Merge 70f6b85a21 into b84637801a

go.mod

@@ -43,7 +43,7 @@ require (
 	github.com/miekg/dns v1.1.62
 	github.com/minio/minio-go/v7 v7.0.80
 	github.com/mitchellh/mapstructure v1.5.0
-	github.com/ncruces/go-sqlite3 v0.20.2
+	github.com/ncruces/go-sqlite3 v0.20.0
 	github.com/oklog/ulid v1.3.1
 	github.com/prometheus/client_golang v1.20.5
 	github.com/spf13/cobra v1.8.1

go.sum

@@ -432,8 +432,8 @@ github.com/moul/http2curl v1.0.0 h1:dRMWoAtb+ePxMlLkrCbAqh4TlPHXvoGUSQ323/9Zahs=
 github.com/moul/http2curl v1.0.0/go.mod h1:8UbvGypXm98wA/IqH45anm5Y2Z6ep6O31QGOAZ3H0fQ=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
-github.com/ncruces/go-sqlite3 v0.20.2 h1:cMLIwrLZQuCWVCEOowSqlIlpzgbag3jnYVW4NM5u01M=
+github.com/ncruces/go-sqlite3 v0.20.0 h1:/nBLvYxj7sk9S6y57nmMFvoQ/KJtGo0pNi8J80s8oJU=
-github.com/ncruces/go-sqlite3 v0.20.2/go.mod h1:yL4ZNWGsr1/8pcLfpPW1RT1WFdvyeHonrgIwwi4rvkg=
+github.com/ncruces/go-sqlite3 v0.20.0/go.mod h1:yL4ZNWGsr1/8pcLfpPW1RT1WFdvyeHonrgIwwi4rvkg=
 github.com/ncruces/go-strftime v0.1.9 h1:bY0MQC28UADQmHmaF5dgpLmImcShSi2kHU9XLdhx/f4=
 github.com/ncruces/go-strftime v0.1.9/go.mod h1:Fwc5htZGVVkseilnfgOVb9mKy6w1naJmn9CehxcKcls=
 github.com/ncruces/julianday v1.0.0 h1:fH0OKwa7NWvniGQtxdJRxAgkBMolni2BjDHaWTxqt7M=

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

@@ -2,7 +2,6 @@
 
 import (
 	"context"
-	"fmt"
 	"strconv"
 
 	"github.com/tetratelabs/wazero/api"
@@ -71,15 +70,6 @@ func logCallback(ctx context.Context, mod api.Module, _, iCode, zMsg uint32) {
 	}
 }
 
-// Log writes a message into the error log established by [Conn.ConfigLog].
-//
-// https://sqlite.org/c3ref/log.html
-func (c *Conn) Log(code ExtendedErrorCode, format string, a ...any) {
-	if c.log != nil {
-		c.log(code, fmt.Sprintf(format, a...))
-	}
-}
-
 // FileControl allows low-level control of database files.
 // Only a subset of opcodes are supported.
 //

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

@@ -89,7 +89,6 @@ func (ctx Context) ResultText(value string) {
 }
 
 // ResultRawText sets the text result of the function to a []byte.
-// Returning a nil slice is the same as calling [Context.ResultNull].
 //
 // https://sqlite.org/c3ref/result_blob.html
 func (ctx Context) ResultRawText(value []byte) {

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

@@ -106,11 +106,6 @@ func (e ErrorCode) Temporary() bool {
 	return e == BUSY
 }
 
-// ExtendedCode returns the extended error code for this error.
-func (e ErrorCode) ExtendedCode() ExtendedErrorCode {
-	return ExtendedErrorCode(e)
-}
-
 // Error implements the error interface.
 func (e ExtendedErrorCode) Error() string {
 	return util.ErrorCodeString(uint32(e))
@@ -141,11 +136,6 @@ func (e ExtendedErrorCode) Timeout() bool {
 	return e == BUSY_TIMEOUT
 }
 
-// Code returns the primary error code for this error.
-func (e ExtendedErrorCode) Code() ErrorCode {
-	return ErrorCode(e)
-}
-
 func errorCode(err error, def ErrorCode) (msg string, code uint32) {
 	switch code := err.(type) {
 	case nil:

vendor/github.com/ncruces/go-sqlite3/internal/util/mmap.go

@@ -1,4 +1,4 @@
-//go:build unix && !sqlite3_nosys
+//go:build unix && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_noshm || sqlite3_nosys)
 
 package util
 
@@ -55,10 +55,10 @@ type MappedRegion struct {
 	used bool
 }
 
-func MapRegion(ctx context.Context, mod api.Module, f *os.File, offset int64, size int32, readOnly bool) (*MappedRegion, error) {
+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, readOnly)
+	err := r.mmap(f, offset, prot)
 	if err != nil {
 		return nil, err
 	}
@@ -75,11 +75,7 @@ func (r *MappedRegion) Unmap() error {
 	return err
 }
 
-func (r *MappedRegion) mmap(f *os.File, offset int64, readOnly bool) error {
+func (r *MappedRegion) mmap(f *os.File, offset int64, prot int) error {
-	prot := unix.PROT_READ
-	if !readOnly {
-		prot |= unix.PROT_WRITE
-	}
 	_, err := unix.MmapPtr(int(f.Fd()), offset, r.addr, uintptr(r.size),
 		prot, unix.MAP_SHARED|unix.MAP_FIXED)
 	r.used = err == nil

vendor/github.com/ncruces/go-sqlite3/internal/util/mmap_other.go

@@ -1,4 +1,4 @@
-//go:build !unix || sqlite3_nosys
+//go:build !unix || !(386 || arm || amd64 || arm64 || riscv64 || ppc64le) || sqlite3_noshm || sqlite3_nosys
 
 package util
 

vendor/github.com/ncruces/go-sqlite3/internal/util/mmap_windows.go

@@ -1,53 +0,0 @@
-//go:build !sqlite3_nosys
-
-package util
-
-import (
-	"context"
-	"os"
-	"reflect"
-	"unsafe"
-
-	"github.com/tetratelabs/wazero/api"
-	"golang.org/x/sys/windows"
-)
-
-type MappedRegion struct {
-	windows.Handle
-	Data []byte
-	addr uintptr
-}
-
-func MapRegion(ctx context.Context, mod api.Module, f *os.File, offset int64, size int32) (*MappedRegion, error) {
-	h, err := windows.CreateFileMapping(windows.Handle(f.Fd()), nil, windows.PAGE_READWRITE, 0, 0, nil)
-	if h == 0 {
-		return nil, err
-	}
-
-	a, err := windows.MapViewOfFile(h, windows.FILE_MAP_WRITE,
-		uint32(offset>>32), uint32(offset), uintptr(size))
-	if a == 0 {
-		windows.CloseHandle(h)
-		return nil, err
-	}
-
-	res := &MappedRegion{Handle: h, addr: a}
-	// SliceHeader, although deprecated, avoids a go vet warning.
-	sh := (*reflect.SliceHeader)(unsafe.Pointer(&res.Data))
-	sh.Len = int(size)
-	sh.Cap = int(size)
-	sh.Data = a
-	return res, nil
-}
-
-func (r *MappedRegion) Unmap() error {
-	if r.Data == nil {
-		return nil
-	}
-	err := windows.UnmapViewOfFile(r.addr)
-	if err != nil {
-		return err
-	}
-	r.Data = nil
-	return windows.CloseHandle(r.Handle)
-}

