update go-sqlite3 => v0.20.0 (#3483)

vendor/github.com/ncruces/go-sqlite3/vfs/README.md

@@ -4,7 +4,7 @@ This package implements the SQLite [OS Interface](https://sqlite.org/vfs.html) (
 
 It replaces the default SQLite VFS with a **pure Go** implementation,
 and exposes [interfaces](https://pkg.go.dev/github.com/ncruces/go-sqlite3/vfs#VFS)
-that should allow you to implement your own custom VFSes.
+that should allow you to implement your own [custom VFSes](#custom-vfses).
 
 Since it is a from scratch reimplementation,
 there are naturally some ways it deviates from the original.
@@ -16,12 +16,12 @@ The main differences are [file locking](#file-locking) and [WAL mode](#write-ahe
 POSIX advisory locks, which SQLite uses on Unix, are
 [broken by design](https://github.com/sqlite/sqlite/blob/b74eb0/src/os_unix.c#L1073-L1161).
 
-On Linux and macOS, this module uses
+On Linux and macOS, this package 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.
 
-This module can also use
+This package can also use
 [BSD locks](https://man.freebsd.org/cgi/man.cgi?query=flock&sektion=2),
 albeit with reduced concurrency (`BEGIN IMMEDIATE` behaves like `BEGIN EXCLUSIVE`).
 On BSD, macOS, and illumos, BSD locks are fully compatible with POSIX advisory locks;
@@ -30,7 +30,7 @@ elsewhere, they are very likely broken.
 BSD locks are the default on BSD and illumos,
 but you can opt into them with the `sqlite3_flock` build tag.
 
-On Windows, this module uses `LockFileEx` and `UnlockFileEx`,
+On Windows, this package uses `LockFileEx` and `UnlockFileEx`,
 like SQLite.
 
 Otherwise, file locking is not supported, and you must use
@@ -46,18 +46,14 @@ to check if your build supports file locking.
 
 ### Write-Ahead Logging
 
-On 64-bit little-endian Unix, this module uses `mmap` to implement
+On little-endian Unix, this package 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 address space each connection reserves,
-use [`WithMemoryLimitPages`](../tests/testcfg/testcfg.go).
-
 With [BSD locks](https://man.freebsd.org/cgi/man.cgi?query=flock&sektion=2)
 a WAL database can only be accessed by a single proccess.
 Other processes that attempt to access a database locked with BSD locks,
-will fail with the `SQLITE_PROTOCOL` error code.
+will fail with the [`SQLITE_PROTOCOL`](https://sqlite.org/rescode.html#protocol) error code.
 
 Otherwise, [WAL support is limited](https://sqlite.org/wal.html#noshm),
 and `EXCLUSIVE` locking mode must be set to create, read, and write WAL databases.
@@ -71,9 +67,22 @@ to check if your build supports shared memory.
 
 ### Batch-Atomic Write
 
-On 64-bit Linux, this module supports [batch-atomic writes](https://sqlite.org/cgi/src/technote/714)
+On 64-bit Linux, this package supports
+[batch-atomic writes](https://sqlite.org/cgi/src/technote/714)
 on the F2FS filesystem.
 
+### Checksums
+
+This package can be [configured](https://pkg.go.dev/github.com/ncruces/go-sqlite3#Conn.EnableChecksums)
+to add an 8-byte checksum to the end of every page in an SQLite database.
+The checksum is added as each page is written
+and verified as each page is read.\
+The checksum is intended to help detect database corruption
+caused by random bit-flips in the mass storage device.
+
+The implementation is compatible with SQLite's
+[Checksum VFS Shim](https://sqlite.org/cksumvfs.html).
+
 ### Build Tags
 
