grp/initgroups.c

   1 /* Copyright (C) 1989, 91, 93, 96, 97, 98, 99 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library 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 GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <alloca.h>
  20 #include <errno.h>
  21 #include <grp.h>
  22 #include <limits.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <sys/types.h>
  27 #include <nsswitch.h>
  28
  29 /* Type of the lookup function.  */
  30 typedef enum nss_status (*initgroups_function) (const char *, gid_t,
  31                                                 long int *, long int *,
  32                                                 gid_t *, long int, int *);
  33 /* Prototype for the setgrent functions we use here.  */
  34 typedef enum nss_status (*set_function) (void);
  35
  36 /* Prototype for the endgrent functions we use here.  */
  37 typedef enum nss_status (*end_function) (void);
  38
  39 /* Prototype for the setgrent functions we use here.  */
  40 typedef enum nss_status (*get_function) (struct group *, char *,
  41                                          size_t, int *);
  42
  43 /* The lookup function for the first entry of this service.  */
  44 extern int __nss_group_lookup (service_user **nip, const char *name,
  45                                    void **fctp);
  46 extern void *__nss_lookup_function (service_user *ni, const char *fct_name);
  47
  48 extern service_user *__nss_group_database;
  49
  50 static enum nss_status
  51 compat_call (service_user *nip, const char *user, gid_t group, long int *start,
  52              long int *size, gid_t *groups, long int limit, int *errnop)
  53 {
  54   struct group grpbuf;
  55   size_t buflen = __sysconf (_SC_GETPW_R_SIZE_MAX);
  56   char *tmpbuf;
  57   enum nss_status status;
  58   set_function setgrent_fct;
  59   get_function getgrent_fct;
  60   end_function endgrent_fct;
  61
  62   getgrent_fct = __nss_lookup_function (nip, "getgrent_r");
  63   if (getgrent_fct == NULL)
  64     return NSS_STATUS_UNAVAIL;
  65
  66   setgrent_fct = __nss_lookup_function (nip, "setgrent");
  67   if (setgrent_fct)
  68     {
  69       status = DL_CALL_FCT (setgrent_fct, ());
  70       if (status != NSS_STATUS_SUCCESS)
  71         return status;
  72     }
  73
  74   endgrent_fct = __nss_lookup_function (nip, "endgrent");
  75
  76   tmpbuf = __alloca (buflen);
  77
  78   do
  79     {
  80       while ((status = DL_CALL_FCT (getgrent_fct,
  81                                      (&grpbuf, tmpbuf, buflen, errnop)),
  82               status == NSS_STATUS_TRYAGAIN)
  83              && *errnop == ERANGE)
  84         {
  85           buflen *= 2;
  86           tmpbuf = __alloca (buflen);
  87         }
  88
  89       if (status != NSS_STATUS_SUCCESS)
  90         goto done;
  91
  92       if (grpbuf.gr_gid != group)
  93         {
  94           char **m;
  95
  96           for (m = grpbuf.gr_mem; *m != NULL; ++m)
  97             if (strcmp (*m, user) == 0)
  98               {
  99                 /* Matches user.  Insert this group.  */
 100                 if (*start == *size && limit <= 0)
 101                   {
 102                     /* Need a bigger buffer.  */
 103                     groups = realloc (groups, 2 * *size * sizeof (*groups));
 104                     if (groups == NULL)
 105                       goto done;
 106                     *size *= 2;
 107                   }
 108
 109                 groups[*start] = grpbuf.gr_gid;
 110                 *start += 1;
 111
 112                 if (*start == limit)
 113                   /* Can't take any more groups; stop searching.  */
 114                   goto done;
 115
 116                 break;
 117               }
 118         }
 119     }
 120   while (status == NSS_STATUS_SUCCESS);
 121
 122  done:
 123   if (endgrent_fct)
 124     DL_CALL_FCT (endgrent_fct, ());
 125
 126   return NSS_STATUS_SUCCESS;
 127 }
 128
 129 /* Initialize the group set for the current user
 130    by reading the group database and using all groups
 131    of which USER is a member.  Also include GROUP.  */
 132 int
 133 initgroups (user, group)
 134      const char *user;
 135      gid_t group;
 136 {
 137 #if defined NGROUPS_MAX && NGROUPS_MAX == 0
 138
 139   /* No extra groups allowed.  */
 140   return 0;
 141
 142 #else
 143
 144   service_user *nip = NULL;
 145   initgroups_function fct;
 146   enum nss_status status = NSS_STATUS_UNAVAIL;
 147   int no_more;
 148   /* Start is one, because we have the first group as parameter.  */
 149   long int start = 1;
 150   long int size;
 151   gid_t *groups;
 152 #ifdef NGROUPS_MAX
 153 # define limit NGROUPS_MAX
 154
 155   size = limit;
 156 #else
 157   long int limit = __sysconf (_SC_NGROUPS_MAX);
 158
 159   if (limit > 0)
 160     size = limit;
 161   else
 162     /* No fixed limit on groups.  Pick a starting buffer size.  */
 163     size = 16;
 164 #endif
 165
 166   groups = malloc (size * sizeof (gid_t *));
 167
 168   groups[0] = group;
 169
 170   if (__nss_group_database != NULL)
 171     {
 172       no_more = 0;
 173       nip = __nss_group_database;
 174     }
 175   else
 176     no_more = __nss_database_lookup ("group", NULL,
 177                                      "compat [NOTFOUND=return] files", &nip);
 178
 179   while (! no_more)
 180     {
 181       fct = __nss_lookup_function (nip, "initgroups");
 182
 183       if (fct == NULL)
 184         {
 185           status = compat_call (nip, user, group, &start, &size, groups,
 186                                 limit, &errno);
 187
 188           if (nss_next_action (nip, NSS_STATUS_UNAVAIL) != NSS_ACTION_CONTINUE)
 189             break;
 190         }
 191       else
 192         status = DL_CALL_FCT (fct, (user, group, &start, &size, groups, limit,
 193                                      &errno));
 194
 195       /* This is really only for debugging.  */
 196       if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
 197         __libc_fatal ("illegal status in " __FUNCTION__);
 198
 199       if (status != NSS_STATUS_SUCCESS
 200           && nss_next_action (nip, status) == NSS_ACTION_RETURN)
 201          break;
 202
 203       if (nip->next == NULL)
 204         no_more = -1;
 205       else
 206         nip = nip->next;
 207     }
 208
 209   return setgroups (start, groups);
 210 #endif
 211 }