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

@@ -255,7 +255,6 @@ func (s *Stmt) BindText(param int, value string) error {
 
 // BindRawText binds a []byte to the prepared statement as text.
 // The leftmost SQL parameter has an index of 1.
-// Binding a nil slice is the same as calling [Stmt.BindNull].
 //
 // https://sqlite.org/c3ref/bind_blob.html
 func (s *Stmt) BindRawText(param int, value []byte) error {

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

@@ -15,23 +15,24 @@ 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).
-Instead, on Linux and macOS, this package 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 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;
+on Linux and z/OS, they are fully functional, but incompatible;
+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 package uses `LockFileEx` and `UnlockFileEx`,
 like SQLite.
 
-You can also opt into a cross-platform locking implementation
-with the `sqlite3_dotlk` build tag.
-The only requirement is an atomic `os.Mkdir`.
-
 Otherwise, 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))
@@ -45,7 +46,7 @@ to check if your build supports file locking.
 
 ### Write-Ahead Logging
 
-On Unix, this package may use `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.
 
@@ -54,11 +55,6 @@ 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`](https://sqlite.org/rescode.html#protocol) error code.
 
-On Windows, this package may use `MapViewOfFile`, like SQLite.
-
-You can also opt into a cross-platform, in-process, memory sharing implementation
-with the `sqlite3_dotlk` build tag.
-
 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.
 To use `EXCLUSIVE` locking mode with the
@@ -71,7 +67,7 @@ to check if your build supports shared memory.
 
 ### Batch-Atomic Write
 
-On Linux, this package may support
+On 64-bit Linux, this package supports
 [batch-atomic writes](https://sqlite.org/cgi/src/technote/714)
 on the F2FS filesystem.
 
@@ -90,27 +86,27 @@ The implementation is compatible with SQLite's
 ### Build Tags
 
 The VFS can be customized with a few build tags:
-- `sqlite3_flock` forces the use of BSD locks.
+- `sqlite3_flock` forces the use of BSD locks; it can be used on z/OS to enable locking,
-- `sqlite3_dotlk` forces the use of dot-file locks.
+  and elsewhere to test BSD locks.
-- `sqlite3_nosys` prevents importing [`x/sys`](https://pkg.go.dev/golang.org/x/sys).
+- `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.
 
 > [!IMPORTANT]
 > The default configuration of this package is compatible with the standard
 > [Unix and Windows SQLite VFSes](https://sqlite.org/vfs.html#multiple_vfses);
 > `sqlite3_flock` builds are compatible with the
-> [`unix-flock` VFS](https://sqlite.org/compile.html#enable_locking_style);
+> [`unix-flock` VFS](https://sqlite.org/compile.html#enable_locking_style).
-> `sqlite3_dotlk` builds are compatible with the
-> [`unix-dotfile` 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/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/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/const.go

@@ -234,8 +234,4 @@ func (e _ErrorCode) Error() string {
 	_SHM_LOCK      _ShmFlag = 2
 	_SHM_SHARED    _ShmFlag = 4
 	_SHM_EXCLUSIVE _ShmFlag = 8
-
-	_SHM_NLOCK = 8
-	_SHM_BASE  = 120
-	_SHM_DMS   = _SHM_BASE + _SHM_NLOCK
 )

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

@@ -35,10 +35,10 @@ func testSymlinks(path string) error {
 
 func (vfsOS) Delete(path string, syncDir bool) error {
 	err := os.Remove(path)
-	if errors.Is(err, fs.ErrNotExist) {
-		return _IOERR_DELETE_NOENT
-	}
 	if err != nil {
+		if errors.Is(err, fs.ErrNotExist) {
+			return _IOERR_DELETE_NOENT
+		}
 		return err
 	}
 	if runtime.GOOS != "windows" && syncDir {
@@ -151,7 +151,6 @@ func (f *vfsFile) Close() error {
 	if f.shm != nil {
 		f.shm.Close()
 	}
-	f.Unlock(LOCK_NONE)
 	return f.File.Close()
 }
 
@@ -207,10 +206,10 @@ func (f *vfsFile) HasMoved() (bool, error) {
 		return false, err
 	}
 	pi, err := os.Stat(f.Name())
-	if errors.Is(err, fs.ErrNotExist) {
-		return true, nil
-	}
 	if err != nil {
+		if errors.Is(err, fs.ErrNotExist) {
+			return true, nil
+		}
 		return false, err
 	}
 	return !os.SameFile(fi, pi), nil

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

@@ -1,4 +1,4 @@
-//go:build ((linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && !sqlite3_nosys) || sqlite3_flock || sqlite3_dotlk
+//go:build (linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) && !sqlite3_nosys
 
 package vfs
 

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

@@ -1,4 +1,4 @@
-//go:build !(((linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && !sqlite3_nosys) || sqlite3_flock || sqlite3_dotlk)
+//go:build !(linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) || sqlite3_nosys
 
 package vfs
 

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

@@ -78,15 +78,19 @@ type memDB struct {
 
 	// +checklocks:dataMtx
 	data []*[sectorSize]byte
+
 	// +checklocks:dataMtx
 	size int64
 
-	// +checklocks:memoryMtx
+	// +checklocks:lockMtx
-	refs int32
+	shared int32
+	// +checklocks:lockMtx
+	reserved bool
+	// +checklocks:lockMtx
+	pending bool
 
-	shared   int32 // +checklocks:lockMtx
+	// +checklocks:memoryMtx
-	pending  bool  // +checklocks:lockMtx
+	refs int
-	reserved bool  // +checklocks:lockMtx
 
 	lockMtx sync.Mutex
 	dataMtx sync.RWMutex
@@ -249,12 +253,12 @@ func (m *memFile) Unlock(lock vfs.LockLevel) error {
 	m.lockMtx.Lock()
 	defer m.lockMtx.Unlock()
 
