Fix sharing violation.

sys_windows.go

@@ -0,0 +1,163 @@
+package sqlite3
+
+import (
+	"io/fs"
+	"os"
+	"path/filepath"
+	"syscall"
+)
+
+// osOpenFile is the Windows implementation of OpenFile.
+func osOpenFile(name string, flag int, perm fs.FileMode) (*os.File, error) {
+	if name == "" {
+		return nil, &os.PathError{Op: "open", Path: name, Err: syscall.ENOENT}
+	}
+	path := osFixLongPath(name)
+	r, e := syscallOpen(path, flag, syscallMode(perm))
+	if e != nil {
+		return nil, &os.PathError{Op: "open", Path: name, Err: e}
+	}
+	return os.NewFile(uintptr(r), name), nil
+}
+
+// fixLongPath returns the extended-length (\\?\-prefixed) form of
+// path when needed, in order to avoid the default 260 character file
+// path limit imposed by Windows. If path is not easily converted to
+// the extended-length form (for example, if path is a relative path
+// or contains .. elements), or is short enough, osFixLongPath returns
+// path unmodified.
+//
+// See https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx#maxpath
+func osFixLongPath(path string) string {
+	// Do nothing (and don't allocate) if the path is "short".
+	// Empirically (at least on the Windows Server 2013 builder),
+	// the kernel is arbitrarily okay with < 248 bytes. That
+	// matches what the docs above say:
+	// "When using an API to create a directory, the specified
+	// path cannot be so long that you cannot append an 8.3 file
+	// name (that is, the directory name cannot exceed MAX_PATH
+	// minus 12)." Since MAX_PATH is 260, 260 - 12 = 248.
+	//
+	// The MSDN docs appear to say that a normal path that is 248 bytes long
+	// will work; empirically the path must be less then 248 bytes long.
+	if len(path) < 248 {
+		// Don't fix. (This is how Go 1.7 and earlier worked,
+		// not automatically generating the \\?\ form)
+		return path
+	}
+
+	// The extended form begins with \\?\, as in
+	// \\?\c:\windows\foo.txt or \\?\UNC\server\share\foo.txt.
+	// The extended form disables evaluation of . and .. path
+	// elements and disables the interpretation of / as equivalent
+	// to \. The conversion here rewrites / to \ and elides
+	// . elements as well as trailing or duplicate separators. For
+	// simplicity it avoids the conversion entirely for relative
+	// paths or paths containing .. elements. For now,
+	// \\server\share paths are not converted to
+	// \\?\UNC\server\share paths because the rules for doing so
+	// are less well-specified.
+	if len(path) >= 2 && path[:2] == `\\` {
+		// Don't canonicalize UNC paths.
+		return path
+	}
+	if !filepath.IsAbs(path) {
+		// Relative path
+		return path
+	}
+
+	const prefix = `\\?`
+
+	pathbuf := make([]byte, len(prefix)+len(path)+len(`\`))
+	copy(pathbuf, prefix)
+	n := len(path)
+	r, w := 0, len(prefix)
+	for r < n {
+		switch {
+		case os.IsPathSeparator(path[r]):
+			// empty block
+			r++
+		case path[r] == '.' && (r+1 == n || os.IsPathSeparator(path[r+1])):
+			// /./
+			r++
+		case r+1 < n && path[r] == '.' && path[r+1] == '.' && (r+2 == n || os.IsPathSeparator(path[r+2])):
+			// /../ is currently unhandled
+			return path
+		default:
+			pathbuf[w] = '\\'
+			w++
+			for ; r < n && !os.IsPathSeparator(path[r]); r++ {
+				pathbuf[w] = path[r]
+				w++
+			}
+		}
+	}
+	// A drive's root directory needs a trailing \
+	if w == len(`\\?\c:`) {
+		pathbuf[w] = '\\'
+		w++
+	}
+	return string(pathbuf[:w])
+}
+
+// syscallMode returns the syscall-specific mode bits from Go's portable mode bits.
+func syscallMode(i fs.FileMode) (o uint32) {
+	o |= uint32(i.Perm())
+	if i&fs.ModeSetuid != 0 {
+		o |= syscall.S_ISUID
+	}
+	if i&fs.ModeSetgid != 0 {
+		o |= syscall.S_ISGID
+	}
+	if i&fs.ModeSticky != 0 {
+		o |= syscall.S_ISVTX
+	}
+	// No mapping for Go's ModeTemporary (plan9 only).
+	return
+}
+
+func syscallOpen(path string, mode int, perm uint32) (fd syscall.Handle, err error) {
+	if len(path) == 0 {
+		return syscall.InvalidHandle, syscall.ERROR_FILE_NOT_FOUND
+	}
+	pathp, err := syscall.UTF16PtrFromString(path)
+	if err != nil {
+		return syscall.InvalidHandle, err
+	}
+	var access uint32
+	switch mode & (syscall.O_RDONLY | syscall.O_WRONLY | syscall.O_RDWR) {
+	case syscall.O_RDONLY:
+		access = syscall.GENERIC_READ
+	case syscall.O_WRONLY:
+		access = syscall.GENERIC_WRITE
+	case syscall.O_RDWR:
+		access = syscall.GENERIC_READ | syscall.GENERIC_WRITE
+	}
+	if mode&syscall.O_CREAT != 0 {
+		access |= syscall.GENERIC_WRITE
+	}
+	if mode&syscall.O_APPEND != 0 {
+		access &^= syscall.GENERIC_WRITE
+		access |= syscall.FILE_APPEND_DATA
+	}
+	sharemode := uint32(syscall.FILE_SHARE_READ | syscall.FILE_SHARE_WRITE | syscall.FILE_SHARE_DELETE)
+	var createmode uint32
+	switch {
+	case mode&(syscall.O_CREAT|syscall.O_EXCL) == (syscall.O_CREAT | syscall.O_EXCL):
+		createmode = syscall.CREATE_NEW
+	case mode&(syscall.O_CREAT|syscall.O_TRUNC) == (syscall.O_CREAT | syscall.O_TRUNC):
+		createmode = syscall.CREATE_ALWAYS
+	case mode&syscall.O_CREAT == syscall.O_CREAT:
+		createmode = syscall.OPEN_ALWAYS
+	case mode&syscall.O_TRUNC == syscall.O_TRUNC:
+		createmode = syscall.TRUNCATE_EXISTING
+	default:
+		createmode = syscall.OPEN_EXISTING
+	}
+	var attrs uint32 = syscall.FILE_ATTRIBUTE_NORMAL
+	if perm&syscall.S_IWRITE == 0 {
+		attrs = syscall.FILE_ATTRIBUTE_READONLY
+	}
+	h, e := syscall.CreateFile(pathp, access, sharemode, nil, createmode, attrs, 0)
+	return h, e
+}

