src/id.c

   1 /* id -- print real and effective UIDs and GIDs
   2    Copyright (C) 1989-1999 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 /* The official name of this program (e.g., no `g' prefix).  */
  33 #define PROGRAM_NAME "id"
  34
  35 #define AUTHORS "Arnold Robbins and David MacKenzie"
  36
  37 #ifndef _POSIX_VERSION
  38 struct passwd *getpwuid ();
  39 struct group *getgrgid ();
  40 uid_t getuid ();
  41 gid_t getgid ();
  42 uid_t geteuid ();
  43 gid_t getegid ();
  44 #endif /* not _POSIX_VERSION */
  45
  46 int getugroups ();
  47
  48 static void print_user PARAMS ((uid_t uid));
  49 static void print_group PARAMS ((gid_t gid));
  50 static void print_group_list PARAMS ((const char *username));
  51 static void print_full_info PARAMS ((const char *username));
  52
  53 /* The name this program was run with. */
  54 char *program_name;
  55
  56 /* If nonzero, output only the group ID(s). -g */
  57 static int just_group = 0;
  58
  59 /* If nonzero, output user/group name instead of ID number. -n */
  60 static int use_name = 0;
  61
  62 /* If nonzero, output real UID/GID instead of default effective UID/GID. -r */
  63 static int use_real = 0;
  64
  65 /* If nonzero, output only the user ID(s). -u */
  66 static int just_user = 0;
  67
  68 /* If nonzero, output only the supplementary groups. -G */
  69 static int just_group_list = 0;
  70
  71 /* The real and effective IDs of the user to print. */
  72 static uid_t ruid, euid;
  73 static gid_t rgid, egid;
  74
  75 /* The number of errors encountered so far. */
  76 static int problems = 0;
  77
  78 static struct option const longopts[] =
  79 {
  80   {"group", no_argument, NULL, 'g'},
  81   {"groups", no_argument, NULL, 'G'},
  82   {"name", no_argument, NULL, 'n'},
  83   {"real", no_argument, NULL, 'r'},
  84   {"user", no_argument, NULL, 'u'},
  85   {GETOPT_HELP_OPTION_DECL},
  86   {GETOPT_VERSION_OPTION_DECL},
  87   {NULL, 0, NULL, 0}
  88 };
  89
  90 void
  91 usage (int status)
  92 {
  93   if (status != 0)
  94     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  95              program_name);
  96   else
  97     {
  98       printf (_("Usage: %s [OPTION]... [USERNAME]\n"), program_name);
  99       printf (_("\
 100 Print information for USERNAME, or the current user.\n\
 101 \n\
 102   -a              ignore, for compatibility with other versions\n\
 103   -g, --group     print only the group ID\n\
 104   -G, --groups    print only the supplementary groups\n\
 105   -n, --name      print a name instead of a number, for -ugG\n\
 106   -r, --real      print the real ID instead of effective ID, for -ugG\n\
 107   -u, --user      print only the user ID\n\
 108       --help      display this help and exit\n\
 109       --version   output version information and exit\n\
 110 \n\
 111 Without any OPTION, print some useful set of identified information.\n\
 112 "));
 113       puts (_("\nReport bugs to <bug-sh-utils@gnu.org>."));
 114     }
 115   exit (status);
 116 }
 117
 118 int
 119 main (int argc, char **argv)
 120 {
 121   int optc;
 122
 123   program_name = argv[0];
 124   setlocale (LC_ALL, "");
 125   bindtextdomain (PACKAGE, LOCALEDIR);
 126   textdomain (PACKAGE);
 127
 128   while ((optc = getopt_long (argc, argv, "agnruG", longopts, NULL)) != -1)
 129     {
 130       switch (optc)
 131         {
 132         case 0:
 133           break;
 134         case 'a':
 135           /* Ignore -a, for compatibility with SVR4.  */
 136           break;
 137         case 'g':
 138           just_group = 1;
 139           break;
 140         case 'n':
 141           use_name = 1;
 142           break;
 143         case 'r':
 144           use_real = 1;
 145           break;
 146         case 'u':
 147           just_user = 1;
 148           break;
 149         case 'G':
 150           just_group_list = 1;
 151           break;
 152         case_GETOPT_HELP_CHAR;
 153         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 154         default:
 155           usage (1);
 156         }
 157     }
 158
 159   if (just_user + just_group + just_group_list > 1)
 160     error (1, 0, _("cannot print only user and only group"));
 161
 162   if (just_user + just_group + just_group_list == 0 && (use_real || use_name))
 163     error (1, 0, _("cannot print only names or real IDs in default format"));
 164
 165   if (argc - optind > 1)
 166     usage (1);
 167
 168   if (argc - optind == 1)
 169     {
 170       struct passwd *pwd = getpwnam (argv[optind]);
 171       if (pwd == NULL)
 172         error (1, 0, _("%s: No such user"), argv[optind]);
 173       ruid = euid = pwd->pw_uid;
 174       rgid = egid = pwd->pw_gid;
 175     }
 176   else
 177     {
 178       euid = geteuid ();
 179       ruid = getuid ();
 180       egid = getegid ();
 181       rgid = getgid ();
 182     }
 183
