cat.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 #include <errno.h>
  18
  19 #include <getopt.h>
  20
  21 #define VERSION "0.01"
  22
  23 void usage(char* program)
  24 {
  25     printf("Usage: %s [options] [file ...]\n", program);
  26     printf("Concatenates file(s) and/or standard input to standard output.\n"
  27            "\n"
  28            "    -u         (ignored)\n"
  29            "\n"
  30            "    --help     Print this message.\n"
  31            "    --version  Show version info.\n");
  32 }
  33
  34 int main(int argc, char* argv[])
  35 {
  36     // read from stdin if run with no args
  37     if (argc == 1) {
  38         int c = fgetc(stdin);
  39         while (c != EOF)
  40         {
  41             printf("%c", c);
  42             c = fgetc(stdin);
  43         }
  44
  45         return 0;
  46     }
  47
  48
  49     int arg = 0;
  50     for (arg = 1; arg < argc; arg++)
  51     {
  52         if (strcmp(argv[arg], "-u") == 0) {
  53             ; // no-op
  54         } else if (strcmp(argv[arg], "--help") == 0){
  55             usage(argv[0]);
  56         } else if (strcmp(argv[arg], "--version") == 0) {
  57             printf("cat (mutos) v"VERSION"\n");
  58             return 0;
  59         } else if (strcmp(argv[arg], "--") == 0) { // the next args will be the actual args
  60             arg++;                                 // jump to first actual args
  61             break;                                 // and break out of flag loop
  62         } else {
  63             // done parsing flags
  64             break;
  65         }
  66     }
  67
  68     for (; arg < argc; arg++)
  69     {
  70         FILE *current_file = NULL;
  71
  72         if (strcmp(argv[arg], "-") == 0) {
  73             current_file = stdin;
  74         } else {
  75             current_file = fopen(argv[arg], "r");
  76         }
  77
  78
  79         if (current_file) {
  80             int c = fgetc(current_file);
  81             while (c != EOF)
  82             {
  83                 printf("%c", c);
  84                 c = fgetc(current_file);
  85             }
  86             fclose(current_file);
  87         } else {
  88             fprintf(stderr, "%s: %s: %s\n", argv[0], strerror(errno), argv[arg]);
  89         }
  90     }
  91
  92     return 0;
  93 }