| // Copyright 2019 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 diff implements a Diff function that compare two inputs |
| // using the 'diff' tool. |
| package diff |
| |
| import ( |
| exec "internal/execabs" |
| "io/ioutil" |
| "os" |
| "runtime" |
| ) |
| |
| // Returns diff of two arrays of bytes in diff tool format. |
| func Diff(prefix string, b1, b2 []byte) ([]byte, error) { |
| f1, err := writeTempFile(prefix, b1) |
| if err != nil { |
| return nil, err |
| } |
| defer os.Remove(f1) |
| |
| f2, err := writeTempFile(prefix, b2) |
| if err != nil { |
| return nil, err |
| } |
| defer os.Remove(f2) |
| |
| cmd := "diff" |
| if runtime.GOOS == "plan9" { |
| cmd = "/bin/ape/diff" |
| } |
| |
| data, err := exec.Command(cmd, "-u", f1, f2).CombinedOutput() |
| if len(data) > 0 { |
| // diff exits with a non-zero status when the files don't match. |
| // Ignore that failure as long as we get output. |
| err = nil |
| } |
| return data, err |
| } |
| |
| func writeTempFile(prefix string, data []byte) (string, error) { |
| file, err := ioutil.TempFile("", prefix) |
| if err != nil { |
| return "", err |
| } |
| _, err = file.Write(data) |
| if err1 := file.Close(); err == nil { |
| err = err1 |
| } |
| if err != nil { |
| os.Remove(file.Name()) |
| return "", err |
| } |
| return file.Name(), nil |
| } |