-	if m.lock >= vfs.LOCK_RESERVED {
+	if m.pending && m.lock >= vfs.LOCK_PENDING {
-		m.reserved = false
-	}
-	if m.lock >= vfs.LOCK_PENDING {
 		m.pending = false
 	}
+	if m.reserved && m.lock >= vfs.LOCK_RESERVED {
+		m.reserved = false
+	}
 	if lock < vfs.LOCK_SHARED {
 		m.shared--
 	}

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

@@ -1,4 +1,4 @@
-//go:build ((freebsd || openbsd || netbsd || dragonfly || illumos) && !(sqlite3_dotlk || sqlite3_nosys)) || sqlite3_flock
+//go:build (freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) && !sqlite3_nosys
 
 package vfs
 

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

@@ -1,143 +0,0 @@
-//go:build sqlite3_dotlk
-
-package vfs
-
-import (
-	"errors"
-	"io/fs"
-	"os"
-	"sync"
-)
-
-var (
-	// +checklocks:vfsDotLocksMtx
-	vfsDotLocks    = map[string]*vfsDotLocker{}
-	vfsDotLocksMtx sync.Mutex
-)
-
-type vfsDotLocker struct {
-	shared   int      // +checklocks:vfsDotLocksMtx
-	pending  *os.File // +checklocks:vfsDotLocksMtx
-	reserved *os.File // +checklocks:vfsDotLocksMtx
-}
-
-func osGetSharedLock(file *os.File) _ErrorCode {
-	vfsDotLocksMtx.Lock()
-	defer vfsDotLocksMtx.Unlock()
-
-	name := file.Name()
-	locker := vfsDotLocks[name]
-	if locker == nil {
-		err := os.Mkdir(name+".lock", 0777)
-		if errors.Is(err, fs.ErrExist) {
-			return _BUSY // Another process has the lock.
-		}
-		if err != nil {
-			return _IOERR_LOCK
-		}
-		locker = &vfsDotLocker{}
-		vfsDotLocks[name] = locker
-	}
-
-	if locker.pending != nil {
-		return _BUSY
-	}
-	locker.shared++
-	return _OK
-}
-
-func osGetReservedLock(file *os.File) _ErrorCode {
-	vfsDotLocksMtx.Lock()
-	defer vfsDotLocksMtx.Unlock()
-
-	name := file.Name()
-	locker := vfsDotLocks[name]
-	if locker == nil {
-		return _IOERR_LOCK
-	}
-
-	if locker.reserved != nil && locker.reserved != file {
-		return _BUSY
-	}
-	locker.reserved = file
-	return _OK
-}
-
-func osGetExclusiveLock(file *os.File, _ *LockLevel) _ErrorCode {
-	vfsDotLocksMtx.Lock()
-	defer vfsDotLocksMtx.Unlock()
-
-	name := file.Name()
-	locker := vfsDotLocks[name]
-	if locker == nil {
-		return _IOERR_LOCK
-	}
-
-	if locker.pending != nil && locker.pending != file {
-		return _BUSY
-	}
-	locker.pending = file
-	if locker.shared > 1 {
-		return _BUSY
-	}
-	return _OK
-}
-
-func osDowngradeLock(file *os.File, _ LockLevel) _ErrorCode {
-	vfsDotLocksMtx.Lock()
-	defer vfsDotLocksMtx.Unlock()
-
-	name := file.Name()
-	locker := vfsDotLocks[name]
-	if locker == nil {
-		return _IOERR_UNLOCK
-	}
-
-	if locker.reserved == file {
-		locker.reserved = nil
-	}
-	if locker.pending == file {
-		locker.pending = nil
-	}
-	return _OK
-}
-
-func osReleaseLock(file *os.File, state LockLevel) _ErrorCode {
-	vfsDotLocksMtx.Lock()
-	defer vfsDotLocksMtx.Unlock()
-
-	name := file.Name()
-	locker := vfsDotLocks[name]
-	if locker == nil {
-		return _IOERR_UNLOCK
-	}
-
-	if locker.shared == 1 {
-		err := os.Remove(name + ".lock")
-		if err != nil && !errors.Is(err, fs.ErrNotExist) {
-			return _IOERR_UNLOCK
-		}
-		delete(vfsDotLocks, name)
-	}
-
-	if locker.reserved == file {
-		locker.reserved = nil
-	}
-	if locker.pending == file {
-		locker.pending = nil
-	}
-	locker.shared--
-	return _OK
-}
-
-func osCheckReservedLock(file *os.File) (bool, _ErrorCode) {
-	vfsDotLocksMtx.Lock()
-	defer vfsDotLocksMtx.Unlock()
-
-	name := file.Name()
-	locker := vfsDotLocks[name]
-	if locker == nil {
-		return false, _OK
-	}
-	return locker.reserved != nil, _OK
-}

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

@@ -1,4 +1,4 @@
-//go:build (linux || darwin) && !(sqlite3_flock || sqlite3_dotlk || sqlite3_nosys)
+//go:build (linux || darwin) && !(sqlite3_flock || sqlite3_nosys)
 
 package vfs
 

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

@@ -1,4 +1,4 @@
-//go:build !(sqlite3_dotlk || sqlite3_nosys)
+//go:build !sqlite3_nosys
 
 package vfs
 

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

@@ -1,7 +1,20 @@
-//go:build ((linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !sqlite3_nosys) || sqlite3_flock || sqlite3_dotlk
+//go:build (darwin || linux) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_flock || sqlite3_noshm || sqlite3_nosys)
 
 package vfs
 
+import (
+	"context"
+	"io"
+	"os"
+	"sync"
+	"time"
+
+	"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.
 // To use [WAL without shared-memory], you need to set [EXCLUSIVE locking mode].
 //
@@ -9,6 +22,12 @@
 // [EXCLUSIVE locking mode]: https://sqlite.org/pragma.html#pragma_locking_mode
 const SupportsSharedMemory = true
 
+const (
+	_SHM_NLOCK = 8
+	_SHM_BASE  = 120
+	_SHM_DMS   = _SHM_BASE + _SHM_NLOCK
+)
+
 func (f *vfsFile) SharedMemory() SharedMemory { return f.shm }
 
