475 lines
12 KiB
Go
475 lines
12 KiB
Go
// Copyright 2011 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
|
|
|
|
import (
|
|
"io"
|
|
"runtime"
|
|
"syscall"
|
|
"time"
|
|
)
|
|
|
|
// File represents an open file descriptor.
|
|
type File struct {
|
|
*file
|
|
}
|
|
|
|
// 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 {
|
|
fd int
|
|
name string
|
|
dirinfo *dirInfo // nil unless directory being read
|
|
}
|
|
|
|
// Fd returns the integer Plan 9 file descriptor referencing the open file.
|
|
// The file descriptor is valid only until f.Close is called or f is garbage collected.
|
|
func (f *File) Fd() uintptr {
|
|
if f == nil {
|
|
return ^(uintptr(0))
|
|
}
|
|
return uintptr(f.fd)
|
|
}
|
|
|
|
// NewFile returns a new File with the given file descriptor and name.
|
|
func NewFile(fd uintptr, name string) *File {
|
|
fdi := int(fd)
|
|
if fdi < 0 {
|
|
return nil
|
|
}
|
|
f := &File{&file{fd: fdi, name: name}}
|
|
runtime.SetFinalizer(f.file, (*file).close)
|
|
return f
|
|
}
|
|
|
|
// Auxiliary information if the File describes a directory
|
|
type dirInfo struct {
|
|
buf [syscall.STATMAX]byte // buffer for directory I/O
|
|
nbuf int // length of buf; return value from Read
|
|
bufp int // location of next record in buf.
|
|
}
|
|
|
|
func epipecheck(file *File, e error) {
|
|
}
|
|
|
|
// 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"
|
|
|
|
// syscallMode returns the syscall-specific mode bits from Go's portable mode bits.
|
|
func syscallMode(i FileMode) (o uint32) {
|
|
o |= uint32(i.Perm())
|
|
if i&ModeAppend != 0 {
|
|
o |= syscall.DMAPPEND
|
|
}
|
|
if i&ModeExclusive != 0 {
|
|
o |= syscall.DMEXCL
|
|
}
|
|
if i&ModeTemporary != 0 {
|
|
o |= syscall.DMTMP
|
|
}
|
|
return
|
|
}
|
|
|
|
// OpenFile is the generalized open call; most users will use Open
|
|
// or Create instead. It opens the named file with specified flag
|
|
// (O_RDONLY etc.) and perm, (0666 etc.) if applicable. If successful,
|
|
// methods on the returned File can be used for I/O.
|
|
// If there is an error, it will be of type *PathError.
|
|
func OpenFile(name string, flag int, perm FileMode) (*File, error) {
|
|
var (
|
|
fd int
|
|
e error
|
|
create bool
|
|
excl bool
|
|
trunc bool
|
|
append bool
|
|
)
|
|
|
|
if flag&O_CREATE == O_CREATE {
|
|
flag = flag & ^O_CREATE
|
|
create = true
|
|
}
|
|
if flag&O_EXCL == O_EXCL {
|
|
excl = true
|
|
}
|
|
if flag&O_TRUNC == O_TRUNC {
|
|
trunc = true
|
|
}
|
|
// O_APPEND is emulated on Plan 9
|
|
if flag&O_APPEND == O_APPEND {
|
|
flag = flag &^ O_APPEND
|
|
append = true
|
|
}
|
|
|
|
if (create && trunc) || excl {
|
|
fd, e = syscall.Create(name, flag, syscallMode(perm))
|
|
} else {
|
|
fd, e = syscall.Open(name, flag)
|
|
if e != nil && create {
|
|
var e1 error
|
|
fd, e1 = syscall.Create(name, flag, syscallMode(perm))
|
|
if e1 == nil {
|
|
e = nil
|
|
}
|
|
}
|
|
}
|
|
|
|
if e != nil {
|
|
return nil, &PathError{"open", name, e}
|
|
}
|
|
|
|
if append {
|
|
if _, e = syscall.Seek(fd, 0, io.SeekEnd); e != nil {
|
|
return nil, &PathError{"seek", name, e}
|
|
}
|
|
}
|
|
|
|
return NewFile(uintptr(fd), name), nil
|
|
}
|
|
|
|
// Close closes the File, rendering it unusable for I/O.
