cmd/netstring/main.go

   1 /*
   2 netstring -- netstring format serialization library
   3 Copyright (C) 2015-2020 Sergey Matveev <stargrave@stargrave.org>
   4
   5 This program is free software: you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation, version 3 of the License.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 package main
  19
  20 import (
  21         "flag"
  22         "fmt"
  23         "io"
  24         "os"
  25         "strconv"
  26
  27         "go.cypherpunks.ru/netstring/v2"
  28 )
  29
  30 func usage() {
  31         fmt.Fprintf(os.Stderr, "ns -- Work with netstring encoded files\n\n")
  32         fmt.Fprintf(os.Stderr, "Usage: %s list FILE\n", os.Args[0])
  33         fmt.Fprintf(os.Stderr, "       %s read FILE CHUNK > data\n", os.Args[0])
  34         fmt.Fprintf(os.Stderr, "       %s write FILE ... > data\n", os.Args[0])
  35         fmt.Fprintf(os.Stderr, "FILE can be \"-\" for reading from stdin\n")
  36         os.Exit(1)
  37 }
  38
  39 func fileRead(path string) io.Reader {
  40         if path == "-" {
  41                 return os.Stdin
  42         }
  43         fd, err := os.Open(path)
  44         if err != nil {
  45                 panic(err)
  46         }
  47         return fd
  48 }
  49
  50 func main() {
  51         flag.Usage = usage
  52         flag.Parse()
  53         if len(os.Args) < 3 {
  54                 usage()
  55         }
  56         switch os.Args[1] {
  57         case "list":
  58                 r := netstring.NewReader(fileRead(os.Args[2]))
  59                 for i := 0; ; i++ {
  60                         size, err := r.Next()
  61                         if err == io.EOF {
  62                                 break
  63                         }
  64                         if err != nil {
  65                                 panic(err)
  66                         }
  67                         fmt.Printf("%d\t%d\n", i, size)
  68                         r.Discard()
  69                 }
  70         case "read":
  71                 if len(os.Args) != 4 {
  72                         usage()
  73                 }
  74                 chunk, err := strconv.Atoi(os.Args[3])
  75                 if err != nil {
  76                         panic(err)
  77                 }
  78                 r := netstring.NewReader(fileRead(os.Args[2]))
  79                 for i := 0; i < chunk; i++ {
  80                         _, err = r.Next()
  81                         if err != nil {
  82                                 panic(err)
  83                         }
  84                         r.Discard()
  85                 }
  86                 _, err = r.Next()
  87                 if err != nil {
  88                         panic(err)
  89                 }
  90                 if _, err = io.Copy(os.Stdout, r); err != nil {
  91                         panic(err)
  92                 }
  93         case "write":
  94                 w := netstring.NewWriter(os.Stdout)
  95                 for i, fn := range os.Args[2:] {
  96                         fd, err := os.Open(fn)
  97                         if err != nil {
  98                                 panic(err)
  99                         }
 100                         fi, err := fd.Stat()
 101                         if err != nil {
 102                                 panic(err)
 103                         }
 104                         size := uint64(fi.Size())
 105                         if _, err = w.WriteSize(size); err != nil {
 106                                 panic(err)
 107                         }
 108                         if _, err = io.Copy(w, fd); err != nil {
 109                                 panic(err)
 110                         }
 111                         fmt.Fprintf(os.Stderr, "%d\t%d\t%s\n", i, size, fn)
 112                 }
 113         }
 114 }