1 files changed, 60 insertions, 0 deletions
diff --git a/compat/reallocarray.c b/compat/reallocarray.c
new file mode 100644
index 000000000000..9ff9c20b30fb
--- /dev/null
+++ b/compat/reallocarray.c
@@ -0,0 +1,60 @@
+/* $NetBSD: reallocarr.c,v 1.4 2015/08/20 20:08:04 joerg Exp $ */
+
+/*-
+ * Copyright (c) 2015 Joerg Sonnenberger <joerg@NetBSD.org>.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <errno.h>
+#include <limits.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+/*
+ * To be clear, this is NetBSD's more refined reallocarr(3) function
+ * made to look like OpenBSD's more useable reallocarray(3) interface.
+ */
+#include "reallocarray.h"
+
+#define SQRT_SIZE_MAX (((size_t)1) << (sizeof(size_t) * CHAR_BIT / 2))
+void *
+reallocarray(void *ptr, size_t n, size_t size)
+{
+
+	/*
+	 * Try to avoid division here.
+	 *
+	 * It isn't possible to overflow during multiplication if neither
+	 * operand uses any of the most significant half of the bits.
+	 */
+	if ((n | size) >= SQRT_SIZE_MAX && n > SIZE_MAX / size) {
+		errno = EOVERFLOW;
+		return NULL;
+	}
+	return realloc(ptr, n * size);
+}