nscd/nscd_initgroups.c

   1 /* Copyright (C) 2004 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <grp.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <not-cancel.h>
  27
  28 #include "nscd-client.h"
  29 #include "nscd_proto.h"
  30
  31
  32 /* We use the same mapping as in nscd_getgr.   */
  33 libc_locked_map_ptr (extern, __gr_map_handle);
  34
  35
  36 int
  37 __nscd_getgrouplist (const char *user, gid_t group, long int *size,
  38                      gid_t **groupsp, long int limit)
  39 {
  40   size_t userlen = strlen (user) + 1;
  41   int gc_cycle;
  42
  43   /* If the mapping is available, try to search there instead of
  44      communicating with the nscd.  */
  45   struct mapped_database *mapped;
  46   mapped = __nscd_get_map_ref (GETFDGR, "group", &__gr_map_handle, &gc_cycle);
  47
  48  retry:;
  49   const initgr_response_header *initgr_resp = NULL;
  50   char *respdata = NULL;
  51   int retval = -1;
  52   int sock = -1;
  53
  54   if (mapped != NO_MAPPING)
  55     {
  56       const struct datahead *found = __nscd_cache_search (INITGROUPS, user,
  57                                                           userlen, mapped);
  58       if (found != NULL)
  59         {
  60           initgr_resp = &found->data[0].initgrdata;
  61           respdata = (char *) (initgr_resp + 1);
  62           char *recend = (char *) found->data + found->recsize;
  63
  64           if (respdata + initgr_resp->ngrps * sizeof (int32_t) > recend)
  65             goto out;
  66         }
  67     }
  68
  69   /* If we do not have the cache mapped, try to get the data over the
  70      socket.  */
  71   initgr_response_header initgr_resp_mem;
  72   if (initgr_resp == NULL)
  73     {
  74       sock = __nscd_open_socket (user, userlen, INITGROUPS, &initgr_resp_mem,
  75                                  sizeof (initgr_resp_mem));
  76       if (sock == -1)
  77         {
  78           /* nscd not running or wrong version or hosts caching disabled.  */
  79           __nss_not_use_nscd_group = 1;
  80           goto out;
  81         }
  82
  83       initgr_resp = &initgr_resp_mem;
  84     }
  85
  86   if (initgr_resp->found == 1)
  87     {
  88       /* The following code assumes that gid_t and int32_t are the
  89          same size.  This is the case for al existing implementation.
  90          If this should change some code needs to be added which
  91          doesn't use memcpy but instead copies each array element one
  92          by one.  */
  93       assert (sizeof (int32_t) == sizeof (gid_t));
  94       assert (initgr_resp->ngrps > 0);
  95
  96       /* Make sure we have enough room.  We always count GROUP in even
  97          though we might not end up adding it.  */
  98       if (*size < initgr_resp->ngrps + 1)
  99         {
 100           gid_t *newp = realloc (*groupsp,
 101                                  (initgr_resp->ngrps + 1) * sizeof (gid_t));
 102           if (newp == NULL)
 103             /* We cannot increase the buffer size.  */
 104             goto out;
 105
 106           *groupsp = newp;
 107           *size = initgr_resp->ngrps + 1;
 108         }
 109
 110       if (respdata == NULL)
 111         {
 112           /* Read the data from the socket.  */
 113           if ((size_t) TEMP_FAILURE_RETRY (__read (sock, *groupsp,
 114                                                    initgr_resp->ngrps
 115                                                    * sizeof (gid_t)))
 116               == initgr_resp->ngrps * sizeof (gid_t))
 117             retval = initgr_resp->ngrps;
 118         }
 119       else
 120         {
 121           /* Just copy the data.  */
 122           retval = initgr_resp->ngrps;
 123           memcpy (*groupsp, respdata, retval * sizeof (gid_t));
 124         }
 125     }
 126   else
 127     {
 128       /* No group found yet.   */
 129       retval = 0;
 130
 131       assert (*size >= 1);
 132     }
 133
 134   /* Check whether GROUP is part of the mix.  If not, add it.  */
 135   if (retval >= 0)
 136     {
 137       int cnt;
 138       for (cnt = 0; cnt < retval; ++cnt)
 139         if ((*groupsp)[cnt] == group)
 140           break;
 141
 142       if (cnt == retval)
 143         (*groupsp)[retval++] = group;
 144     }
 145
 146   if (sock != -1)
 147     close_not_cancel_no_status (sock);
 148  out:
 149   if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0 && retval != -1)
 150     {
 151       /* When we come here this means there has been a GC cycle while we
 152          were looking for the data.  This means the data might have been
 153          inconsistent.  Retry if possible.  */
 154       if ((gc_cycle & 1) != 0)
 155         {
 156           /* nscd is just running gc now.  Disable using the mapping.  */
 157           __nscd_unmap (mapped);
 158           mapped = NO_MAPPING;
 159         }
 160
 161       goto retry;
 162     }
 163
 164   return retval;
 165 }