cmp.c

   1 /*
   2     Copyright © 2013 Alastair Stuart
   3
   4     This program is open source 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, either version 3 of the License, or
   7     (at your option) any later version.
   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
  15 #include <stdio.h>
  16 #include <string.h>
  17
  18 #define VERSION "0.01"
  19
  20 int main(int argc, char* argv[])
  21 {
  22     FILE* first_file  = NULL;
  23     FILE* second_file = NULL;
  24
  25     int arg = 0;
  26     for (arg = 1; arg < argc; arg++)
  27     {
  28         if (strcmp("--help", argv[arg]) == 0 || strcmp("-h", argv[arg]) == 0) {
  29             printf("Usage: %s [file1] [file2]\n", argv[0]);
  30             printf("\n"
  31                    "If a file is '-' or missing, standard input is read.\n");
  32             return 0;
  33         } else if (strcmp("--version", argv[arg]) == 0 || strcmp("-v", argv[arg]) == 0) {
  34             printf("cmp (mutos) v"VERSION"\n");
  35             return 0;
  36         } else {
  37             break;
  38         }
  39
  40     }
  41
  42     switch (argc - arg) // number of args left
  43     {
  44         case 0:
  45             fprintf(stderr, "%s: missing operand\n"
  46                             "Run '%s --help' for usage.\n",
  47                             argv[0], argv[0]);
  48             return 2;
  49         case 1:
  50             first_file  = strcmp("-", argv[arg]) == 0 ? stdin : fopen(argv[arg], "r");
  51             second_file = stdin;
  52             break;
  53         case 2:
  54             first_file  = strcmp("-", argv[arg]) == 0 ? stdin : fopen(argv[arg], "r");
  55             second_file = strcmp("-", argv[arg+1]) == 0 ? stdin : fopen(argv[arg+1], "r");
  56             break;
  57         default:
  58             fprintf(stderr, "%s: too many arguments\n",
  59                              argv[0]);
  60             return 2;
  61     }
  62
  63     if (first_file == second_file) {
  64         return 0;
  65     }
  66
  67     char* first_name  = first_file == stdin ? "-" : argv[arg];
  68     char* second_name = second_file == stdin ? "-" : argv[arg+1];
  69
  70     int differ = 0;
  71
  72     int byte_count = 0;
  73     int line_count = 1;
  74
  75     int first_byte  = 0;
  76     int second_byte = 0;
  77
  78
  79     while (first_byte != EOF && second_byte != EOF)
  80     {
  81         first_byte  = fgetc(first_file);
  82         second_byte = fgetc(second_file);
  83         byte_count++;
  84
  85         if (first_byte != second_byte) {
  86             differ = 1;
  87             break;
  88         }
  89
  90         if (first_byte == '\n') {
  91             line_count++;
  92         }
  93     }
  94
  95     if (differ) {
  96         printf("%s %s differ: byte %d, line %d\n",
  97                 first_name, second_name,  byte_count, line_count);
  98         fclose(first_file);
  99         fclose(second_file);
 100         return 1;
 101     } else {
 102         fclose(first_file);
 103         fclose(second_file);
 104         return 0;
 105     }
 106
 107 }