nss/nss_db/db-open.c

   1 /* Common database routines for nss_db.
   2    Copyright (C) 2000-2014 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 <kernel-features.h>
  29 #include "nss_db.h"
  30
  31 /* Open the database stored in FILE.  If succesful, store either a
  32    pointer to the mapped file or a file handle for the file in H and
  33    return NSS_STATUS_SUCCESS.  On failure, return the appropriate
  34    lookup status.  */
  35 enum nss_status
  36 internal_setent (const char *file, struct nss_db_map *mapping)
  37 {
  38   enum nss_status status = NSS_STATUS_UNAVAIL;
  39
  40   int mode = O_RDONLY | O_LARGEFILE;
  41 #ifdef O_CLOEXEC
  42   mode |= O_CLOEXEC;
  43 #endif
  44   int fd = open_not_cancel_2 (file, mode);
  45   if (fd != -1)
  46     {
  47       struct nss_db_header header;
  48
  49       if (read (fd, &header, sizeof (header)) == sizeof (header))
  50         {
  51           mapping->header = mmap (NULL, header.allocate, PROT_READ,
  52                                   MAP_PRIVATE, fd, 0);
  53           mapping->len = header.allocate;
  54           if (mapping->header != MAP_FAILED)
  55             status = NSS_STATUS_SUCCESS;
  56           else if (errno == ENOMEM)
  57             status = NSS_STATUS_TRYAGAIN;
  58         }
  59
  60       close_not_cancel_no_status (fd);
  61     }
  62
  63   return status;
  64 }
  65
  66
  67 /* Close the database.  */
  68 void
  69 internal_endent (struct nss_db_map *mapping)
  70 {
  71   munmap (mapping->header, mapping->len);
  72 }