipping in CI")
 	}
 
-	ctx := util.NewContext(newContext(t))
+	ctx := util.NewContext(newContext(t), false)
 	name := filepath.Join(t.TempDir(), "test.db")
 	cfg := config(ctx).WithArgs("mptest", name, "config02.test")
 	mod, err := rt.InstantiateModule(ctx, module, cfg)
@@ -136,7 +136,7 @@ func Test_crash01(t *testing.T) {
 		t.Skip("skipping in CI")
 	}
 
-	ctx := util.NewContext(newContext(t))
+	ctx := util.NewContext(newContext(t), false)
 	name := filepath.Join(t.TempDir(), "test.db")
 	cfg := config(ctx).WithArgs("mptest", name, "crash01.test")
 	mod, err := rt.InstantiateModule(ctx, module, cfg)
@@ -151,7 +151,7 @@ func Test_multiwrite01(t *testing.T) {
 		t.Skip("skipping in short mode")
 	}
 
-	ctx := util.NewContext(newContext(t))
+	ctx := util.NewContext(newContext(t), false)
 	name := filepath.Join(t.TempDir(), "test.db")
 	cfg := config(ctx).WithArgs("mptest", name, "multiwrite01.test")
 	mod, err := rt.InstantiateModule(ctx, module, cfg)
@@ -162,7 +162,8 @@ func Test_multiwrite01(t *testing.T) {
 }
 
 func Test_config01_memory(t *testing.T) {
-	ctx := util.NewContext(newContext(t))
+	memdb.Delete("test.db")
+	ctx := util.NewContext(newContext(t), false)
 	cfg := config(ctx).WithArgs("mptest", "/test.db", "config01.test",
 		"--vfs", "memdb")
 	mod, err := rt.InstantiateModule(ctx, module, cfg)
@@ -177,7 +178,8 @@ func Test_multiwrite01_memory(t *testing.T) {
 		t.Skip("skipping in short mode")
 	}
 
-	ctx := util.NewContext(newContext(t))
+	memdb.Delete("test.db")
+	ctx := util.NewContext(newContext(t), false)
 	cfg := config(ctx).WithArgs("mptest", "/test.db", "multiwrite01.test",
 		"--vfs", "memdb")
 	mod, err := rt.InstantiateModule(ctx, module, cfg)
@@ -187,6 +189,47 @@ func Test_multiwrite01_memory(t *testing.T) {
 	mod.Close(ctx)
 }
 
+func Test_crash01_wal(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping in short mode")
+	}
+	if os.Getenv("CI") != "" {
+		t.Skip("skipping in CI")
+	}
+	if !vfs.SupportsSharedMemory {
+		t.Skip("skipping without shared memory")
+	}
+
+	ctx := util.NewContext(newContext(t), true)
+	name := filepath.Join(t.TempDir(), "test.db")
+	cfg := config(ctx).WithArgs("mptest", name, "crash01.test",
+		"--journalmode", "wal")
+	mod, err := rt.InstantiateModule(ctx, module, cfg)
+	if err != nil {
+		t.Fatal(err)
+	}
+	mod.Close(ctx)
+}
+
+func Test_multiwrite01_wal(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping in short mode")
+	}
+	if !vfs.SupportsSharedMemory {
+		t.Skip("skipping without shared memory")
+	}
+
+	ctx := util.NewContext(newContext(t), true)
+	name := filepath.Join(t.TempDir(), "test.db")
+	cfg := config(ctx).WithArgs("mptest", name, "multiwrite01.test",
+		"--journalmode", "wal")
+	mod, err := rt.InstantiateModule(ctx, module, cfg)
+	if err != nil {
+		t.Fatal(err)
+	}
+	mod.Close(ctx)
+}
+
 func newContext(t *testing.T) context.Context {
 	return context.WithValue(context.Background(), logger{}, &testWriter{T: t})
 }

vfs/tests/mptest/testdata/build.sh

@@ -5,7 +5,7 @@ cd -P -- "$(dirname -- "$0")"
 
 ROOT=../../../../
 BINARYEN="$ROOT/tools/binaryen-version_117/bin"
-WASI_SDK="$ROOT/tools/wasi-sdk-21.0/bin"
+WASI_SDK="$ROOT/tools/wasi-sdk-22.0/bin"
 
