mirror of
https://github.com/golang/go
synced 2024-10-05 08:21:22 -06:00
e38a1053a9
R=golang-dev, bradfitz CC=golang-dev https://golang.org/cl/5432071
320 lines
8.5 KiB
Go
320 lines
8.5 KiB
Go
// 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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package os
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import (
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"io"
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"runtime"
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"sync"
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"syscall"
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"unicode/utf16"
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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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*file
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}
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// file is the real representation of *File.
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// The extra level of indirection ensures that no clients of os
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// can overwrite this data, which could cause the finalizer
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// to close the wrong file descriptor.
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type file struct {
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fd syscall.Handle
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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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l sync.Mutex // used to implement windows pread/pwrite
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}
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// Fd returns the Windows handle referencing the open file.
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func (file *File) Fd() syscall.Handle {
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if file == nil {
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return syscall.InvalidHandle
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}
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return file.fd
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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(fd syscall.Handle, name string) *File {
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if fd < 0 {
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return nil
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}
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f := &File{&file{fd: fd, name: name}}
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runtime.SetFinalizer(f.file, (*file).close)
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return f
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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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data syscall.Win32finddata
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needdata bool
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}
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const DevNull = "NUL"
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func (file *file) isdir() bool { return file != nil && file.dirinfo != nil }
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func openFile(name string, flag int, perm uint32) (file *File, err error) {
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r, e := syscall.Open(name, flag|syscall.O_CLOEXEC, perm)
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if e != nil {
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return nil, &PathError{"open", name, 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), nil
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}
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func openDir(name string) (file *File, err error) {
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d := new(dirInfo)
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r, e := syscall.FindFirstFile(syscall.StringToUTF16Ptr(name+`\*`), &d.data)
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if e != nil {
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return nil, &PathError{"open", name, e}
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}
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f := NewFile(r, name)
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f.dirinfo = d
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return f, nil
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}
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// OpenFile is the generalized open call; most users will use Open
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// or Create instead. It opens the named file with specified flag
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// (O_RDONLY etc.) and perm, (0666 etc.) if applicable. If successful,
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// 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 OpenFile(name string, flag int, perm uint32) (file *File, err error) {
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if name == "" {
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return nil, &PathError{"open", name, syscall.ENOENT}
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}
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// TODO(brainman): not sure about my logic of assuming it is dir first, then fall back to file
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r, e := openDir(name)
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if e == nil {
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if flag&O_WRONLY != 0 || flag&O_RDWR != 0 {
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r.Close()
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return nil, &PathError{"open", name, EISDIR}
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}
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return r, nil
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}
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r, e = openFile(name, flag, perm)
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if e == nil {
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return r, nil
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}
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return nil, 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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return file.file.close()
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}
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func (file *file) close() error {
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if file == nil || file.fd < 0 {
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return EINVAL
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}
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var e error
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if file.isdir() {
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e = syscall.FindClose(syscall.Handle(file.fd))
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} else {
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e = syscall.CloseHandle(syscall.Handle(file.fd))
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}
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var err error
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if e != nil {
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err = &PathError{"close", file.name, e}
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}
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file.fd = syscall.InvalidHandle // so it can't be closed again
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// no need for a finalizer anymore
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runtime.SetFinalizer(file, nil)
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return err
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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 n FileInfo structures, as would be returned
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// by Lstat, in directory order. Subsequent calls on the same file will yield
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// further FileInfos.
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//
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// If n > 0, Readdir returns at most n FileInfo structures. In this case, if
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// Readdir returns an empty slice, it will return a non-nil error
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// explaining why. At the end of a directory, the error is io.EOF.
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//
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// If n <= 0, Readdir returns all the FileInfo from the directory in
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// a single slice. In this case, if Readdir succeeds (reads all
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// the way to the end of the directory), it returns the slice and a
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// nil error. If it encounters an error before the end of the
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// directory, Readdir returns the FileInfo read until that point
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// and a non-nil error.
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func (file *File) Readdir(n int) (fi []FileInfo, err error) {
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if file == nil || file.fd < 0 {
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return nil, EINVAL
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}
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if !file.isdir() {
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return nil, &PathError{"Readdir", file.name, ENOTDIR}
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}
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wantAll := n <= 0
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size := n
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if wantAll {
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n = -1
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size = 100
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}
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fi = make([]FileInfo, 0, size) // Empty with room to grow.
