blob: e9d2c237800a9c6c658eb41db1b58dcff102fe18 [file] [log] [blame]
// 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 (
"io/ioutil"
"os"
"os/exec"
"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
}