241 lines
7.0 KiB
Go
241 lines
7.0 KiB
Go
// 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 provides a platform-independent interface to operating system
|
|
// functionality. The design is Unix-like, although the error handling is
|
|
// Go-like; failing calls return values of type error rather than error numbers.
|
|
// Often, more information is available within the error. For example,
|
|
// if a call that takes a file name fails, such as Open or Stat, the error
|
|
// will include the failing file name when printed and will be of type
|
|
// *PathError, which may be unpacked for more information.
|
|
//
|
|
// The os interface is intended to be uniform across all operating systems.
|
|
// Features not generally available appear in the system-specific package syscall.
|
|
//
|
|
// Here is a simple example, opening a file and reading some of it.
|
|
//
|
|
// file, err := os.Open("file.go") // For read access.
|
|
// if err != nil {
|
|
// log.Fatal(err)
|
|
// }
|
|
//
|
|
// If the open fails, the error string will be self-explanatory, like
|
|
//
|
|
// open file.go: no such file or directory
|
|
//
|
|
// The file's data can then be read into a slice of bytes. Read and
|
|
// Write take their byte counts from the length of the argument slice.
|
|
//
|
|
// data := make([]byte, 100)
|
|
// count, err := file.Read(data)
|
|
// if err != nil {
|
|
// log.Fatal(err)
|
|
// }
|
|
// fmt.Printf("read %d bytes: %q\n", count, data[:count])
|
|
//
|
|
package os
|
|
|
|
import (
|
|
"io"
|
|
"syscall"
|
|
)
|
|
|
|
// Name returns the name of the file as presented to Open.
|
|
func (f *File) Name() string { return f.name }
|
|
|
|
// Stdin, Stdout, and Stderr are open Files pointing to the standard input,
|
|
// standard output, and standard error file descriptors.
|
|
var (
|
|
Stdin = NewFile(uintptr(syscall.Stdin), "/dev/stdin")
|
|
Stdout = NewFile(uintptr(syscall.Stdout), "/dev/stdout")
|
|
Stderr = NewFile(uintptr(syscall.Stderr), "/dev/stderr")
|
|
)
|
|
|
|
// Flags to Open wrapping those of the underlying system. Not all flags
|
|
// may be implemented on a given system.
|
|
const (
|
|
O_RDONLY int = syscall.O_RDONLY // open the file read-only.
|
|
O_WRONLY int = syscall.O_WRONLY // open the file write-only.
|
|
O_RDWR int = syscall.O_RDWR // open the file read-write.
|
|
O_APPEND int = syscall.O_APPEND // append data to the file when writing.
|
|
O_CREATE int = syscall.O_CREAT // create a new file if none exists.
|
|
O_EXCL int = syscall.O_EXCL // used with O_CREATE, file must not exist
|
|
O_SYNC int = syscall.O_SYNC // open for synchronous I/O.
|
|
O_TRUNC int = syscall.O_TRUNC // if possible, truncate file when opened.
|
|
)
|
|
|
|
// Seek whence values.
|
|
const (
|
|
SEEK_SET int = 0 // seek relative to the origin of the file
|
|
SEEK_CUR int = 1 // seek relative to the current offset
|
|
SEEK_END int = 2 // seek relative to the end
|
|
)
|
|
|
|
// LinkError records an error during a link or symlink or rename
|
|
// system call and the paths that caused it.
|
|
type LinkError struct {
|
|
Op string
|
|
Old string
|
|
New string
|
|
Err error
|
|
}
|
|
|
|
func (e *LinkError) Error() string {
|
|
return e.Op + " " + e.Old + " " + e.New + ": " + e.Err.Error()
|
|
}
|
|
|
|
// Read reads up to len(b) bytes from the File.
|
|
// It returns the number of bytes read and an error, if any.
|
|
// EOF is signaled by a zero count with err set to io.EOF.
|
|
func (f *File) Read(b []byte) (n int, err error) {
|
|
if f == nil {
|
|
return 0, ErrInvalid
|
|
}
|
|
n, e := f.read(b)
|
|
if n < 0 {
|
|
n = 0
|
|
}
|
|
if n == 0 && len(b) > 0 && e == nil {
|
|
return 0, io.EOF
|
|
}
|
|
if e != nil {
|
|
err = &PathError{"read", f.name, e}
|
|
}
|
|
return n, err
|
|
}
|
|
|
|
// ReadAt reads len(b) bytes from the File starting at byte offset off.
