1 // Copyright 2009 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
5 // +build darwin freebsd linux netbsd openbsd
15 // File represents an open file descriptor.
20 // file is the real representation of *File.
21 // The extra level of indirection ensures that no clients of os
22 // can overwrite this data, which could cause the finalizer
23 // to close the wrong file descriptor.
27 dirinfo *dirInfo // nil unless directory being read
28 nepipe int32 // number of consecutive EPIPE in Write
31 // Fd returns the integer Unix file descriptor referencing the open file.
32 func (f *File) Fd() uintptr {
39 // NewFile returns a new File with the given file descriptor and name.
40 func NewFile(fd uintptr, name string) *File {
45 f := &File{&file{fd: fdi, name: name}}
46 runtime.SetFinalizer(f.file, (*file).close)
50 // Auxiliary information if the File describes a directory
52 buf []byte // buffer for directory I/O
53 dir *syscall.DIR // from opendir
56 func epipecheck(file *File, e error) {
57 if e == syscall.EPIPE {
58 if atomic.AddInt32(&file.nepipe, 1) >= 10 {
62 atomic.StoreInt32(&file.nepipe, 0)
66 // DevNull is the name of the operating system's ``null device.''
67 // On Unix-like systems, it is "/dev/null"; on Windows, "NUL".
68 const DevNull = "/dev/null"
70 // OpenFile is the generalized open call; most users will use Open
71 // or Create instead. It opens the named file with specified flag
72 // (O_RDONLY etc.) and perm, (0666 etc.) if applicable. If successful,
73 // methods on the returned File can be used for I/O.
74 // If there is an error, it will be of type *PathError.
75 func OpenFile(name string, flag int, perm FileMode) (file *File, err error) {
76 r, e := syscall.Open(name, flag|syscall.O_CLOEXEC, syscallMode(perm))
78 return nil, &PathError{"open", name, e}
81 // There's a race here with fork/exec, which we are
82 // content to live with. See ../syscall/exec_unix.go.
83 // On OS X 10.6, the O_CLOEXEC flag is not respected.
84 // On OS X 10.7, the O_CLOEXEC flag works.
85 // Without a cheap & reliable way to detect 10.6 vs 10.7 at
86 // runtime, we just always call syscall.CloseOnExec on Darwin.
87 // Once >=10.7 is prevalent, this extra call can removed.
88 if syscall.O_CLOEXEC == 0 || runtime.GOOS == "darwin" { // O_CLOEXEC not supported
89 syscall.CloseOnExec(r)
92 return NewFile(uintptr(r), name), nil
95 // Close closes the File, rendering it unusable for I/O.
96 // It returns an error, if any.
97 func (f *File) Close() error {
101 func (file *file) close() error {
102 if file == nil || file.fd < 0 {
103 return syscall.EINVAL
106 if e := syscall.Close(file.fd); e != nil {
107 err = &PathError{"close", file.name, e}
110 if file.dirinfo != nil {
111 if libc_closedir(file.dirinfo.dir) < 0 && err == nil {
112 err = &PathError{"closedir", file.name, syscall.GetErrno()}
116 file.fd = -1 // so it can't be closed again
118 // no need for a finalizer anymore
119 runtime.SetFinalizer(file, nil)
123 // Stat returns the FileInfo structure describing file.
124 // If there is an error, it will be of type *PathError.
125 func (f *File) Stat() (fi FileInfo, err error) {
126 var stat syscall.Stat_t
127 err = syscall.Fstat(f.fd, &stat)
129 return nil, &PathError{"stat", f.name, err}
131 return fileInfoFromStat(&stat, f.name), nil
134 // Stat returns a FileInfo describing the named file.
135 // If there is an error, it will be of type *PathError.
136 func Stat(name string) (fi FileInfo, err error) {
137 var stat syscall.Stat_t
138 err = syscall.Stat(name, &stat)
140 return nil, &PathError{"stat", name, err}
142 return fileInfoFromStat(&stat, name), nil
145 // Lstat returns a FileInfo describing the named file.
146 // If the file is a symbolic link, the returned FileInfo
147 // describes the symbolic link. Lstat makes no attempt to follow the link.
148 // If there is an error, it will be of type *PathError.
