234 lines
6.9 KiB
Go
234 lines
6.9 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.
|
|
|
|
// The os package provides a platform-independent interface to operating
|
|
// system functionality. The design is Unix-like.
|
|
package os
|
|
|
|
import (
|
|
"runtime"
|
|
"syscall"
|
|
)
|
|
|
|
// File represents an open file descriptor.
|
|
type File struct {
|
|
fd int
|
|
name string
|
|
dirinfo *dirInfo // nil unless directory being read
|
|
nepipe int // number of consecutive EPIPE in Write
|
|
}
|
|
|
|
// Fd returns the integer Unix file descriptor referencing the open file.
|
|
func (file *File) Fd() int { return file.fd }
|
|
|
|
// Name returns the name of the file as presented to Open.
|
|
func (file *File) Name() string { return file.name }
|
|
|
|
// NewFile returns a new File with the given file descriptor and name.
|
|
func NewFile(fd int, name string) *File {
|
|
if fd < 0 {
|
|
return nil
|
|
}
|
|
f := &File{fd, name, nil, 0}
|
|
runtime.SetFinalizer(f, (*File).Close)
|
|
return f
|
|
}
|
|
|
|
// Stdin, Stdout, and Stderr are open Files pointing to the standard input,
|
|
// standard output, and standard error file descriptors.
|
|
var (
|
|
Stdin = NewFile(syscall.Stdin, "/dev/stdin")
|
|
Stdout = NewFile(syscall.Stdout, "/dev/stdout")
|
|
Stderr = NewFile(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_ASYNC int = syscall.O_ASYNC // generate a signal when I/O is available.
|
|
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_NOCTTY int = syscall.O_NOCTTY // do not make file the controlling tty.
|
|
O_NONBLOCK int = syscall.O_NONBLOCK // open in non-blocking mode.
|
|
O_NDELAY int = O_NONBLOCK // synonym for O_NONBLOCK
|
|
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
|
|
)
|
|
|
|
type eofError int
|
|
|
|
func (eofError) String() string { return "EOF" }
|
|
|
|
// EOF is the Error returned by Read when no more input is available.
|
|
// Functions should return EOF only to signal a graceful end of input.
|
|
// If the EOF occurs unexpectedly in a structured data stream,
|
|
// the appropriate error is either io.ErrUnexpectedEOF or some other error
|
|
// giving more detail.
|
|
var EOF Error = eofError(0)
|
|
|
|
// 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 EOF.
|
|
func (file *File) Read(b []byte) (n int, err Error) {
|
|
if file == nil {
|
|
return 0, EINVAL
|
|
}
|
|
n, e := syscall.Read(file.fd, b)
|
|
if n < 0 {
|
|
n = 0
|
|
}
|
|
if n == 0 && !iserror(e) {
|
|
return 0, EOF
|
|
}
|
|
if iserror(e) {
|
|
err = &PathError{"read", file.name, Errno(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.
|
|
// EOF is signaled by a zero count with err set to EOF.
|
|
// ReadAt always returns a non-nil Error when n != len(b).
|
|
func (file *File) ReadAt(b []byte, off int64) (n int, err Error) {
|
|
if file == nil {
|
|
return 0, EINVAL
|
|
}
|
|
for len(b) > 0 {
|
|
m, e := syscall.Pread(file.fd, b, off)
|
|
if m == 0 && !iserror(e) {
|
|
return n, EOF
|
|
}
|
|
if iserror(e) {
|
|
err = &PathError{"read", file.name, Errno(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 (file *File) Write(b []byte) (n int, err Error) {
|
|
if file == nil {
|
|
return 0, EINVAL
|
|
}
|
|
n, e := syscall.Write(file.fd, b)
|
|
if n < 0 {
|
|
n = 0
|
|
}
|
|
|
|
epipecheck(file, e)
|
|
|
|
if iserror(e) {
|
|
err = &PathError{"write", file.name, Errno(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 (file *File) WriteAt(b []byte, off int64) (n int, err Error) {
|
|
if file == nil {
|
|
return 0, EINVAL
|
|
}
|
|
for len(b) > 0 {
|
|
m, e := syscall.Pwrite(file.fd, b, off)
|
|
if iserror(e) {
|
|
err = &PathError{"write", file.name, Errno(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 (file *File) Seek(offset int64, whence int) (ret int64, err Error) {
|
|
r, e := syscall.Seek(file.fd, offset, whence)
|
|
if !iserror(e) && file.dirinfo != nil && r != 0 {
|
|
e = syscall.EISDIR
|
|
}
|
|
if iserror(e) {
|
|
return 0, &PathError{"seek", file.name, Errno(e)}
|
|
}
|
|
return r, nil
|
|
}
|
|
|
|
// WriteString is like Write, but writes the contents of string s rather than
|
|
// an array of bytes.
|
|
func (file *File) WriteString(s string) (ret int, err Error) {
|
|
if file == nil {
|
|
return 0, EINVAL
|
|
}
|
|
b := syscall.StringByteSlice(s)
|
|
b = b[0 : len(b)-1]
|
|
return file.Write(b)
|
|
}
|
|
|
|
// Mkdir creates a new directory with the specified name and permission bits.
|
|
// It returns an error, if any.
|
|
func Mkdir(name string, perm uint32) Error {
|
|
e := syscall.Mkdir(name, perm)
|
|
if iserror(e) {
|
|
return &PathError{"mkdir", name, Errno(e)}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Chdir changes the current working directory to the named directory.
|
|
func Chdir(dir string) Error {
|
|
if e := syscall.Chdir(dir); iserror(e) {
|
|
return &PathError{"chdir", dir, Errno(e)}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Chdir changes the current working directory to the file,
|
|
// which must be a directory.
|
|
func (f *File) Chdir() Error {
|
|
if e := syscall.Fchdir(f.fd); iserror(e) {
|
|
return &PathError{"chdir", f.name, Errno(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.
|
|
// It returns the File and an Error, if any.
|
|
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.
|
|
// It returns the File and an Error, if any.
|
|
func Create(name string) (file *File, err Error) {
|
|
return OpenFile(name, O_RDWR|O_CREATE|O_TRUNC, 0666)
|
|
}
|