util: add reallocarray wrapper for win32

Acked-by: Dylan Baker <dylan@pnwbakers.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17746>

meson.build

@@ -1089,6 +1089,10 @@ if cc.compiles('__uint128_t foo(void) { return 0; }',
   pre_args += '-DHAVE_UINT128'
 endif
 
+if cc.has_function('reallocarray')
+   pre_args += '-DHAVE_REALLOCARRAY'
+endif
+
 # TODO: this is very incomplete
 if ['linux', 'cygwin', 'gnu', 'freebsd', 'gnu/kfreebsd', 'haiku', 'android'].contains(host_machine.system())
   pre_args += '-D_GNU_SOURCE'

src/util/reallocarray.h

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2022 Red Hat
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#ifndef REALLOCARRAY_H
+#define REALLOCARRAY_H
+
+#if !defined(HAVE_REALLOCARRAY)
+
+#include <stdlib.h> // size_t
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* taken from the X server */
+/*
+ * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
+ * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
+ */
+#define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
+
+static inline void *
+reallocarray(void *optr, size_t nmemb, size_t size)
+{
+        if ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
+            nmemb > 0 && SIZE_MAX / nmemb < size) {
+                errno = ENOMEM;
+                return NULL;
+        }
+        return realloc(optr, size * nmemb);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* !defined(HAVE_REALLOCARRAY) */
+
+#endif /* REALLOCARRAY_H */