 // NewSharedMemory returns a shared-memory WAL-index
@@ -22,5 +41,172 @@ func NewSharedMemory(path string, flags OpenFlag) SharedMemory {
 	if flags&OPEN_MAIN_DB == 0 || flags&(OPEN_DELETEONCLOSE|OPEN_MEMORY) != 0 {
 		return nil
 	}
-	return &vfsShm{path: path}
+	return &vfsShm{
+		path:     path,
+		readOnly: flags&OPEN_READONLY != 0,
+	}
+}
+
+var _ blockingSharedMemory = &vfsShm{}
+
+type vfsShm struct {
+	*os.File
+	path     string
+	regions  []*util.MappedRegion
+	readOnly bool
+	blocking bool
+	sync.Mutex
+}
+
+func (s *vfsShm) shmOpen() _ErrorCode {
+	if s.File == nil {
+		var flag int
+		if s.readOnly {
+			flag = unix.O_RDONLY
+		} else {
+			flag = unix.O_RDWR
+		}
+		f, err := os.OpenFile(s.path,
+			flag|unix.O_CREAT|unix.O_NOFOLLOW, 0666)
+		if err != nil {
+			return _CANTOPEN
+		}
+		s.File = f
+	}
+
+	// Dead man's switch.
+	if lock, rc := osTestLock(s.File, _SHM_DMS, 1); rc != _OK {
+		return _IOERR_LOCK
+	} else if lock == unix.F_WRLCK {
+		return _BUSY
+	} else if lock == unix.F_UNLCK {
+		if s.readOnly {
+			return _READONLY_CANTINIT
+		}
+		// Do not use a blocking lock here.
+		// If the lock cannot be obtained immediately,
+		// it means some other connection is truncating the file.
+		// And after it has done so, it will not release its lock,
+		// but only downgrade it to a shared lock.
+		// So no point in blocking here.
+		// The call below to obtain the shared DMS lock may use a blocking lock.
+		if rc := osWriteLock(s.File, _SHM_DMS, 1, 0); rc != _OK {
+			return rc
+		}
+		if err := s.Truncate(0); err != nil {
+			return _IOERR_SHMOPEN
+		}
+	}
+	if rc := osReadLock(s.File, _SHM_DMS, 1, time.Millisecond); rc != _OK {
+		return rc
+	}
+	return _OK
+}
+
+func (s *vfsShm) shmMap(ctx context.Context, mod api.Module, id, size int32, extend bool) (uint32, _ErrorCode) {
+	// Ensure size is a multiple of the OS page size.
+	if int(size)&(unix.Getpagesize()-1) != 0 {
+		return 0, _IOERR_SHMMAP
+	}
+
+	if rc := s.shmOpen(); rc != _OK {
+		return 0, rc
+	}
+
+	// Check if file is big enough.
+	o, err := s.Seek(0, io.SeekEnd)
+	if err != nil {
+		return 0, _IOERR_SHMSIZE
+	}
+	if n := (int64(id) + 1) * int64(size); n > o {
+		if !extend {
+			return 0, _OK
+		}
+		err := osAllocate(s.File, n)
+		if err != nil {
+			return 0, _IOERR_SHMSIZE
+		}
+	}
+
+	var prot int
+	if s.readOnly {
+		prot = unix.PROT_READ
+	} else {
+		prot = unix.PROT_READ | unix.PROT_WRITE
+	}
+	r, err := util.MapRegion(ctx, mod, s.File, int64(id)*int64(size), size, prot)
+	if err != nil {
+		return 0, _IOERR_SHMMAP
+	}
+	s.regions = append(s.regions, r)
+	if s.readOnly {
+		return r.Ptr, _READONLY
+	}
+	return r.Ptr, _OK
+}
+
+func (s *vfsShm) shmLock(offset, n int32, flags _ShmFlag) _ErrorCode {
+	// 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())
+	}
+
+	var timeout time.Duration
+	if s.blocking {
+		timeout = time.Millisecond
+	}
+
+	switch {
+	case flags&_SHM_UNLOCK != 0:
+		return osUnlock(s.File, _SHM_BASE+int64(offset), int64(n))
+	case flags&_SHM_SHARED != 0:
+		return osReadLock(s.File, _SHM_BASE+int64(offset), int64(n), timeout)
+	case flags&_SHM_EXCLUSIVE != 0:
+		return osWriteLock(s.File, _SHM_BASE+int64(offset), int64(n), timeout)
+	default:
+		panic(util.AssertErr())
+	}
+}
+
+func (s *vfsShm) shmUnmap(delete bool) {
+	if s.File == nil {
+		return
+	}
+
+	// Unmap regions.
+	for _, r := range s.regions {
+		r.Unmap()
+	}
+	clear(s.regions)
+	s.regions = s.regions[:0]
+
+	// Close the file.
+	if delete {
+		os.Remove(s.path)
+	}
+	s.Close()
+	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) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_dotlk || sqlite3_nosys)) || sqlite3_flock
+//go:build (freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_noshm || sqlite3_nosys)
 
 package vfs
 
@@ -14,14 +14,44 @@
 	"github.com/ncruces/go-sqlite3/internal/util"
 )
 
+// SupportsSharedMemory is false on platforms that do not support shared memory.
+// To use [WAL without shared-memory], you need to set [EXCLUSIVE locking mode].
+//
+// [WAL without shared-memory]: https://sqlite.org/wal.html#noshm
+// [EXCLUSIVE locking mode]: https://sqlite.org/pragma.html#pragma_locking_mode
+const SupportsSharedMemory = true
+
+const _SHM_NLOCK = 8
+
+func (f *vfsFile) SharedMemory() SharedMemory { return f.shm }
+
+// NewSharedMemory returns a shared-memory WAL-index
+// backed by a file with the given path.
+// It will return nil if shared-memory is not supported,
+// or not appropriate for the given flags.
+// Only [OPEN_MAIN_DB] databases may need a WAL-index.
+// You must ensure all concurrent accesses to a database
+// use shared-memory instances created with the same path.
+func NewSharedMemory(path string, flags OpenFlag) SharedMemory {
+	if flags&OPEN_MAIN_DB == 0 || flags&(OPEN_DELETEONCLOSE|OPEN_MEMORY) != 0 {
+		return nil
+	}
+	return &vfsShm{
+		path:     path,
+		readOnly: flags&OPEN_READONLY != 0,
+	}
+}
+
 type vfsShmFile struct {
 	*os.File
 	info os.FileInfo
 
-	refs int // +checklocks:vfsShmFilesMtx
+	// +checklocks:vfsShmFilesMtx
+	refs int
 
