// 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 } } }