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 not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <ctype.h>
  22 #include <errno.h>
  23 #include <grp.h>
  24 #include <paths.h>
  25
  26 #include "nss_db.h"
  27
  28 /* The hashing function we use.  */
  29 #include "../intl/hash-string.h"
  30
  31
  32 enum nss_status
  33 _nss_db_initgroups_dyn (const char *user, gid_t group, long int *start,
  34                         long int *size, gid_t **groupsp, long int limit,
  35                         int *errnop)
  36 {
  37   struct nss_db_map state = { NULL, 0 };
  38   enum nss_status status = internal_setent (_PATH_VARDB "group.db", &state);
  39   if (status != NSS_STATUS_SUCCESS)
  40     {
  41       *errnop = errno;
  42       return status;
  43     }
  44
  45   const struct nss_db_header *header = state.header;
  46   int i;
  47   for (i = 0; i < header->ndbs; ++i)
  48     if (header->dbs[i].id == ':')
  49       break;
  50   if (i == header->ndbs)
  51     {
  52       status = NSS_STATUS_UNAVAIL;
  53       goto out;
  54     }
  55
  56   const stridx_t *hashtable
  57     = (const stridx_t *) ((const char *) header
  58                           + header->dbs[i].hashoffset);
  59   const char *valstrtab = (const char *) header + header->valstroffset;
  60   size_t userlen = strlen (user);
  61   uint32_t hashval = __hash_string (user);
  62   size_t hidx = hashval % header->dbs[i].hashsize;
  63   size_t hval2 = 1 + hashval % (header->dbs[i].hashsize - 2);
  64
  65   gid_t *groups = *groupsp;
  66
  67   status = NSS_STATUS_NOTFOUND;
  68   while (hashtable[hidx] != ~((stridx_t) 0))
  69     {
  70       const char *valstr = valstrtab + hashtable[hidx];
  71       while (isblank (*valstr))
  72         ++valstr;
  73
  74       if (strncmp (valstr, user, userlen) == 0 && isblank (valstr[userlen]))
  75         {
  76           valstr += userlen + 1;
  77           while (isblank (*valstr))
  78             ++valstr;
  79
  80           while (*valstr != '\0')
  81             {
  82               errno = 0;
  83               char *endp;
  84               unsigned long int n = strtoul (valstr, &endp, 10);
  85               if (*endp != ',' && *endp != '\0')
  86                 break;
  87               valstr = *endp == '\0' ? endp : endp + 1;
  88
  89               if (n != ULONG_MAX || errno != ERANGE)
  90                 {
  91                   /* Insert the group.  */
  92                   if (*start == *size)
  93                     {
  94                       /* Need a bigger buffer.  */
  95                       if (limit > 0 && *size == limit)
  96                         {
  97                           /* We reached the maximum.  */
  98                           status = NSS_STATUS_SUCCESS;
  99                           goto out;
 100                         }
 101
 102                       long int newsize;
 103                       if (limit <= 0)
 104                         newsize = 2 * *size;
 105                       else
 106                         newsize = MIN (limit, 2 * *size);
 107
 108                       gid_t *newgroups = realloc (groups,
 109                                                   newsize * sizeof (*groups));
 110                       if (newgroups == NULL)
 111                         {
 112                           *errnop = ENOMEM;
 113                           status = NSS_STATUS_TRYAGAIN;
 114                           goto out;
 115                         }
 116
 117                       *groupsp = groups = newgroups;
 118                       *size = newsize;
 119                     }
 120
 121                   groups[*start] = n;
 122                   *start += 1;
 123                 }
 124             }
 125
 126           status = NSS_STATUS_SUCCESS;
 127           break;
 128         }
 129
 130       if ((hidx += hval2) >= header->dbs[i].hashsize)
 131         hidx -= header->dbs[i].hashsize;
 132     }
 133
 134  out:
 135   internal_endent (&state);
 136
 137   return status;
 138 }