src/id.c

   1 /* id -- print real and effective UIDs and GIDs
   2    Copyright (C) 89, 90, 91, 92, 93, 94, 95, 1996 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 Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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 "system.h"
  30 #include "error.h"
  31
  32 #ifdef _POSIX_VERSION
  33 #include <limits.h>
  34
  35 #else /* not _POSIX_VERSION */
  36 struct passwd *getpwuid ();
  37 struct group *getgrgid ();
  38 uid_t getuid ();
  39 gid_t getgid ();
  40 uid_t geteuid ();
  41 gid_t getegid ();
  42 #include <sys/param.h>
  43 #endif /* not _POSIX_VERSION */
  44
  45 char *xmalloc ();
  46 int getugroups ();
  47
  48 static void print_user __P ((int uid));
  49 static void print_group __P ((int gid));
  50 static void print_group_list __P ((char *username));
  51 static void print_full_info __P ((char *username));
  52 static void usage __P ((int status));
  53
  54 /* The name this program was run with. */
  55 char *program_name;
  56
  57 /* If nonzero, output only the group ID(s). -g */
  58 static int just_group = 0;
  59
  60 /* If nonzero, output user/group name instead of ID number. -n */
  61 static int use_name = 0;
  62
  63 /* If nonzero, output real UID/GID instead of default effective UID/GID. -r */
  64 static int use_real = 0;
  65
  66 /* If nonzero, output only the user ID(s). -u */
  67 static int just_user = 0;
  68
  69 /* If nonzero, output only the supplementary groups. -G */
  70 static int just_group_list = 0;
  71
  72 /* The real and effective IDs of the user to print. */
  73 static uid_t ruid, euid;
  74 static gid_t rgid, egid;
  75
  76 /* The number of errors encountered so far. */
  77 static int problems = 0;
  78
  79 /* If nonzero, display usage information and exit.  */
  80 static int show_help;
  81
  82 /* If nonzero, print the version on standard output and exit.  */
  83 static int show_version;
  84
  85 static struct option const longopts[] =
  86 {
  87   {"group", no_argument, NULL, 'g'},
  88   {"groups", no_argument, NULL, 'G'},
  89   {"help", no_argument, &show_help, 1},
  90   {"name", no_argument, NULL, 'n'},
  91   {"real", no_argument, NULL, 'r'},
  92   {"user", no_argument, NULL, 'u'},
  93   {"version", no_argument, &show_version, 1},
  94   {NULL, 0, NULL, 0}
  95 };
  96
  97 int
  98 main (int argc, char **argv)
  99 {
 100   int optc;
 101
 102   program_name = argv[0];
 103   setlocale (LC_ALL, "");
 104   bindtextdomain (PACKAGE, LOCALEDIR);
 105   textdomain (PACKAGE);
 106
 107   while ((optc = getopt_long (argc, argv, "gnruG", longopts, (int *) 0))
 108          != EOF)
 109     {
 110       switch (optc)
 111         {
 112         case 0:
 113           break;
 114         case 'g':
 115           just_group = 1;
 116           break;
 117         case 'n':
 118           use_name = 1;
 119           break;
 120         case 'r':
 121           use_real = 1;
 122           break;
 123         case 'u':
 124           just_user = 1;
 125           break;
 126         case 'G':
 127           just_group_list = 1;
 128           break;
 129         default:
 130           usage (1);
 131         }
 132     }
 133
 134   if (show_version)
 135     {
 136       printf ("id - %s\n", PACKAGE_VERSION);
 137       exit (0);
 138     }
 139
 140   if (show_help)
 141     usage (0);
 142
 143   if (just_user + just_group + just_group_list > 1)
 144     error (1, 0, _("cannot print only user and only group"));
 145
 146   if (just_user + just_group + just_group_list == 0 && (use_real || use_name))
 147     error (1, 0, _("cannot print only names or real IDs in default format"));
 148
 149   if (argc - optind > 1)
 150     usage (1);
 151
 152   if (argc - optind == 1)
 153     {
 154       struct passwd *pwd = getpwnam (argv[optind]);
 155       if (pwd == NULL)
 156         error (1, 0, _("%s: No such user"), argv[optind]);
 157       ruid = euid = pwd->pw_uid;
 158       rgid = egid = pwd->pw_gid;
 159     }
 160   else
 161     {
 162       euid = geteuid ();
 163       ruid = getuid ();
 164       egid = getegid ();
 165       rgid = getgid ();
 166     }
 167
 168   if (just_user)
 169     print_user (use_real ? ruid : euid);
 170   else if (just_group)
 171     print_group (use_real ? rgid : egid);
 172   else if (just_group_list)
 173     print_group_list (argv[optind]);
 174   else
 175     print_full_info (argv[optind]);
 176   putchar ('\n');
 177
 178   exit (problems != 0);
 179 }
 180
 181 /* Print the name or value of user ID UID. */
 182
 183 static void
 184 print_user (int uid)
 185 {
 186   struct passwd *pwd = NULL;
 187
 188   if (use_name)
 189     {
 190       pwd = getpwuid (uid);
 191       if (pwd == NULL)
 192         problems++;
 193     }
 194
 195   if (pwd == NULL)
 196     printf ("%u", (unsigned) uid);
 197   else