 The VFS can be customized with a few build tags:
@@ -90,3 +99,14 @@ The VFS can be customized with a few build tags:
 > [`unix-flock` VFS](https://sqlite.org/compile.html#enable_locking_style).
 > If incompatible file locking is used, accessing databases concurrently with
 > _other_ SQLite libraries will eventually corrupt data.
+
+### Custom VFSes
+
+- [`github.com/ncruces/go-sqlite3/vfs/adiantum`](https://pkg.go.dev/github.com/ncruces/go-sqlite3/vfs/adiantum)
+  wraps a VFS to offer encryption at rest.
+- [`github.com/ncruces/go-sqlite3/vfs/memdb`](https://pkg.go.dev/github.com/ncruces/go-sqlite3/vfs/memdb)
+  implements an in-memory VFS.
+- [`github.com/ncruces/go-sqlite3/vfs/readervfs`](https://pkg.go.dev/github.com/ncruces/go-sqlite3/vfs/readervfs)
+  implements a VFS for immutable databases.
+- [`github.com/ncruces/go-sqlite3/vfs/xts`](https://pkg.go.dev/github.com/ncruces/go-sqlite3/vfs/xts)
+  wraps a VFS to offer encryption at rest.

vendor/github.com/ncruces/go-sqlite3/vfs/api.go

@@ -49,6 +49,13 @@ type File interface {
 	DeviceCharacteristics() DeviceCharacteristic
 }
 
+// FileUnwrap should be implemented by a File
+// that wraps another File implementation.
+type FileUnwrap interface {
+	File
+	Unwrap() File
+}
+
 // FileLockState extends File to implement the
 // SQLITE_FCNTL_LOCKSTATE file control opcode.
 //
@@ -58,6 +65,26 @@ type FileLockState interface {
 	LockState() LockLevel
 }
 
+// FilePersistentWAL extends File to implement the
+// SQLITE_FCNTL_PERSIST_WAL file control opcode.
+//
+// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlpersistwal
+type FilePersistentWAL interface {
+	File
+	PersistentWAL() bool
+	SetPersistentWAL(bool)
+}
+
+// FilePowersafeOverwrite extends File to implement the
+// SQLITE_FCNTL_POWERSAFE_OVERWRITE file control opcode.
+//
+// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlpowersafeoverwrite
+type FilePowersafeOverwrite interface {
+	File
+	PowersafeOverwrite() bool
+	SetPowersafeOverwrite(bool)
+}
+
 // FileChunkSize extends File to implement the
 // SQLITE_FCNTL_CHUNK_SIZE file control opcode.
 //
@@ -94,26 +121,6 @@ type FileOverwrite interface {
 	Overwrite() error
 }
 
-// FilePersistentWAL extends File to implement the
-// SQLITE_FCNTL_PERSIST_WAL file control opcode.
-//
-// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlpersistwal
-type FilePersistentWAL interface {
-	File
-	PersistentWAL() bool
-	SetPersistentWAL(bool)
-}
-
-// FilePowersafeOverwrite extends File to implement the
-// SQLITE_FCNTL_POWERSAFE_OVERWRITE file control opcode.
-//
-// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlpowersafeoverwrite
-type FilePowersafeOverwrite interface {
-	File
-	PowersafeOverwrite() bool
-	SetPowersafeOverwrite(bool)
-}
-
 // FileCommitPhaseTwo extends File to implement the
 // SQLITE_FCNTL_COMMIT_PHASETWO file control opcode.
 //
@@ -135,15 +142,6 @@ type FileBatchAtomicWrite interface {
 	RollbackAtomicWrite() error
 }
 
-// FilePragma extends File to implement the
-// SQLITE_FCNTL_PRAGMA file control opcode.
-//
-// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlpragma
-type FilePragma interface {
-	File
-	Pragma(name, value string) (string, error)
-}
-
 // FileCheckpoint extends File to implement the
 // SQLITE_FCNTL_CKPT_START and SQLITE_FCNTL_CKPT_DONE
 // file control opcodes.
@@ -151,8 +149,17 @@ type FilePragma interface {
 // https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlckptstart
 type FileCheckpoint interface {
 	File
-	CheckpointDone() error
-	CheckpointStart() error
+	CheckpointStart()
+	CheckpointDone()
+}
+
+// FilePragma extends File to implement the
+// SQLITE_FCNTL_PRAGMA file control opcode.
+//
+// https://sqlite.org/c3ref/c_fcntl_begin_atomic_write.html#sqlitefcntlpragma
+type FilePragma interface {
+	File
+	Pragma(name, value string) (string, error)
 }
 
