src/groups.c

   1 /* groups -- print the groups a user is in
   2    Copyright (C) 1989-2019 Free Software Foundation, Inc.
   3
   4    This program is free 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    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by James Youngman based on id.c and groups.sh,
  18    which were written by Arnold Robbins and David MacKenzie. */
  19
  20 #include <config.h>
  21 #include <stdio.h>
  22 #include <sys/types.h>
  23 #include <pwd.h>
  24 #include <grp.h>
  25 #include <getopt.h>
  26
  27 #include "system.h"
  28 #include "die.h"
  29 #include "group-list.h"
  30 #include "quote.h"
  31
  32 /* The official name of this program (e.g., no 'g' prefix).  */
  33 #define PROGRAM_NAME "groups"
  34
  35 #define AUTHORS \
  36   proper_name ("David MacKenzie"), \
  37   proper_name ("James Youngman")
  38
  39
  40 static struct option const longopts[] =
  41 {
  42   {GETOPT_HELP_OPTION_DECL},
  43   {GETOPT_VERSION_OPTION_DECL},
  44   {NULL, 0, NULL, 0}
  45 };
  46
  47 void
  48 usage (int status)
  49 {
  50   if (status != EXIT_SUCCESS)
  51     emit_try_help ();
  52   else
  53     {
  54       printf (_("Usage: %s [OPTION]... [USERNAME]...\n"), program_name);
  55       fputs (_("\
  56 Print group memberships for each USERNAME or, if no USERNAME is specified, for\
  57 \n\
  58 the current process (which may differ if the groups database has changed).\n"),
  59              stdout);
  60       fputs (HELP_OPTION_DESCRIPTION, stdout);
  61       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  62       emit_ancillary_info (PROGRAM_NAME);
  63     }
  64   exit (status);
  65 }
  66
  67 int
  68 main (int argc, char **argv)
  69 {
  70   int optc;
  71   bool ok = true;
  72   gid_t rgid, egid;
  73   uid_t ruid;
  74
  75   initialize_main (&argc, &argv);
  76   set_program_name (argv[0]);
  77   setlocale (LC_ALL, "");
  78   bindtextdomain (PACKAGE, LOCALEDIR);
  79   textdomain (PACKAGE);
  80
  81   atexit (close_stdout);
  82
  83   /* Processing the arguments this way makes groups.c behave differently to
  84    * groups.sh if one of the arguments is "--".
  85    */
  86   while ((optc = getopt_long (argc, argv, "", longopts, NULL)) != -1)
  87     {
  88       switch (optc)
  89         {
  90         case_GETOPT_HELP_CHAR;
  91         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
  92         default:
  93           usage (EXIT_FAILURE);
  94         }
  95     }
  96
  97   if (optind == argc)
  98     {
  99       /* No arguments.  Divulge the details of the current process. */
 100       uid_t NO_UID = -1;
 101       gid_t NO_GID = -1;
 102
 103       errno = 0;
 104       ruid = getuid ();
 105       if (ruid == NO_UID && errno)
 106         die (EXIT_FAILURE, errno, _("cannot get real UID"));
 107
 108       errno = 0;
 109       egid = getegid ();
 110       if (egid == NO_GID && errno)
 111         die (EXIT_FAILURE, errno, _("cannot get effective GID"));
 112
 113       errno = 0;
 114       rgid = getgid ();
 115       if (rgid == NO_GID && errno)
 116         die (EXIT_FAILURE, errno, _("cannot get real GID"));
 117
 118       if (!print_group_list (NULL, ruid, rgid, egid, true, ' '))
 119         ok = false;
 120       putchar ('\n');
 121     }
 122   else
 123     {
 124       /* At least one argument.  Divulge the details of the specified users.  */
 125       for ( ; optind < argc; optind++)
 126         {
 127           struct passwd *pwd = getpwnam (argv[optind]);
 128           if (pwd == NULL)
 129             {
 130               error (0, 0, _("%s: no such user"), quote (argv[optind]));
 131               ok = false;
 132               continue;
 133             }
 134           ruid = pwd->pw_uid;
 135           rgid = egid = pwd->pw_gid;
 136
 137           printf ("%s : ", argv[optind]);
 138           if (!print_group_list (argv[optind], ruid, rgid, egid, true, ' '))
 139             ok = false;
 140           putchar ('\n');
 141         }
 142     }
 143
 144   return ok ? EXIT_SUCCESS : EXIT_FAILURE;
 145 }