hexutils/hexutils.js

   1 var fs = require("fs");
   2
   3 var buffer_to_hex = function(data) {
   4     var output = "";
   5
   6     for(var i=0; i<data.length; i++) {
   7         var c = data[i].toString(16);
   8
   9         while(c.length < 2) {
  10             c = "0" + c;
  11         }
  12
  13         output += c;
  14     }
  15
  16     return output;
  17 };
  18
  19 var buffer_from_hex = function(data) {
  20     var buf = new Buffer(data.length / 2);
  21
  22     for(var i=0; i<data.length; i++) {
  23         var c = "" + data[i*2] + data[(i*2)+1];
  24         c = parseInt(c, 16);
  25         buf[i] = c;
  26     }
  27
  28     return buf;
  29 };
  30
  31 function help() {
  32     console.log("Usage: hexutils [OPTION] [INFILE] [OUTFILE]");
  33     console.log("Convert hex string to characters or vice versa");
  34     console.log();
  35     console.log("  -h, --hex   Convert characters to hex string");
  36     console.log("  -c, --char  Convert hex string to characters");
  37     console.log();
  38     console.log("With no INFILE and OUTFILE, or when INFILE is -, read standard input.");
  39     console.log("With no OUTFILE, or when OUTFILE is -, write to standard output.");
  40     console.log();
  41     console.log("Report bugs to <steve@offend.me.uk>.");
  42 }
  43
  44 if(process.argv.length < 3) {
  45         help();
  46     process.exit();
  47 }
  48
  49 var mode = null;
  50 if(process.argv[2] == "-h" || process.argv[2] == "--hex") {
  51     mode = "hex";
  52 } else if(process.argv[2] == "-c" || process.argv[2] == "--char") {
  53     mode = "char";
  54 } else {
  55     help();
  56     process.exit();
  57 }
  58
  59 var instream, outstream = null;
  60 if(process.argv.length < 4 || process.argv[3] == "-") {
  61     instream = process.stdin;
  62     if(mode == "char") {
  63         process.stdin.setEncoding("utf8");
  64     }
  65     process.stdin.resume();
  66 } else {
  67     instream = fs.createReadStream(process.argv[3], {
  68         encoding: (mode == "char" ? "utf8" : null)
  69     });
  70 }
  71
  72 if(process.argv.length < 5 || process.argv[4] == "-") {
  73     outstream = process.stdout;
  74     process.stdout.setEncoding("utf8");
  75 } else {
  76     outstream = fs.createWriteStream(process.argv[4]);
  77 }
  78
  79 function convert(data) {
  80     return (mode == "hex" ? buffer_to_hex(data) : buffer_from_hex(data));
  81 }
  82
  83 instream.on("error", function(err) {
  84     console.error("Error reading input");
  85     process.exit();
  86 });
  87
  88 outstream.on("error", function(err) {
  89     console.error("Error writing output");
  90     process.exit();
  91 });
  92
  93 instream.on("data", function(data) {
  94     try {
  95         data = convert(data);
  96     } catch(err) {
  97         console.error("Failed to encode");
  98         process.exit();
  99     }
 100
 101     outstream.write(data);
 102 });
 103
 104 instream.on("end", function(data) {
 105     outstream.end();
 106 });