-	lock [_SHM_NLOCK]int16 // +checklocks:Mutex
+	// +checklocks:lockMtx
-	sync.Mutex
+	lock    [_SHM_NLOCK]int16
+	lockMtx sync.Mutex
 }
 
 var (
@@ -32,9 +62,10 @@ type vfsShmFile struct {
 
 type vfsShm struct {
 	*vfsShmFile
-	path    string
+	path     string
-	lock    [_SHM_NLOCK]bool
+	lock     [_SHM_NLOCK]bool
-	regions []*util.MappedRegion
+	regions  []*util.MappedRegion
+	readOnly bool
 }
 
 func (s *vfsShm) Close() error {
@@ -49,7 +80,7 @@ func (s *vfsShm) Close() error {
 	s.shmLock(0, _SHM_NLOCK, _SHM_UNLOCK)
 
 	// Decrease reference count.
-	if s.vfsShmFile.refs > 0 {
+	if s.vfsShmFile.refs > 1 {
 		s.vfsShmFile.refs--
 		s.vfsShmFile = nil
 		return nil
@@ -66,7 +97,7 @@ func (s *vfsShm) Close() error {
 	panic(util.AssertErr())
 }
 
-func (s *vfsShm) shmOpen() _ErrorCode {
+func (s *vfsShm) shmOpen() (rc _ErrorCode) {
 	if s.vfsShmFile != nil {
 		return _OK
 	}
@@ -97,29 +128,34 @@ func (s *vfsShm) shmOpen() _ErrorCode {
 		}
 	}
 
-	// Lock and truncate the file.
+	// Lock and truncate the file, if not readonly.
 	// The lock is only released by closing the file.
-	if rc := osLock(f, unix.LOCK_EX|unix.LOCK_NB, _IOERR_LOCK); rc != _OK {
+	if s.readOnly {
-		return rc
+		rc = _READONLY_CANTINIT
-	}
+	} else {
-	if err := f.Truncate(0); err != nil {
+		if rc := osLock(f, unix.LOCK_EX|unix.LOCK_NB, _IOERR_LOCK); rc != _OK {
-		return _IOERR_SHMOPEN
+			return rc
+		}
+		if err := f.Truncate(0); err != nil {
+			return _IOERR_SHMOPEN
+		}
 	}
 
 	// Add the new shared file.
 	s.vfsShmFile = &vfsShmFile{
 		File: f,
 		info: fi,
+		refs: 1,
 	}
 	f = nil // Don't close the file.
 	for i, g := range vfsShmFiles {
 		if g == nil {
 			vfsShmFiles[i] = s.vfsShmFile
-			return _OK
+			return rc
 		}
 	}
 	vfsShmFiles = append(vfsShmFiles, s.vfsShmFile)
-	return _OK
+	return rc
 }
 
 func (s *vfsShm) shmMap(ctx context.Context, mod api.Module, id, size int32, extend bool) (uint32, _ErrorCode) {
@@ -141,22 +177,32 @@ func (s *vfsShm) shmMap(ctx context.Context, mod api.Module, id, size int32, ext
 		if !extend {
 			return 0, _OK
 		}
-		if osAllocate(s.File, n) != nil {
+		err := osAllocate(s.File, n)
+		if err != nil {
 			return 0, _IOERR_SHMSIZE
 		}
 	}
 
-	r, err := util.MapRegion(ctx, mod, s.File, int64(id)*int64(size), size, false)
+	var prot int
+	if s.readOnly {
+		prot = unix.PROT_READ
+	} else {
+		prot = unix.PROT_READ | unix.PROT_WRITE
+	}
+	r, err := util.MapRegion(ctx, mod, s.File, int64(id)*int64(size), size, prot)
 	if err != nil {
 		return 0, _IOERR_SHMMAP
 	}
 	s.regions = append(s.regions, r)
+	if s.readOnly {
+		return r.Ptr, _READONLY
+	}
 	return r.Ptr, _OK
 }
 
 func (s *vfsShm) shmLock(offset, n int32, flags _ShmFlag) _ErrorCode {
-	s.Lock()
+	s.lockMtx.Lock()
-	defer s.Unlock()
+	defer s.lockMtx.Unlock()
 
 	switch {
 	case flags&_SHM_UNLOCK != 0:
@@ -178,7 +224,7 @@ func (s *vfsShm) shmLock(offset, n int32, flags _ShmFlag) _ErrorCode {
 			if s.lock[i] {
 				panic(util.AssertErr())
 			}
-			if s.vfsShmFile.lock[i]+1 <= 0 {
+			if s.vfsShmFile.lock[i] < 0 {
 				return _BUSY
 			}
 		}
@@ -215,7 +261,8 @@ func (s *vfsShm) shmUnmap(delete bool) {
 	for _, r := range s.regions {
 		r.Unmap()
 	}
-	s.regions = nil
+	clear(s.regions)
+	s.regions = s.regions[:0]
 
 	// Close the file.
 	if delete {
@@ -225,7 +272,7 @@ func (s *vfsShm) shmUnmap(delete bool) {
 }
 
 func (s *vfsShm) shmBarrier() {
-	s.Lock()
+	s.lockMtx.Lock()
 	//lint:ignore SA2001 memory barrier.
-	s.Unlock()
+	s.lockMtx.Unlock()
 }

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

@@ -1,84 +0,0 @@
-//go:build (windows && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !sqlite3_nosys) || sqlite3_dotlk
-
-package vfs
-
-import (
-	"unsafe"
-
-	"github.com/ncruces/go-sqlite3/internal/util"
-)
-
-const (
-	_WALINDEX_HDR_SIZE = 136
-	_WALINDEX_PGSZ     = 32768
-)
-
-// This looks like a safe way of keeping the WAL-index in sync.
-//
-// The WAL-index file starts with a header,
-// and the index doesn't meaningfully change if the header doesn't change.
-//
-// The header starts with two 48 byte, checksummed, copies of the same information,
-// which are accessed independently between memory barriers.
-// The checkpoint information that follows uses 4 byte aligned words.
-//
-// Finally, we have the WAL-index hash tables,
-// which are only modified holding the exclusive WAL_WRITE_LOCK.
-//
-// Since all the data is either redundant+checksummed,
-// 4 byte aligned, or modified under an exclusive lock,
-// the copies below should correctly keep copies in sync.
-//
-// https://sqlite.org/walformat.html#the_wal_index_file_format
-
-func (s *vfsShm) shmAcquire() {
-	if len(s.ptrs) == 0 || shmUnmodified(s.shadow[0][:], s.shared[0][:]) {
-		return
-	}
-	// Copies modified words from shared to private memory.
-	for id, p := range s.ptrs {
-		shared := shmPage(s.shared[id][:])
-		shadow := shmPage(s.shadow[id][:])
-		privat := shmPage(util.View(s.mod, p, _WALINDEX_PGSZ))
-		for i, shared := range shared {
-			if shadow[i] != shared {
-				shadow[i] = shared
-				privat[i] = shared
-			}
-		}
-	}
-}
-
-func (s *vfsShm) shmRelease() {
-	if len(s.ptrs) == 0 || shmUnmodified(s.shadow[0][:], util.View(s.mod, s.ptrs[0], _WALINDEX_HDR_SIZE)) {
-		return
-	}
-	// Copies modified words from private to shared memory.
-	for id, p := range s.ptrs {
-		shared := shmPage(s.shared[id][:])
-		shadow := shmPage(s.shadow[id][:])
-		privat := shmPage(util.View(s.mod, p, _WALINDEX_PGSZ))
-		for i, privat := range privat {
-			if shadow[i] != privat {
-				shadow[i] = privat
-				shared[i] = privat
-			}
-		}
-	}
-}
-
-func (s *vfsShm) shmBarrier() {
-	s.Lock()
-	s.shmAcquire()
-	s.shmRelease()
-	s.Unlock()
-}
-
-func shmPage(s []byte) *[_WALINDEX_PGSZ / 4]uint32 {
-	p := (*uint32)(unsafe.Pointer(unsafe.SliceData(s)))
-	return (*[_WALINDEX_PGSZ / 4]uint32)(unsafe.Slice(p, _WALINDEX_PGSZ/4))
-}
-
-func shmUnmodified(v1, v2 []byte) bool {
-	return *(*[_WALINDEX_HDR_SIZE]byte)(v1[:]) == *(*[_WALINDEX_HDR_SIZE]byte)(v2[:])
-}

