Subversion Repositories openrisc

// 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"
        "path/filepath"
        "strconv"
        "time"
)

// 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 {
        return uint32(time.Now().UnixNano() + 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 error) {
        if dir == "" {
                dir = os.TempDir()
        }

        nconflict := 0
        for i := 0; i < 10000; i++ {
                name := filepath.Join(dir, prefix+nextSuffix())
                f, err = os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
                if pe, ok := err.(*os.PathError); ok && pe.Err == 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 error) {
        if dir == "" {
                dir = os.TempDir()
        }

        nconflict := 0
        for i := 0; i < 10000; i++ {
                try := filepath.Join(dir, prefix+nextSuffix())
                err = os.Mkdir(try, 0700)
                if pe, ok := err.(*os.PathError); ok && pe.Err == os.EEXIST {
                        if nconflict++; nconflict > 10 {
                                rand = reseed()
                        }
                        continue
                }
                if err == nil {
                        name = try
                }
                break
        }
        return
}