312 lines
8.6 KiB
Go
312 lines
8.6 KiB
Go
package sysfs
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import (
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"io"
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"io/fs"
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"os"
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"runtime"
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experimentalsys "github.com/tetratelabs/wazero/experimental/sys"
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"github.com/tetratelabs/wazero/internal/fsapi"
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"github.com/tetratelabs/wazero/sys"
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)
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func newOsFile(path string, flag experimentalsys.Oflag, perm fs.FileMode, f *os.File) fsapi.File {
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// Windows cannot read files written to a directory after it was opened.
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// This was noticed in #1087 in zig tests. Use a flag instead of a
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// different type.
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reopenDir := runtime.GOOS == "windows"
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return &osFile{path: path, flag: flag, perm: perm, reopenDir: reopenDir, file: f, fd: f.Fd()}
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}
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// osFile is a file opened with this package, and uses os.File or syscalls to
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// implement api.File.
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type osFile struct {
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path string
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flag experimentalsys.Oflag
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perm fs.FileMode
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file *os.File
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fd uintptr
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// reopenDir is true if reopen should be called before Readdir. This flag
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// is deferred until Readdir to prevent redundant rewinds. This could
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// happen if Seek(0) was called twice, or if in Windows, Seek(0) was called
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// before Readdir.
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reopenDir bool
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// closed is true when closed was called. This ensures proper sys.EBADF
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closed bool
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// cachedStat includes fields that won't change while a file is open.
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cachedSt *cachedStat
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}
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// cachedStat returns the cacheable parts of sys.Stat_t or an error if they
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// couldn't be retrieved.
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func (f *osFile) cachedStat() (dev uint64, ino sys.Inode, isDir bool, errno experimentalsys.Errno) {
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if f.cachedSt == nil {
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if _, errno = f.Stat(); errno != 0 {
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return
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}
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}
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return f.cachedSt.dev, f.cachedSt.ino, f.cachedSt.isDir, 0
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}
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// Dev implements the same method as documented on sys.File
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func (f *osFile) Dev() (uint64, experimentalsys.Errno) {
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dev, _, _, errno := f.cachedStat()
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return dev, errno
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}
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// Ino implements the same method as documented on sys.File
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func (f *osFile) Ino() (sys.Inode, experimentalsys.Errno) {
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_, ino, _, errno := f.cachedStat()
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return ino, errno
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}
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// IsDir implements the same method as documented on sys.File
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func (f *osFile) IsDir() (bool, experimentalsys.Errno) {
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_, _, isDir, errno := f.cachedStat()
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return isDir, errno
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}
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// IsAppend implements File.IsAppend
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func (f *osFile) IsAppend() bool {
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return f.flag&experimentalsys.O_APPEND == experimentalsys.O_APPEND
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}
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// SetAppend implements the same method as documented on sys.File
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func (f *osFile) SetAppend(enable bool) (errno experimentalsys.Errno) {
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if enable {
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f.flag |= experimentalsys.O_APPEND
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} else {
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f.flag &= ^experimentalsys.O_APPEND
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}
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// appendMode cannot be changed later, so we have to re-open the file
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// https://github.com/golang/go/blob/go1.23/src/os/file_unix.go#L60
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return fileError(f, f.closed, f.reopen())
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}
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func (f *osFile) reopen() (errno experimentalsys.Errno) {
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var (
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isDir bool
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offset int64
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err error
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)
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isDir, errno = f.IsDir()
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if errno != 0 {
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return errno
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}
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if !isDir {
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offset, err = f.file.Seek(0, io.SeekCurrent)
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if err != nil {
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return experimentalsys.UnwrapOSError(err)
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}
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}
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// Clear any create or trunc flag, as we are re-opening, not re-creating.
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flag := f.flag &^ (experimentalsys.O_CREAT | experimentalsys.O_TRUNC)
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file, errno := OpenFile(f.path, flag, f.perm)
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if errno != 0 {
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return errno
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}
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errno = f.checkSameFile(file)
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if errno != 0 {
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return errno
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}
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if !isDir {
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_, err = file.Seek(offset, io.SeekStart)
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if err != nil {
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_ = file.Close()
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return experimentalsys.UnwrapOSError(err)
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}
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}
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// Only update f on success.
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_ = f.file.Close()
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f.file = file
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f.fd = file.Fd()
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return 0
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}
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func (f *osFile) checkSameFile(osf *os.File) experimentalsys.Errno {
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fi1, err := f.file.Stat()
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if err != nil {
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return experimentalsys.UnwrapOSError(err)
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}
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fi2, err := osf.Stat()
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if err != nil {
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return experimentalsys.UnwrapOSError(err)
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}
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if os.SameFile(fi1, fi2) {
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return 0
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}
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return experimentalsys.ENOENT
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}
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// IsNonblock implements the same method as documented on fsapi.File
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func (f *osFile) IsNonblock() bool {
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return isNonblock(f)
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}
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// SetNonblock implements the same method as documented on fsapi.File
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func (f *osFile) SetNonblock(enable bool) (errno experimentalsys.Errno) {
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if enable {
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f.flag |= experimentalsys.O_NONBLOCK
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} else {
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f.flag &= ^experimentalsys.O_NONBLOCK
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}
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if errno = setNonblock(f.fd, enable); errno != 0 {
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return fileError(f, f.closed, errno)
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}
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return 0
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}
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// Stat implements the same method as documented on sys.File
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func (f *osFile) Stat() (sys.Stat_t, experimentalsys.Errno) {
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if f.closed {
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return sys.Stat_t{}, experimentalsys.EBADF
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}
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st, errno := statFile(f.file)
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switch errno {
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case 0:
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f.cachedSt = &cachedStat{dev: st.Dev, ino: st.Ino, isDir: st.Mode&fs.ModeDir == fs.ModeDir}
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case experimentalsys.EIO:
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errno = experimentalsys.EBADF
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}
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return st, errno
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}
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// Read implements the same method as documented on sys.File
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func (f *osFile) Read(buf []byte) (n int, errno experimentalsys.Errno) {
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if len(buf) == 0 {
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return 0, 0 // Short-circuit 0-len reads.
