golang file_unix 代码
文件路径：/src/os/file_unix.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.
/go:build unix || (js && wasm)
package os
import (
"internal/poll"
"internal/syscall/unix"
"runtime"
"syscall"
)
/ fixLongPath is a noop on non-Windows platforms.
func fixLongPath(path string) string {
return path
}
func rename(oldname, newname string) error {
fi, err := Lstat(newname)
if err == nil && fi.IsDir() {
/ There are two independent errors this function can return:
/ one for a bad oldname, and one for a bad newname.
/ At this point we've determined the newname is bad.
/ But just in case oldname is also bad, prioritize returning
/ the oldname error because that's what we did historically.
/ However, if the old name and new name are not the same, yet
/ they refer to the same file, it implies a case-only
/ rename on a case-insensitive filesystem, which is ok.
if ofi, err := Lstat(oldname); err != nil {
if pe, ok := err.(*PathError); ok {
err = pe.Err
}
return &LinkError{"rename", oldname, newname, err}
} else if newname == oldname || !SameFile(fi, ofi) {
return &LinkError{"rename", oldname, newname, syscall.EEXIST}
}
}
err = ignoringEINTR(func() error {
return syscall.Rename(oldname, newname)
})
if err != nil {
return &LinkError{"rename", oldname, newname, err}
}
return nil
}
/ file is the real representation of *File.
/ The extra level of indirection ensures that no clients of os
/ can overwrite this data, which could cause the finalizer
/ to close the wrong file descriptor.
type file struct {
pfd poll.FD
name string
dirinfo *dirInfo / nil unless directory being read
nonblock bool / whether we set nonblocking mode
stdoutOrErr bool / whether this is stdout or stderr
appendMode bool / whether file is opened for appending
}
/ Fd returns the integer Unix file descriptor referencing the open file.
/ If f is closed, the file descriptor becomes invalid.
/ If f is garbage collected, a finalizer may close the file descriptor,
/ making it invalid; see runtime.SetFinalizer for more information on when
/ a finalizer might be run. On Unix systems this will cause the SetDeadline
/ methods to stop working.
/ Because file descriptors can be reused, the returned file descriptor may
/ only be closed through the Close method of f, or by its finalizer during
/ garbage collection. Otherwise, during garbage collection the finalizer
/ may close an unrelated file descriptor with the same (reused) number.
/
/ As an alternative, see the f.SyscallConn method.
func (f *File) Fd() uintptr {
if f == nil {
return ^(uintptr(0))
}
/ If we put the file descriptor into nonblocking mode,
/ then set it to blocking mode before we return it,
/ because historically we have always returned a descriptor
/ opened in blocking mode. The File will continue to work,
/ but any blocking operation will tie up a thread.
if f.nonblock {
f.pfd.SetBlocking()
}
return uintptr(f.pfd.Sysfd)
}
/ NewFile returns a new File with the given file descriptor and
/ name. The returned value will be nil if fd is not a valid file
/ descriptor. On Unix systems, if the file descriptor is in
/ non-blocking mode, NewFile will attempt to return a pollable File
/ (one for which the SetDeadline methods work).
/
/ After passing it to NewFile, fd may become invalid under the same
/ conditions described in the comments of the Fd method, and the same
/ constraints apply.
func NewFile(fd uintptr, name string) *File {
kind := kindNewFile
if nb, err := unix.IsNonblock(int(fd)); err == nil && nb {
kind = kindNonBlock
}
return newFile(fd, name, kind)
}
/ newFileKind describes the kind of file to newFile.
type newFileKind int
const (
kindNewFile newFileKind = iota
kindOpenFile
kindPipe
kindNonBlock
)
/ newFile is like NewFile, but if called from OpenFile or Pipe
/ (as passed in the kind parameter) it tries to add the file to
/ the runtime poller.
func newFile(fd uintptr, name string, kind newFileKind) *File {
fdi := int(fd)
if fdi < 0 {
return nil
}
f := &File{&file{
pfd: poll.FD{
Sysfd: fdi,
IsStream: true,
ZeroReadIsEOF: true,
},
name: name,
stdoutOrErr: fdi == 1 || fdi == 2,
}}
pollable := kind == kindOpenFile || kind == kindPipe || kind == kindNonBlock
/ If the caller passed a non-blocking filedes (kindNonBlock),
/ we assume they know what they are doing so we allow it to be
/ used with kqueue.
if kind == kindOpenFile {
switch runtime.GOOS {
case "darwin", "ios", "dragonfly", "freebsd", "netbsd", "openbsd":
var st syscall.Stat_t
err := ignoringEINTR(func() error {
return syscall.Fstat(fdi, &st)
})
typ := st.Mode & syscall.S_IFMT
/ Don't try to use kqueue with regular files on *BSDs.
/ On FreeBSD a regular file is always
/ reported as ready for writing.
/ On Dragonfly, NetBSD and OpenBSD the fd is signaled
/ only once as ready (both read and write).
/ Issue 19093.
/ Also don't add directories to the netpoller.
if err == nil && (typ == syscall.S_IFREG || typ == syscall.S_IFDIR) {
pollable = false
}
/ In addition to the behavior described above for regular files,
/ on Darwin, kqueue does not work properly with fifos:
/ closing the last writer does not cause a kqueue event
/ for any readers. See issue #24164.
if (runtime.GOOS == "darwin" || runtime.GOOS == "ios") && typ == syscall.S_IFIFO {
pollable = false
}
}
}
if err := f.pfd.Init("file", pollable); err != nil {
/ An error here indicates a failure to register
/ with the netpoll system. That can happen for
/ a file descriptor that is not supported by
/ epoll/kqueue; for example, disk files on
/ Linux systems. We assume that any real error
/ will show up in later I/O.
