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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build unix || (js && wasm) || wasip1 || windows
package os
import (
"runtime"
"syscall"
"time"
)
// Close closes the File, rendering it unusable for I/O.
// On files that support SetDeadline, any pending I/O operations will
// be canceled and return immediately with an ErrClosed error.
// Close will return an error if it has already been called.
func (f *File) Close() error {
if f == nil {
return ErrInvalid
}
return f.file.close()
}
// read reads up to len(b) bytes from the File.
// It returns the number of bytes read and an error, if any.
func (f *File) read(b []byte) (n int, err error) {
n, err = f.pfd.Read(b)
runtime.KeepAlive(f)
return n, err
}
// pread reads len(b) bytes from the File starting at byte offset off.
// It returns the number of bytes read and the error, if any.
// EOF is signaled by a zero count with err set to nil.
func (f *File) pread(b []byte, off int64) (n int, err error) {
n, err = f.pfd.Pread(b, off)
runtime.KeepAlive(f)
return n, err
}
// write writes len(b) bytes to the File.
// It returns the number of bytes written and an error, if any.
func (f *File) write(b []byte) (n int, err error) {
n, err = f.pfd.Write(b)
runtime.KeepAlive(f)
return n, err
}
// pwrite writes len(b) bytes to the File starting at byte offset off.
// It returns the number of bytes written and an error, if any.
func (f *File) pwrite(b []byte, off int64) (n int, err error) {
n, err = f.pfd.Pwrite(b, off)
runtime.KeepAlive(f)
return n, err
}
// syscallMode returns the syscall-specific mode bits from Go's portable mode bits.
func syscallMode(i FileMode) (o uint32) {
o |= uint32(i.Perm())
if i&ModeSetuid != 0 {
o |= syscall.S_ISUID
}
if i&ModeSetgid != 0 {
o |= syscall.S_ISGID
}
if i&ModeSticky != 0 {
o |= syscall.S_ISVTX
}
// No mapping for Go's ModeTemporary (plan9 only).
return
}
// See docs in file.go:Chmod.
func chmod(name string, mode FileMode) error {
longName := fixLongPath(name)
e := ignoringEINTR(func() error {
return syscall.Chmod(longName, syscallMode(mode))
})
if e != nil {
return &PathError{Op: "chmod", Path: name, Err: e}
}
return nil
}
// See docs in file.go:(*File).Chmod.
func (f *File) chmod(mode FileMode) error {
if err := f.checkValid("chmod"); err != nil {
return err
}
if e := f.pfd.Fchmod(syscallMode(mode)); e != nil {
return f.wrapErr("chmod", e)
}
return nil
}
// Chown changes the numeric uid and gid of the named file.
// If the file is a symbolic link, it changes the uid and gid of the link's target.
// A uid or gid of -1 means to not change that value.
// If there is an error, it will be of type *PathError.
//
// On Windows or Plan 9, Chown always returns the syscall.EWINDOWS or
// EPLAN9 error, wrapped in *PathError.
func Chown(name string, uid, gid int) error {
e := ignoringEINTR(func() error {
return syscall.Chown(name, uid, gid)
})
if e != nil {
return &PathError{Op: "chown", Path: name, Err: e}
}
return nil
}
// Lchown changes the numeric uid and gid of the named file.
// If the file is a symbolic link, it changes the uid and gid of the link itself.
// If there is an error, it will be of type *PathError.
//
// On Windows, it always returns the syscall.EWINDOWS error, wrapped
// in *PathError.
func Lchown(name string, uid, gid int) error {
e := ignoringEINTR(func() error {
return syscall.Lchown(name, uid, gid)
})
if e != nil {
return &PathError{Op: "lchown", Path: name, Err: e}
}
return nil
}
// Chown changes the numeric uid and gid of the named file.
// If there is an error, it will be of type *PathError.
//
// On Windows, it always returns the syscall.EWINDOWS error, wrapped
// in *PathError.
func (f *File) Chown(uid, gid int) error {
if err := f.checkValid("chown"); err != nil {
return err
}
if e := f.pfd.Fchown(uid, gid); e != nil {
return f.wrapErr("chown", e)
}
return nil
}
// Truncate changes the size of the file.
// It does not change the I/O offset.
// If there is an error, it will be of type *PathError.
func (f *File) Truncate(size int64) error {
if err := f.checkValid("truncate"); err != nil {
return err
}
if e := f.pfd.Ftruncate(size); e != nil {
return f.wrapErr("truncate", e)
}
return nil
}
// Sync commits the current contents of the file to stable storage.
// Typically, this means flushing the file system's in-memory copy
// of recently written data to disk.
func (f *File) Sync() error {
if err := f.checkValid("sync"); err != nil {
return err
}
if e := f.pfd.Fsync(); e != nil {
return f.wrapErr("sync", e)
}
return nil
}
// Chtimes changes the access and modification times of the named
// file, similar to the Unix utime() or utimes() functions.
// A zero time.Time value will leave the corresponding file time unchanged.
//
// The underlying filesystem may truncate or round the values to a
// less precise time unit.
// If there is an error, it will be of type *PathError.
func Chtimes(name string, atime time.Time, mtime time.Time) error {
var utimes [2]syscall.Timespec
set := func(i int, t time.Time) {
if t.IsZero() {
utimes[i] = syscall.Timespec{Sec: _UTIME_OMIT, Nsec: _UTIME_OMIT}
} else {
utimes[i] = syscall.NsecToTimespec(t.UnixNano())
}
}
set(0, atime)
set(1, mtime)
if e := syscall.UtimesNano(fixLongPath(name), utimes[0:]); e != nil {
return &PathError{Op: "chtimes", Path: name, Err: e}
}
return nil
}
// Chdir changes the current working directory to the file,
// which must be a directory.
// If there is an error, it will be of type *PathError.
func (f *File) Chdir() error {
if err := f.checkValid("chdir"); err != nil {
return err
}
if e := f.pfd.Fchdir(); e != nil {
return f.wrapErr("chdir", e)
}
return nil
}
// setDeadline sets the read and write deadline.
func (f *File) setDeadline(t time.Time) error {
if err := f.checkValid("SetDeadline"); err != nil {
return err
}
return f.pfd.SetDeadline(t)
}
// setReadDeadline sets the read deadline.
func (f *File) setReadDeadline(t time.Time) error {
if err := f.checkValid("SetReadDeadline"); err != nil {
return err
}
return f.pfd.SetReadDeadline(t)
}
// setWriteDeadline sets the write deadline.
func (f *File) setWriteDeadline(t time.Time) error {
if err := f.checkValid("SetWriteDeadline"); err != nil {
return err
}
return f.pfd.SetWriteDeadline(t)
}
// checkValid checks whether f is valid for use.
// If not, it returns an appropriate error, perhaps incorporating the operation name op.
func (f *File) checkValid(op string) error {
if f == nil {
return ErrInvalid
}
return nil
}
// ignoringEINTR makes a function call and repeats it if it returns an
// EINTR error. This appears to be required even though we install all
// signal handlers with SA_RESTART: see #22838, #38033, #38836, #40846.
// Also #20400 and #36644 are issues in which a signal handler is
// installed without setting SA_RESTART. None of these are the common case,
// but there are enough of them that it seems that we can't avoid
// an EINTR loop.
func ignoringEINTR(fn func() error) error {
for {
err := fn()
if err != syscall.EINTR {
return err
}
}
}
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