 // FileSharedMemory extends File to possibly implement
@@ -171,5 +178,16 @@ type SharedMemory interface {
 	shmMap(context.Context, api.Module, int32, int32, bool) (uint32, _ErrorCode)
 	shmLock(int32, int32, _ShmFlag) _ErrorCode
 	shmUnmap(bool)
+	shmBarrier()
 	io.Closer
 }
+
+type blockingSharedMemory interface {
+	SharedMemory
+	shmEnableBlocking(block bool)
+}
+
+type fileControl interface {
+	File
+	fileControl(ctx context.Context, mod api.Module, op _FcntlOpcode, pArg uint32) _ErrorCode
+}

vendor/github.com/ncruces/go-sqlite3/vfs/cksm.go

@@ -0,0 +1,149 @@
+package vfs
+
+import (
+	"bytes"
+	"context"
+	_ "embed"
+	"encoding/binary"
+	"strconv"
+
+	"github.com/tetratelabs/wazero/api"
+
+	"github.com/ncruces/go-sqlite3/internal/util"
+	"github.com/ncruces/go-sqlite3/util/sql3util"
+)
+
+func cksmWrapFile(name *Filename, flags OpenFlag, file File) File {
+	// Checksum only main databases and WALs.
+	if flags&(OPEN_MAIN_DB|OPEN_WAL) == 0 {
+		return file
+	}
+
+	cksm := cksmFile{File: file}
+
+	if flags&OPEN_WAL != 0 {
+		main, _ := name.DatabaseFile().(cksmFile)
+		cksm.cksmFlags = main.cksmFlags
+	} else {
+		cksm.cksmFlags = new(cksmFlags)
+		cksm.isDB = true
+	}
+
+	return cksm
+}
+
+type cksmFile struct {
+	File
+	*cksmFlags
+	isDB bool
+}
+
+type cksmFlags struct {
+	computeCksm bool
+	verifyCksm  bool
+	inCkpt      bool
+	pageSize    int
+}
+
+func (c cksmFile) ReadAt(p []byte, off int64) (n int, err error) {
+	n, err = c.File.ReadAt(p, off)
+
+	// SQLite is reading the header of a database file.
+	if c.isDB && off == 0 && len(p) >= 100 &&
+		bytes.HasPrefix(p, []byte("SQLite format 3\000")) {
+		c.init(p)
+	}
+
+	// Verify checksums.
+	if c.verifyCksm && !c.inCkpt && len(p) == c.pageSize {
+		cksm1 := cksmCompute(p[:len(p)-8])
+		cksm2 := *(*[8]byte)(p[len(p)-8:])
+		if cksm1 != cksm2 {
+			return 0, _IOERR_DATA
+		}
+	}
+	return n, err
+}
+
+func (c cksmFile) WriteAt(p []byte, off int64) (n int, err error) {
+	// SQLite is writing the first page of a database file.
+	if c.isDB && off == 0 && len(p) >= 100 &&
+		bytes.HasPrefix(p, []byte("SQLite format 3\000")) {
+		c.init(p)
+	}
+
+	// Compute checksums.
+	if c.computeCksm && !c.inCkpt && len(p) == c.pageSize {
+		*(*[8]byte)(p[len(p)-8:]) = cksmCompute(p[:len(p)-8])
+	}
+
+	return c.File.WriteAt(p, off)
+}
+
+func (c cksmFile) Pragma(name string, value string) (string, error) {
+	switch name {
+	case "checksum_verification":
+		b, ok := sql3util.ParseBool(value)
+		if ok {
+			c.verifyCksm = b && c.computeCksm
+		}
+		if !c.verifyCksm {
+			return "0", nil
+		}
+		return "1", nil
+
+	case "page_size":
+		if c.computeCksm {
+			// Do not allow page size changes on a checksum database.
+			return strconv.Itoa(c.pageSize), nil
+		}
+	}
+	return "", _NOTFOUND
+}
+
+func (c cksmFile) fileControl(ctx context.Context, mod api.Module, op _FcntlOpcode, pArg uint32) _ErrorCode {
+	switch op {
+	case _FCNTL_CKPT_START:
+		c.inCkpt = true
+	case _FCNTL_CKPT_DONE:
+		c.inCkpt = false
+	}
+	if rc := vfsFileControlImpl(ctx, mod, c, op, pArg); rc != _NOTFOUND {
+		return rc
+	}
+	return vfsFileControlImpl(ctx, mod, c.File, op, pArg)
+}
+
+func (f *cksmFlags) init(header []byte) {
+	f.pageSize = 256 * int(binary.LittleEndian.Uint16(header[16:18]))
+	if r := header[20] == 8; r != f.computeCksm {
+		f.computeCksm = r
+		f.verifyCksm = r
+	}
+}
+
+func cksmCompute(a []byte) (cksm [8]byte) {
+	var s1, s2 uint32
+	for len(a) >= 8 {
+		s1 += binary.LittleEndian.Uint32(a[0:4]) + s2
+		s2 += binary.LittleEndian.Uint32(a[4:8]) + s1
+		a = a[8:]
+	}
+	if len(a) != 0 {
+		panic(util.AssertErr())
+	}
+	binary.LittleEndian.PutUint32(cksm[0:4], s1)
+	binary.LittleEndian.PutUint32(cksm[4:8], s2)
+	return
+}
+
+func (c cksmFile) SharedMemory() SharedMemory {
+	if f, ok := c.File.(FileSharedMemory); ok {
+		return f.SharedMemory()
+	}
+	return nil
+}
+
+func (c cksmFile) Unwrap() File {
+	return c.File
+}