} else if pollable {
/ We successfully registered with netpoll, so put
/ the file into nonblocking mode.
if err := syscall.SetNonblock(fdi, true); err == nil {
f.nonblock = true
}
}
runtime.SetFinalizer(f.file, (*file).close)
return f
}
/ epipecheck raises SIGPIPE if we get an EPIPE error on standard
/ output or standard error. See the SIGPIPE docs in os/signal, and
/ issue 11845.
func epipecheck(file *File, e error) {
if e == syscall.EPIPE && file.stdoutOrErr {
sigpipe()
}
}
/ 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"
/ openFileNolog is the Unix implementation of OpenFile.
/ Changes here should be reflected in openFdAt, if relevant.
func openFileNolog(name string, flag int, perm FileMode) (*File, error) {
setSticky := false
if !supportsCreateWithStickyBit && flag&O_CREATE != 0 && perm&ModeSticky != 0 {
if _, err := Stat(name); IsNotExist(err) {
setSticky = true
}
}
var r int
for {
var e error
r, e = syscall.Open(name, flag|syscall.O_CLOEXEC, syscallMode(perm))
if e == nil {
break
}
/ We have to check EINTR here, per issues 11180 and 39237.
if e == syscall.EINTR {
continue
}
return nil, &PathError{Op: "open", Path: name, Err: e}
}
/ open(2) itself won't handle the sticky bit on *BSD and Solaris
if setSticky {
setStickyBit(name)
}
/ There's a race here with fork/exec, which we are
/ content to live with. See ../syscall/exec_unix.go.
if !supportsCloseOnExec {
syscall.CloseOnExec(r)
}
return newFile(uintptr(r), name, kindOpenFile), nil
}
func (file *file) close() error {
if file == nil {
return syscall.EINVAL
}
if file.dirinfo != nil {
file.dirinfo.close()
file.dirinfo = nil
}
var err error
if e := file.pfd.Close(); e != nil {
if e == poll.ErrFileClosing {
e = ErrClosed
}
err = &PathError{Op: "close", Path: file.name, Err: e}
}
/ no need for a finalizer anymore
runtime.SetFinalizer(file, nil)
return err
}
/ 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) {
if f.dirinfo != nil {
/ Free cached dirinfo, so we allocate a new one if we
/ access this file as a directory again. See #35767 and #37161.
f.dirinfo.close()
f.dirinfo = nil
}
ret, err = f.pfd.Seek(offset, whence)
runtime.KeepAlive(f)
return ret, err
}
/ Truncate changes the size of the named file.
/ If the file is a symbolic link, it changes the size of the link's target.
/ If there is an error, it will be of type *PathError.
func Truncate(name string, size int64) error {
e := ignoringEINTR(func() error {
return syscall.Truncate(name, size)
})
if e != nil {
return &PathError{Op: "truncate", Path: name, Err: e}
}
return nil
}
/ Remove removes the named file or (empty) directory.
/ If there is an error, it will be of type *PathError.
func Remove(name string) error {
/ 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.
e := ignoringEINTR(func() error {
return syscall.Unlink(name)
})
if e == nil {
return nil
}
e1 := ignoringEINTR(func() error {
return syscall.Rmdir(name)
})
if e1 == nil {
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.
/ Rmdir might also return ENOTDIR if given a bad
/ 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
}
return &PathError{Op: "remove", Path: name, Err: e}
}
func tempDir() string {
dir := Getenv("TMPDIR")
if dir == "" {
if runtime.GOOS == "android" {
dir = "/data/local/tmp"
} else {
dir = "/tmp"
}
}
return dir
}
/ Link creates newname as a hard link to the oldname file.
/ If there is an error, it will be of type *LinkError.
func Link(oldname, newname string) error {
e := ignoringEINTR(func() error {
return syscall.Link(oldname, newname)
})
if e != nil {
return &LinkError{"link", oldname, newname, e}
}
return nil
}
/ Symlink creates newname as a symbolic link to oldname.
/ On Windows, a symlink to a non-existent oldname creates a file symlink;
/ if oldname is later created as a directory the symlink will not work.
/ If there is an error, it will be of type *LinkError.
func Symlink(oldname, newname string) error {
e := ignoringEINTR(func() error {
return syscall.Symlink(oldname, newname)
})
if e != nil {
return &LinkError{"symlink", oldname, newname, e}
}
return nil
}
/ Readlink returns the destination of the named symbolic link.
/ If there is an error, it will be of type *PathError.
func Readlink(name string) (string, error) {
for len := 128; ; len *= 2 {
b := make([]byte, len)
var (
n int
e error
)
for {
n, e = fixCount(syscall.Readlink(name, b))
if e != syscall.EINTR {
break
}
}
/ buffer too small
if runtime.GOOS == "aix" && e == syscall.ERANGE {
continue
}
if e != nil {
return "", &PathError{Op: "readlink", Path: name, Err: e}
}
if n < len {
return string(b[0:n]), nil
}
}
}
type unixDirent struct {
parent string
name string
typ FileMode
info FileInfo
}
func (d *unixDirent) Name() string { return d.name }
func (d *unixDirent) IsDir() bool { return d.typ.IsDir() }
func (d *unixDirent) Type() FileMode { return d.typ }
func (d *unixDirent) Info() (FileInfo, error) {
if d.info != nil {
return d.info, nil
}
return lstat(d.parent + "/" + d.name)
}
func newUnixDirent(parent, name string, typ FileMode) (DirEntry, error) {
ude := &unixDirent{
parent: parent,
name: name,
typ: typ,
}
if typ != ^FileMode(0) && !testingForceReadDirLstat {
return ude, nil
}
info, err := lstat(parent + "/" + name)
if err != nil {
return nil, err
}
ude.typ = info.Mode().Type()
ude.info = info
return ude, nil
}