From: Darren Tucker <dtucker@dtucker.net>
Date: Sat, 24 Feb 2018 23:20:31 +0000 (+1100)
Subject: Handle calloc(0,x) where different from malloc.
X-Git-Tag: V_7_7_P1~72
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e9dede06e5bc582a4aeb5b1cd5a7a640d7de3609;p=thirdparty%2Fopenssh-portable.git

Handle calloc(0,x) where different from malloc.

Configure assumes that if malloc(0) returns null then calloc(0,n)
also does.  On some old platforms (SunOS4) malloc behaves as expected
(as determined by AC_FUNC_MALLOC) but calloc doesn't.  Test for this
at configure time and activate the replacement function if found, plus
handle this case in rpl_calloc.
---

diff --git a/configure.ac b/configure.ac
index 03cc3f869..605844ba2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1337,8 +1337,23 @@ AC_FUNC_STRFTIME
 AC_FUNC_MALLOC
 AC_FUNC_REALLOC
 # autoconf doesn't have AC_FUNC_CALLOC so fake it if malloc returns NULL;
-if test "x$ac_cv_func_malloc_0_nonnull" != "xyes"; then
-	AC_DEFINE(HAVE_CALLOC, 0, [calloc(x, 0) returns NULL])
+AC_MSG_CHECKING([if calloc(0, N) returns non-null])
+AC_RUN_IFELSE(
+	[AC_LANG_PROGRAM(
+		[[ #include <stdlib.h> ]],
+		[[ void *p = calloc(0, 1); exit(p == NULL); ]]
+	)],
+	[ func_calloc_0_nonnull=yes ],
+	[ func_calloc_0_nonnull=no ],
+	[ AC_MSG_WARN([cross compiling: assuming same as malloc])
+	  func_calloc_0_nonnull="$ac_cv_func_malloc_0_nonnull"]
+)
+AC_MSG_RESULT([$func_calloc_0_nonnull])
+
+if test "x$func_calloc_0_nonnull" == "xyes"; then
+	AC_DEFINE(HAVE_CALLOC, 1, [calloc(0, x) returns non-null])
+else
+	AC_DEFINE(HAVE_CALLOC, 0, [calloc(0, x) returns NULL])
 	AC_DEFINE(calloc, rpl_calloc,
 	    [Define to rpl_calloc if the replacement function should be used.])
 fi
diff --git a/openbsd-compat/bsd-malloc.c b/openbsd-compat/bsd-malloc.c
index 6402ab588..482facdc9 100644
--- a/openbsd-compat/bsd-malloc.c
+++ b/openbsd-compat/bsd-malloc.c
@@ -50,6 +50,8 @@ rpl_realloc(void *ptr, size_t size)
 {
 	if (size == 0)
 		size = 1;
+	if (ptr == 0)
+		return malloc(size);
 	return realloc(ptr, size);
 }
 #endif