vendor/github.com/ncruces/go-sqlite3/vfs/const.go

@@ -51,6 +51,7 @@ const (
 	_IOERR_BEGIN_ATOMIC      _ErrorCode = util.IOERR_BEGIN_ATOMIC
 	_IOERR_COMMIT_ATOMIC     _ErrorCode = util.IOERR_COMMIT_ATOMIC
 	_IOERR_ROLLBACK_ATOMIC   _ErrorCode = util.IOERR_ROLLBACK_ATOMIC
+	_IOERR_DATA              _ErrorCode = util.IOERR_DATA
 	_BUSY_SNAPSHOT           _ErrorCode = util.BUSY_SNAPSHOT
 	_CANTOPEN_FULLPATH       _ErrorCode = util.CANTOPEN_FULLPATH
 	_CANTOPEN_ISDIR          _ErrorCode = util.CANTOPEN_ISDIR

vendor/github.com/ncruces/go-sqlite3/vfs/filename.go

@@ -4,8 +4,9 @@ import (
 	"context"
 	"net/url"
 
-	"github.com/ncruces/go-sqlite3/internal/util"
 	"github.com/tetratelabs/wazero/api"
+
+	"github.com/ncruces/go-sqlite3/internal/util"
 )
 
 // Filename is used by SQLite to pass filenames

vendor/github.com/ncruces/go-sqlite3/vfs/os_f2fs_linux.go

@@ -1,4 +1,4 @@
-//go:build (amd64 || arm64 || riscv64 || ppc64le) && !sqlite3_nosys
+//go:build (amd64 || arm64 || riscv64) && !sqlite3_nosys
 
 package vfs
 
@@ -13,7 +13,7 @@ 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_IOC_GET_FEATURES        = 2147808524 // -2147158772
 	_F2FS_FEATURE_ATOMIC_WRITE    = 4
 )
 

vendor/github.com/ncruces/go-sqlite3/vfs/os_std_atomic.go

@@ -1,4 +1,4 @@
-//go:build !linux || !(amd64 || arm64 || riscv64 || ppc64le) || sqlite3_nosys
+//go:build !linux || !(amd64 || arm64 || riscv64) || sqlite3_nosys
 
 package vfs
 

vendor/github.com/ncruces/go-sqlite3/vfs/shm.go

@@ -1,4 +1,4 @@
-//go:build (darwin || linux) && (amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_flock || sqlite3_noshm || sqlite3_nosys)
+//go:build (darwin || linux) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_flock || sqlite3_noshm || sqlite3_nosys)
 
 package vfs
 
@@ -6,11 +6,13 @@ import (
 	"context"
 	"io"
 	"os"
+	"sync"
 	"time"
 
