nss/nss_db/db-initgroups.c

   1 /* Initgroups handling in nss_db module.
   2    Copyright (C) 2011-2014 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 <stdint.h>
  28 #include <sys/param.h>
  29
  30 #include "nss_db.h"
  31
  32 /* The hashing function we use.  */
  33 #include "../intl/hash-string.h"
  34
  35
  36 enum nss_status
  37 _nss_db_initgroups_dyn (const char *user, gid_t group, long int *start,
  38                         long int *size, gid_t **groupsp, long int limit,
  39                         int *errnop)
  40 {
  41   struct nss_db_map state = { NULL, 0 };
  42   enum nss_status status = internal_setent (_PATH_VARDB "group.db", &state);
  43   if (status != NSS_STATUS_SUCCESS)
  44     {
  45       *errnop = errno;
  46       return status;
  47     }
  48
  49   const struct nss_db_header *header = state.header;
  50   int i;
  51   for (i = 0; i < header->ndbs; ++i)
  52     if (header->dbs[i].id == ':')
  53       break;
  54   if (i == header->ndbs)
  55     {
  56       status = NSS_STATUS_UNAVAIL;
  57       goto out;
  58     }
  59
  60   const stridx_t *hashtable
  61     = (const stridx_t *) ((const char *) header
  62                           + header->dbs[i].hashoffset);
  63   const char *valstrtab = (const char *) header + header->valstroffset;
  64   size_t userlen = strlen (user);
  65   uint32_t hashval = __hash_string (user);
  66   size_t hidx = hashval % header->dbs[i].hashsize;
  67   size_t hval2 = 1 + hashval % (header->dbs[i].hashsize - 2);
  68
  69   gid_t *groups = *groupsp;
  70
  71   status = NSS_STATUS_NOTFOUND;
  72   while (hashtable[hidx] != ~((stridx_t) 0))
  73     {
  74       const char *valstr = valstrtab + hashtable[hidx];
  75       while (isblank (*valstr))
  76         ++valstr;
  77
  78       if (strncmp (valstr, user, userlen) == 0 && isblank (valstr[userlen]))
  79         {
  80           valstr += userlen + 1;
  81           while (isblank (*valstr))
  82             ++valstr;
  83
  84           while (*valstr != '\0')
  85             {
  86               errno = 0;
  87               char *endp;
  88               unsigned long int n = strtoul (valstr, &endp, 10);
  89               if (*endp != ',' && *endp != '\0')
  90                 break;
  91               valstr = *endp == '\0' ? endp : endp + 1;
  92
  93               if (n != ULONG_MAX || errno != ERANGE)
  94                 {
  95                   /* Insert the group.  */
  96                   if (*start == *size)
  97                     {
  98                       /* Need a bigger buffer.  */
  99                       if (limit > 0 && *size == limit)
 100                         {
 101                           /* We reached the maximum.  */
 102                           status = NSS_STATUS_SUCCESS;
 103                           goto out;
 104                         }
 105
 106                       long int newsize;
 107                       if (limit <= 0)
 108                         newsize = 2 * *size;
 109                       else
 110                         newsize = MIN (limit, 2 * *size);
 111
 112                       gid_t *newgroups = realloc (groups,
 113                                                   newsize * sizeof (*groups));
 114                       if (newgroups == NULL)
 115                         {
 116                           *errnop = ENOMEM;
 117                           status = NSS_STATUS_TRYAGAIN;
 118                           goto out;
 119                         }
 120
 121                       *groupsp = groups = newgroups;
 122                       *size = newsize;
 123                     }
 124
 125                   groups[*start] = n;
 126                   *start += 1;
 127                 }
 128             }
 129
 130           status = NSS_STATUS_SUCCESS;
 131           break;
 132         }
 133
 134       if ((hidx += hval2) >= header->dbs[i].hashsize)
 135         hidx -= header->dbs[i].hashsize;
 136     }
 137
 138  out:
 139   internal_endent (&state);
 140
 141   return status;
 142 }