[experiment] add alternative wasm sqlite3 implementation available via build-tag (#2863)

This allows for building GoToSocial with [SQLite transpiled to WASM](https://github.com/ncruces/go-sqlite3) and accessed through [Wazero](https://wazero.io/).

1 files changed, 295 insertions, 0 deletions

diff --git a/vendor/github.com/tetratelabs/wazero/internal/sysfs/osfile.go b/vendor/github.com/tetratelabs/wazero/internal/sysfs/osfile.go
new file mode 100644
index 000000000..490f0fa68
--- /dev/null
+++ b/vendor/github.com/tetratelabs/wazero/internal/sysfs/osfile.go
@@ -0,0 +1,295 @@
+package sysfs
+
+import (
+	"io"
+	"io/fs"
+	"os"
+	"runtime"
+
+	experimentalsys "github.com/tetratelabs/wazero/experimental/sys"
+	"github.com/tetratelabs/wazero/internal/fsapi"
+	"github.com/tetratelabs/wazero/sys"
+)
+
+func newOsFile(path string, flag experimentalsys.Oflag, perm fs.FileMode, f *os.File) fsapi.File {
+	// Windows cannot read files written to a directory after it was opened.
+	// This was noticed in #1087 in zig tests. Use a flag instead of a
+	// different type.
+	reopenDir := runtime.GOOS == "windows"
+	return &osFile{path: path, flag: flag, perm: perm, reopenDir: reopenDir, file: f, fd: f.Fd()}
+}
+
+// osFile is a file opened with this package, and uses os.File or syscalls to
+// implement api.File.
+type osFile struct {
+	path string
+	flag experimentalsys.Oflag
+	perm fs.FileMode
+	file *os.File
+	fd   uintptr
+
+	// reopenDir is true if reopen should be called before Readdir. This flag
+	// is deferred until Readdir to prevent redundant rewinds. This could
+	// happen if Seek(0) was called twice, or if in Windows, Seek(0) was called
+	// before Readdir.
+	reopenDir bool
+
+	// closed is true when closed was called. This ensures proper sys.EBADF
+	closed bool
+
+	// cachedStat includes fields that won't change while a file is open.
+	cachedSt *cachedStat
+}
+
+// cachedStat returns the cacheable parts of sys.Stat_t or an error if they
+// couldn't be retrieved.
+func (f *osFile) cachedStat() (dev uint64, ino sys.Inode, isDir bool, errno experimentalsys.Errno) {
+	if f.cachedSt == nil {
+		if _, errno = f.Stat(); errno != 0 {
+			return
+		}
+	}
+	return f.cachedSt.dev, f.cachedSt.ino, f.cachedSt.isDir, 0
+}
+
+// Dev implements the same method as documented on sys.File
+func (f *osFile) Dev() (uint64, experimentalsys.Errno) {
+	dev, _, _, errno := f.cachedStat()
+	return dev, errno
+}
+
+// Ino implements the same method as documented on sys.File
+func (f *osFile) Ino() (sys.Inode, experimentalsys.Errno) {
+	_, ino, _, errno := f.cachedStat()
+	return ino, errno
+}
+
+// IsDir implements the same method as documented on sys.File
+func (f *osFile) IsDir() (bool, experimentalsys.Errno) {
+	_, _, isDir, errno := f.cachedStat()
+	return isDir, errno
+}
+
+// IsAppend implements File.IsAppend
+func (f *osFile) IsAppend() bool {
+	return f.flag&experimentalsys.O_APPEND == experimentalsys.O_APPEND
+}
+
+// SetAppend implements the same method as documented on sys.File
+func (f *osFile) SetAppend(enable bool) (errno experimentalsys.Errno) {
+	if enable {
+		f.flag |= experimentalsys.O_APPEND
+	} else {
+		f.flag &= ^experimentalsys.O_APPEND
+	}
+
+	// Clear any create or trunc flag, as we are re-opening, not re-creating.
+	f.flag &= ^(experimentalsys.O_CREAT | experimentalsys.O_TRUNC)
+
+	// appendMode (bool) cannot be changed later, so we have to re-open the
+	// file. https://github.com/golang/go/blob/go1.20/src/os/file_unix.go#L60
+	return fileError(f, f.closed, f.reopen())
+}
+
+// compile-time check to ensure osFile.reopen implements reopenFile.
+var _ reopenFile = (*osFile)(nil).reopen
+
+func (f *osFile) reopen() (errno experimentalsys.Errno) {
+	// Clear any create flag, as we are re-opening, not re-creating.
+	f.flag &= ^experimentalsys.O_CREAT
+
+	var (
+		isDir  bool
+		offset int64
+		err    error
+	)
+
+	isDir, errno = f.IsDir()
+	if errno != 0 {
+		return errno
+	}
+
+	if !isDir {
+		offset, err = f.file.Seek(0, io.SeekCurrent)
+		if err != nil {
+			return experimentalsys.UnwrapOSError(err)
+		}
+	}
+
+	_ = f.close()
+	f.file, errno = OpenFile(f.path, f.flag, f.perm)
+	if errno != 0 {
+		return errno
+	}
+
+	if !isDir {
+		_, err = f.file.Seek(offset, io.SeekStart)
+		if err != nil {
+			return experimentalsys.UnwrapOSError(err)
+		}
+	}
+
+	return 0
+}
+
+// IsNonblock implements the same method as documented on fsapi.File
+func (f *osFile) IsNonblock() bool {
+	return isNonblock(f)
+}
+
+// SetNonblock implements the same method as documented on fsapi.File
+func (f *osFile) SetNonblock(enable bool) (errno experimentalsys.Errno) {
+	if enable {
+		f.flag |= experimentalsys.O_NONBLOCK
+	} else {
+		f.flag &= ^experimentalsys.O_NONBLOCK