 "$WASI_SDK/clang" --target=wasm32-wasi -std=c17 -flto -g0 -O2 \
   -o mptest.wasm main.c \
@@ -21,7 +21,8 @@ WASI_SDK="$ROOT/tools/wasi-sdk-21.0/bin"
 	-DSQLITE_DEFAULT_LOCKING_MODE=0 \
 	-DHAVE_USLEEP -DSQLITE_NO_SYNC \
 	-DSQLITE_THREADSAFE=0 -DSQLITE_OMIT_LOAD_EXTENSION \
-	-D_WASI_EMULATED_GETPID -lwasi-emulated-getpid
+	-D_WASI_EMULATED_GETPID -lwasi-emulated-getpid \
+	-Wl,--export=aligned_alloc
 
 "$BINARYEN/wasm-opt" -g --strip --strip-producers -c -O3 \
 	mptest.wasm -o mptest.tmp \

vfs/tests/mptest/testdata/mptest.wasm.bz2

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:b5f4778b49a6b99a1be11db5cb07e3c5b52f91a932a97e33c895f52c6f54bf57
-size 469149
+oid sha256:7bf8ef8a52def8dec9b4af62b21cbea22a6cd2a702770aa9c75f445691f1abd5
+size 469700

vfs/tests/speedtest1/speedtest1_test.go

@@ -84,7 +84,7 @@ func initFlags() {
 
 func Benchmark_speedtest1(b *testing.B) {
 	output.Reset()
-	ctx := util.NewContext(context.Background())
+	ctx := util.NewContext(context.Background(), true)
 	name := filepath.Join(b.TempDir(), "test.db")
 	args := append(options, "--size", strconv.Itoa(b.N), name)
 	cfg := wazero.NewModuleConfig().

vfs/tests/speedtest1/testdata/build.sh

@@ -5,7 +5,7 @@ cd -P -- "$(dirname -- "$0")"
 
 ROOT=../../../../
 BINARYEN="$ROOT/tools/binaryen-version_117/bin"
-WASI_SDK="$ROOT/tools/wasi-sdk-21.0/bin"
+WASI_SDK="$ROOT/tools/wasi-sdk-22.0/bin"
 
 "$WASI_SDK/clang" --target=wasm32-wasi -std=c17 -flto -g0 -O2 \
 	-o speedtest1.wasm main.c \
@@ -16,7 +16,8 @@ WASI_SDK="$ROOT/tools/wasi-sdk-21.0/bin"
 	-fno-stack-protector -fno-stack-clash-protection \
 	-Wl,--stack-first \
 	-Wl,--import-undefined \
-	-D_HAVE_SQLITE_CONFIG_H
+	-D_HAVE_SQLITE_CONFIG_H \
+	-Wl,--export=aligned_alloc
 
 "$BINARYEN/wasm-opt" -g --strip --strip-producers -c -O3 \
 	speedtest1.wasm -o speedtest1.tmp \

vfs/tests/speedtest1/testdata/speedtest1.wasm.bz2

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:06882576fdea2c8e164dd2d97dce394dc825dca3cee30c9efc9601b84de92865
-size 483191
+oid sha256:7f669eede3ba9c9a104d37c3a90ecec26086a87aea54c1f650df202923d75cb9
+size 483426

vfs/vfs.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"net/url"
 	"reflect"
+	"sync"
 	"time"
 
 	"github.com/ncruces/go-sqlite3/internal/util"
@@ -27,7 +28,7 @@ func ExportHostFunctions(env wazero.HostModuleBuilder) wazero.HostModuleBuilder
 	util.ExportFuncIIIII(env, "go_full_pathname", vfsFullPathname)
 	util.ExportFuncIIII(env, "go_delete", vfsDelete)
 	util.ExportFuncIIIII(env, "go_access", vfsAccess)
-	util.ExportFuncIIIIII(env, "go_open", vfsOpen)
+	util.ExportFuncIIIIIII(env, "go_open", vfsOpen)
 	util.ExportFuncII(env, "go_close", vfsClose)
 	util.ExportFuncIIIIJ(env, "go_read", vfsRead)
 	util.ExportFuncIIIIJ(env, "go_write", vfsWrite)
@@ -40,6 +41,10 @@ func ExportHostFunctions(env wazero.HostModuleBuilder) wazero.HostModuleBuilder
 	util.ExportFuncIII(env, "go_lock", vfsLock)
 	util.ExportFuncIII(env, "go_unlock", vfsUnlock)
 	util.ExportFuncIII(env, "go_check_reserved_lock", vfsCheckReservedLock)
+	util.ExportFuncIIIIII(env, "go_shm_map", vfsShmMap)
+	util.ExportFuncIIIII(env, "go_shm_lock", vfsShmLock)
+	util.ExportFuncIII(env, "go_shm_unmap", vfsShmUnmap)
+	util.ExportFuncVI(env, "go_shm_barrier", vfsShmBarrier)
 	return env
 }
 
