libgo/go/cmd/buildid/buildid.go

   1 // Copyright 2017 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package main
   6
   7 import (
   8         "flag"
   9         "fmt"
  10         "log"
  11         "os"
  12         "strings"
  13
  14         "cmd/internal/buildid"
  15 )
  16
  17 func usage() {
  18         fmt.Fprintf(os.Stderr, "usage: go tool buildid [-w] file\n")
  19         flag.PrintDefaults()
  20         os.Exit(2)
  21 }
  22
  23 var wflag = flag.Bool("w", false, "write build ID")
  24
  25 func main() {
  26         log.SetPrefix("buildid: ")
  27         log.SetFlags(0)
  28         flag.Usage = usage
  29         flag.Parse()
  30         if flag.NArg() != 1 {
  31                 usage()
  32         }
  33
  34         file := flag.Arg(0)
  35         id, err := buildid.ReadFile(file)
  36         if err != nil {
  37                 log.Fatal(err)
  38         }
  39         if !*wflag {
  40                 fmt.Printf("%s\n", id)
  41                 return
  42         }
  43
  44         f, err := os.Open(file)
  45         if err != nil {
  46                 log.Fatal(err)
  47         }
  48         matches, hash, err := buildid.FindAndHash(f, id, 0)
  49         if err != nil {
  50                 log.Fatal(err)
  51         }
  52         f.Close()
  53
  54         tail := id
  55         if i := strings.LastIndex(id, "."); i >= 0 {
  56                 tail = tail[i+1:]
  57         }
  58         if len(tail) != len(hash)*2 {
  59                 log.Fatalf("%s: cannot find %d-byte hash in id %s", file, len(hash), id)
  60         }
  61         newID := id[:len(id)-len(tail)] + fmt.Sprintf("%x", hash)
  62
  63         f, err = os.OpenFile(file, os.O_WRONLY, 0)
  64         if err != nil {
  65                 log.Fatal(err)
  66         }
  67         if err := buildid.Rewrite(f, matches, newID); err != nil {
  68                 log.Fatal(err)
  69         }
  70         if err := f.Close(); err != nil {
  71                 log.Fatal(err)
  72         }
  73 }