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

@@ -1,224 +0,0 @@
-//go:build sqlite3_dotlk
-
-package vfs
-
-import (
-	"context"
-	"errors"
-	"io/fs"
-	"os"
-	"sync"
-
-	"github.com/ncruces/go-sqlite3/internal/util"
-	"github.com/tetratelabs/wazero/api"
-)
-
-type vfsShmBuffer struct {
-	shared [][_WALINDEX_PGSZ]byte
-	refs   int // +checklocks:vfsShmBuffersMtx
-
-	lock [_SHM_NLOCK]int16 // +checklocks:Mutex
-	sync.Mutex
-}
-
-var (
-	// +checklocks:vfsShmBuffersMtx
-	vfsShmBuffers    = map[string]*vfsShmBuffer{}
-	vfsShmBuffersMtx sync.Mutex
-)
-
-type vfsShm struct {
-	*vfsShmBuffer
-	mod    api.Module
-	alloc  api.Function
-	free   api.Function
-	path   string
-	shadow [][_WALINDEX_PGSZ]byte
-	ptrs   []uint32
-	stack  [1]uint64
-	lock   [_SHM_NLOCK]bool
-}
-
-func (s *vfsShm) Close() error {
-	if s.vfsShmBuffer == nil {
-		return nil
-	}
-
-	vfsShmBuffersMtx.Lock()
-	defer vfsShmBuffersMtx.Unlock()
-
-	// Unlock everything.
-	s.shmLock(0, _SHM_NLOCK, _SHM_UNLOCK)
-
-	// Decrease reference count.
-	if s.vfsShmBuffer.refs > 0 {
-		s.vfsShmBuffer.refs--
-		s.vfsShmBuffer = nil
-		return nil
-	}
-
-	err := os.Remove(s.path)
-	if err != nil && !errors.Is(err, fs.ErrNotExist) {
-		return _IOERR_UNLOCK
-	}
-	delete(vfsShmBuffers, s.path)
-	s.vfsShmBuffer = nil
-	return nil
-}
-
-func (s *vfsShm) shmOpen() _ErrorCode {
-	if s.vfsShmBuffer != nil {
-		return _OK
-	}
-
-	vfsShmBuffersMtx.Lock()
-	defer vfsShmBuffersMtx.Unlock()
-
-	// Find a shared buffer, increase the reference count.
-	if g, ok := vfsShmBuffers[s.path]; ok {
-		s.vfsShmBuffer = g
-		g.refs++
-		return _OK
-	}
-
-	// Create a directory on disk to ensure only this process
-	// uses this path to register a shared memory.
-	err := os.Mkdir(s.path, 0777)
-	if errors.Is(err, fs.ErrExist) {
-		return _BUSY
-	}
-	if err != nil {
-		return _IOERR_LOCK
-	}
-
-	// Add the new shared buffer.
-	s.vfsShmBuffer = &vfsShmBuffer{}
-	vfsShmBuffers[s.path] = s.vfsShmBuffer
-	return _OK
-}
-
-func (s *vfsShm) shmMap(ctx context.Context, mod api.Module, id, size int32, extend bool) (uint32, _ErrorCode) {
-	if size != _WALINDEX_PGSZ {
-		return 0, _IOERR_SHMMAP
-	}
-	if s.mod == nil {
-		s.mod = mod
-		s.free = mod.ExportedFunction("sqlite3_free")
-		s.alloc = mod.ExportedFunction("sqlite3_malloc64")
-	}
-	if rc := s.shmOpen(); rc != _OK {
-		return 0, rc
-	}
-
-	s.Lock()
-	defer s.Unlock()
-	defer s.shmAcquire()
-
-	// Extend shared memory.
-	if int(id) >= len(s.shared) {
-		if !extend {
-			return 0, _OK
-		}
-		s.shared = append(s.shared, make([][_WALINDEX_PGSZ]byte, int(id)-len(s.shared)+1)...)
-	}
-
-	// Allocate shadow memory.
-	if int(id) >= len(s.shadow) {
-		s.shadow = append(s.shadow, make([][_WALINDEX_PGSZ]byte, int(id)-len(s.shadow)+1)...)
-		s.shadow[0][4] = 1 // force invalidation
-	}
-
-	// Allocate local memory.
-	for int(id) >= len(s.ptrs) {
-		s.stack[0] = uint64(size)
-		if err := s.alloc.CallWithStack(ctx, s.stack[:]); err != nil {
-			panic(err)
-		}
-		if s.stack[0] == 0 {
-			panic(util.OOMErr)
-		}
-		clear(util.View(s.mod, uint32(s.stack[0]), _WALINDEX_PGSZ))
-		s.ptrs = append(s.ptrs, uint32(s.stack[0]))
-	}
-
-	return s.ptrs[id], _OK
-}
-
-func (s *vfsShm) shmLock(offset, n int32, flags _ShmFlag) _ErrorCode {
-	s.Lock()
-	defer s.Unlock()
-
-	switch {
-	case flags&_SHM_LOCK != 0:
-		defer s.shmAcquire()
-	case flags&_SHM_EXCLUSIVE != 0:
-		s.shmRelease()
-	}
-
-	switch {
-	case flags&_SHM_UNLOCK != 0:
-		for i := offset; i < offset+n; i++ {
-			if s.lock[i] {
-				if s.vfsShmBuffer.lock[i] == 0 {
-					panic(util.AssertErr())
-				}
-				if s.vfsShmBuffer.lock[i] <= 0 {
-					s.vfsShmBuffer.lock[i] = 0
-				} else {
-					s.vfsShmBuffer.lock[i]--
-				}
-				s.lock[i] = false
-			}
-		}
-	case flags&_SHM_SHARED != 0:
-		for i := offset; i < offset+n; i++ {
-			if s.lock[i] {
-				panic(util.AssertErr())
-			}
-			if s.vfsShmBuffer.lock[i]+1 <= 0 {
-				return _BUSY
-			}
-		}
-		for i := offset; i < offset+n; i++ {
-			s.vfsShmBuffer.lock[i]++
-			s.lock[i] = true
-		}
-	case flags&_SHM_EXCLUSIVE != 0:
-		for i := offset; i < offset+n; i++ {
-			if s.lock[i] {
-				panic(util.AssertErr())
-			}
-			if s.vfsShmBuffer.lock[i] != 0 {
-				return _BUSY
-			}
-		}
-		for i := offset; i < offset+n; i++ {
-			s.vfsShmBuffer.lock[i] = -1
-			s.lock[i] = true
-		}
-	default:
-		panic(util.AssertErr())
-	}
-
-	return _OK
-}
-
-func (s *vfsShm) shmUnmap(delete bool) {
-	if s.vfsShmBuffer == nil {
-		return
-	}
-	defer s.Close()
-
-	s.Lock()
-	s.shmRelease()
-	defer s.Unlock()
-
-	for _, p := range s.ptrs {
-		s.stack[0] = uint64(p)
-		if err := s.free.CallWithStack(context.Background(), s.stack[:]); err != nil {
-			panic(err)
-		}
-	}
-	s.ptrs = nil
-	s.shadow = nil
-}

