tinc/m4/malloc.m4

#serial 1

dnl From Jim Meyering.
dnl Determine whether malloc accepts 0 as its argument.
dnl If it doesn't, arrange to use the replacement function.
dnl
dnl If you use this macro in a package, you should
dnl add the following two lines to acconfig.h:
dnl  /* Define to rpl_malloc if the replacement function should be used.  */
dnl  #undef malloc
dnl

AC_DEFUN([jm_FUNC_MALLOC],
[
 if test x = y; then
   dnl This code is deliberately never run via ./configure.
   dnl FIXME: this is a gross hack to make autoheader put an entry
   dnl for this symbol in config.h.in.
   AC_CHECK_FUNCS(DONE_WORKING_MALLOC_CHECK)
 fi
 dnl xmalloc.c requires that this symbol be defined so it doesn't
 dnl mistakenly use a broken malloc -- as it might if this test were omitted.
 AC_DEFINE(HAVE_DONE_WORKING_MALLOC_CHECK, 1, [Needed for xmalloc.c])

 AC_CACHE_CHECK([for working malloc], jm_cv_func_working_malloc,
  [AC_RUN_IFELSE([AC_LANG_SOURCE([
    char *malloc ();
    int
    main ()
    {
      exit (malloc (0) ? 0 : 1);
    }
   ])],
   [jm_cv_func_working_malloc=yes],
   [jm_cv_func_working_malloc=no],
   [When crosscompiling])
  ])
  if test $jm_cv_func_working_malloc = no; then
    AC_LIBOBJ([malloc])
    AC_DEFINE(malloc, rpl_malloc, [Replacement malloc()])
  fi
])