1// Copyright 2017 The Bazel Authors. All rights reserved. 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// http://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14 15// md5sum replicates the equivalent functionality of the unix tool of the same name. 16package main 17 18import ( 19 "crypto/md5" 20 "flag" 21 "fmt" 22 "io" 23 "log" 24 "os" 25 "path/filepath" 26) 27 28func md5SumFile(filename string) ([]byte, error) { 29 var result []byte 30 f, err := os.Open(filename) 31 if err != nil { 32 return result, err 33 } 34 defer f.Close() 35 hash := md5.New() 36 if _, err := io.Copy(hash, f); err != nil { 37 return nil, err 38 } 39 return hash.Sum(result), nil 40} 41 42func run(args []string) error { 43 // Prepare our flags 44 flags := flag.NewFlagSet("md5sum", flag.ExitOnError) 45 output := flags.String("output", "", "If set, write the results to this file, instead of stdout.") 46 if err := flags.Parse(args); err != nil { 47 return err 48 } 49 // print the outputs if we need not 50 to := os.Stdout 51 if *output != "" { 52 f, err := os.Create(*output) 53 if err != nil { 54 return err 55 } 56 defer f.Close() 57 to = f 58 } 59 for _, path := range flags.Args() { 60 walkFn := func(path string, info os.FileInfo, err error) error { 61 if err != nil { 62 return err 63 } 64 if info.IsDir() { 65 return nil 66 } 67 68 if b, err := md5SumFile(path); err != nil { 69 return err 70 } else { 71 fmt.Fprintf(to, "%s %x\n", path, b) 72 } 73 return nil 74 } 75 76 if err := filepath.Walk(path, walkFn); err != nil { 77 return err 78 } 79 } 80 return nil 81} 82 83func main() { 84 log.SetFlags(0) 85 log.SetPrefix("GoMd5sum: ") 86 if err := run(os.Args[1:]); err != nil { 87 log.Fatal(err) 88 } 89} 90