-	"github.com/ncruces/go-sqlite3/internal/util"
 	"github.com/tetratelabs/wazero/api"
 	"golang.org/x/sys/unix"
+
+	"github.com/ncruces/go-sqlite3/internal/util"
 )
 
 // SupportsSharedMemory is false on platforms that do not support shared memory.
@@ -45,12 +47,15 @@ func NewSharedMemory(path string, flags OpenFlag) SharedMemory {
 	}
 }
 
+var _ blockingSharedMemory = &vfsShm{}
+
 type vfsShm struct {
 	*os.File
 	path     string
 	regions  []*util.MappedRegion
 	readOnly bool
 	blocking bool
+	sync.Mutex
 }
 
 func (s *vfsShm) shmOpen() _ErrorCode {
@@ -196,6 +201,12 @@ func (s *vfsShm) shmUnmap(delete bool) {
 	s.File = nil
 }
 
+func (s *vfsShm) shmBarrier() {
+	s.Lock()
+	//lint:ignore SA2001 memory barrier.
+	s.Unlock()
+}
+
 func (s *vfsShm) shmEnableBlocking(block bool) {
 	s.blocking = block
 }

vendor/github.com/ncruces/go-sqlite3/vfs/shm_bsd.go

@@ -1,4 +1,4 @@
-//go:build (freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) && (amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_noshm || sqlite3_nosys)
+//go:build (freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_noshm || sqlite3_nosys)
 
 package vfs
 
@@ -8,9 +8,10 @@ import (
 	"os"
 	"sync"
 
-	"github.com/ncruces/go-sqlite3/internal/util"
 	"github.com/tetratelabs/wazero/api"
 	"golang.org/x/sys/unix"
+
+	"github.com/ncruces/go-sqlite3/internal/util"
 )
 
 // SupportsSharedMemory is false on platforms that do not support shared memory.
@@ -269,3 +270,9 @@ func (s *vfsShm) shmUnmap(delete bool) {
 	}
 	s.Close()
 }
+
+func (s *vfsShm) shmBarrier() {
+	s.lockMtx.Lock()
+	//lint:ignore SA2001 memory barrier.
+	s.lockMtx.Unlock()
+}

vendor/github.com/ncruces/go-sqlite3/vfs/shm_other.go

@@ -1,4 +1,4 @@
-//go:build !(darwin || linux || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) || !(amd64 || arm64 || riscv64 || ppc64le) || sqlite3_noshm || sqlite3_nosys
+//go:build !(darwin || linux || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) || !(386 || arm || amd64 || arm64 || riscv64 || ppc64le) || sqlite3_noshm || sqlite3_nosys
 
 package vfs
 

vendor/github.com/ncruces/go-sqlite3/vfs/vfs.go

@@ -5,13 +5,15 @@ import (
 	"crypto/rand"
 	"io"
 	"reflect"
-	"sync"
+	"strings"
 	"time"
 
-	"github.com/ncruces/go-sqlite3/internal/util"
-	"github.com/ncruces/julianday"
 	"github.com/tetratelabs/wazero"
 	"github.com/tetratelabs/wazero/api"
+
+	"github.com/ncruces/go-sqlite3/internal/util"
+	"github.com/ncruces/go-sqlite3/util/sql3util"
+	"github.com/ncruces/julianday"
 )
 
 // ExportHostFunctions is an internal API users need not call directly.
@@ -146,7 +148,7 @@ func vfsOpen(ctx context.Context, mod api.Module, pVfs, zPath, pFile uint32, fla
 	}
 
 	if file, ok := file.(FilePowersafeOverwrite); ok {
-		if b, ok := util.ParseBool(name.URIParameter("psow")); ok {
+		if b, ok := sql3util.ParseBool(name.URIParameter("psow")); ok {
 			file.SetPowersafeOverwrite(b)
 		}
 	}
@@ -157,6 +159,7 @@ func vfsOpen(ctx context.Context, mod api.Module, pVfs, zPath, pFile uint32, fla
 	if pOutFlags != 0 {
 		util.WriteUint32(mod, pOutFlags, uint32(flags))
 	}
+	file = cksmWrapFile(name, flags, file)
 	vfsFileRegister(ctx, mod, pFile, file)
 	return _OK
 }
@@ -235,20 +238,19 @@ func vfsCheckReservedLock(ctx context.Context, mod api.Module, pFile, pResOut ui
 
