nss/nss_files_fopen.c

   1 /* Open an nss_files database file.
   2    Copyright (C) 2020-2024 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 <nss_files.h>
  20
  21 #include <errno.h>
  22 #include <stdio_ext.h>
  23
  24 FILE *
  25 __nss_files_fopen (const char *path)
  26 {
  27   FILE *fp = fopen (path, "rce");
  28   if (fp == NULL)
  29     return NULL;
  30
  31   /* The stream is not shared across threads.  */
  32   __fsetlocking (fp, FSETLOCKING_BYCALLER);
  33
  34   /* This tells libio that the file is seekable, and that fp->_offset
  35      is correct, ensuring that __ftello64 is efficient (bug 26257).  */
  36   if (__fseeko64 (fp, 0, SEEK_SET) < 0)
  37     {
  38       /* nss_files requires seekable files, to deal with repeated
  39          reads of the same line after reporting ERANGE.  */
  40       fclose (fp);
  41       __set_errno (ESPIPE);
  42       return NULL;
  43     }
  44
  45   return fp;
  46 }
  47 libc_hidden_def (__nss_files_fopen)