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d := &file.dirinfo.data
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for n != 0 {
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if file.dirinfo.needdata {
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e := syscall.FindNextFile(syscall.Handle(file.fd), d)
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if e != nil {
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if e == syscall.ERROR_NO_MORE_FILES {
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break
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} else {
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err = &PathError{"FindNextFile", file.name, e}
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if !wantAll {
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fi = nil
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}
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return
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}
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}
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}
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var f FileInfo
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setFileInfo(&f, string(syscall.UTF16ToString(d.FileName[0:])), d.FileAttributes, d.FileSizeHigh, d.FileSizeLow, d.CreationTime, d.LastAccessTime, d.LastWriteTime)
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file.dirinfo.needdata = true
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if f.Name == "." || f.Name == ".." { // Useless names
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continue
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}
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n--
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fi = append(fi, f)
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}
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if !wantAll && len(fi) == 0 {
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return fi, io.EOF
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}
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return fi, nil
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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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func (f *File) read(b []byte) (n int, err error) {
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f.l.Lock()
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defer f.l.Unlock()
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return syscall.Read(f.fd, b)
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}
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// pread reads len(b) bytes from the File starting at byte offset off.
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// It returns the number of bytes read and the error, if any.
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// EOF is signaled by a zero count with err set to 0.
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func (f *File) pread(b []byte, off int64) (n int, err error) {
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f.l.Lock()
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defer f.l.Unlock()
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curoffset, e := syscall.Seek(f.fd, 0, 1)
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if e != nil {
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return 0, e
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}
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defer syscall.Seek(f.fd, curoffset, 0)
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o := syscall.Overlapped{
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OffsetHigh: uint32(off >> 32),
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Offset: uint32(off),
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}
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var done uint32
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e = syscall.ReadFile(syscall.Handle(f.fd), b, &done, &o)
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if e != nil {
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return 0, e
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}
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return int(done), nil
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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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func (f *File) write(b []byte) (n int, err error) {
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f.l.Lock()
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defer f.l.Unlock()
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return syscall.Write(f.fd, b)
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}
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// pwrite writes len(b) bytes to the File starting at byte offset off.
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// It returns the number of bytes written and an error, if any.
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func (f *File) pwrite(b []byte, off int64) (n int, err error) {
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f.l.Lock()
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defer f.l.Unlock()
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curoffset, e := syscall.Seek(f.fd, 0, 1)
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if e != nil {
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return 0, e
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}
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defer syscall.Seek(f.fd, curoffset, 0)
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o := syscall.Overlapped{
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OffsetHigh: uint32(off >> 32),
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Offset: uint32(off),
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}
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var done uint32
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e = syscall.WriteFile(syscall.Handle(f.fd), b, &done, &o)
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if e != nil {
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return 0, e
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}
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return int(done), nil
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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 (f *File) seek(offset int64, whence int) (ret int64, err error) {
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f.l.Lock()
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defer f.l.Unlock()
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return syscall.Seek(f.fd, offset, whence)
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}
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// Truncate changes the size of the named file.
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// If the file is a symbolic link, it changes the size of the link's target.
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func Truncate(name string, size int64) error {
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f, e := OpenFile(name, O_WRONLY|O_CREATE, 0666)
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if e != nil {
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return e
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}
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defer f.Close()
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e1 := f.Truncate(size)
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if e1 != nil {
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return e1
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}
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return nil
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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]syscall.Handle
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// See ../syscall/exec.go for description of lock.
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syscall.ForkLock.RLock()
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e := syscall.Pipe(p[0:])
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if e != nil {
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syscall.ForkLock.RUnlock()
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return nil, nil, NewSyscallError("pipe", 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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// TempDir returns the default directory to use for temporary files.
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func TempDir() string {
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const pathSep = '\\'
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dirw := make([]uint16, syscall.MAX_PATH)
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n, _ := syscall.GetTempPath(uint32(len(dirw)), &dirw[0])
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if n > uint32(len(dirw)) {
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dirw = make([]uint16, n)
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n, _ = syscall.GetTempPath(uint32(len(dirw)), &dirw[0])
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if n > uint32(len(dirw)) {
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n = 0
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}
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}
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if n > 0 && dirw[n-1] == pathSep {
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n--
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}
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return string(utf16.Decode(dirw[0:n]))
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}
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