2008-09-11 14:03:46 -06:00
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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2009-03-07 17:56:44 -07:00
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// The os package provides a platform-independent interface to operating
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// system functionality. The design is Unix-like.
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package os
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import (
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"os";
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"syscall";
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)
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// Auxiliary information if the File describes a directory
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type dirInfo struct {
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buf []byte; // buffer for directory I/O
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nbuf int64; // length of buf; return value from Getdirentries
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bufp int64; // location of next record in buf.
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}
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// File represents an open file descriptor.
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type File struct {
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fd int64;
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name string;
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dirinfo *dirInfo; // nil unless directory being read
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nepipe int; // number of consecutive EPIPE in Write
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}
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// Fd returns the integer Unix file descriptor referencing the open file.
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func (file *File) Fd() int64 {
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return file.fd
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}
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// Name returns the name of the file as presented to Open.
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func (file *File) Name() string {
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return file.name
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}
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// NewFile returns a new File with the given file descriptor and name.
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func NewFile(file int64, name string) *File {
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if file < 0 {
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return nil
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}
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return &File{file, name, nil, 0}
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}
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// Stdin, Stdout, and Stderr are open Files pointing to the standard input,
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// standard output, and standard error file descriptors.
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var (
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Stdin = NewFile(0, "/dev/stdin");
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Stdout = NewFile(1, "/dev/stdout");
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Stderr = NewFile(2, "/dev/stderr");
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)
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// Flags to Open wrapping those of the underlying system. Not all flags
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// may be implemented on a given system.
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const (
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O_RDONLY = syscall.O_RDONLY; // open the file read-only.
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O_WRONLY = syscall.O_WRONLY; // open the file write-only.
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O_RDWR = syscall.O_RDWR; // open the file read-write.
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O_APPEND = syscall.O_APPEND; // open the file append-only.
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O_ASYNC = syscall.O_ASYNC; // generate a signal when I/O is available.
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O_CREAT = syscall.O_CREAT; // create a new file if none exists.
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O_NOCTTY = syscall.O_NOCTTY; // do not make file the controlling tty.
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O_NONBLOCK = syscall.O_NONBLOCK; // open in non-blocking mode.
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O_NDELAY = O_NONBLOCK; // synonym for O_NONBLOCK
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O_SYNC = syscall.O_SYNC; // open for synchronous I/O.
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O_TRUNC = syscall.O_TRUNC; // if possible, truncate file when opened.
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)
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// Open opens the named file with specified flag (O_RDONLY etc.) and perm, (0666 etc.)
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// if applicable. If successful, methods on the returned File can be used for I/O.
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// It returns the File and an Error, if any.
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func Open(name string, flag int, perm int) (file *File, err Error) {
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r, e := syscall.Open(name, int64(flag | syscall.O_CLOEXEC), int64(perm));
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if e != 0 {
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return nil, ErrnoToError(e);
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}
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// There's a race here with fork/exec, which we are
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// content to live with. See ../syscall/exec.go
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if syscall.O_CLOEXEC == 0 { // O_CLOEXEC not supported
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syscall.CloseOnExec(r);
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}
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return NewFile(r, name), ErrnoToError(e)
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}
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// Close closes the File, rendering it unusable for I/O.
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// It returns an Error, if any.
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func (file *File) Close() Error {
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if file == nil {
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return EINVAL
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}
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r, e := syscall.Close(file.fd);
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file.fd = -1; // so it can't be closed again
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return ErrnoToError(e)
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}
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// Read reads up to len(b) bytes from the File.
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// It returns the number of bytes read and an Error, if any.
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// EOF is signaled by a zero count with a nil Error.
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// TODO(r): Add Pread, Pwrite (maybe ReadAt, WriteAt).
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func (file *File) Read(b []byte) (ret int, err Error) {
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if file == nil {
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return 0, EINVAL
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}
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var r, e int64;
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if len(b) > 0 { // because we access b[0]
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r, e = syscall.Read(file.fd, &b[0], int64(len(b)));
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if r < 0 {
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r = 0
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}
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}
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return int(r), ErrnoToError(e)
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}
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// Write writes len(b) bytes to the File.
