1  /* Common database routines for nss_db.
       2     Copyright (C) 2000-2023 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     <https://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 successful, 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    if (mapping->header != NULL)
      67      {
      68        munmap (mapping->header, mapping->len);
      69        mapping->header = NULL;
      70      }
      71  }