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			295 lines
		
	
	
	
		
			8.4 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			295 lines
		
	
	
	
		
			8.4 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
| package sysfs
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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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| 	// Clear any create or trunc flag, as we are re-opening, not re-creating.
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| 	f.flag &= ^(experimentalsys.O_CREAT | experimentalsys.O_TRUNC)
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| 
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| 	// appendMode (bool) cannot be changed later, so we have to re-open the
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| 	// file. https://github.com/golang/go/blob/go1.20/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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| 
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| // compile-time check to ensure osFile.reopen implements reopenFile.
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| var _ reopenFile = (*osFile)(nil).reopen
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| 
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| func (f *osFile) reopen() (errno experimentalsys.Errno) {
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| 	// Clear any create flag, as we are re-opening, not re-creating.
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| 	f.flag &= ^experimentalsys.O_CREAT
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| 
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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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| 
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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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| 
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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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| 
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| 	_ = f.close()
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| 	f.file, errno = OpenFile(f.path, f.flag, f.perm)
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| 	if errno != 0 {
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| 		return errno
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| 	}
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| 
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| 	if !isDir {
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| 		_, err = f.file.Seek(offset, io.SeekStart)
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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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| 
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| 	return 0
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| }
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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| 
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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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