149 func Lstat(name string) (fi FileInfo, err error) {
150 var stat syscall.Stat_t
151 err = syscall.Lstat(name, &stat)
153 return nil, &PathError{"lstat", name, err}
155 return fileInfoFromStat(&stat, name), nil
158 func (f *File) readdir(n int) (fi []FileInfo, err error) {
164 names, err := f.Readdirnames(n)
165 fi = make([]FileInfo, len(names))
166 for i, filename := range names {
167 fip, err := Lstat(dirname + filename)
171 fi[i] = &fileStat{name: filename}
177 // read reads up to len(b) bytes from the File.
178 // It returns the number of bytes read and an error, if any.
179 func (f *File) read(b []byte) (n int, err error) {
180 return syscall.Read(f.fd, b)
183 // pread reads len(b) bytes from the File starting at byte offset off.
184 // It returns the number of bytes read and the error, if any.
185 // EOF is signaled by a zero count with err set to 0.
186 func (f *File) pread(b []byte, off int64) (n int, err error) {
187 return syscall.Pread(f.fd, b, off)
190 // write writes len(b) bytes to the File.
191 // It returns the number of bytes written and an error, if any.
192 func (f *File) write(b []byte) (n int, err error) {
194 m, err := syscall.Write(f.fd, b)
197 // If the syscall wrote some data but not all (short write)
198 // or it returned EINTR, then assume it stopped early for
199 // reasons that are uninteresting to the caller, and try again.
200 if 0 < m && m < len(b) || err == syscall.EINTR {
210 // pwrite writes len(b) bytes to the File starting at byte offset off.
211 // It returns the number of bytes written and an error, if any.
212 func (f *File) pwrite(b []byte, off int64) (n int, err error) {
213 return syscall.Pwrite(f.fd, b, off)
216 // seek sets the offset for the next Read or Write on file to offset, interpreted
217 // according to whence: 0 means relative to the origin of the file, 1 means
218 // relative to the current offset, and 2 means relative to the end.
219 // It returns the new offset and an error, if any.
220 func (f *File) seek(offset int64, whence int) (ret int64, err error) {
221 return syscall.Seek(f.fd, offset, whence)
224 // Truncate changes the size of the named file.
225 // If the file is a symbolic link, it changes the size of the link's target.
226 // If there is an error, it will be of type *PathError.
227 func Truncate(name string, size int64) error {
228 if e := syscall.Truncate(name, size); e != nil {
229 return &PathError{"truncate", name, e}
234 // Remove removes the named file or directory.
235 // If there is an error, it will be of type *PathError.
236 func Remove(name string) error {
237 // System call interface forces us to know
238 // whether name is a file or directory.
239 // Try both: it is cheaper on average than
240 // doing a Stat plus the right one.
241 e := syscall.Unlink(name)
245 e1 := syscall.Rmdir(name)
250 // Both failed: figure out which error to return.
251 // OS X and Linux differ on whether unlink(dir)
252 // returns EISDIR, so can't use that. However,
253 // both agree that rmdir(file) returns ENOTDIR,
254 // so we can use that to decide which error is real.
255 // Rmdir might also return ENOTDIR if given a bad
256 // file path, like /etc/passwd/foo, but in that case,
257 // both errors will be ENOTDIR, so it's okay to
258 // use the error from unlink.
259 if e1 != syscall.ENOTDIR {
262 return &PathError{"remove", name, e}
265 // basename removes trailing slashes and the leading directory name from path name
266 func basename(name string) string {
268 // Remove trailing slashes
269 for ; i > 0 && name[i] == '/'; i-- {
272 // Remove leading directory name
273 for i--; i >= 0; i-- {
283 // Pipe returns a connected pair of Files; reads from r return bytes written to w.
284 // It returns the files and an error, if any.
285 func Pipe() (r *File, w *File, err error) {
288 // See ../syscall/exec.go for description of lock.
289 syscall.ForkLock.RLock()
290 e := syscall.Pipe(p[0:])
292 syscall.ForkLock.RUnlock()
293 return nil, nil, NewSyscallError("pipe", e)
295 syscall.CloseOnExec(p[0])
296 syscall.CloseOnExec(p[1])
297 syscall.ForkLock.RUnlock()
299 return NewFile(uintptr(p[0]), "|0"), NewFile(uintptr(p[1]), "|1"), nil
302 // TempDir returns the default directory to use for temporary files.
303 func TempDir() string {
304 dir := Getenv("TMPDIR")