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

@@ -1,168 +0,0 @@
-//go:build (linux || darwin) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_flock || sqlite3_dotlk || sqlite3_nosys)
-
-package vfs
-
-import (
-	"context"
-	"io"
-	"os"
-	"sync"
-	"time"
-
-	"github.com/tetratelabs/wazero/api"
-	"golang.org/x/sys/unix"
-
-	"github.com/ncruces/go-sqlite3/internal/util"
-)
-
-type vfsShm struct {
-	*os.File
-	path     string
-	regions  []*util.MappedRegion
-	readOnly bool
-	blocking bool
-	sync.Mutex
-}
-
-var _ blockingSharedMemory = &vfsShm{}
-
-func (s *vfsShm) shmOpen() _ErrorCode {
-	if s.File == nil {
-		f, err := os.OpenFile(s.path,
-			unix.O_RDWR|unix.O_CREAT|unix.O_NOFOLLOW, 0666)
-		if err != nil {
-			f, err = os.OpenFile(s.path,
-				unix.O_RDONLY|unix.O_CREAT|unix.O_NOFOLLOW, 0666)
-			s.readOnly = true
-		}
-		if err != nil {
-			return _CANTOPEN
-		}
-		s.File = f
-	}
-
-	// Dead man's switch.
-	if lock, rc := osTestLock(s.File, _SHM_DMS, 1); rc != _OK {
-		return _IOERR_LOCK
-	} else if lock == unix.F_WRLCK {
-		return _BUSY
-	} else if lock == unix.F_UNLCK {
-		if s.readOnly {
-			return _READONLY_CANTINIT
-		}
-		// Do not use a blocking lock here.
-		// If the lock cannot be obtained immediately,
-		// it means some other connection is truncating the file.
-		// And after it has done so, it will not release its lock,
-		// but only downgrade it to a shared lock.
-		// So no point in blocking here.
-		// The call below to obtain the shared DMS lock may use a blocking lock.
-		if rc := osWriteLock(s.File, _SHM_DMS, 1, 0); rc != _OK {
-			return rc
-		}
-		if err := s.Truncate(0); err != nil {
-			return _IOERR_SHMOPEN
-		}
-	}
-	return osReadLock(s.File, _SHM_DMS, 1, time.Millisecond)
-}
-
-func (s *vfsShm) shmMap(ctx context.Context, mod api.Module, id, size int32, extend bool) (uint32, _ErrorCode) {
-	// Ensure size is a multiple of the OS page size.
-	if int(size)&(unix.Getpagesize()-1) != 0 {
-		return 0, _IOERR_SHMMAP
-	}
-
-	if rc := s.shmOpen(); rc != _OK {
-		return 0, rc
-	}
-
-	// Check if file is big enough.
-	o, err := s.Seek(0, io.SeekEnd)
-	if err != nil {
-		return 0, _IOERR_SHMSIZE
-	}
-	if n := (int64(id) + 1) * int64(size); n > o {
-		if !extend {
-			return 0, _OK
-		}
-		if s.readOnly || osAllocate(s.File, n) != nil {
-			return 0, _IOERR_SHMSIZE
-		}
-	}
-
-	r, err := util.MapRegion(ctx, mod, s.File, int64(id)*int64(size), size, s.readOnly)
-	if err != nil {
-		return 0, _IOERR_SHMMAP
-	}
-	s.regions = append(s.regions, r)
-	if s.readOnly {
-		return r.Ptr, _READONLY
-	}
-	return r.Ptr, _OK
-}
-
-func (s *vfsShm) shmLock(offset, n int32, flags _ShmFlag) _ErrorCode {
-	// 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())
-	}
-
-	var timeout time.Duration
-	if s.blocking {
-		timeout = time.Millisecond
-	}
-
-	switch {
-	case flags&_SHM_UNLOCK != 0:
-		return osUnlock(s.File, _SHM_BASE+int64(offset), int64(n))
-	case flags&_SHM_SHARED != 0:
-		return osReadLock(s.File, _SHM_BASE+int64(offset), int64(n), timeout)
-	case flags&_SHM_EXCLUSIVE != 0:
-		return osWriteLock(s.File, _SHM_BASE+int64(offset), int64(n), timeout)
-	default:
-		panic(util.AssertErr())
-	}
-}
-
-func (s *vfsShm) shmUnmap(delete bool) {
-	if s.File == nil {
-		return
-	}
-
-	// Unmap regions.
-	for _, r := range s.regions {
-		r.Unmap()
-	}
-	s.regions = nil
-
-	// Close the file.
-	if delete {
-		os.Remove(s.path)
-	}
-	s.Close()
-	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_other.go

