tools/gnulib/m4/realloc.m4

# realloc.m4 serial 17
dnl Copyright (C) 2007, 2009-2019 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

m4_version_prereq([2.70], [] ,[

# This is adapted with modifications from upstream Autoconf here:
# https://git.savannah.gnu.org/cgit/autoconf.git/commit/?id=04be2b7a29d65d9a08e64e8e56e594c91749598c
AC_DEFUN([_AC_FUNC_REALLOC_IF],
[
  AC_REQUIRE([AC_HEADER_STDC])dnl
  AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
  AC_CHECK_HEADERS([stdlib.h])
  AC_CACHE_CHECK([for GNU libc compatible realloc],
    [ac_cv_func_realloc_0_nonnull],
    [AC_RUN_IFELSE(
       [AC_LANG_PROGRAM(
          [[#if defined STDC_HEADERS || defined HAVE_STDLIB_H
            # include <stdlib.h>
            #else
            char *realloc ();
            #endif
          ]],
          [[char *p = realloc (0, 0);
            int result = !p;
            free (p);
            return result;]])
       ],
       [ac_cv_func_realloc_0_nonnull=yes],
       [ac_cv_func_realloc_0_nonnull=no],
       [case "$host_os" in
          # Guess yes on platforms where we know the result.
          *-gnu* | gnu* | *-musl* | freebsd* | netbsd* | openbsd* \
          | hpux* | solaris* | cygwin* | mingw*)
            ac_cv_func_realloc_0_nonnull="guessing yes" ;;
          # If we don't know, assume the worst.
          *) ac_cv_func_realloc_0_nonnull="guessing no" ;;
        esac
       ])
    ])
  case "$ac_cv_func_realloc_0_nonnull" in
    *yes)
      $1
      ;;
    *)
      $2
      ;;
  esac
])# AC_FUNC_REALLOC

])

# gl_FUNC_REALLOC_GNU
# -------------------
# Test whether 'realloc (0, 0)' is handled like in GNU libc, and replace
# realloc if it is not.
AC_DEFUN([gl_FUNC_REALLOC_GNU],
[
  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
  dnl _AC_FUNC_REALLOC_IF is defined in Autoconf.
  _AC_FUNC_REALLOC_IF(
    [AC_DEFINE([HAVE_REALLOC_GNU], [1],
               [Define to 1 if your system has a GNU libc compatible 'realloc'
                function, and to 0 otherwise.])],
    [AC_DEFINE([HAVE_REALLOC_GNU], [0])
     REPLACE_REALLOC=1
    ])
])# gl_FUNC_REALLOC_GNU

# gl_FUNC_REALLOC_POSIX
# ---------------------
# Test whether 'realloc' is POSIX compliant (sets errno to ENOMEM when it
# fails), and replace realloc if it is not.
AC_DEFUN([gl_FUNC_REALLOC_POSIX],
[
  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
  AC_REQUIRE([gl_CHECK_MALLOC_POSIX])
  if test $gl_cv_func_malloc_posix = yes; then
    AC_DEFINE([HAVE_REALLOC_POSIX], [1],
      [Define if the 'realloc' function is POSIX compliant.])
  else
    REPLACE_REALLOC=1
  fi
])