chgrp.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 <grp.h>
  17 #include <unistd.h>
  18 #include <errno.h>
  19 #include <string.h>
  20
  21 #define VERSION "0.01"
  22
  23 int main(int argc, char* argv[])
  24 {
  25     if (argc == 1) {
  26         fprintf(stderr, "%s: missing operand\n"
  27                         "Run '%s --help' for usage.\n",
  28                         argv[0], argv[0]);
  29         return 1;
  30     }
  31
  32     // flag parsing
  33     int arg = 0;
  34     for (arg = 1; arg < argc; arg++)
  35     {
  36         if (strcmp(argv[arg], "--help") == 0) {
  37             printf("Usage: %s [group] [file ...]\n", argv[0]);
  38             return 0;
  39         } else if (strcmp(argv[arg], "--version") == 0) {
  40             printf("chgrp (mutos) v"VERSION"\n");
  41             return 0;
  42         } else {
  43             break;
  44         }
  45     }
  46
  47     struct group *group = getgrnam(argv[arg]);
  48
  49     if (!group) {
  50         fprintf(stderr, "%s: invalid group: '%s'\n", argv[0], argv[arg]);
  51         return 1;
  52     }
  53
  54     arg++; // go to next arg
  55
  56     if (argc - arg < 1) {
  57         fprintf(stderr, "%s: No file specified\n", argv[0]);
  58         return 1;
  59     }
  60
  61     for ( ; arg < argc; arg++)
  62     {
  63         int rc = chown(argv[arg], -1, group->gr_gid);
  64         if (rc == -1) {
  65             fprintf(stderr, "%s: %s: %s\n", argv[0], strerror(errno), argv[arg]);
  66             return 1;
  67         }
  68     }
  69
  70     return 0;
  71 }