|
|
// It returns an error, if any.
|
|
func (f *File) Close() error {
|
|
if f == nil {
|
|
return ErrInvalid
|
|
}
|
|
return f.file.close()
|
|
}
|
|
|
|
func (file *file) close() error {
|
|
if file == nil || file.fd < 0 {
|
|
return ErrInvalid
|
|
}
|
|
var err error
|
|
if e := syscall.Close(file.fd); e != nil {
|
|
err = &PathError{"close", file.name, e}
|
|
}
|
|
file.fd = -1 // so it can't be closed again
|
|
|
|
// no need for a finalizer anymore
|
|
runtime.SetFinalizer(file, nil)
|
|
return err
|
|
}
|
|
|
|
// Stat returns the FileInfo structure describing file.
|
|
// If there is an error, it will be of type *PathError.
|
|
func (f *File) Stat() (FileInfo, error) {
|
|
if f == nil {
|
|
return nil, ErrInvalid
|
|
}
|
|
d, err := dirstat(f)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return fileInfoFromStat(d), nil
|
|
}
|
|
|
|
// Truncate changes the size of the file.
|
|
// It does not change the I/O offset.
|
|
// If there is an error, it will be of type *PathError.
|
|
func (f *File) Truncate(size int64) error {
|
|
if f == nil {
|
|
return ErrInvalid
|
|
}
|
|
|
|
var d syscall.Dir
|
|
d.Null()
|
|
d.Length = size
|
|
|
|
var buf [syscall.STATFIXLEN]byte
|
|
n, err := d.Marshal(buf[:])
|
|
if err != nil {
|
|
return &PathError{"truncate", f.name, err}
|
|
}
|
|
if err = syscall.Fwstat(f.fd, buf[:n]); err != nil {
|
|
return &PathError{"truncate", f.name, err}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
const chmodMask = uint32(syscall.DMAPPEND | syscall.DMEXCL | syscall.DMTMP | ModePerm)
|
|
|
|
// Chmod changes the mode of the file to mode.
|
|
// If there is an error, it will be of type *PathError.
|
|
func (f *File) Chmod(mode FileMode) error {
|
|
if f == nil {
|
|
return ErrInvalid
|
|
}
|
|
var d syscall.Dir
|
|
|
|
odir, e := dirstat(f)
|
|
if e != nil {
|
|
return &PathError{"chmod", f.name, e}
|
|
}
|
|
d.Null()
|
|
d.Mode = odir.Mode&^chmodMask | syscallMode(mode)&chmodMask
|
|
|
|
var buf [syscall.STATFIXLEN]byte
|
|
n, err := d.Marshal(buf[:])
|
|
if err != nil {
|
|
return &PathError{"chmod", f.name, err}
|
|
}
|
|
if err = syscall.Fwstat(f.fd, buf[:n]); err != nil {
|
|
return &PathError{"chmod", f.name, err}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Sync commits the current contents of the file to stable storage.
|
|
// Typically, this means flushing the file system's in-memory copy
|
|
// of recently written data to disk.
|
|
func (f *File) Sync() error {
|
|
if f == nil {
|
|
return ErrInvalid
|
|
}
|
|
var d syscall.Dir
|
|
d.Null()
|
|
|
|
var buf [syscall.STATFIXLEN]byte
|
|
n, err := d.Marshal(buf[:])
|
|
if err != nil {
|
|
return NewSyscallError("fsync", err)
|
|
}
|
|
if err = syscall.Fwstat(f.fd, buf[:n]); err != nil {
|
|
return NewSyscallError("fsync", err)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// read reads up to len(b) bytes from the File.
|
|
// It returns the number of bytes read and an error, if any.
