src/id.c

   1 /* id -- print real and effective UIDs and GIDs
   2    Copyright (C) 89, 90, 91, 92, 93, 94, 1995 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 2, or (at your option)
   7    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, write to the Free Software
  16    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  17
  18 /* Written by Arnold Robbins, arnold@audiofax.com.
  19    Major rewrite by David MacKenzie, djm@gnu.ai.mit.edu. */
  20
  21 #include <config.h>
  22 #include <stdio.h>
  23 #include <getopt.h>
  24 #include <sys/types.h>
  25 #include <pwd.h>
  26 #include <grp.h>
  27 #include <getopt.h>
  28
  29 #include "version.h"
  30 #include "system.h"
  31 #include "error.h"
  32
  33 #ifdef _POSIX_VERSION
  34 #include <limits.h>
  35
  36 #else /* not _POSIX_VERSION */
  37 struct passwd *getpwuid ();
  38 struct group *getgrgid ();
  39 uid_t getuid ();
  40 gid_t getgid ();
  41 uid_t geteuid ();
  42 gid_t getegid ();
  43 #include <sys/param.h>
  44 #endif /* not _POSIX_VERSION */
  45
  46 char *xmalloc ();
  47 int getugroups ();
  48
  49 static void print_user __P ((int uid));
  50 static void print_group __P ((int gid));
  51 static void print_group_list __P ((char *username));
  52 static void print_full_info __P ((char *username));
  53 static void usage __P ((int status));
  54
  55 /* The name this program was run with. */
  56 char *program_name;
  57
  58 /* If nonzero, output only the group ID(s). -g */
  59 static int just_group = 0;
  60
  61 /* If nonzero, output user/group name instead of ID number. -n */
  62 static int use_name = 0;
  63
  64 /* If nonzero, output real UID/GID instead of default effective UID/GID. -r */
  65 static int use_real = 0;
  66
  67 /* If nonzero, output only the user ID(s). -u */
  68 static int just_user = 0;
  69
  70 /* If nonzero, output only the supplementary groups. -G */
  71 static int just_group_list = 0;
  72
  73 /* The real and effective IDs of the user to print. */
  74 static uid_t ruid, euid;
  75 static gid_t rgid, egid;
  76
  77 /* The number of errors encountered so far. */
  78 static int problems = 0;
  79
  80 /* If nonzero, display usage information and exit.  */
  81 static int show_help;
  82
  83 /* If nonzero, print the version on standard output and exit.  */
  84 static int show_version;
  85
  86 static struct option const longopts[] =
  87 {
  88   {"group", no_argument, NULL, 'g'},
  89   {"groups", no_argument, NULL, 'G'},
  90   {"help", no_argument, &show_help, 1},
  91   {"name", no_argument, NULL, 'n'},
  92   {"real", no_argument, NULL, 'r'},
  93   {"user", no_argument, NULL, 'u'},
  94   {"version", no_argument, &show_version, 1},
  95   {NULL, 0, NULL, 0}
  96 };
  97
  98 void
  99 main (int argc, char **argv)
 100 {
 101   int optc;
 102
 103   program_name = argv[0];
 104   setlocale (LC_ALL, "");
 105   bindtextdomain (PACKAGE, LOCALEDIR);
 106   textdomain (PACKAGE);
 107
 108   while ((optc = getopt_long (argc, argv, "gnruG", longopts, (int *) 0))
 109          != EOF)
 110     {
 111       switch (optc)
 112         {
 113         case 0:
 114           break;
 115         case 'g':
 116           just_group = 1;
 117           break;
 118         case 'n':
 119           use_name = 1;
 120           break;
 121         case 'r':
 122           use_real = 1;
 123           break;
 124         case 'u':
 125           just_user = 1;
 126           break;
 127         case 'G':
 128           just_group_list = 1;
 129           break;
 130         default:
 131           usage (1);
 132         }
 133     }
 134
 135   if (show_version)
 136     {
 137       printf ("id - %s\n", version_string);
 138       exit (0);
 139     }
 140
 141   if (show_help)
 142     usage (0);
 143
 144   if (just_user + just_group + just_group_list > 1)
 145     error (1, 0, _("cannot print only user and only group"));
 146
 147   if (just_user + just_group + just_group_list == 0 && (use_real || use_name))
 148     error (1, 0, _("cannot print only names or real IDs in default format"));
 149
 150   if (argc - optind > 1)
 151     usage (1);
 152
 153   if (argc - optind == 1)
 154     {
 155       struct passwd *pwd = getpwnam (argv[optind]);
 156       if (pwd == NULL)
 157         error (1, 0, _("%s: No such user"), argv[optind]);
 158       ruid = euid = pwd->pw_uid;
 159       rgid = egid = pwd->pw_gid;
 160     }
 161   else
 162     {
 163       euid = geteuid ();
 164       ruid = getuid ();
 165       egid = getegid ();
 166       rgid = getgid ();
 167     }
 168
 169   if (just_user)
 170     print_user (use_real ? ruid : euid);
 171   else if (just_group)
 172     print_group (use_real ? rgid : egid);
 173   else if (just_group_list)
 174     print_group_list (argv[optind]);
 175   else
 176     print_full_info (argv[optind]);
 177   putchar ('\n');
 178
 179   exit (problems != 0);
 180 }
 181
 182 /* Print the name or value of user ID UID. */
 183