@@ -72,13 +77,13 @@ func vfsLocaltime(ctx context.Context, mod api.Module, pTm uint32, t int64) _Err
 	return _OK
 }
 
-func vfsRandomness(ctx context.Context, mod api.Module, pVfs, nByte, zByte uint32) uint32 {
+func vfsRandomness(ctx context.Context, mod api.Module, pVfs uint32, nByte int32, zByte uint32) uint32 {
 	mem := util.View(mod, zByte, uint64(nByte))
 	n, _ := rand.Reader.Read(mem)
 	return uint32(n)
 }
 
-func vfsSleep(ctx context.Context, mod api.Module, pVfs, nMicro uint32) _ErrorCode {
+func vfsSleep(ctx context.Context, mod api.Module, pVfs uint32, nMicro int32) _ErrorCode {
 	osSleep(time.Duration(nMicro) * time.Microsecond)
 	return _OK
 }
@@ -90,19 +95,16 @@ func vfsCurrentTime64(ctx context.Context, mod api.Module, pVfs, piNow uint32) _
 	return _OK
 }
 
-func vfsFullPathname(ctx context.Context, mod api.Module, pVfs, zRelative, nFull, zFull uint32) _ErrorCode {
+func vfsFullPathname(ctx context.Context, mod api.Module, pVfs, zRelative uint32, nFull int32, zFull uint32) _ErrorCode {
 	vfs := vfsGet(mod, pVfs)
 	path := util.ReadString(mod, zRelative, _MAX_PATHNAME)
 
 	path, err := vfs.FullPathname(path)
 
-	size := uint64(len(path) + 1)
-	if size > uint64(nFull) {
+	if len(path) >= int(nFull) {
 		return _CANTOPEN_FULLPATH
 	}
-	mem := util.View(mod, zFull, size)
-	mem[len(path)] = 0
-	copy(mem, path)
+	util.WriteString(mod, zFull, path)
 
 	return vfsErrorCode(err, _CANTOPEN_FULLPATH)
 }
@@ -129,7 +131,7 @@ func vfsAccess(ctx context.Context, mod api.Module, pVfs, zPath uint32, flags Ac
 	return vfsErrorCode(err, _IOERR_ACCESS)
 }
 
-func vfsOpen(ctx context.Context, mod api.Module, pVfs, zPath, pFile uint32, flags OpenFlag, pOutFlags uint32) _ErrorCode {
+func vfsOpen(ctx context.Context, mod api.Module, pVfs, zPath, pFile uint32, flags OpenFlag, pOutFlags, pOutVFS uint32) _ErrorCode {
 	vfs := vfsGet(mod, pVfs)
 
 	var path string
@@ -165,6 +167,9 @@ func vfsOpen(ctx context.Context, mod api.Module, pVfs, zPath, pFile uint32, fla
 	if pOutFlags != 0 {
 		util.WriteUint32(mod, pOutFlags, uint32(flags))
 	}
+	if pOutVFS != 0 && util.CanMap(ctx) {
+		util.WriteUint32(mod, pOutVFS, 1)
+	}
 	vfsFileRegister(ctx, mod, pFile, file)
 	return _OK
 }
@@ -177,7 +182,7 @@ func vfsClose(ctx context.Context, mod api.Module, pFile uint32) _ErrorCode {
 	return _OK
 }
 
-func vfsRead(ctx context.Context, mod api.Module, pFile, zBuf, iAmt uint32, iOfst int64) _ErrorCode {
+func vfsRead(ctx context.Context, mod api.Module, pFile, zBuf uint32, iAmt int32, iOfst int64) _ErrorCode {
 	file := vfsFileGet(ctx, mod, pFile)
 	buf := util.View(mod, zBuf, uint64(iAmt))
 
@@ -192,7 +197,7 @@ func vfsRead(ctx context.Context, mod api.Module, pFile, zBuf, iAmt uint32, iOfs
 	return _IOERR_SHORT_READ
 }
 
