1 files changed, 76 insertions, 0 deletions
diff --git a/m4/realloc.m4 b/m4/realloc.m4
new file mode 100644
index 0000000..53967f4
--- /dev/null
+++ b/m4/realloc.m4
@@ -0,0 +1,76 @@
+# realloc.m4 serial 19
+dnl Copyright (C) 2007, 2009-2020 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.
+
+# 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_CANONICAL_HOST])dnl for cross-compiles
+  AC_CACHE_CHECK([for GNU libc compatible realloc],
+    [ac_cv_func_realloc_0_nonnull],
+    [AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <stdlib.h>
+          ]],
+          [[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 "$host_os" in
+          # Guess yes on platforms where we know the result.
+          *-gnu* | gnu* | *-musl* | freebsd* | netbsd* | openbsd* \
+          | hpux* | solaris* | cygwin* | mingw*)
+            ac_cv_func_realloc_0_nonnull="guessing yes" ;;
+          # If we don't know, obey --enable-cross-guesses.
+          *) ac_cv_func_realloc_0_nonnull="$gl_cross_guess_normal" ;;
+        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
+])