|
|
// It returns the number of bytes read and the error, if any.
|
|
// ReadAt always returns a non-nil error when n < len(b).
|
|
// At end of file, that error is io.EOF.
|
|
func (f *File) ReadAt(b []byte, off int64) (n int, err error) {
|
|
if f == nil {
|
|
return 0, ErrInvalid
|
|
}
|
|
for len(b) > 0 {
|
|
m, e := f.pread(b, off)
|
|
if m == 0 && e == nil {
|
|
return n, io.EOF
|
|
}
|
|
if e != nil {
|
|
err = &PathError{"read", f.name, e}
|
|
break
|
|
}
|
|
n += m
|
|
b = b[m:]
|
|
off += int64(m)
|
|
}
|
|
return
|
|
}
|
|
|
|
// Write writes len(b) bytes to the File.
|
|
// It returns the number of bytes written and an error, if any.
|
|
// Write returns a non-nil error when n != len(b).
|
|
func (f *File) Write(b []byte) (n int, err error) {
|
|
if f == nil {
|
|
return 0, ErrInvalid
|
|
}
|
|
n, e := f.write(b)
|
|
if n < 0 {
|
|
n = 0
|
|
}
|
|
|
|
epipecheck(f, e)
|
|
|
|
if e != nil {
|
|
err = &PathError{"write", f.name, e}
|
|
}
|
|
return n, err
|
|
}
|
|
|
|
// WriteAt writes len(b) bytes to the File starting at byte offset off.
|
|
// It returns the number of bytes written and an error, if any.
|
|
// WriteAt returns a non-nil error when n != len(b).
|
|
func (f *File) WriteAt(b []byte, off int64) (n int, err error) {
|
|
if f == nil {
|
|
return 0, ErrInvalid
|
|
}
|
|
for len(b) > 0 {
|
|
m, e := f.pwrite(b, off)
|
|
if e != nil {
|
|
err = &PathError{"write", f.name, e}
|
|
break
|
|
}
|
|
n += m
|
|
b = b[m:]
|
|
off += int64(m)
|
|
}
|
|
return
|
|
}
|
|
|
|
// 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 error) {
|
|
r, e := f.seek(offset, whence)
|
|
if e == nil && f.dirinfo != nil && r != 0 {
|
|
e = syscall.EISDIR
|
|
}
|
|
if e != nil {
|
|
return 0, &PathError{"seek", f.name, e}
|
|
}
|
|
return r, nil
|
|
}
|
|
|
|
// WriteString is like Write, but writes the contents of string s rather than
|
|
// an array of bytes.
|
|
func (f *File) WriteString(s string) (ret int, err error) {
|
|
if f == nil {
|
|
return 0, ErrInvalid
|
|
}
|
|
return f.Write([]byte(s))
|
|
}
|
|
|
|
// Mkdir creates a new directory with the specified name and permission bits.
|
|
// If there is an error, it will be of type *PathError.
|
|
func Mkdir(name string, perm FileMode) error {
|
|
e := syscall.Mkdir(name, syscallMode(perm))
|
|
if e != nil {
|
|
return &PathError{"mkdir", name, e}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Chdir changes the current working directory to the named directory.
|
|
// If there is an error, it will be of type *PathError.
|
|
func Chdir(dir string) error {
|
|
if e := syscall.Chdir(dir); e != nil {
|
|
return &PathError{"chdir", dir, 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 e := syscall.Fchdir(f.fd); e != nil {
|
|
return &PathError{"chdir", f.name, e}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Open opens the named file for reading. If successful, methods on
|
|
// the returned file can be used for reading; the associated file
|
|
// descriptor has mode O_RDONLY.
|
|
// If there is an error, it will be of type *PathError.
|
|
func Open(name string) (file *File, err error) {
|
|
return OpenFile(name, O_RDONLY, 0)
|
|
}
|
|
|
|
// Create creates the named file mode 0666 (before umask), truncating
|
|
// it if it already exists. If successful, methods on the returned
|
|
// File can be used for I/O; the associated file descriptor has mode
|
|
// O_RDWR.
|
|
// If there is an error, it will be of type *PathError.
|
|
func Create(name string) (file *File, err error) {
|
|
return OpenFile(name, O_RDWR|O_CREATE|O_TRUNC, 0666)
|
|
}
|