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jeremybenn |
// 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 ioutil
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import (
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"os"
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"path/filepath"
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"strconv"
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"time"
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)
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// Random number state, accessed without lock; racy but harmless.
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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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var rand uint32
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func reseed() uint32 {
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return uint32(time.Now().UnixNano() + int64(os.Getpid()))
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}
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func nextSuffix() string {
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r := rand
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if r == 0 {
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r = reseed()
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}
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r = r*1664525 + 1013904223 // constants from Numerical Recipes
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rand = r
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return strconv.Itoa(int(1e9 + r%1e9))[1:]
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}
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// TempFile creates a new temporary file in the directory dir
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// with a name beginning with prefix, opens the file for reading
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// and writing, and returns the resulting *os.File.
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// If dir is the empty string, TempFile uses the default directory
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// for temporary files (see os.TempDir).
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// Multiple programs calling TempFile simultaneously
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// will not choose the same file. The caller can use f.Name()
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// to find the name of the file. It is the caller's responsibility to
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// remove the file when no longer needed.
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func TempFile(dir, prefix string) (f *os.File, err error) {
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if dir == "" {
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dir = os.TempDir()
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}
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nconflict := 0
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for i := 0; i < 10000; i++ {
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name := filepath.Join(dir, prefix+nextSuffix())
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f, err = os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
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if pe, ok := err.(*os.PathError); ok && pe.Err == os.EEXIST {
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if nconflict++; nconflict > 10 {
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rand = reseed()
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}
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continue
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}
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break
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}
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return
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}
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// TempDir creates a new temporary directory in the directory dir
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// with a name beginning with prefix and returns the path of the
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// new directory. If dir is the empty string, TempDir uses the
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// default directory for temporary files (see os.TempDir).
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// Multiple programs calling TempDir simultaneously
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// will not choose the same directory. It is the caller's responsibility
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// to remove the directory when no longer needed.
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func TempDir(dir, prefix string) (name string, err error) {
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if dir == "" {
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dir = os.TempDir()
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}
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nconflict := 0
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for i := 0; i < 10000; i++ {
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try := filepath.Join(dir, prefix+nextSuffix())
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err = os.Mkdir(try, 0700)
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if pe, ok := err.(*os.PathError); ok && pe.Err == os.EEXIST {
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if nconflict++; nconflict > 10 {
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rand = reseed()
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}
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continue
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}
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if err == nil {
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name = try
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}
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break
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}
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return
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}
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