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