|
|
func (f *File) read(b []byte) (n int, err error) {
|
|
return fixCount(syscall.Read(f.fd, b))
|
|
}
|
|
|
|
// pread 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 nil.
|
|
func (f *File) pread(b []byte, off int64) (n int, err error) {
|
|
return fixCount(syscall.Pread(f.fd, b, off))
|
|
}
|
|
|
|
// write writes len(b) bytes to the File.
|
|
// It returns the number of bytes written and an error, if any.
|
|
// Since Plan 9 preserves message boundaries, never allow
|
|
// a zero-byte write.
|
|
func (f *File) write(b []byte) (n int, err error) {
|
|
if len(b) == 0 {
|
|
return 0, nil
|
|
}
|
|
return fixCount(syscall.Write(f.fd, b))
|
|
}
|
|
|
|
// pwrite writes len(b) bytes to the File starting at byte offset off.
|
|
// It returns the number of bytes written and an error, if any.
|
|
// Since Plan 9 preserves message boundaries, never allow
|
|
// a zero-byte write.
|
|
func (f *File) pwrite(b []byte, off int64) (n int, err error) {
|
|
if len(b) == 0 {
|
|
return 0, nil
|
|
}
|
|
return fixCount(syscall.Pwrite(f.fd, b, off))
|
|
}
|
|
|
|
// 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) {
|
|
return syscall.Seek(f.fd, offset, whence)
|
|
}
|
|
|
|
// 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 {
|
|
var d syscall.Dir
|
|
|
|
d.Null()
|
|
d.Length = size
|
|
|
|
var buf [syscall.STATFIXLEN]byte
|
|
n, err := d.Marshal(buf[:])
|
|
if err != nil {
|
|
return &PathError{"truncate", name, err}
|
|
}
|
|
if err = syscall.Wstat(name, buf[:n]); err != nil {
|
|
return &PathError{"truncate", name, err}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Remove removes the named file or directory.
|
|
// If there is an error, it will be of type *PathError.
|
|
func Remove(name string) error {
|
|
if e := syscall.Remove(name); e != nil {
|
|
return &PathError{"remove", name, e}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// HasPrefix from the strings package.
|
|
func hasPrefix(s, prefix string) bool {
|
|
return len(s) >= len(prefix) && s[0:len(prefix)] == prefix
|
|
}
|
|
|
|
// LastIndexByte from the strings package.
|
|
func lastIndex(s string, sep byte) int {
|
|
for i := len(s) - 1; i >= 0; i-- {
|
|
if s[i] == sep {
|
|
return i
|
|
}
|
|
}
|
|
return -1
|
|
}
|
|
|
|
func rename(oldname, newname string) error {
|
|
dirname := oldname[:lastIndex(oldname, '/')+1]
|
|
if hasPrefix(newname, dirname) {
|
|
newname = newname[len(dirname):]
|
|
} else {
|
|
return &LinkError{"rename", oldname, newname, ErrInvalid}
|
|
}
|
|
|
|
// If newname still contains slashes after removing the oldname
|
|
// prefix, the rename is cross-directory and must be rejected.
|
|
if lastIndex(newname, '/') >= 0 {
|
|
return &LinkError{"rename", oldname, newname, ErrInvalid}
|
|
}
|
|
|
|
var d syscall.Dir
|
|
|
|
d.Null()
|
|
d.Name = newname
|
|
|
|
buf := make([]byte, syscall.STATFIXLEN+len(d.Name))
|
|
n, err := d.Marshal(buf[:])
|
|
if err != nil {
|
|
return &LinkError{"rename", oldname, newname, err}
|
|
}
|
|
|
|
// If newname already exists and is not a directory, rename replaces it.
|
|
f, err := Stat(dirname + newname)
|
|
if err == nil && !f.IsDir() {
|
|
Remove(dirname + newname)
|
|
}
|
|
|
|
if err = syscall.Wstat(oldname, buf[:n]); err != nil {
|
|
return &LinkError{"rename", oldname, newname, err}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Chmod changes the mode of the named file to mode.
|
|
// If the file is a symbolic link, it changes the mode of the link's target.
