ln.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 <errno.h>
  16 #include <stdbool.h>
  17 #include <stdio.h>
  18 #include <string.h>
  19
  20 #include <getopt.h>
  21 #include <unistd.h>
  22
  23 #define VERSION "0.01"
  24
  25 // option flags
  26 struct {
  27     bool symbolic;
  28 } flags;
  29
  30 void usage(char* program)
  31 {
  32     printf("Usage: %s [options] [mode] [file ...]\n", program);
  33     printf("Changes file permissions.\n"
  34            "\n"
  35            "    -s, --symbolic    Create a symbolic link.\n"
  36            "\n"
  37            "    --help            Print this message.\n"
  38            "    --version         Show version info.\n");
  39 }
  40
  41 int main(int argc, char* argv[])
  42 {
  43     char* linkname   = NULL;
  44     char* sourcename = NULL;
  45
  46     flags.symbolic = false;
  47     static struct option long_options[] = {
  48         {"symbolic",  no_argument, NULL, 's'},
  49         {"help",      no_argument, NULL,  1},
  50         {"version",   no_argument, NULL,  2},
  51         {NULL, 0, NULL, 0}
  52     };
  53
  54     int c = 0;
  55     while ((c = getopt_long(argc, argv, "s",
  56                             long_options, NULL)) != -1)
  57     {
  58         switch (c)
  59         {
  60             case 's':
  61                 flags.symbolic = true;
  62                 break;
  63             case 1:
  64                 usage(argv[0]);
  65                 return 0;
  66             case 2:
  67                 printf("ln (mutos) v"VERSION"\n");
  68                 return 0;
  69             default:
  70                 fprintf(stderr,"Run '%s --help' for usage.\n",
  71                                      argv[0]);
  72                 return 1;
  73         }
  74     }
  75
  76
  77     if ((argc - optind) < 1) {
  78         fprintf(stderr, "%s: missing operands\n"
  79                         "Run '%s --help' for usage.\n",
  80                         argv[0], argv[0]);
  81         return 1;
  82     } else if ((argc - optind) == 1) {
  83         sourcename = argv[optind];
  84         linkname   = argv[optind];
  85         for (size_t i = strlen(argv[optind]); i != 0; i--)
  86         {
  87             if (argv[optind][i] == '/') {
  88                 linkname = argv[optind] + i + 1;
  89                 break;
  90             }
  91         }
  92     } else if ((argc - optind) == 2) {
  93         sourcename = argv[optind];
  94         linkname   = argv[optind+1];
  95     } else {
  96         fprintf(stderr, "%s: extra operand: %s\n",
  97                          argv[0],           argv[optind+2]);
  98         return 1;
  99     }
 100
 101     int rc = 0;
 102     if (flags.symbolic) {
 103         rc = symlink(sourcename, linkname);
 104     } else {
 105         rc = link(sourcename, linkname);
 106     }
 107
 108     if (rc != 0) {
 109         fprintf(stderr, "%s: %s: %s\n",
 110                         argv[0], strerror(errno), linkname);
 111         return 1;
 112     }
 113
 114     return 0;
 115 }