-func vfsWrite(ctx context.Context, mod api.Module, pFile, zBuf, iAmt uint32, iOfst int64) _ErrorCode {
+func vfsWrite(ctx context.Context, mod api.Module, pFile, zBuf uint32, iAmt int32, iOfst int64) _ErrorCode {
 	file := vfsFileGet(ctx, mod, pFile)
 	buf := util.View(mod, zBuf, uint64(iAmt))
 
@@ -348,6 +353,35 @@ func vfsDeviceCharacteristics(ctx context.Context, mod api.Module, pFile uint32)
 	return file.DeviceCharacteristics()
 }
 
+var shmBarrier sync.Mutex
+
+func vfsShmBarrier(ctx context.Context, mod api.Module, pFile uint32) {
+	shmBarrier.Lock()
+	defer shmBarrier.Unlock()
+}
+
+func vfsShmMap(ctx context.Context, mod api.Module, pFile uint32, iRegion, szRegion int32, bExtend, pp uint32) _ErrorCode {
+	file := vfsFileGet(ctx, mod, pFile).(fileShm)
+	p, err := file.shmMap(ctx, mod, iRegion, szRegion, bExtend != 0)
+	if err != nil {
+		return vfsErrorCode(err, _IOERR_SHMMAP)
+	}
+	util.WriteUint32(mod, pp, p)
+	return _OK
+}
+
+func vfsShmLock(ctx context.Context, mod api.Module, pFile uint32, offset, n int32, flags _ShmFlag) _ErrorCode {
+	file := vfsFileGet(ctx, mod, pFile).(fileShm)
+	err := file.shmLock(offset, n, flags)
+	return vfsErrorCode(err, _IOERR_SHMLOCK)
+}
+
+func vfsShmUnmap(ctx context.Context, mod api.Module, pFile, bDelete uint32) _ErrorCode {
+	file := vfsFileGet(ctx, mod, pFile).(fileShm)
+	file.shmUnmap(bDelete != 0)
+	return _OK
+}
+
 func vfsURIParameters(ctx context.Context, mod api.Module, zPath uint32, flags OpenFlag) url.Values {
 	if flags&OPEN_URI == 0 {
 		return nil

vfs/vfs_test.go

@@ -209,10 +209,10 @@ func Test_vfsAccess(t *testing.T) {
 
 func Test_vfsFile(t *testing.T) {
 	mod := wazerotest.NewModule(wazerotest.NewMemory(wazerotest.PageSize))
-	ctx := util.NewContext(context.TODO())
+	ctx := util.NewContext(context.TODO(), false)
 
 	// Open a temporary file.
-	rc := vfsOpen(ctx, mod, 0, 0, 4, OPEN_CREATE|OPEN_EXCLUSIVE|OPEN_READWRITE|OPEN_DELETEONCLOSE, 0)
+	rc := vfsOpen(ctx, mod, 0, 0, 4, OPEN_CREATE|OPEN_EXCLUSIVE|OPEN_READWRITE|OPEN_DELETEONCLOSE, 0, 0)
 	if rc != _OK {
 		t.Fatal("returned", rc)
 	}
@@ -225,7 +225,7 @@ func Test_vfsFile(t *testing.T) {
 	// Write stuff.
 	text := "Hello world!"
 	util.WriteString(mod, 16, text)
-	rc = vfsWrite(ctx, mod, 4, 16, uint32(len(text)), 0)
+	rc = vfsWrite(ctx, mod, 4, 16, int32(len(text)), 0)
 	if rc != _OK {
 		t.Fatal("returned", rc)
 	}
@@ -240,7 +240,7 @@ func Test_vfsFile(t *testing.T) {
 	}
 
 	// Partial read at offset.
-	rc = vfsRead(ctx, mod, 4, 16, uint32(len(text)), 4)
+	rc = vfsRead(ctx, mod, 4, 16, int32(len(text)), 4)
 	if rc != _IOERR_SHORT_READ {
 		t.Fatal("returned", rc)
 	}
@@ -281,10 +281,10 @@ func Test_vfsFile(t *testing.T) {
 
 func Test_vfsFile_psow(t *testing.T) {
 	mod := wazerotest.NewModule(wazerotest.NewMemory(wazerotest.PageSize))
-	ctx := util.NewContext(context.TODO())
+	ctx := util.NewContext(context.TODO(), false)
 