 198     printf ("%s", pwd->pw_name);
 199 }
 200
 201 /* Print the name or value of group ID GID. */
 202
 203 static void
 204 print_group (int gid)
 205 {
 206   struct group *grp = NULL;
 207
 208   if (use_name)
 209     {
 210       grp = getgrgid (gid);
 211       if (grp == NULL)
 212         problems++;
 213     }
 214
 215   if (grp == NULL)
 216     printf ("%u", (unsigned) gid);
 217   else
 218     printf ("%s", grp->gr_name);
 219 }
 220
 221 static int
 222 xgetgroups (const char *username, int *n_groups, GETGROUPS_T **groups)
 223 {
 224   int max_n_groups;
 225   int ng;
 226   GETGROUPS_T *g;
 227   int fail = 0;
 228
 229   if (username == 0)
 230     max_n_groups = getgroups (0, NULL);
 231   else
 232     max_n_groups = getugroups (0, NULL, username);
 233
 234   /* Add 1 just in case max_n_groups is zero.  */
 235   g = (GETGROUPS_T *) xmalloc (max_n_groups * sizeof (GETGROUPS_T) + 1);
 236   if (username == 0)
 237     ng = getgroups (max_n_groups, g);
 238   else
 239     ng = getugroups (max_n_groups, g, username);
 240
 241   if (ng < 0)
 242     {
 243       error (0, errno, _("cannot get supplemental group list"));
 244       ++fail;
 245       free (groups);
 246     }
 247   if (!fail)
 248     {
 249       *n_groups = ng;
 250       *groups = g;
 251     }
 252   return fail;
 253 }
 254
 255 /* Print all of the distinct groups the user is in. */
 256
 257 static void
 258 print_group_list (char *username)
 259 {
 260   print_group (rgid);
 261   if (egid != rgid)
 262     {
 263       putchar (' ');
 264       print_group (egid);
 265     }
 266
 267 #if HAVE_GETGROUPS
 268   {
 269     int n_groups;
 270     GETGROUPS_T *groups;
 271     register int i;
 272
 273     if (xgetgroups (username, &n_groups, &groups))
 274       {
 275         ++problems;
 276         return;
 277       }
 278
 279     for (i = 0; i < n_groups; i++)
 280       if (groups[i] != rgid && groups[i] != egid)
 281         {
 282           putchar (' ');
 283           print_group (groups[i]);
 284         }
 285     free (groups);
 286   }
 287 #endif
 288 }
 289
 290 /* Print all of the info about the user's user and group IDs. */
 291
 292 static void
 293 print_full_info (char *username)
 294 {
 295   struct passwd *pwd;
 296   struct group *grp;
 297
 298   printf ("uid=%u", (unsigned) ruid);
 299   pwd = getpwuid (ruid);
 300   if (pwd == NULL)
 301     problems++;
 302   else
 303     printf ("(%s)", pwd->pw_name);
 304
 305   printf (" gid=%u", (unsigned) rgid);
 306   grp = getgrgid (rgid);
 307   if (grp == NULL)
 308     problems++;
 309   else
 310     printf ("(%s)", grp->gr_name);
 311
 312   if (euid != ruid)
 313     {
 314       printf (" euid=%u", (unsigned) euid);
 315       pwd = getpwuid (euid);
 316       if (pwd == NULL)
 317         problems++;
 318       else
 319         printf ("(%s)", pwd->pw_name);
 320     }
 321
 322   if (egid != rgid)
 323     {
 324       printf (" egid=%u", (unsigned) egid);
 325       grp = getgrgid (egid);
 326       if (grp == NULL)
 327         problems++;
 328       else
 329         printf ("(%s)", grp->gr_name);
 330     }
 331
 332 #if HAVE_GETGROUPS
 333   {
 334     int n_groups;
 335     GETGROUPS_T *groups;
 336     register int i;
 337
 338     if (xgetgroups (username, &n_groups, &groups))
 339       {
 340         ++problems;
 341         return;
 342       }
 343
 344     if (n_groups > 0)
 345       fputs (_(" groups="), stdout);
 346     for (i = 0; i < n_groups; i++)
 347       {
 348         if (i > 0)
 349           putchar (',');
 350         printf ("%u", (unsigned) groups[i]);
 351         grp = getgrgid (groups[i]);
 352         if (grp == NULL)
 353           problems++;
 354         else
 355           printf ("(%s)", grp->gr_name);
 356       }
 357     free (groups);
 358   }
 359 #endif
 360 }
 361
 362 static void
 363 usage (int status)
 364 {
 365   if (status != 0)
 366     fprintf (stderr, _("Try `%s --help' for more information.\n"),
 367              program_name);
 368   else
 369     {
 370       printf (_("Usage: %s [OPTION]... [USERNAME]\n"), program_name);
 371       printf (_("\
 372 Print information for USERNAME, or the current user.\n\
 373 \n\
 374   -g, --group     print only the group ID\n\
 375   -G, --groups    print only the supplementary groups\n\
 376   -n, --name      print a name instead of a number, for -ugG\n\
 377   -r, --real      print the real ID instead of effective ID, for -ugG\n\
 378   -u, --user      print only the user ID\n\
 379       --help      display this help and exit\n\
 380       --version   output version information and exit\n\
 381 \n\
 382 Without any OPTION, print some useful set of identified information.\n\
 383 "));
 384       puts (_("\nReport bugs to bug-gnu-utils@gnu.ai.mit.edu"));
 385     }
 386   exit (status);
 387 }