 184 static void
 185 print_user (int uid)
 186 {
 187   struct passwd *pwd = NULL;
 188
 189   if (use_name)
 190     {
 191       pwd = getpwuid (uid);
 192       if (pwd == NULL)
 193         problems++;
 194     }
 195
 196   if (pwd == NULL)
 197     printf ("%u", (unsigned) uid);
 198   else
 199     printf ("%s", pwd->pw_name);
 200 }
 201
 202 /* Print the name or value of group ID GID. */
 203
 204 static void
 205 print_group (int gid)
 206 {
 207   struct group *grp = NULL;
 208
 209   if (use_name)
 210     {
 211       grp = getgrgid (gid);
 212       if (grp == NULL)
 213         problems++;
 214     }
 215
 216   if (grp == NULL)
 217     printf ("%u", (unsigned) gid);
 218   else
 219     printf ("%s", grp->gr_name);
 220 }
 221
 222 /* Print all of the distinct groups the user is in . */
 223
 224 static void
 225 print_group_list (char *username)
 226 {
 227   print_group (rgid);
 228   if (egid != rgid)
 229     {
 230       putchar (' ');
 231       print_group (egid);
 232     }
 233
 234 #if HAVE_GETGROUPS
 235   {
 236     int ng, n_groups;
 237     GETGROUPS_T *groups;
 238     register int i;
 239
 240     n_groups = getgroups (0, NULL);
 241     /* Add 1 just in case n_groups is zero.  */
 242     groups = (GETGROUPS_T *) xmalloc (n_groups * sizeof (GETGROUPS_T) + 1);
 243     if (username == 0)
 244       ng = getgroups (n_groups, groups);
 245     else
 246       ng = getugroups (n_groups, groups, username);
 247
 248     if (ng < 0)
 249       {
 250         error (0, errno, _("cannot get supplemental group list"));
 251         ++problems;
 252         free (groups);
 253         return;
 254       }
 255
 256     for (i = 0; i < n_groups; i++)
 257       if (groups[i] != rgid && groups[i] != egid)
 258         {
 259           putchar (' ');
 260           print_group (groups[i]);
 261         }
 262     free (groups);
 263   }
 264 #endif
 265 }
 266
 267 /* Print all of the info about the user's user and group IDs. */
 268
 269 static void
 270 print_full_info (char *username)
 271 {
 272   struct passwd *pwd;
 273   struct group *grp;
 274
 275   printf ("uid=%u", (unsigned) ruid);
 276   pwd = getpwuid (ruid);
 277   if (pwd == NULL)
 278     problems++;
 279   else
 280     printf ("(%s)", pwd->pw_name);
 281
 282   printf (" gid=%u", (unsigned) rgid);
 283   grp = getgrgid (rgid);
 284   if (grp == NULL)
 285     problems++;
 286   else
 287     printf ("(%s)", grp->gr_name);
 288
 289   if (euid != ruid)
 290     {
 291       printf (" euid=%u", (unsigned) euid);
 292       pwd = getpwuid (euid);
 293       if (pwd == NULL)
 294         problems++;
 295       else
 296         printf ("(%s)", pwd->pw_name);
 297     }
 298
 299   if (egid != rgid)
 300     {
 301       printf (" egid=%u", (unsigned) egid);
 302       grp = getgrgid (egid);
 303       if (grp == NULL)
 304         problems++;
 305       else
 306         printf ("(%s)", grp->gr_name);
 307     }
 308
 309 #if HAVE_GETGROUPS
 310   {
 311     int ng, n_groups;
 312     GETGROUPS_T *groups;
 313     register int i;
 314
 315     n_groups = getgroups (0, NULL);
 316     /* Add 1 just in case n_groups is zero.  */
 317     groups = (GETGROUPS_T *) xmalloc (n_groups * sizeof (GETGROUPS_T) + 1);
 318     if (username == 0)
 319       ng = getgroups (n_groups, groups);
 320     else
 321       ng = getugroups (n_groups, groups, username);
 322     if (ng < 0)
 323       {
 324         error (0, errno, _("cannot get supplemental group list"));
 325         problems++;
 326         free (groups);
 327         return;
 328       }
 329
 330     if (n_groups > 0)
 331       fputs (_(" groups="), stdout);
 332     for (i = 0; i < n_groups; i++)
 333       {
 334         if (i > 0)
 335           putchar (',');
 336         printf ("%u", (unsigned) groups[i]);
 337         grp = getgrgid (groups[i]);
 338         if (grp == NULL)
 339           problems++;
 340         else
 341           printf ("(%s)", grp->gr_name);
 342       }
 343     free (groups);
 344   }
 345 #endif
 346 }
 347
 348 static void
 349 usage (int status)
 350 {
 351   if (status != 0)
 352     fprintf (stderr, _("Try `%s --help' for more information.\n"),
 353              program_name);
 354   else
 355     {
 356       printf (_("Usage: %s [OPTION]... [USERNAME]\n"), program_name);
 357       printf (_("\
 358 Print information for USERNAME, or the current user.\n\
 359 \n\
 360   -g, --group     print only the group ID\n\
 361   -G, --groups    print only the supplementary groups\n\
 362   -n, --name      print a name instead of a number, for -ugG\n\
 363   -r, --real      print the real ID instead of effective ID, for -ugG\n\
 364   -u, --user      print only the user ID\n\
 365       --help      display this help and exit\n\
 366       --version   output version information and exit\n\
 367 \n\
 368 Without any OPTION, print some useful set of identified information.\n\
 369 "));
 370     }
 371   exit (status);
 372 }