|
|
// If there is an error, it will be of type *PathError.
|
|
func Chmod(name string, mode FileMode) error {
|
|
var d syscall.Dir
|
|
|
|
odir, e := dirstat(name)
|
|
if e != nil {
|
|
return &PathError{"chmod", name, e}
|
|
}
|
|
d.Null()
|
|
d.Mode = odir.Mode&^chmodMask | syscallMode(mode)&chmodMask
|
|
|
|
var buf [syscall.STATFIXLEN]byte
|
|
n, err := d.Marshal(buf[:])
|
|
if err != nil {
|
|
return &PathError{"chmod", name, err}
|
|
}
|
|
if err = syscall.Wstat(name, buf[:n]); err != nil {
|
|
return &PathError{"chmod", name, err}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Chtimes changes the access and modification times of the named
|
|
// file, similar to the Unix utime() or utimes() functions.
|
|
//
|
|
// The underlying filesystem may truncate or round the values to a
|
|
// less precise time unit.
|
|
// If there is an error, it will be of type *PathError.
|
|
func Chtimes(name string, atime time.Time, mtime time.Time) error {
|
|
var d syscall.Dir
|
|
|
|
d.Null()
|
|
d.Atime = uint32(atime.Unix())
|
|
d.Mtime = uint32(mtime.Unix())
|
|
|
|
var buf [syscall.STATFIXLEN]byte
|
|
n, err := d.Marshal(buf[:])
|
|
if err != nil {
|
|
return &PathError{"chtimes", name, err}
|
|
}
|
|
if err = syscall.Wstat(name, buf[:n]); err != nil {
|
|
return &PathError{"chtimes", name, err}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Pipe returns a connected pair of Files; reads from r return bytes
|
|
// written to w. It returns the files and an error, if any.
|
|
func Pipe() (r *File, w *File, err error) {
|
|
var p [2]int
|
|
|
|
if e := syscall.Pipe(p[0:]); e != nil {
|
|
return nil, nil, NewSyscallError("pipe", e)
|
|
}
|
|
|
|
return NewFile(uintptr(p[0]), "|0"), NewFile(uintptr(p[1]), "|1"), nil
|
|
}
|
|
|
|
// not supported on Plan 9
|
|
|
|
// 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 {
|
|
return &LinkError{"link", oldname, newname, syscall.EPLAN9}
|
|
}
|
|
|
|
// Symlink creates newname as a symbolic link to oldname.
|
|
// If there is an error, it will be of type *LinkError.
|
|
func Symlink(oldname, newname string) error {
|
|
return &LinkError{"symlink", oldname, newname, syscall.EPLAN9}
|
|
}
|
|
|
|
// 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) {
|
|
return "", &PathError{"readlink", name, syscall.EPLAN9}
|
|
}
|
|
|
|
// Chown changes the numeric uid and gid of the named file.
|
|
// If the file is a symbolic link, it changes the uid and gid of the link's target.
|
|
// If there is an error, it will be of type *PathError.
|
|
func Chown(name string, uid, gid int) error {
|
|
return &PathError{"chown", name, syscall.EPLAN9}
|
|
}
|
|
|
|
// Lchown changes the numeric uid and gid of the named file.
|
|
// If the file is a symbolic link, it changes the uid and gid of the link itself.
|
|
// If there is an error, it will be of type *PathError.
|
|
func Lchown(name string, uid, gid int) error {
|
|
return &PathError{"lchown", name, syscall.EPLAN9}
|
|
}
|
|
|
|
// Chown changes the numeric uid and gid of the named file.
|
|
// If there is an error, it will be of type *PathError.
|
|
func (f *File) Chown(uid, gid int) error {
|
|
if f == nil {
|
|
return ErrInvalid
|
|
}
|
|
return &PathError{"chown", f.name, syscall.EPLAN9}
|
|
}
|
|
|
|
// TempDir returns the default directory to use for temporary files.
|
|
func TempDir() string {
|
|
return "/tmp"
|
|
}
|