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