@@ -1,4 +1,4 @@
-//go:build !(((linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !sqlite3_nosys) || sqlite3_flock || sqlite3_dotlk)
+//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/shm_windows.go

@@ -1,182 +0,0 @@
-//go:build (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_dotlk || sqlite3_nosys)
-
-package vfs
-
-import (
-	"context"
-	"io"
-	"os"
-	"sync"
-	"time"
-
-	"github.com/tetratelabs/wazero/api"
-	"golang.org/x/sys/windows"
-
-	"github.com/ncruces/go-sqlite3/internal/util"
-	"github.com/ncruces/go-sqlite3/util/osutil"
-)
-
-type vfsShm struct {
-	*os.File
-	mod      api.Module
-	alloc    api.Function
-	free     api.Function
-	path     string
-	regions  []*util.MappedRegion
-	shared   [][]byte
-	shadow   [][_WALINDEX_PGSZ]byte
-	ptrs     []uint32
-	stack    [1]uint64
-	blocking bool
-	sync.Mutex
-}
-
-var _ blockingSharedMemory = &vfsShm{}
-
-func (s *vfsShm) Close() error {
-	// Unmap regions.
-	for _, r := range s.regions {
-		r.Unmap()
-	}
-	s.regions = nil
-
-	// Close the file.
-	return s.File.Close()
-}
-
-func (s *vfsShm) shmOpen() _ErrorCode {
-	if s.File == nil {
-		f, err := osutil.OpenFile(s.path, os.O_RDWR|os.O_CREATE, 0666)
-		if err != nil {
-			return _CANTOPEN
-		}
-		s.File = f
-	}
-
-	// Dead man's switch.
-	if rc := osWriteLock(s.File, _SHM_DMS, 1, 0); rc == _OK {
-		err := s.Truncate(0)
-		osUnlock(s.File, _SHM_DMS, 1)
-		if err != nil {
-			return _IOERR_SHMOPEN
-		}
-	}
-	return osReadLock(s.File, _SHM_DMS, 1, time.Millisecond)
-}
-
-func (s *vfsShm) shmMap(ctx context.Context, mod api.Module, id, size int32, extend bool) (uint32, _ErrorCode) {
-	// Ensure size is a multiple of the OS page size.
-	if size != _WALINDEX_PGSZ || (windows.Getpagesize()-1)&_WALINDEX_PGSZ != 0 {
-		return 0, _IOERR_SHMMAP
-	}
-	if s.mod == nil {
-		s.mod = mod
-		s.free = mod.ExportedFunction("sqlite3_free")
-		s.alloc = mod.ExportedFunction("sqlite3_malloc64")
-	}
-	if rc := s.shmOpen(); rc != _OK {
-		return 0, rc
-	}
-
-	defer s.shmAcquire()
-
-	// Check if file is big enough.
-	o, err := s.Seek(0, io.SeekEnd)
-	if err != nil {
-		return 0, _IOERR_SHMSIZE
-	}
-	if n := (int64(id) + 1) * int64(size); n > o {
-		if !extend {
-			return 0, _OK
-		}
-		if osAllocate(s.File, n) != nil {
-			return 0, _IOERR_SHMSIZE
-		}
-	}
-
-	// Maps regions into memory.
-	for int(id) >= len(s.shared) {
-		r, err := util.MapRegion(ctx, mod, s.File, int64(id)*int64(size), size)
-		if err != nil {
-			return 0, _IOERR_SHMMAP
-		}
-		s.regions = append(s.regions, r)
-		s.shared = append(s.shared, r.Data)
-	}
-
-	// Allocate shadow memory.
-	if int(id) >= len(s.shadow) {
-		s.shadow = append(s.shadow, make([][_WALINDEX_PGSZ]byte, int(id)-len(s.shadow)+1)...)
-		s.shadow[0][4] = 1 // force invalidation
-	}
-
-	// Allocate local memory.
-	for int(id) >= len(s.ptrs) {
-		s.stack[0] = uint64(size)
-		if err := s.alloc.CallWithStack(ctx, s.stack[:]); err != nil {
-			panic(err)
-		}
-		if s.stack[0] == 0 {
-			panic(util.OOMErr)
-		}
-		clear(util.View(s.mod, uint32(s.stack[0]), _WALINDEX_PGSZ))
-		s.ptrs = append(s.ptrs, uint32(s.stack[0]))
-	}
-
-	return s.ptrs[id], _OK
-}
-
-func (s *vfsShm) shmLock(offset, n int32, flags _ShmFlag) _ErrorCode {
-	switch {
-	case flags&_SHM_LOCK != 0:
-		defer s.shmAcquire()
-	case flags&_SHM_EXCLUSIVE != 0:
-		s.shmRelease()
-	}
-
-	var timeout time.Duration
-	if s.blocking {
-		timeout = time.Millisecond
-	}
-
-	switch {
-	case flags&_SHM_UNLOCK != 0:
-		return osUnlock(s.File, _SHM_BASE+uint32(offset), uint32(n))
-	case flags&_SHM_SHARED != 0:
-		return osReadLock(s.File, _SHM_BASE+uint32(offset), uint32(n), timeout)
-	case flags&_SHM_EXCLUSIVE != 0:
-		return osWriteLock(s.File, _SHM_BASE+uint32(offset), uint32(n), timeout)
-	default:
-		panic(util.AssertErr())
-	}
-}
-
-func (s *vfsShm) shmUnmap(delete bool) {
-	if s.File == nil {
-		return
-	}
-
-	s.shmRelease()
-
-	// Free local memory.
-	for _, p := range s.ptrs {
-		s.stack[0] = uint64(p)
-		if err := s.free.CallWithStack(context.Background(), s.stack[:]); err != nil {
-			panic(err)
-		}
-	}
-	s.ptrs = nil
-	s.shadow = nil
-	s.shared = nil
-
-	// Close the file.
-	s.Close()
-	s.File = nil
-	if delete {
-		os.Remove(s.path)
-	}
-}
-
-func (s *vfsShm) shmEnableBlocking(block bool) {
-	s.blocking = block
-}

vendor/modules.txt

@@ -514,7 +514,7 @@ github.com/modern-go/reflect2
 # github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822
 ## explicit
 github.com/munnerz/goautoneg
-# github.com/ncruces/go-sqlite3 v0.20.2
+# github.com/ncruces/go-sqlite3 v0.20.0
 ## explicit; go 1.21
 github.com/ncruces/go-sqlite3
 github.com/ncruces/go-sqlite3/driver