/
fileutil.go
67 lines (62 loc) · 1.72 KB
/
fileutil.go
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// Copyright 2015 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
package osutil
import (
"fmt"
"io"
"os"
)
// CopyFile atomically copies oldFile to newFile preserving permissions and modification time.
func CopyFile(oldFile, newFile string) error {
oldf, err := os.Open(oldFile)
if err != nil {
return err
}
defer oldf.Close()
stat, err := oldf.Stat()
if err != nil {
return err
}
tmpFile := newFile + ".tmp"
newf, err := os.OpenFile(tmpFile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, stat.Mode()&os.ModePerm)
if err != nil {
return err
}
defer newf.Close()
_, err = io.Copy(newf, oldf)
if err != nil {
return err
}
if err := newf.Close(); err != nil {
return err
}
if err := os.Chtimes(tmpFile, stat.ModTime(), stat.ModTime()); err != nil {
return err
}
return os.Rename(tmpFile, newFile)
}
// Rename is similar to os.Rename but handles cross-device renaming (by copying).
func Rename(oldFile, newFile string) error {
err := os.Rename(oldFile, newFile)
if err != nil {
// Can't use syscall.EXDEV because this is used in appengine app.
err = CopyFile(oldFile, newFile)
os.Remove(oldFile)
}
return err
}
// WriteTempFile writes data to a temp file and returns its name.
func WriteTempFile(data []byte) (string, error) {
// Note: pkg/report knows about "syzkaller" prefix as it appears in crashes as process name.
f, err := os.CreateTemp("", "syzkaller")
if err != nil {
return "", fmt.Errorf("failed to create a temp file: %w", err)
}
if _, err := f.Write(data); err != nil {
f.Close()
os.Remove(f.Name())
return "", fmt.Errorf("failed to write a temp file: %w", err)
}
f.Close()
return f.Name(), nil
}