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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 fileutils
-
- import (
- "os"
- "path/filepath"
- "strconv"
- "sync"
- "time"
- )
-
- // Random number state.
- // 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.
- var rand uint32
- var randmu sync.Mutex
-
- func reseed() uint32 {
- return uint32(time.Now().UnixNano() + int64(os.Getpid()))
- }
-
- func nextSuffix() string {
- randmu.Lock()
- r := rand
- if r == 0 {
- r = reseed()
- }
- r = r*1664525 + 1013904223 // constants from Numerical Recipes
- rand = r
- randmu.Unlock()
- return strconv.Itoa(int(1e9 + r%1e9))[1:]
- }
-
- // TempFile creates a new temporary file in the directory dir
- // with a name beginning with prefix and ending with ext, opens the
- // file for reading and writing, and returns the resulting *os.File.
- // If dir is the empty string, TempFile uses the default directory
- // for temporary files (see os.TempDir).
- // Multiple programs calling TempFile simultaneously
- // will not choose the same file. The caller can use f.Name()
- // to find the pathname of the file. It is the caller's responsibility
- // to remove the file when no longer needed.
- func TempFile(dir, prefix, ext string) (f *os.File, err error) {
- if dir == "" {
- dir = os.TempDir()
- }
-
- nconflict := 0
- for i := 0; i < 10000; i++ {
- name := filepath.Join(dir, prefix+nextSuffix()+"."+ext)
- f, err = os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
- if os.IsExist(err) {
- if nconflict++; nconflict > 10 {
- randmu.Lock()
- rand = reseed()
- randmu.Unlock()
- }
- continue
- }
- break
- }
- return
- }
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