 184   if (just_user)
 185     print_user (use_real ? ruid : euid);
 186   else if (just_group)
 187     print_group (use_real ? rgid : egid);
 188   else if (just_group_list)
 189     print_group_list (argv[optind]);
 190   else
 191     print_full_info (argv[optind]);
 192   putchar ('\n');
 193
 194   exit (problems != 0);
 195 }
 196
 197 /* Print the name or value of user ID UID. */
 198
 199 static void
 200 print_user (uid_t uid)
 201 {
 202   struct passwd *pwd = NULL;
 203
 204   if (use_name)
 205     {
 206       pwd = getpwuid (uid);
 207       if (pwd == NULL)
 208         problems++;
 209     }
 210
 211   if (pwd == NULL)
 212     printf ("%u", (unsigned) uid);
 213   else
 214     printf ("%s", pwd->pw_name);
 215 }
 216
 217 /* Print the name or value of group ID GID. */
 218
 219 static void
 220 print_group (gid_t gid)
 221 {
 222   struct group *grp = NULL;
 223
 224   if (use_name)
 225     {
 226       grp = getgrgid (gid);
 227       if (grp == NULL)
 228         problems++;
 229     }
 230
 231   if (grp == NULL)
 232     printf ("%u", (unsigned) gid);
 233   else
 234     printf ("%s", grp->gr_name);
 235 }
 236
 237 #if HAVE_GETGROUPS
 238
 239 /* FIXME: document */
 240
 241 static int
 242 xgetgroups (const char *username, gid_t gid, int *n_groups,
 243             GETGROUPS_T **groups)
 244 {
 245   int max_n_groups;
 246   int ng;
 247   GETGROUPS_T *g;
 248   int fail = 0;
 249
 250   if (username == 0)
 251     max_n_groups = getgroups (0, NULL);
 252   else
 253     max_n_groups = getugroups (0, NULL, username, gid);
 254
 255   /* Add 1 just in case max_n_groups is zero.  */
 256   g = (GETGROUPS_T *) xmalloc (max_n_groups * sizeof (GETGROUPS_T) + 1);
 257   if (username == 0)
 258     ng = getgroups (max_n_groups, g);
 259   else
 260     ng = getugroups (max_n_groups, g, username, gid);
 261
 262   if (ng < 0)
 263     {
 264       error (0, errno, _("cannot get supplemental group list"));
 265       ++fail;
 266       free (groups);
 267     }
 268   if (!fail)
 269     {
 270       *n_groups = ng;
 271       *groups = g;
 272     }
 273   return fail;
 274 }
 275
 276 #endif /* HAVE_GETGROUPS */
 277
 278 /* Print all of the distinct groups the user is in. */
 279
 280 static void
 281 print_group_list (const char *username)
 282 {
 283   struct passwd *pwd;
 284
 285   pwd = getpwuid (ruid);
 286   if (pwd == NULL)
 287     problems++;
 288
 289   print_group (rgid);
 290   if (egid != rgid)
 291     {
 292       putchar (' ');
 293       print_group (egid);
 294     }
 295
 296 #if HAVE_GETGROUPS
 297   {
 298     int n_groups;
 299     GETGROUPS_T *groups;
 300     register int i;
 301
 302     if (xgetgroups (username, pwd ? pwd->pw_gid : -1, &n_groups, &groups))
 303       {
 304         ++problems;
 305         return;
 306       }
 307
 308     for (i = 0; i < n_groups; i++)
 309       if (groups[i] != rgid && groups[i] != egid)
 310         {
 311           putchar (' ');
 312           print_group (groups[i]);
 313         }
 314     free (groups);
 315   }
 316 #endif /* HAVE_GETGROUPS */
 317 }
 318
 319 /* Print all of the info about the user's user and group IDs. */
 320
 321 static void
 322 print_full_info (const char *username)
 323 {
 324   struct passwd *pwd;
 325   struct group *grp;
 326
 327   printf ("uid=%u", (unsigned) ruid);
 328   pwd = getpwuid (ruid);
 329   if (pwd == NULL)
 330     problems++;
 331   else
 332     printf ("(%s)", pwd->pw_name);
 333
 334   printf (" gid=%u", (unsigned) rgid);
 335   grp = getgrgid (rgid);
 336   if (grp == NULL)
 337     problems++;
 338   else
 339     printf ("(%s)", grp->gr_name);
 340
 341   if (euid != ruid)
 342     {
 343       printf (" euid=%u", (unsigned) euid);
 344       pwd = getpwuid (euid);
 345       if (pwd == NULL)
 346         problems++;
 347       else
 348         printf ("(%s)", pwd->pw_name);
 349     }
 350
 351   if (egid != rgid)
 352     {
 353       printf (" egid=%u", (unsigned) egid);
 354       grp = getgrgid (egid);
 355       if (grp == NULL)
 356         problems++;
 357       else
 358         printf ("(%s)", grp->gr_name);
 359     }
 360
 361 #if HAVE_GETGROUPS
 362   {
 363     int n_groups;
 364     GETGROUPS_T *groups;
 365     register int i;
 366
 367     if (xgetgroups (username, pwd ? pwd->pw_gid : -1, &n_groups, &groups))
 368       {
 369         ++problems;
 370         return;
 371       }
 372
 373     if (n_groups > 0)
 374       fputs (_(" groups="), stdout);
 375     for (i = 0; i < n_groups; i++)
 376       {
 377         if (i > 0)
 378           putchar (',');
 379         printf ("%u", (unsigned) groups[i]);
 380         grp = getgrgid (groups[i]);
 381         if (grp == NULL)
 382           problems++;
 383         else
 384           printf ("(%s)", grp->gr_name);
 385       }
 386     free (groups);
 387   }
 388 #endif /* HAVE_GETGROUPS */
 389 }