comm.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 <stdlib.h>
  17 #include <string.h>
  18
  19 #include <getopt.h>
  20
  21 #define VERSION "0.01"
  22
  23 char* readline(FILE* stream)
  24 {
  25     if (feof(stream)) {
  26         return NULL;
  27     }
  28     size_t length = 0;
  29     long int curr_pos = ftell(stream);
  30
  31     int c = fgetc(stream);
  32     while (c != '\n' && c != EOF)
  33     {
  34         length++;
  35         c = fgetc(stream);
  36     }
  37
  38     fseek(stream, curr_pos, SEEK_SET);
  39
  40
  41     char* line = calloc(1, length + 1);
  42
  43     for (size_t i = 0; i < length; i++)
  44     {
  45         line[i] = fgetc(stream);
  46     }
  47     line[length] = '\0';
  48
  49     fgetc(stream); // move past the newline
  50
  51     return line;
  52 }
  53
  54 void usage(char* program)
  55 {
  56     printf("Usage: %s [options] [file1] [file2]\n", program);
  57     printf("Compares 2 sorted files line by line.\n"
  58            "\n"
  59            "    --help     Print this message.\n"
  60            "    --version  Show version info.\n"
  61            "\n"
  62            "If only one file is given, standard input is used for the second file.\n");
  63 }
  64
  65 int main(int argc, char* argv[])
  66 {
  67     static struct option long_options[] = {
  68         {"help",      no_argument, NULL,  1},
  69         {"version",   no_argument, NULL,  2},
  70         {NULL, 0, NULL, 0}
  71     };
  72
  73     int c = 0;
  74     while ((c = getopt_long(argc, argv, "",
  75                             long_options, NULL)) != -1)
  76     {
  77         switch (c)
  78         {
  79             case 1:
  80                 usage(argv[0]);
  81                 return 0;
  82             case 2:
  83                 printf("comm (mutos) v"VERSION"\n");
  84                 return 0;
  85             default:
  86                 fprintf(stderr,"Run '%s --help' for usage.\n",
  87                                      argv[0]);
  88                 return 1;
  89         }
  90     }
  91
  92     FILE* file1 = NULL;
  93     FILE* file2 = NULL;
  94
  95     if ((argc - optind) < 1) {
  96         fprintf(stderr, "%s: missing operands\n"
  97                         "Run '%s --help' for usage.\n",
  98                         argv[0], argv[0]);
  99         return 1;
 100     } else if ((argc - optind) == 1) {
 101         file1 = fopen(argv[optind], "r");
 102         file2 = stdin;
 103     } else if ((argc - optind) == 2) {
 104         file1 = fopen(argv[optind],   "r");
 105         file2 = fopen(argv[optind+1], "r");
 106     } else {
 107         fprintf(stderr, "%s: extra operand: %s\n",
 108                          argv[0],           argv[optind+2]);
 109         return 1;
 110     }
 111
 112     char* line1 = readline(file1);
 113     char* line2 = readline(file2);
 114
 115     while (!feof(file1) || !feof(file2))
 116     {
 117         if (line1 && line2) {
 118             if (strcmp(line1, line2) == 0) {
 119                 printf("\t\t%s\n", (line1 ? line1 : line2));
 120             } else {
 121                 printf("\t%s\n", line2);
 122                 printf("%s\n", line1);
 123             }
 124
 125         } else {
 126             if (line1) {
 127                 printf("%s\n", line1);
 128             }
 129
 130             if (line2) {
 131                 printf("\t%s\n", line2);
 132             }
 133         }
 134         free(line1);
 135         free(line2);
 136
 137         line1 = readline(file1);
 138         line2 = readline(file2);
 139     }
 140
 141     return 0;
 142 }