1  /* Make free() preserve errno.
       2  
       3     Copyright (C) 2003, 2006, 2009-2023 Free Software Foundation, Inc.
       4  
       5     This file is free software: you can redistribute it and/or modify
       6     it under the terms of the GNU Lesser General Public License as
       7     published by the Free Software Foundation; either version 2.1 of the
       8     License, or (at your option) any later version.
       9  
      10     This file 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
      13     GNU Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public License
      16     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      17  
      18  /* written by Paul Eggert */
      19  
      20  #include <config.h>
      21  
      22  /* Specification.  */
      23  #include <stdlib.h>
      24  
      25  /* A function definition is only needed if HAVE_FREE_POSIX is not defined.  */
      26  #if !HAVE_FREE_POSIX
      27  
      28  # include <errno.h>
      29  
      30  void
      31  rpl_free (void *p)
      32  # undef free
      33  {
      34  # if defined __GNUC__ && !defined __clang__
      35    /* An invalid GCC optimization
      36       <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98396>
      37       would optimize away the assignments in the code below, when link-time
      38       optimization (LTO) is enabled.  Make the code more complicated, so that
      39       GCC does not grok how to optimize it.  */
      40    int err[2];
      41    err[0] = errno;
      42    err[1] = errno;
      43    errno = 0;
      44    free (p);
      45    errno = err[errno == 0];
      46  # else
      47    int err = errno;
      48    free (p);
      49    errno = err;
      50  # endif
      51  }
      52  
      53  #endif