src/groups.c

   1 /* groups -- print the groups a user is in
   2    Copyright (C) 1989-2024 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 "group-list.h"
  29 #include "quote.h"
  30
  31 /* The official name of this program (e.g., no 'g' prefix).  */
  32 #define PROGRAM_NAME "groups"
  33
  34 #define AUTHORS \
  35   proper_name ("David MacKenzie"), \
  36   proper_name ("James Youngman")
  37
  38
  39 static struct option const longopts[] =
  40 {
  41   {GETOPT_HELP_OPTION_DECL},
  42   {GETOPT_VERSION_OPTION_DECL},
  43   {nullptr, 0, nullptr, 0}
  44 };
  45
  46 void
  47 usage (int status)
  48 {
  49   if (status != EXIT_SUCCESS)
  50     emit_try_help ();
  51   else
  52     {
  53       printf (_("Usage: %s [OPTION]... [USERNAME]...\n"), program_name);
  54       fputs (_("\
  55 Print group memberships for each USERNAME or, if no USERNAME is specified, for\
  56 \n\
  57 the current process (which may differ if the groups database has changed).\n"),
  58              stdout);
  59       fputs (HELP_OPTION_DESCRIPTION, stdout);
  60       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  61       emit_ancillary_info (PROGRAM_NAME);
  62     }
  63   exit (status);
  64 }
  65
  66 int
  67 main (int argc, char **argv)
  68 {
  69   int optc;
  70   bool ok = true;
  71   gid_t rgid, egid;
  72   uid_t ruid;
  73
  74   initialize_main (&argc, &argv);
  75   set_program_name (argv[0]);
  76   setlocale (LC_ALL, "");
  77   bindtextdomain (PACKAGE, LOCALEDIR);
  78   textdomain (PACKAGE);
  79
  80   atexit (close_stdout);
  81
  82   /* Processing the arguments this way makes groups.c behave differently to
  83    * groups.sh if one of the arguments is "--".
  84    */
  85   while ((optc = getopt_long (argc, argv, "", longopts, nullptr)) != -1)
  86     {
  87       switch (optc)
  88         {
  89         case_GETOPT_HELP_CHAR;
  90         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
  91         default:
  92           usage (EXIT_FAILURE);
  93         }
  94     }
  95
  96   if (optind == argc)
  97     {
  98       /* No arguments.  Divulge the details of the current process. */
  99       uid_t NO_UID = -1;
 100       gid_t NO_GID = -1;
 101
 102       errno = 0;
 103       ruid = getuid ();
 104       if (ruid == NO_UID && errno)
 105         error (EXIT_FAILURE, errno, _("cannot get real UID"));
 106
 107       errno = 0;
 108       egid = getegid ();
 109       if (egid == NO_GID && errno)
 110         error (EXIT_FAILURE, errno, _("cannot get effective GID"));
 111
 112       errno = 0;
 113       rgid = getgid ();
 114       if (rgid == NO_GID && errno)
 115         error (EXIT_FAILURE, errno, _("cannot get real GID"));
 116
 117       if (!print_group_list (nullptr, ruid, rgid, egid, true, ' '))
 118         ok = false;
 119       putchar ('\n');
 120     }
 121   else
 122     {
 123       /* At least one argument.  Divulge the details of the specified users.  */
 124       for ( ; optind < argc; optind++)
 125         {
 126           struct passwd *pwd = getpwnam (argv[optind]);
 127           if (pwd == nullptr)
 128             {
 129               error (0, 0, _("%s: no such user"), quote (argv[optind]));
 130               ok = false;
 131               continue;
 132             }
 133           ruid = pwd->pw_uid;
 134           rgid = egid = pwd->pw_gid;
 135
 136           printf ("%s : ", argv[optind]);
 137           if (!print_group_list (argv[optind], ruid, rgid, egid, true, ' '))
 138             ok = false;
 139           putchar ('\n');
 140         }
 141     }
 142
 143   return ok ? EXIT_SUCCESS : EXIT_FAILURE;
 144 }