nss/nss_db/db-open.c

   1 /* Common database routines for nss_db.
   2    Copyright (C) 2000-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <dlfcn.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25 #include <sys/mman.h>
  26 #include <not-cancel.h>
  27
  28 #include "nss_db.h"
  29
  30 /* Open the database stored in FILE.  If succesful, store either a
  31    pointer to the mapped file or a file handle for the file in H and
  32    return NSS_STATUS_SUCCESS.  On failure, return the appropriate
  33    lookup status.  */
  34 enum nss_status
  35 internal_setent (const char *file, struct nss_db_map *mapping)
  36 {
  37   enum nss_status status = NSS_STATUS_UNAVAIL;
  38
  39   int fd = __open_nocancel (file, O_RDONLY | O_LARGEFILE | O_CLOEXEC);
  40   if (fd != -1)
  41     {
  42       struct nss_db_header header;
  43
  44       if (read (fd, &header, sizeof (header)) == sizeof (header))
  45         {
  46           mapping->header = mmap (NULL, header.allocate, PROT_READ,
  47                                   MAP_PRIVATE, fd, 0);
  48           mapping->len = header.allocate;
  49           if (mapping->header != MAP_FAILED)
  50             status = NSS_STATUS_SUCCESS;
  51           else if (errno == ENOMEM)
  52             status = NSS_STATUS_TRYAGAIN;
  53         }
  54
  55       __close_nocancel_nostatus (fd);
  56     }
  57
  58   return status;
  59 }
  60
  61
  62 /* Close the database.  */
  63 void
  64 internal_endent (struct nss_db_map *mapping)
  65 {
  66   munmap (mapping->header, mapping->len);
  67 }