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}
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if nonBlockingFileReadSupported && f.IsNonblock() {
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n, errno = readFd(f.fd, buf)
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} else {
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n, errno = read(f.file, buf)
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}
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if errno != 0 {
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// Defer validation overhead until we've already had an error.
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errno = fileError(f, f.closed, errno)
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}
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return
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}
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// Pread implements the same method as documented on sys.File
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func (f *osFile) Pread(buf []byte, off int64) (n int, errno experimentalsys.Errno) {
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if n, errno = pread(f.file, buf, off); errno != 0 {
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// Defer validation overhead until we've already had an error.
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errno = fileError(f, f.closed, errno)
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}
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return
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}
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// Seek implements the same method as documented on sys.File
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func (f *osFile) Seek(offset int64, whence int) (newOffset int64, errno experimentalsys.Errno) {
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if newOffset, errno = seek(f.file, offset, whence); errno != 0 {
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// Defer validation overhead until we've already had an error.
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errno = fileError(f, f.closed, errno)
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// If the error was trying to rewind a directory, re-open it. Notably,
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// seeking to zero on a directory doesn't work on Windows with Go 1.19.
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if errno == experimentalsys.EISDIR && offset == 0 && whence == io.SeekStart {
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errno = 0
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f.reopenDir = true
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}
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}
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return
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}
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// Poll implements the same method as documented on fsapi.File
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func (f *osFile) Poll(flag fsapi.Pflag, timeoutMillis int32) (ready bool, errno experimentalsys.Errno) {
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return poll(f.fd, flag, timeoutMillis)
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}
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// Readdir implements File.Readdir. Notably, this uses "Readdir", not
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// "ReadDir", from os.File.
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func (f *osFile) Readdir(n int) (dirents []experimentalsys.Dirent, errno experimentalsys.Errno) {
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if f.reopenDir { // re-open the directory if needed.
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f.reopenDir = false
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if errno = adjustReaddirErr(f, f.closed, f.reopen()); errno != 0 {
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return
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}
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}
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if dirents, errno = readdir(f.file, f.path, n); errno != 0 {
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errno = adjustReaddirErr(f, f.closed, errno)
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}
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return
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}
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// Write implements the same method as documented on sys.File
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func (f *osFile) Write(buf []byte) (n int, errno experimentalsys.Errno) {
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if len(buf) == 0 {
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return 0, 0 // Short-circuit 0-len writes.
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}
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if nonBlockingFileWriteSupported && f.IsNonblock() {
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n, errno = writeFd(f.fd, buf)
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} else if n, errno = write(f.file, buf); errno != 0 {
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// Defer validation overhead until we've already had an error.
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errno = fileError(f, f.closed, errno)
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}
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return
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}
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// Pwrite implements the same method as documented on sys.File
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func (f *osFile) Pwrite(buf []byte, off int64) (n int, errno experimentalsys.Errno) {
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if n, errno = pwrite(f.file, buf, off); errno != 0 {
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// Defer validation overhead until we've already had an error.
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errno = fileError(f, f.closed, errno)
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}
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return
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}
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// Truncate implements the same method as documented on sys.File
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func (f *osFile) Truncate(size int64) (errno experimentalsys.Errno) {
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if errno = experimentalsys.UnwrapOSError(f.file.Truncate(size)); errno != 0 {
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// Defer validation overhead until we've already had an error.
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errno = fileError(f, f.closed, errno)
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}
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return
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}
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// Sync implements the same method as documented on sys.File
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func (f *osFile) Sync() experimentalsys.Errno {
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return fsync(f.file)
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}
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// Datasync implements the same method as documented on sys.File
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func (f *osFile) Datasync() experimentalsys.Errno {
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return datasync(f.file)
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}
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// Utimens implements the same method as documented on sys.File
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func (f *osFile) Utimens(atim, mtim int64) experimentalsys.Errno {
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if f.closed {
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return experimentalsys.EBADF
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}
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err := futimens(f.fd, atim, mtim)
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return experimentalsys.UnwrapOSError(err)
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}
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// Close implements the same method as documented on sys.File
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func (f *osFile) Close() experimentalsys.Errno {
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if f.closed {
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return 0
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}
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f.closed = true
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return f.close()
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}
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func (f *osFile) close() experimentalsys.Errno {
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return experimentalsys.UnwrapOSError(f.file.Close())
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}
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