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// It returns the number of bytes written and an Error, if any.
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// If the byte count differs from len(b), it usually implies an error occurred.
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func (file *File) Write(b []byte) (ret int, err Error) {
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if file == nil {
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return 0, EINVAL
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}
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var r, e int64;
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if len(b) > 0 { // because we access b[0]
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r, e = syscall.Write(file.fd, &b[0], int64(len(b)));
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if r < 0 {
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r = 0
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}
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}
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if e == syscall.EPIPE {
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file.nepipe++;
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if file.nepipe >= 10 {
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os.Exit(syscall.EPIPE);
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}
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} else {
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file.nepipe = 0;
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}
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return int(r), ErrnoToError(e)
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}
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// Seek sets the offset for the next Read or Write on file to offset, interpreted
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// according to whence: 0 means relative to the origin of the file, 1 means
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// relative to the current offset, and 2 means relative to the end.
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// It returns the new offset and an Error, if any.
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func (file *File) Seek(offset int64, whence int) (ret int64, err Error) {
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r, e := syscall.Seek(file.fd, offset, int64(whence));
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if e != 0 {
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return -1, ErrnoToError(e)
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}
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if file.dirinfo != nil && r != 0 {
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return -1, ErrnoToError(syscall.EISDIR)
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}
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return r, nil
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}
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// WriteString is like Write, but writes the contents of string s rather than
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// an array of bytes.
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func (file *File) WriteString(s string) (ret int, err Error) {
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if file == nil {
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return 0, EINVAL
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}
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r, e := syscall.Write(file.fd, syscall.StringBytePtr(s), int64(len(s)));
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if r < 0 {
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r = 0
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}
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return int(r), ErrnoToError(e)
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}
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// Pipe returns a connected pair of Files; reads from r return bytes written to w.
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// It returns the files and an Error, if any.
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func Pipe() (r *File, w *File, err Error) {
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var p [2]int64;
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// See ../syscall/exec.go for description of lock.
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syscall.ForkLock.RLock();
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ret, e := syscall.Pipe(&p);
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if e != 0 {
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syscall.ForkLock.RUnlock();
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return nil, nil, ErrnoToError(e)
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}
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syscall.CloseOnExec(p[0]);
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syscall.CloseOnExec(p[1]);
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syscall.ForkLock.RUnlock();
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return NewFile(p[0], "|0"), NewFile(p[1], "|1"), nil
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}
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// Mkdir creates a new directory with the specified name and permission bits.
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// It returns an error, if any.
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func Mkdir(name string, perm int) Error {
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r, e := syscall.Mkdir(name, int64(perm));
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return ErrnoToError(e)
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}
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// Stat returns the Dir structure describing the named file. If the file
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// is a symbolic link, it returns information about the file the link
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// references.
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// It returns the Dir and an error, if any.
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func Stat(name string) (dir *Dir, err Error) {
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stat := new(syscall.Stat_t);
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r, e := syscall.Stat(name, stat);
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if e != 0 {
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return nil, ErrnoToError(e)
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}
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return dirFromStat(name, new(Dir), stat), nil
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}
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// Stat returns the Dir structure describing file.
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// It returns the Dir and an error, if any.
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func (file *File) Stat() (dir *Dir, err Error) {
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stat := new(syscall.Stat_t);
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r, e := syscall.Fstat(file.fd, stat);
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if e != 0 {
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return nil, ErrnoToError(e)
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}
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return dirFromStat(file.name, new(Dir), stat), nil
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}
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// Lstat returns the Dir structure describing the named file. If the file
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// is a symbolic link, it returns information about the link itself.
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// It returns the Dir and an error, if any.