 	// Open a temporary file.
-	rc := vfsOpen(ctx, mod, 0, 0, 4, OPEN_CREATE|OPEN_EXCLUSIVE|OPEN_READWRITE|OPEN_DELETEONCLOSE, 0)
+	rc := vfsOpen(ctx, mod, 0, 0, 4, OPEN_CREATE|OPEN_EXCLUSIVE|OPEN_READWRITE|OPEN_DELETEONCLOSE, 0, 0)
 	if rc != _OK {
 		t.Fatal("returned", rc)
 	}

vtab.go

@@ -206,9 +206,6 @@ type VTabTxn interface {
 	Rollback() error
 }
 
-// Deprecated: renamed for consistency with [Conn.TxnState].
-type VTabTx = VTabTxn
-
 // A VTabSavepointer allows a virtual table to implement
 // nested transactions.
 //
@@ -492,7 +489,7 @@ func vtabRenameCallback(ctx context.Context, mod api.Module, pVTab, zNew uint32)
 	return vtabError(ctx, mod, pVTab, _VTAB_ERROR, err)
 }
 
-func vtabFindFuncCallback(ctx context.Context, mod api.Module, pVTab, nArg, zName, pxFunc uint32) uint32 {
+func vtabFindFuncCallback(ctx context.Context, mod api.Module, pVTab uint32, nArg int32, zName, pxFunc uint32) uint32 {
 	vtab := vtabGetHandle(ctx, mod, pVTab).(VTabOverloader)
 	f, op := vtab.FindFunction(int(nArg), util.ReadString(mod, zName, _MAX_NAME))
 	if op != 0 {
@@ -542,19 +539,19 @@ func vtabRollbackCallback(ctx context.Context, mod api.Module, pVTab uint32) uin
 	return vtabError(ctx, mod, pVTab, _VTAB_ERROR, err)
 }
 
-func vtabSavepointCallback(ctx context.Context, mod api.Module, pVTab, id uint32) uint32 {
+func vtabSavepointCallback(ctx context.Context, mod api.Module, pVTab uint32, id int32) uint32 {
 	vtab := vtabGetHandle(ctx, mod, pVTab).(VTabSavepointer)
 	err := vtab.Savepoint(int(id))
 	return vtabError(ctx, mod, pVTab, _VTAB_ERROR, err)
 }
 
-func vtabReleaseCallback(ctx context.Context, mod api.Module, pVTab, id uint32) uint32 {
+func vtabReleaseCallback(ctx context.Context, mod api.Module, pVTab uint32, id int32) uint32 {
 	vtab := vtabGetHandle(ctx, mod, pVTab).(VTabSavepointer)
 	err := vtab.Release(int(id))
 	return vtabError(ctx, mod, pVTab, _VTAB_ERROR, err)
 }
 
-func vtabRollbackToCallback(ctx context.Context, mod api.Module, pVTab, id uint32) uint32 {
+func vtabRollbackToCallback(ctx context.Context, mod api.Module, pVTab uint32, id int32) uint32 {
 	vtab := vtabGetHandle(ctx, mod, pVTab).(VTabSavepointer)
 	err := vtab.RollbackTo(int(id))
 	return vtabError(ctx, mod, pVTab, _VTAB_ERROR, err)
@@ -576,7 +573,7 @@ func cursorCloseCallback(ctx context.Context, mod api.Module, pCur uint32) uint3
 	return vtabError(ctx, mod, 0, _VTAB_ERROR, err)
 }
 
-func cursorFilterCallback(ctx context.Context, mod api.Module, pCur, idxNum, idxStr, nArg, pArg uint32) uint32 {
+func cursorFilterCallback(ctx context.Context, mod api.Module, pCur uint32, idxNum int32, idxStr, nArg, pArg uint32) uint32 {
 	cursor := vtabGetHandle(ctx, mod, pCur).(VTabCursor)
 	db := ctx.Value(connKey{}).(*Conn)
 	args := make([]Value, nArg)
@@ -603,7 +600,7 @@ func cursorNextCallback(ctx context.Context, mod api.Module, pCur uint32) uint32
 	return vtabError(ctx, mod, pCur, _CURSOR_ERROR, err)
 }
 
-func cursorColumnCallback(ctx context.Context, mod api.Module, pCur, pCtx, n uint32) uint32 {
+func cursorColumnCallback(ctx context.Context, mod api.Module, pCur, pCtx uint32, n int32) uint32 {
 	cursor := vtabGetHandle(ctx, mod, pCur).(VTabCursor)
 	db := ctx.Value(connKey{}).(*Conn)
 	err := cursor.Column(&Context{db, pCtx}, int(n))