128 lines
3.8 KiB
Go
128 lines
3.8 KiB
Go
// Copyright 2010 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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"errors"
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"internal/itoa"
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)
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// fastrand provided by runtime.
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// We generate random temporary file names so that there's a good
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// chance the file doesn't exist yet - keeps the number of tries in
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// TempFile to a minimum.
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func fastrand() uint32
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func nextRandom() string {
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return itoa.Uitoa(uint(fastrand()))
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}
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// CreateTemp creates a new temporary file in the directory dir,
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// opens the file for reading and writing, and returns the resulting file.
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// The filename is generated by taking pattern and adding a random string to the end.
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// If pattern includes a "*", the random string replaces the last "*".
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// If dir is the empty string, CreateTemp uses the default directory for temporary files, as returned by TempDir.
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// Multiple programs or goroutines calling CreateTemp simultaneously will not choose the same file.
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// The caller can use the file's Name method to find the pathname of the file.
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// It is the caller's responsibility to remove the file when it is no longer needed.
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func CreateTemp(dir, pattern string) (*File, error) {
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if dir == "" {
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dir = TempDir()
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}
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prefix, suffix, err := prefixAndSuffix(pattern)
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if err != nil {
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return nil, &PathError{Op: "createtemp", Path: pattern, Err: err}
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}
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prefix = joinPath(dir, prefix)
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try := 0
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for {
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name := prefix + nextRandom() + suffix
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f, err := OpenFile(name, O_RDWR|O_CREATE|O_EXCL, 0600)
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if IsExist(err) {
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if try++; try < 10000 {
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continue
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}
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return nil, &PathError{Op: "createtemp", Path: prefix + "*" + suffix, Err: ErrExist}
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}
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return f, err
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}
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}
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var errPatternHasSeparator = errors.New("pattern contains path separator")
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// prefixAndSuffix splits pattern by the last wildcard "*", if applicable,
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// returning prefix as the part before "*" and suffix as the part after "*".
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func prefixAndSuffix(pattern string) (prefix, suffix string, err error) {
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for i := 0; i < len(pattern); i++ {
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if IsPathSeparator(pattern[i]) {
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return "", "", errPatternHasSeparator
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}
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}
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if pos := lastIndex(pattern, '*'); pos != -1 {
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prefix, suffix = pattern[:pos], pattern[pos+1:]
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} else {
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prefix = pattern
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}
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return prefix, suffix, nil
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}
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// MkdirTemp creates a new temporary directory in the directory dir
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// and returns the pathname of the new directory.
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// The new directory's name is generated by adding a random string to the end of pattern.
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// If pattern includes a "*", the random string replaces the last "*" instead.
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// If dir is the empty string, MkdirTemp uses the default directory for temporary files, as returned by TempDir.
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// Multiple programs or goroutines calling MkdirTemp simultaneously will not choose the same directory.
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// It is the caller's responsibility to remove the directory when it is no longer needed.
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func MkdirTemp(dir, pattern string) (string, error) {
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if dir == "" {
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dir = TempDir()
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}
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prefix, suffix, err := prefixAndSuffix(pattern)
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if err != nil {
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return "", &PathError{Op: "mkdirtemp", Path: pattern, Err: err}
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}
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prefix = joinPath(dir, prefix)
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try := 0
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for {
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name := prefix + nextRandom() + suffix
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err := Mkdir(name, 0700)
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if err == nil {
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return name, nil
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}
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if IsExist(err) {
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if try++; try < 10000 {
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continue
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}
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return "", &PathError{Op: "mkdirtemp", Path: dir + string(PathSeparator) + prefix + "*" + suffix, Err: ErrExist}
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}
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if IsNotExist(err) {
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if _, err := Stat(dir); IsNotExist(err) {
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return "", err
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}
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}
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return "", err
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}
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}
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func joinPath(dir, name string) string {
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if len(dir) > 0 && IsPathSeparator(dir[len(dir)-1]) {
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return dir + name
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}
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return dir + string(PathSeparator) + name
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}
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// LastIndexByte from the strings package.
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func lastIndex(s string, sep byte) int {
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for i := len(s) - 1; i >= 0; i-- {
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if s[i] == sep {
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return i
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}
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}
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return -1
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}
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