nss/nss_db/db-initgroups.c

   1 /* Initgroups handling in nss_db module.
   2    Copyright (C) 2011-2013 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 <limits.h>
  24 #include <paths.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <sys/param.h>
  28
  29 #include "nss_db.h"
  30
  31 /* The hashing function we use.  */
  32 #include "../intl/hash-string.h"
  33
  34
  35 enum nss_status
  36 _nss_db_initgroups_dyn (const char *user, gid_t group, long int *start,
  37                         long int *size, gid_t **groupsp, long int limit,
  38                         int *errnop)
  39 {
  40   struct nss_db_map state = { NULL, 0 };
  41   enum nss_status status = internal_setent (_PATH_VARDB "group.db", &state);
  42   if (status != NSS_STATUS_SUCCESS)
  43     {
  44       *errnop = errno;
  45       return status;
  46     }
  47
  48   const struct nss_db_header *header = state.header;
  49   int i;
  50   for (i = 0; i < header->ndbs; ++i)
  51     if (header->dbs[i].id == ':')
  52       break;
  53   if (i == header->ndbs)
  54     {
  55       status = NSS_STATUS_UNAVAIL;
  56       goto out;
  57     }
  58
  59   const stridx_t *hashtable
  60     = (const stridx_t *) ((const char *) header
  61                           + header->dbs[i].hashoffset);
  62   const char *valstrtab = (const char *) header + header->valstroffset;
  63   size_t userlen = strlen (user);
  64   uint32_t hashval = __hash_string (user);
  65   size_t hidx = hashval % header->dbs[i].hashsize;
  66   size_t hval2 = 1 + hashval % (header->dbs[i].hashsize - 2);
  67
  68   gid_t *groups = *groupsp;
  69
  70   status = NSS_STATUS_NOTFOUND;
  71   while (hashtable[hidx] != ~((stridx_t) 0))
  72     {
  73       const char *valstr = valstrtab + hashtable[hidx];
  74       while (isblank (*valstr))
  75         ++valstr;
  76
  77       if (strncmp (valstr, user, userlen) == 0 && isblank (valstr[userlen]))
  78         {
  79           valstr += userlen + 1;
  80           while (isblank (*valstr))
  81             ++valstr;
  82
  83           while (*valstr != '\0')
  84             {
  85               errno = 0;
  86               char *endp;
  87               unsigned long int n = strtoul (valstr, &endp, 10);
  88               if (*endp != ',' && *endp != '\0')
  89                 break;
  90               valstr = *endp == '\0' ? endp : endp + 1;
  91
  92               if (n != ULONG_MAX || errno != ERANGE)
  93                 {
  94                   /* Insert the group.  */
  95                   if (*start == *size)
  96                     {
  97                       /* Need a bigger buffer.  */
  98                       if (limit > 0 && *size == limit)
  99                         {
 100                           /* We reached the maximum.  */
 101                           status = NSS_STATUS_SUCCESS;
 102                           goto out;
 103                         }
 104
 105                       long int newsize;
 106                       if (limit <= 0)
 107                         newsize = 2 * *size;
 108                       else
 109                         newsize = MIN (limit, 2 * *size);
 110
 111                       gid_t *newgroups = realloc (groups,
 112                                                   newsize * sizeof (*groups));
 113                       if (newgroups == NULL)
 114                         {
 115                           *errnop = ENOMEM;
 116                           status = NSS_STATUS_TRYAGAIN;
 117                           goto out;
 118                         }
 119
 120                       *groupsp = groups = newgroups;
 121                       *size = newsize;
 122                     }
 123
 124                   groups[*start] = n;
 125                   *start += 1;
 126                 }
 127             }
 128
 129           status = NSS_STATUS_SUCCESS;
 130           break;
 131         }
 132
 133       if ((hidx += hval2) >= header->dbs[i].hashsize)
 134         hidx -= header->dbs[i].hashsize;
 135     }
 136
 137  out:
 138   internal_endent (&state);
 139
 140   return status;
 141 }