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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.
package os
import (
"runtime"
"syscall"
)
// Auxiliary information if the File describes a directory
type dirInfo struct {
buf []byte // buffer for directory I/O
dir *syscall.DIR // from opendir
}
// DevNull is the name of the operating system's ``null device.''
// On Unix-like systems, it is "/dev/null"; on Windows, "NUL".
const DevNull = "/dev/null"
// OpenFile is the generalized open call; most users will use Open
// or Create instead. It opens the named file with specified flag
// (O_RDONLY etc.) and perm, (0666 etc.) if applicable. If successful,
// methods on the returned File can be used for I/O.
// It returns the File and an Error, if any.
func OpenFile(name string, flag int, perm uint32) (file *File, err Error) {
r, e := syscall.Open(name, flag|syscall.O_CLOEXEC, perm)
if e != 0 {
return nil, &PathError{"open", name, Errno(e)}
}
// There's a race here with fork/exec, which we are
// content to live with. See ../syscall/exec.go
if syscall.O_CLOEXEC == 0 { // O_CLOEXEC not supported
syscall.CloseOnExec(r)
}
return NewFile(r, name), nil
}
// Close closes the File, rendering it unusable for I/O.
// It returns an Error, if any.
func (file *File) Close() Error {
if file == nil || file.fd < 0 {
return EINVAL
}
var err Error
if e := syscall.Close(file.fd); e != 0 {
err = &PathError{"close", file.name, Errno(e)}
}
if file.dirinfo != nil {
if libc_closedir(file.dirinfo.dir) < 0 && err == nil {
err = &PathError{"closedir", file.name, Errno(syscall.GetErrno())}
}
}
file.fd = -1 // so it can't be closed again
// no need for a finalizer anymore
runtime.SetFinalizer(file, nil)
return err
}
// Stat returns the FileInfo structure describing file.
// It returns the FileInfo and an error, if any.
func (file *File) Stat() (fi *FileInfo, err Error) {
var stat syscall.Stat_t
e := syscall.Fstat(file.fd, &stat)
if e != 0 {
return nil, &PathError{"stat", file.name, Errno(e)}
}
return fileInfoFromStat(file.name, new(FileInfo), &stat, &stat), nil
}
// Readdir reads the contents of the directory associated with file and
// returns an array of up to count FileInfo structures, as would be returned
// by Lstat, in directory order. Subsequent calls on the same file will yield
// further FileInfos.
// A negative count means to read until EOF.
// Readdir returns the array and an Error, if any.
func (file *File) Readdir(count int) (fi []FileInfo, err Error) {
dirname := file.name
if dirname == "" {
dirname = "."
}
dirname += "/"
names, err1 := file.Readdirnames(count)
if err1 != nil {
return nil, err1
}
fi = make([]FileInfo, len(names))
for i, filename := range names {
fip, err := Lstat(dirname + filename)
if fip == nil || err != nil {
fi[i].Name = filename // rest is already zeroed out
} else {
fi[i] = *fip
}
}
return
}
// 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 int) {
return syscall.Read(f.fd, b)
}
// 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 0.
func (f *File) pread(b []byte, off int64) (n int, err int) {
return syscall.Pread(f.fd, b, off)
}
// 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 int) {
return syscall.Write(f.fd, b)
}
// 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 int) {
return syscall.Pwrite(f.fd, b, off)
}
// seek sets the offset for the next Read or Write on file to offset, interpreted
// according to whence: 0 means relative to the origin of the file, 1 means
// relative to the current offset, and 2 means relative to the end.
// It returns the new offset and an error, if any.
func (f *File) seek(offset int64, whence int) (ret int64, err int) {
return syscall.Seek(f.fd, offset, whence)
}
// Truncate changes the size of the named file.
// If the file is a symbolic link, it changes the size of the link's target.
func Truncate(name string, size int64) Error {
if e := syscall.Truncate(name, size); e != 0 {
return &PathError{"truncate", name, Errno(e)}
}
return nil
}
// basename removes trailing slashes and the leading directory name from path name
func basename(name string) string {
i := len(name) - 1
// Remove trailing slashes
for ; i > 0 && name[i] == '/'; i-- {
name = name[:i]
}
// Remove leading directory name
for i--; i >= 0; i-- {
if name[i] == '/' {
name = name[i+1:]
break
}
}
return name
}
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