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func Lstat(name string) (dir *Dir, err Error) {
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stat := new(syscall.Stat_t);
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r, e := syscall.Lstat(name, stat);
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if e != 0 {
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return nil, ErrnoToError(e)
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}
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return dirFromStat(name, new(Dir), stat), nil
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}
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// Readdirnames has a non-portable implemenation so its code is separated into an
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// operating-system-dependent file.
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func readdirnames(file *File, count int) (names []string, err Error)
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// Readdirnames reads the contents of the directory associated with file and
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// returns an array of up to count names, in directory order. Subsequent
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// calls on the same file will yield further names.
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// A negative count means to read until EOF.
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// It returns the array and an Error, if any.
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func (file *File) Readdirnames(count int) (names []string, err Error) {
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return readdirnames(file, count);
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}
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// Readdir reads the contents of the directory associated with file and
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// returns an array of up to count Dir structures, in directory order. Subsequent
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// calls on the same file will yield further Dirs.
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// A negative count means to read until EOF.
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// It returns the array and an Error, if any.
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func (file *File) Readdir(count int) (dirs []Dir, err Error) {
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dirname := file.name;
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if dirname == "" {
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dirname = ".";
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}
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dirname += "/";
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names, err1 := file.Readdirnames(count);
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if err1 != nil {
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return nil, err1
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}
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dirs = make([]Dir, len(names));
|
|
|
|
for i, filename := range names {
|
|
|
|
dirp, err := Stat(dirname + filename);
|
|
|
|
if dirp == nil || err != nil {
|
|
|
|
dirs[i].Name = filename // rest is already zeroed out
|
|
|
|
} else {
|
|
|
|
dirs[i] = *dirp
|
|
|
|
}
|
|
|
|
}
|
|
|
|
return
|
|
|
|
}
|
|
|
|
|
2009-04-07 01:40:36 -06:00
|
|
|
// Chdir changes the current working directory to the named directory.
|
2009-04-17 01:08:24 -06:00
|
|
|
func Chdir(dir string) Error {
|
2009-04-07 01:40:36 -06:00
|
|
|
r, e := syscall.Chdir(dir);
|
|
|
|
return ErrnoToError(e);
|
|
|
|
}
|
|
|
|
|
2009-04-13 17:50:42 -06:00
|
|
|
// Remove removes the named file or directory.
|
2009-04-17 01:08:24 -06:00
|
|
|
func Remove(name string) Error {
|
2009-04-13 17:50:42 -06:00
|
|
|
// System call interface forces us to know
|
|
|
|
// whether name is a file or directory.
|
|
|
|
// Try both: it is cheaper on average than
|
|
|
|
// doing a Stat plus the right one.
|
|
|
|
r, e := syscall.Unlink(name);
|
|
|
|
if e == 0 {
|
|
|
|
return nil;
|
|
|
|
}
|
|
|
|
r1, e1 := syscall.Rmdir(name);
|
|
|
|
if e1 == 0 {
|
|
|
|
return nil;
|
|
|
|
}
|
|
|
|
|
|
|
|
// Both failed: figure out which error to return.
|
|
|
|
// OS X and Linux differ on whether unlink(dir)
|
|
|
|
// returns EISDIR, so can't use that. However,
|
|
|
|
// both agree that rmdir(file) returns ENOTDIR,
|
|
|
|
// so we can use that to decide which error is real.
|
2009-04-13 20:14:09 -06:00
|
|
|
// Rmdir might also return ENOTDIR if given a bad
|
2009-04-13 17:50:42 -06:00
|
|
|
// file path, like /etc/passwd/foo, but in that case,
|
|
|
|
// both errors will be ENOTDIR, so it's okay to
|
|
|
|
// use the error from unlink.
|
|
|
|
if e1 != syscall.ENOTDIR {
|
|
|
|
e = e1;
|
|
|
|
}
|
2009-04-13 20:14:09 -06:00
|
|
|
return ErrnoToError(e);
|
2009-04-13 17:50:42 -06:00
|
|
|
}
|
|
|
|
|