blob: bc6b9a2b97352c68a131094948ffb2ed315ffca6 [file] [log] [blame]
// Copyright 2017 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
import (
"fmt"
"io/ioutil"
"os"
"os/exec"
"runtime"
)
func writeTempFile(dir, prefix string, data []byte) (string, error) {
file, err := ioutil.TempFile(dir, 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
}
// Diff returns a human-readable description of the differences between s1 and s2.
// If the "diff" command is available, it returns the output of unified diff on s1 and s2.
// If the result is non-empty, the strings differ or the diff command failed.
func Diff(s1, s2 string) string {
if s1 == s2 {
return ""
}
if _, err := exec.LookPath("diff"); err != nil {
return fmt.Sprintf("diff command unavailable\nold: %q\nnew: %q", s1, s2)
}
f1, err := writeTempFile("", "benchfmt_test", []byte(s1))
if err != nil {
return err.Error()
}
defer os.Remove(f1)
f2, err := writeTempFile("", "benchfmt_test", []byte(s2))
if err != nil {
return err.Error()
}
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
}
if err != nil {
data = append(data, []byte(err.Error())...)
}
return string(data)
}