1  /* areadlinkat.c -- readlinkat wrapper to return malloc'd link name
       2     Unlike xreadlinkat, only call exit on failure to change directory.
       3  
       4     Copyright (C) 2001, 2003-2007, 2009-2023 Free Software Foundation, Inc.
       5  
       6     This program is free software: you can redistribute it and/or modify
       7     it under the terms of the GNU General Public License as published by
       8     the Free Software Foundation, either version 3 of the License, or
       9     (at your option) any later version.
      10  
      11     This program 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
      14     GNU General Public License for more details.
      15  
      16     You should have received a copy of the GNU General Public License
      17     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      18  
      19  /* Written by Jim Meyering <jim@meyering.net>,
      20     and Bruno Haible <bruno@clisp.org>,
      21     and Eric Blake <ebb9@byu.net>.  */
      22  
      23  #include <config.h>
      24  
      25  /* Specification.  */
      26  #include "areadlink.h"
      27  
      28  #include <stdlib.h>
      29  
      30  #include "careadlinkat.h"
      31  
      32  #if HAVE_READLINKAT
      33  
      34  /* Call readlinkat to get the symbolic link value of FILENAME relative to FD.
      35     Return a pointer to that NUL-terminated string in malloc'd storage.
      36     If readlinkat fails, return NULL and set errno (although failure to
      37     change directory will issue a diagnostic and exit).
      38     If allocation fails, or if the link value is longer than SIZE_MAX :-),
      39     return NULL and set errno to ENOMEM.  */
      40  
      41  char *
      42  areadlinkat (int fd, char const *filename)
      43  {
      44    return careadlinkat (fd, filename, NULL, 0, NULL, readlinkat);
      45  }
      46  
      47  #else /* !HAVE_READLINKAT */
      48  
      49  /* It is more efficient to change directories only once and call
      50     areadlink, rather than repeatedly call the replacement
      51     readlinkat.  */
      52  
      53  # define AT_FUNC_NAME areadlinkat
      54  # define AT_FUNC_F1 areadlink
      55  # define AT_FUNC_POST_FILE_PARAM_DECLS /* empty */
      56  # define AT_FUNC_POST_FILE_ARGS        /* empty */
      57  # define AT_FUNC_RESULT char *
      58  # define AT_FUNC_FAIL NULL
      59  # include "at-func.c"
      60  # undef AT_FUNC_NAME
      61  # undef AT_FUNC_F1
      62  # undef AT_FUNC_POST_FILE_PARAM_DECLS
      63  # undef AT_FUNC_POST_FILE_ARGS
      64  # undef AT_FUNC_RESULT
      65  # undef AT_FUNC_FAIL
      66  
      67  #endif /* !HAVE_READLINKAT */