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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [io/] [ioutil/] [tempfile.go] - Blame information for rev 747

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Line No. Rev Author Line
1 747 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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