nss/nss_db/db-initgroups.c

   1 /* Initgroups handling in nss_db module.
   2    Copyright (C) 2011 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@gmail.com>.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If
  18    not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include <ctype.h>
  21 #include <errno.h>
  22 #include <grp.h>
  23 #include <paths.h>
  24
  25 #include "nss_db.h"
  26
  27 /* The hashing function we use.  */
  28 #include "../intl/hash-string.h"
  29
  30
  31 enum nss_status
  32 _nss_db_initgroups_dyn (const char *user, gid_t group, long int *start,
  33                         long int *size, gid_t **groupsp, long int limit,
  34                         int *errnop)
  35 {
  36   struct nss_db_map state = { NULL, 0 };
  37   enum nss_status status = internal_setent (_PATH_VARDB "group.db", &state);
  38   if (status != NSS_STATUS_SUCCESS)
  39     {
  40       *errnop = errno;
  41       return status;
  42     }
  43
  44   const struct nss_db_header *header = state.header;
  45   int i;
  46   for (i = 0; i < header->ndbs; ++i)
  47     if (header->dbs[i].id == ':')
  48       break;
  49   if (i == header->ndbs)
  50     {
  51       status = NSS_STATUS_UNAVAIL;
  52       goto out;
  53     }
  54
  55   const stridx_t *hashtable
  56     = (const stridx_t *) ((const char *) header
  57                           + header->dbs[i].hashoffset);
  58   const char *valstrtab = (const char *) header + header->valstroffset;
  59   size_t userlen = strlen (user);
  60   uint32_t hashval = __hash_string (user);
  61   size_t hidx = hashval % header->dbs[i].hashsize;
  62   size_t hval2 = 1 + hashval % (header->dbs[i].hashsize - 2);
  63
  64   gid_t *groups = *groupsp;
  65
  66   status = NSS_STATUS_NOTFOUND;
  67   while (hashtable[hidx] != ~((stridx_t) 0))
  68     {
  69       const char *valstr = valstrtab + hashtable[hidx];
  70       while (isblank (*valstr))
  71         ++valstr;
  72
  73       if (strncmp (valstr, user, userlen) == 0 && isblank (valstr[userlen]))
  74         {
  75           valstr += userlen + 1;
  76           while (isblank (*valstr))
  77             ++valstr;
  78
  79           while (*valstr != '\0')
  80             {
  81               errno = 0;
  82               char *endp;
  83               unsigned long int n = strtoul (valstr, &endp, 10);
  84               if (*endp != ',' && *endp != '\0')
  85                 break;
  86               valstr = *endp == '\0' ? endp : endp + 1;
  87
  88               if (n != ULONG_MAX || errno != ERANGE)
  89                 {
  90                   /* Insert the group.  */
  91                   if (*start == *size)
  92                     {
  93                       /* Need a bigger buffer.  */
  94                       if (limit > 0 && *size == limit)
  95                         {
  96                           /* We reached the maximum.  */
  97                           status = NSS_STATUS_SUCCESS;
  98                           goto out;
  99                         }
 100
 101                       long int newsize;
 102                       if (limit <= 0)
 103                         newsize = 2 * *size;
 104                       else
 105                         newsize = MIN (limit, 2 * *size);
 106
 107                       gid_t *newgroups = realloc (groups,
 108                                                   newsize * sizeof (*groups));
 109                       if (newgroups == NULL)
 110                         {
 111                           *errnop = ENOMEM;
 112                           status = NSS_STATUS_TRYAGAIN;
 113                           goto out;
 114                         }
 115
 116                       *groupsp = groups = newgroups;
 117                       *size = newsize;
 118                     }
 119
 120                   groups[*start] = n;
 121                   *start += 1;
 122                 }
 123             }
 124
 125           status = NSS_STATUS_SUCCESS;
 126           break;
 127         }
 128
 129       if ((hidx += hval2) >= header->dbs[i].hashsize)
 130         hidx -= header->dbs[i].hashsize;
 131     }
 132
 133  out:
 134   internal_endent (&state);
 135
 136   return status;
 137 }