vfs.go

@@ -169,8 +169,6 @@ func vfsDelete(ctx context.Context, mod api.Module, pVfs, zPath, syncDir uint32)
 		return _OK
 	}
 	if err != nil {
-		// TODO: fix windows.ERROR_SHARING_VIOLATION
-		// https://github.com/golang/go/issues/32088
 		return uint32(IOERR_DELETE)
 	}
 	if runtime.GOOS != "windows" && syncDir != 0 {
@@ -251,14 +249,14 @@ func vfsOpen(ctx context.Context, mod api.Module, pVfs, zName, pFile uint32, fla
 		file, err = os.CreateTemp("", "*.db")
 	} else {
 		name := memory{mod}.readString(zName, _MAX_PATHNAME)
-		file, err = os.OpenFile(name, oflags, 0600)
+		file, err = vfsOS.OpenFile(name, oflags, 0600)
 	}
 	if err != nil {
 		return uint32(CANTOPEN)
 	}
 
 	if flags&OPEN_DELETEONCLOSE != 0 {
-		vfsOS.DeleteOnClose(file)
+		os.Remove(file.Name())
 	}
 
 	vfsFile.Open(ctx, mod, pFile, file)

vfs_unix.go

@@ -8,8 +8,8 @@ import (
 	"syscall"
 )
 
-func (vfsOSMethods) DeleteOnClose(file *os.File) {
-	_ = os.Remove(file.Name())
+func (vfsOSMethods) OpenFile(name string, flag int, perm os.FileMode) (*os.File, error) {
+	return os.OpenFile(name, flag, perm)
 }
 
 func (vfsOSMethods) GetExclusiveLock(file *os.File) xErrorCode {

vfs_windows.go

@@ -7,7 +7,9 @@ import (
 	"golang.org/x/sys/windows"
 )
 
-func (vfsOSMethods) DeleteOnClose(file *os.File) {}
+func (vfsOSMethods) OpenFile(name string, flag int, perm os.FileMode) (*os.File, error) {
+	return osOpenFile(name, flag, perm)
+}
 
 func (vfsOSMethods) GetExclusiveLock(file *os.File) xErrorCode {
 	// Release the SHARED lock.