Bring in reallocarray() from OpenBSD

Makefile

@@ -6,6 +6,7 @@ SRC = \
 	stagit.c\
 	stagit-index.c
 COMPATSRC = \
+	reallocarray.c\
 	strlcat.c\
 	strlcpy.c
 BIN = \

compat.h

@@ -3,4 +3,6 @@
 size_t strlcat(char *, const char *, size_t);
 #undef strlcpy
 size_t strlcpy(char *, const char *, size_t);
+#undef reallocarray
+void *reallocarray(void *, size_t, size_t);
 #endif

config.mk

@@ -28,8 +28,8 @@ LDFLAGS = ${LIBS}
 
 # uncomment for compat
 CFLAGS += -DCOMPAT
-# uncomment if your libc doesn't support strlcat, strlcpy.
-COMPATOBJ = strlcat.o strlcpy.o
+# uncomment if your libc doesn't support reallocarray, strlcat, strlcpy.
+COMPATOBJ = reallocarray.o strlcat.o strlcpy.o
 
 # compiler and linker
 #CC = cc

reallocarray.c

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2008 Otto Moerbeek <otto@drijf.net>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "compat.h"
+
+/*
+ * 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	(1UL << (sizeof(size_t) * 4))
+
+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);
+}

strlcat.c

@@ -19,6 +19,8 @@
 #include <sys/types.h>
 #include <string.h>
 
+#include "compat.h"
+
 /*
  * Appends src to string dst of size dsize (unlike strncat, dsize is the
  * full size of dst, not space left).  At most dsize-1 characters

strlcpy.c

@@ -19,6 +19,8 @@
 #include <sys/types.h>
 #include <string.h>
 
+#include "compat.h"
+
 /*
  * Copy string src to buffer dst of size dsize.  At most dsize-1
  * chars will be copied.  Always NUL terminates (unless dsize == 0).