nscd/nscd_initgroups.c

   1 /* Copyright (C) 2004, 2005 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.  */
  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_close;
 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) __readall (sock, *groupsp, initgr_resp->ngrps
 114                                                   * sizeof (gid_t))
 115               == initgr_resp->ngrps * sizeof (gid_t))
 116             retval = initgr_resp->ngrps;
 117         }
 118       else
 119         {
 120           /* Just copy the data.  */
 121           retval = initgr_resp->ngrps;
 122           memcpy (*groupsp, respdata, retval * sizeof (gid_t));
 123         }
 124     }
 125   else
 126     {
 127       if (__builtin_expect (initgr_resp->found == -1, 0))
 128         {
 129           /* The daemon does not cache this database.  */
 130           __nss_not_use_nscd_group = 1;
 131           goto out_close;
 132         }
 133
 134       /* No group found yet.   */
 135       retval = 0;
 136
 137       assert (*size >= 1);
 138     }
 139
 140   /* Check whether GROUP is part of the mix.  If not, add it.  */
 141   if (retval >= 0)
 142     {
 143       int cnt;
 144       for (cnt = 0; cnt < retval; ++cnt)
 145         if ((*groupsp)[cnt] == group)
 146           break;
 147
 148       if (cnt == retval)
 149         (*groupsp)[retval++] = group;
 150     }
 151
 152  out_close:
 153   if (sock != -1)
 154     close_not_cancel_no_status (sock);
 155  out:
 156   if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0 && retval != -1)
 157     {
 158       /* When we come here this means there has been a GC cycle while we
 159          were looking for the data.  This means the data might have been
 160          inconsistent.  Retry if possible.  */
 161       if ((gc_cycle & 1) != 0)
 162         {
 163           /* nscd is just running gc now.  Disable using the mapping.  */
 164           __nscd_unmap (mapped);
 165           mapped = NO_MAPPING;
 166         }
 167
 168       goto retry;
 169     }
 170
 171   return retval;
 172 }