1  /* Error-checking, allocating wrapper for readlink.
       2     Copyright (C) 2017-2023 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 <scratch_buffer.h>
      20  #include <support/check.h>
      21  #include <support/support.h>
      22  #include <xunistd.h>
      23  
      24  char *
      25  xreadlink (const char *path)
      26  {
      27    struct scratch_buffer buf;
      28    scratch_buffer_init (&buf);
      29  
      30    while (true)
      31      {
      32        ssize_t count = readlink (path, buf.data, buf.length);
      33        if (count < 0)
      34          FAIL_EXIT1 ("readlink (\"%s\"): %m", path);
      35        if (count < buf.length)
      36          {
      37            char *result = xstrndup (buf.data, count);
      38            scratch_buffer_free (&buf);
      39            return result;
      40          }
      41        if (!scratch_buffer_grow (&buf))
      42          FAIL_EXIT1 ("scratch_buffer_grow in xreadlink");
      43      }
      44  }