 func vfsFileControl(ctx context.Context, mod api.Module, pFile uint32, op _FcntlOpcode, pArg uint32) _ErrorCode {
 	file := vfsFileGet(ctx, mod, pFile).(File)
+	if file, ok := file.(fileControl); ok {
+		return file.fileControl(ctx, mod, op, pArg)
+	}
+	return vfsFileControlImpl(ctx, mod, file, op, pArg)
+}
 
+func vfsFileControlImpl(ctx context.Context, mod api.Module, file File, op _FcntlOpcode, pArg uint32) _ErrorCode {
 	switch op {
 	case _FCNTL_LOCKSTATE:
 		if file, ok := file.(FileLockState); ok {
-			util.WriteUint32(mod, pArg, uint32(file.LockState()))
-			return _OK
-		}
-
-	case _FCNTL_LOCK_TIMEOUT:
-		if file, ok := file.(FileSharedMemory); ok {
-			if iface, ok := file.SharedMemory().(interface{ shmEnableBlocking(bool) }); ok {
-				if i := util.ReadUint32(mod, pArg); i == 0 || i == 1 {
-					iface.shmEnableBlocking(i != 0)
-				}
+			if lk := file.LockState(); lk <= LOCK_EXCLUSIVE {
+				util.WriteUint32(mod, pArg, uint32(lk))
+				return _OK
 			}
 		}
 
@@ -329,15 +331,15 @@ func vfsFileControl(ctx context.Context, mod api.Module, pFile uint32, op _Fcntl
 			return vfsErrorCode(err, _IOERR_ROLLBACK_ATOMIC)
 		}
 
-	case _FCNTL_CKPT_DONE:
-		if file, ok := file.(FileCheckpoint); ok {
-			err := file.CheckpointDone()
-			return vfsErrorCode(err, _IOERR)
-		}
 	case _FCNTL_CKPT_START:
 		if file, ok := file.(FileCheckpoint); ok {
-			err := file.CheckpointStart()
-			return vfsErrorCode(err, _IOERR)
+			file.CheckpointStart()
+			return _OK
+		}
+	case _FCNTL_CKPT_DONE:
+		if file, ok := file.(FileCheckpoint); ok {
+			file.CheckpointDone()
+			return _OK
 		}
 
 	case _FCNTL_PRAGMA:
@@ -349,7 +351,7 @@ func vfsFileControl(ctx context.Context, mod api.Module, pFile uint32, op _Fcntl
 				value = util.ReadString(mod, ptr, _MAX_SQL_LENGTH)
 			}
 
-			out, err := file.Pragma(name, value)
+			out, err := file.Pragma(strings.ToLower(name), value)
 
 			ret := vfsErrorCode(err, _ERROR)
 			if ret == _ERROR {
@@ -366,6 +368,14 @@ func vfsFileControl(ctx context.Context, mod api.Module, pFile uint32, op _Fcntl
 			}
 			return ret
 		}
+
+	case _FCNTL_LOCK_TIMEOUT:
+		if file, ok := file.(FileSharedMemory); ok {
+			if shm, ok := file.SharedMemory().(blockingSharedMemory); ok {
+				shm.shmEnableBlocking(util.ReadUint32(mod, pArg) != 0)
+				return _OK
+			}
+		}
 	}
 
 	// Consider also implementing these opcodes (in use by SQLite):
@@ -385,11 +395,9 @@ 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()
+	shm := vfsFileGet(ctx, mod, pFile).(FileSharedMemory).SharedMemory()
+	shm.shmBarrier()
 }
 
 func vfsShmMap(ctx context.Context, mod api.Module, pFile uint32, iRegion, szRegion int32, bExtend, pp uint32) _ErrorCode {