cmd/netstring/main.go

   1 // netstring -- netstring format serialization library
   2 // Copyright (C) 2015-2024 Sergey Matveev <stargrave@stargrave.org>
   3 //
   4 // This program is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, version 3 of the License.
   7 //
   8 // This program is distributed in the hope that it will be useful,
   9 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 // GNU General Public License for more details.
  12 //
  13 // You should have received a copy of the GNU General Public License
  14 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15
  16 package main
  17
  18 import (
  19         "flag"
  20         "fmt"
  21         "io"
  22         "os"
  23         "strconv"
  24
  25         "go.cypherpunks.ru/netstring/v2"
  26 )
  27
  28 func usage() {
  29         fmt.Fprintf(os.Stderr, "ns -- Work with netstring encoded files\n\n")
  30         fmt.Fprintf(os.Stderr, "Usage: %s list FILE\n", os.Args[0])
  31         fmt.Fprintf(os.Stderr, "       %s read FILE CHUNK > data\n", os.Args[0])
  32         fmt.Fprintf(os.Stderr, "       %s write FILE ... > data\n", os.Args[0])
  33         fmt.Fprintf(os.Stderr, "FILE can be \"-\" for reading from stdin\n")
  34         os.Exit(1)
  35 }
  36
  37 func fileRead(path string) io.Reader {
  38         if path == "-" {
  39                 return os.Stdin
  40         }
  41         fd, err := os.Open(path)
  42         if err != nil {
  43                 panic(err)
  44         }
  45         return fd
  46 }
  47
  48 func main() {
  49         flag.Usage = usage
  50         flag.Parse()
  51         if len(os.Args) < 3 {
  52                 usage()
  53         }
  54         switch os.Args[1] {
  55         case "list":
  56                 r := netstring.NewReader(fileRead(os.Args[2]))
  57                 for i := 0; ; i++ {
  58                         size, err := r.Next()
  59                         if err == io.EOF {
  60                                 break
  61                         }
  62                         if err != nil {
  63                                 panic(err)
  64                         }
  65                         fmt.Printf("%d\t%d\n", i, size)
  66                         r.Discard()
  67                 }
  68         case "read":
  69                 if len(os.Args) != 4 {
  70                         usage()
  71                 }
  72                 chunk, err := strconv.Atoi(os.Args[3])
  73                 if err != nil {
  74                         panic(err)
  75                 }
  76                 r := netstring.NewReader(fileRead(os.Args[2]))
  77                 for i := 0; i < chunk; i++ {
  78                         _, err = r.Next()
  79                         if err != nil {
  80                                 panic(err)
  81                         }
  82                         r.Discard()
  83                 }
  84                 _, err = r.Next()
  85                 if err != nil {
  86                         panic(err)
  87                 }
  88                 if _, err = io.Copy(os.Stdout, r); err != nil {
  89                         panic(err)
  90                 }
  91         case "write":
  92                 w := netstring.NewWriter(os.Stdout)
  93                 for i, fn := range os.Args[2:] {
  94                         fd, err := os.Open(fn)
  95                         if err != nil {
  96                                 panic(err)
  97                         }
  98                         fi, err := fd.Stat()
  99                         if err != nil {
 100                                 panic(err)
 101                         }
 102                         size := uint64(fi.Size())
 103                         if _, err = w.WriteSize(size); err != nil {
 104                                 panic(err)
 105                         }
 106                         if _, err = io.Copy(w, fd); err != nil {
 107                                 panic(err)
 108                         }
 109                         fmt.Fprintf(os.Stderr, "%d\t%d\t%s\n", i, size, fn)
 110                 }
 111         }
 112 }