+	}
+	if errno = setNonblock(f.fd, enable); errno != 0 {
+		return fileError(f, f.closed, errno)
+	}
+	return 0
+}
+
+// Stat implements the same method as documented on sys.File
+func (f *osFile) Stat() (sys.Stat_t, experimentalsys.Errno) {
+	if f.closed {
+		return sys.Stat_t{}, experimentalsys.EBADF
+	}
+
+	st, errno := statFile(f.file)
+	switch errno {
+	case 0:
+		f.cachedSt = &cachedStat{dev: st.Dev, ino: st.Ino, isDir: st.Mode&fs.ModeDir == fs.ModeDir}
+	case experimentalsys.EIO:
+		errno = experimentalsys.EBADF
+	}
+	return st, errno
+}
+
+// Read implements the same method as documented on sys.File
+func (f *osFile) Read(buf []byte) (n int, errno experimentalsys.Errno) {
+	if len(buf) == 0 {
+		return 0, 0 // Short-circuit 0-len reads.
+	}
+	if nonBlockingFileReadSupported && f.IsNonblock() {
+		n, errno = readFd(f.fd, buf)
+	} else {
+		n, errno = read(f.file, buf)
+	}
+	if errno != 0 {
+		// Defer validation overhead until we've already had an error.
+		errno = fileError(f, f.closed, errno)
+	}
+	return
+}
+
+// Pread implements the same method as documented on sys.File
+func (f *osFile) Pread(buf []byte, off int64) (n int, errno experimentalsys.Errno) {
+	if n, errno = pread(f.file, buf, off); errno != 0 {
+		// Defer validation overhead until we've already had an error.
+		errno = fileError(f, f.closed, errno)
+	}
+	return
+}
+
+// Seek implements the same method as documented on sys.File
+func (f *osFile) Seek(offset int64, whence int) (newOffset int64, errno experimentalsys.Errno) {
+	if newOffset, errno = seek(f.file, offset, whence); errno != 0 {
+		// Defer validation overhead until we've already had an error.
+		errno = fileError(f, f.closed, errno)
+
+		// If the error was trying to rewind a directory, re-open it. Notably,
+		// seeking to zero on a directory doesn't work on Windows with Go 1.19.
+		if errno == experimentalsys.EISDIR && offset == 0 && whence == io.SeekStart {
+			errno = 0
+			f.reopenDir = true
+		}
+	}
+	return
+}
+
+// Poll implements the same method as documented on fsapi.File
+func (f *osFile) Poll(flag fsapi.Pflag, timeoutMillis int32) (ready bool, errno experimentalsys.Errno) {
+	return poll(f.fd, flag, timeoutMillis)
+}
+
+// Readdir implements File.Readdir. Notably, this uses "Readdir", not
+// "ReadDir", from os.File.
+func (f *osFile) Readdir(n int) (dirents []experimentalsys.Dirent, errno experimentalsys.Errno) {
+	if f.reopenDir { // re-open the directory if needed.
+		f.reopenDir = false
+		if errno = adjustReaddirErr(f, f.closed, f.reopen()); errno != 0 {
+			return
+		}
+	}
+
+	if dirents, errno = readdir(f.file, f.path, n); errno != 0 {
+		errno = adjustReaddirErr(f, f.closed, errno)
+	}
+	return
+}
+
+// Write implements the same method as documented on sys.File
+func (f *osFile) Write(buf []byte) (n int, errno experimentalsys.Errno) {
+	if len(buf) == 0 {
+		return 0, 0 // Short-circuit 0-len writes.
+	}
+	if nonBlockingFileWriteSupported && f.IsNonblock() {
+		n, errno = writeFd(f.fd, buf)
+	} else if n, errno = write(f.file, buf); errno != 0 {
+		// Defer validation overhead until we've already had an error.
+		errno = fileError(f, f.closed, errno)
+	}
+	return
+}
+
+// Pwrite implements the same method as documented on sys.File
+func (f *osFile) Pwrite(buf []byte, off int64) (n int, errno experimentalsys.Errno) {
+	if n, errno = pwrite(f.file, buf, off); errno != 0 {
+		// Defer validation overhead until we've already had an error.
+		errno = fileError(f, f.closed, errno)
+	}
+	return
+}
+
+// Truncate implements the same method as documented on sys.File
+func (f *osFile) Truncate(size int64) (errno experimentalsys.Errno) {
+	if errno = experimentalsys.UnwrapOSError(f.file.Truncate(size)); errno != 0 {
+		// Defer validation overhead until we've already had an error.
+		errno = fileError(f, f.closed, errno)
+	}
+	return
+}
+
+// Sync implements the same method as documented on sys.File
+func (f *osFile) Sync() experimentalsys.Errno {
+	return fsync(f.file)
+}
+
+// Datasync implements the same method as documented on sys.File
+func (f *osFile) Datasync() experimentalsys.Errno {
+	return datasync(f.file)
+}
+
+// Utimens implements the same method as documented on sys.File
+func (f *osFile) Utimens(atim, mtim int64) experimentalsys.Errno {
+	if f.closed {
+		return experimentalsys.EBADF
+	}
+
+	err := futimens(f.fd, atim, mtim)
+	return experimentalsys.UnwrapOSError(err)
+}
+
+// Close implements the same method as documented on sys.File
+func (f *osFile) Close() experimentalsys.Errno {
+	if f.closed {
+		return 0
+	}
+	f.closed = true
+	return f.close()
+}
+
+func (f *osFile) close() experimentalsys.Errno {
+	return experimentalsys.UnwrapOSError(f.file.Close())
+}