compat: test stdckdint

Test C23 header, clang/gcc builtins and compat versions.

(cherry picked from commit a7ff7c3c00)
Signed-off-by: Thomas Guillem <thomas@gllm.fr>

compat/Makefile.am

@@ -14,9 +14,23 @@ dummy.c:
 
 
 check_PROGRAMS = \
-	test_strnstr
+	test_strnstr \
+	test_ckd_ckd \
+	test_ckd_builtin \
+	test_ckd_compat \
+	$(NULL)
 
 TESTS = $(check_PROGRAMS)
 
 test_strnstr_SOURCES = test/strnstr.c
 test_strnstr_LDADD = libcompat.la
+
+test_ckd_ckd_SOURCES = test/ckd.c
+test_ckd_ckd_CFLAGS = -DTEST_CKD
+if HAVE_STDCKDINT
+test_ckd_ckd_CFLAGS += -DHAVE_CKD
+endif
+test_ckd_builtin_SOURCES = $(test_ckd_ckd_SOURCES)
+test_ckd_builtin_CFLAGS = -DTEST_BUILTIN
+test_ckd_compat_SOURCES = $(test_ckd_ckd_SOURCES)
+test_ckd_compat_CFLAGS = -DTEST_COMPAT

compat/test/ckd.c

@@ -0,0 +1,115 @@
+/*****************************************************************************
+ * stdckdint.h test case
+ *****************************************************************************
+ * Copyright © 2025 VideoLabs, VLC authors and VideoLAN
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <limits.h>
+#undef NDEBUG
+#include <assert.h>
+
+#if defined (TEST_CKD)
+# ifdef HAVE_CKD
+#  include "../include/stdckdint.h" /* Force include on the compiler path */
+# else
+#  define SKIP /* can't test it */
+# endif
+#elif defined (TEST_BUILTIN)
+# if defined(__GNUC__) || defined(__clang__)
+#  undef __STDC_VERSION_STDCKDINT_H__
+#  include "../stdckdint/stdckdint.h" /* Force include on the compat path */
+# else
+#  define SKIP /* can't test it */
+# endif
+#elif defined (TEST_COMPAT)
+# undef __STDC_VERSION_STDCKDINT_H__
+# undef __GNUC__
+# undef __clang__
+# include "../stdckdint/stdckdint.h"
+#else
+# error TEST_ not defined
+#endif
+
+int main(void)
+{
+#ifdef SKIP
+    return 77;
+#else
+    unsigned long long ures;
+    long long res;
+
+    /* multiplication */
+
+    /* zero */
+    assert(!ckd_mul(&ures, 0, 0) && ures == 0);
+    assert(!ckd_mul(&ures, 0, 1) && ures == 0);
+    assert(!ckd_mul(&ures, 1, 0) && ures == 0);
+
+    /* small cases */
+    assert(!ckd_mul(&ures, 2, 3) && ures == 6);
+    assert(!ckd_mul(&res, -3, 3) && res == -9);
+    assert(!ckd_mul(&res, -3, -3) && res == 9);
+
+    /* near positive overflow */
+    assert(!ckd_mul(&res, LLONG_MAX, 1) && res == LLONG_MAX);
+    assert(!ckd_mul(&res, LLONG_MAX / 2, 2) && res == LLONG_MAX / 2 * 2);
+    assert(ckd_mul(&res, LLONG_MAX, 2) && res == -2);
+    assert(!ckd_mul(&res, LLONG_MAX, -1) && res == -LLONG_MAX);
+
+    /* near negative overflow */
+    assert(!ckd_mul(&res, LLONG_MIN, 1) && res == LLONG_MIN);
+    assert(ckd_mul(&res, LLONG_MIN, -1) && res == LLONG_MIN);
+
+    /* additions */
+
+    /* small cases */
+    assert(!ckd_add(&ures, 0, 0) && ures == 0);
+    assert(!ckd_add(&ures, 0, 1) && ures == 1);
+    assert(!ckd_add(&ures, 1, 0) && ures == 1);
+    assert(!ckd_add(&ures, 1, 1) && ures == 2);
+
+    /* big edge cases */
+    assert(!ckd_add(&ures, ULLONG_MAX, 0ULL) && ures == ULLONG_MAX);
+    assert(!ckd_add(&ures, ULLONG_MAX - 1ULL, 1ULL) && ures == ULLONG_MAX);
+    assert(ckd_add(&ures, ULLONG_MAX, 1ULL) && ures == 0);
+    assert(ckd_add(&res, LLONG_MAX, 1ULL) && res == LLONG_MIN);
+
+    /* subtractions */
+
+    /* small cases */
+    assert(!ckd_sub(&ures, 0, 0) && ures == 0);
+    assert(!ckd_sub(&ures, 1, 0) && ures == 1);
+    assert(!ckd_sub(&ures, 1, 1) && ures == 0);
+
+    /* 0 - 1 */
+    assert(ckd_sub(&ures, 0, 1) && ures == ULLONG_MAX);
+    assert(!ckd_sub(&res, 0, 1) && res == -1);
+
+    /* edge cases: */
+    assert(!ckd_sub(&ures, ULLONG_MAX, 0) && ures == ULLONG_MAX);
+    assert(!ckd_sub(&ures, ULLONG_MAX, 1) && ures == ULLONG_MAX - 1ULL);
+    assert(ckd_sub(&ures, 0ULL, ULLONG_MAX) && ures == 1);
+    assert(ckd_sub(&ures, 2, 3) && ures == ULLONG_MAX);
+    assert(ckd_sub(&res, LLONG_MIN, 1) && res == LLONG_MAX);
+
+    return 0;
+#endif
+}

configure.ac

@@ -870,9 +870,13 @@ dnl
 dnl Check for headers
 dnl
 
-AC_CHECK_HEADER([stdckdint.h],, [
+have_stdckdint="no"
+AC_CHECK_HEADER([stdckdint.h], [
+  have_stdckdint="yes"
+], [
   CPPFLAGS="${CPPFLAGS} -I\$(top_srcdir)/compat/stdckdint"
 ])
+AM_CONDITIONAL([HAVE_STDCKDINT], [test "${have_stdckdint}" = "yes"])
 
 dnl  POSIX
 AC_CHECK_HEADERS([arpa/inet.h pthread.h search.h sys/shm.h sys/socket.h sys/uio.h])