1  /* areadlink.c -- readlink wrapper to return the link name in malloc'd storage
       2     Unlike xreadlink and xreadlink_with_size, don't ever call exit.
       3  
       4     Copyright (C) 2001, 2003-2007, 2009-2023 Free Software Foundation, Inc.
       5  
       6     This file is free software: you can redistribute it and/or modify
       7     it under the terms of the GNU Lesser General Public License as
       8     published by the Free Software Foundation; either version 2.1 of the
       9     License, or (at your option) any later version.
      10  
      11     This file 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 Lesser General Public License for more details.
      15  
      16     You should have received a copy of the GNU Lesser 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  
      22  #include <config.h>
      23  
      24  /* Specification.  */
      25  #include "areadlink.h"
      26  
      27  #include "careadlinkat.h"
      28  
      29  #include <stdlib.h>
      30  #include <unistd.h>
      31  
      32  /* Get the symbolic link value of FILENAME and put it into BUFFER, with
      33     size BUFFER_SIZE.  This function acts like readlink but has
      34     readlinkat's signature.  */
      35  static ssize_t
      36  careadlinkatcwd (int fd, char const *filename, char *buffer,
      37                   size_t buffer_size)
      38  {
      39    /* FD must be AT_FDCWD here, otherwise the caller is using this
      40       function in contexts it was not meant for.  */
      41    if (fd != AT_FDCWD)
      42      abort ();
      43    return readlink (filename, buffer, buffer_size);
      44  }
      45  
      46  /* Call readlink to get the symbolic link value of FILENAME.
      47     Return a pointer to that NUL-terminated string in malloc'd storage.
      48     If readlink fails, return NULL and set errno.
      49     If allocation fails, or if the link value is longer than SIZE_MAX :-),
      50     return NULL and set errno to ENOMEM.  */
      51  
      52  char *
      53  areadlink (char const *filename)
      54  {
      55    return careadlinkat (AT_FDCWD, filename, NULL, 0, NULL, careadlinkatcwd);
      56  }