(AC_FUNC_CALLOC, _AC_FUNC_CALLOC_IF): New file/macros.

diff --git a/m4/calloc.m4 b/m4/calloc.m4
new file mode 100644 (file)
index 0000000..fbeaacc
--- /dev/null
+++ b/m4/calloc.m4
@@ -0,0 +1,44 @@
+#serial 1
+
+# Determine whether calloc (N, S) works when N*S is zero.
+# If so, define HAVE_CALLOC.  Otherwise, define calloc to rpl_calloc
+# and arrange to use a calloc wrapper function that does work in that case.
+
+# _AC_FUNC_CALLOC_IF(IF-WORKS, IF-NOT)
+# -------------------------------------
+# If `calloc (0, 0)' is properly handled, run IF-WORKS, otherwise, IF-NOT.
+AC_DEFUN([_AC_FUNC_CALLOC_IF],
+[AC_REQUIRE([AC_HEADER_STDC])dnl
+AC_CHECK_HEADERS(stdlib.h)
+AC_CACHE_CHECK([for GNU libc compatible calloc], ac_cv_func_calloc_0_nonnull,
+[AC_RUN_IFELSE(
+[AC_LANG_PROGRAM(
+[[#if STDC_HEADERS || HAVE_STDLIB_H
+# include <stdlib.h>
+#else
+char *calloc ();
+#endif
+]],
+                [exit (calloc (0, 0) ? 0 : 1);])],
+              [ac_cv_func_calloc_0_nonnull=yes],
+              [ac_cv_func_calloc_0_nonnull=no],
+              [ac_cv_func_calloc_0_nonnull=no])])
+AS_IF([test $ac_cv_func_calloc_0_nonnull = yes], [$1], [$2])
+])# AC_FUNC_CALLOC
+
+
+# AC_FUNC_CALLOC
+# ---------------
+# Report whether `calloc (0, 0)' is properly handled, and replace calloc if
+# needed.
+AN_FUNCTION([calloc], [AC_FUNC_CALLOC])
+AC_DEFUN([AC_FUNC_CALLOC],
+[_AC_FUNC_CALLOC_IF(
+  [AC_DEFINE([HAVE_CALLOC], 1,
+            [Define to 1 if your system has a GNU libc compatible `calloc'
+             function, and to 0 otherwise.])],
+  [AC_DEFINE([HAVE_CALLOC], 0)
+   AC_LIBOBJ([calloc])
+   AC_DEFINE([calloc], [rpl_calloc],
+      [Define to rpl_calloc if the replacement function should be used.])])
+])# AC_FUNC_CALLOC