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fmtcmd.go
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fmtcmd.go
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// Derivative work from:
// - https://golang.org/src/cmd/gofmt/gofmt.go
// - https://github.com/fatih/hclfmt
package fmtcmd
import (
"bytes"
"errors"
"fmt"
"io"
"io/ioutil"
"os"
"os/exec"
"path/filepath"
"strings"
"github.com/hashicorp/hcl/hcl/printer"
)
var (
ErrWriteStdin = errors.New("cannot use write option with standard input")
)
type Options struct {
List bool // list files whose formatting differs
Write bool // write result to (source) file instead of stdout
Diff bool // display diffs instead of rewriting files
}
func isValidFile(f os.FileInfo, extensions []string) bool {
if !f.IsDir() && !strings.HasPrefix(f.Name(), ".") {
for _, ext := range extensions {
if strings.HasSuffix(f.Name(), "."+ext) {
return true
}
}
}
return false
}
// If in == nil, the source is the contents of the file with the given filename.
func processFile(filename string, in io.Reader, out io.Writer, stdin bool, opts Options) error {
if in == nil {
f, err := os.Open(filename)
if err != nil {
return err
}
defer f.Close()
in = f
}
src, err := ioutil.ReadAll(in)
if err != nil {
return err
}
res, err := printer.Format(src)
if err != nil {
return err
}
// Files should end with newlines
res = append(res, []byte("\n")...)
if !bytes.Equal(src, res) {
// formatting has changed
if opts.List {
fmt.Fprintln(out, filename)
}
if opts.Write {
err = ioutil.WriteFile(filename, res, 0644)
if err != nil {
return err
}
}
if opts.Diff {
data, err := diff(src, res)
if err != nil {
return fmt.Errorf("computing diff: %s", err)
}
fmt.Fprintf(out, "diff a/%s b/%s\n", filename, filename)
out.Write(data)
}
}
if !opts.List && !opts.Write && !opts.Diff {
_, err = out.Write(res)
}
return err
}
func walkDir(path string, extensions []string, stdout io.Writer, opts Options) error {
visitFile := func(path string, f os.FileInfo, err error) error {
if err == nil && isValidFile(f, extensions) {
err = processFile(path, nil, stdout, false, opts)
}
return err
}
return filepath.Walk(path, visitFile)
}
func Run(
paths, extensions []string,
stdin io.Reader,
stdout io.Writer,
opts Options,
) error {
if len(paths) == 0 {
if opts.Write {
return ErrWriteStdin
}
if err := processFile("<standard input>", stdin, stdout, true, opts); err != nil {
return err
}
return nil
}
for _, path := range paths {
switch dir, err := os.Stat(path); {
case err != nil:
return err
case dir.IsDir():
if err := walkDir(path, extensions, stdout, opts); err != nil {
return err
}
default:
if err := processFile(path, nil, stdout, false, opts); err != nil {
return err
}
}
}
return nil
}
func diff(b1, b2 []byte) (data []byte, err error) {
f1, err := ioutil.TempFile("", "")
if err != nil {
return
}
defer os.Remove(f1.Name())
defer f1.Close()
f2, err := ioutil.TempFile("", "")
if err != nil {
return
}
defer os.Remove(f2.Name())
defer f2.Close()
f1.Write(b1)
f2.Write(b2)
data, err = exec.Command("diff", "-u", f1.Name(), f2.Name()).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
}