Add configure option to enable GNU GCC stack smash protection.

This option is disabled by default because it is known not to work
on FreeBSD 9.1 and for Linux -> Windows cross compiling using the
Debian MinGW-w64 tool chain.

It is known to work for native compiles in Debian testing and
OpenBSD 5.2.

2 files changed, 74 insertions, 0 deletions

diff --git a/m4/Makefile.am b/m4/Makefile.am
index c5da5bbd..89d5a898 100644
--- a/m4/Makefile.am
+++ b/m4/Makefile.am
@@ -22,4 +22,5 @@ EXTRA_DIST = \
 	endian.m4 \
 	gcc_version.m4 \
 	ogg.m4 \
+	stack_protect.m4 \
 	xmms.m4
diff --git a/m4/stack_protect.m4 b/m4/stack_protect.m4
new file mode 100644
index 00000000..bf27e6e7
--- /dev/null
+++ b/m4/stack_protect.m4
@@ -0,0 +1,73 @@
+dnl Copyright (C) 2013  Xiph.org Foundation
+dnl
+dnl Redistribution and use in source and binary forms, with or without
+dnl modification, are permitted provided that the following conditions
+dnl are met:
+dnl
+dnl - Redistributions of source code must retain the above copyright
+dnl notice, this list of conditions and the following disclaimer.
+dnl
+dnl - Redistributions in binary form must reproduce the above copyright
+dnl notice, this list of conditions and the following disclaimer in the
+dnl documentation and/or other materials provided with the distribution.
+dnl
+dnl - Neither the name of the Xiph.org Foundation nor the names of its
+dnl contributors may be used to endorse or promote products derived from
+dnl this software without specific prior written permission.
+dnl
+dnl THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+dnl ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+dnl LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+dnl A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
+dnl CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+dnl EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+dnl PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+dnl PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+dnl LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+dnl NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+dnl SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+dnl Want to know of GCC stack protector works, botfor the C and for the C++
+dnl compiler.
+dnl
+dnl Just checking if the compiler accepts the required CFLAGSs is not enough
+dnl because we have seen at least one instance where this check was
+dnl in-sufficient.
+dnl
+dnl Instead, try to compile and link a test program with the stack protector
+dnl flags. If that works, we use it.
+
+AC_DEFUN([XIPH_GCC_STACK_PROTECTOR],
+[AC_LANG_ASSERT(C)
+	AC_MSG_CHECKING([if $CC supports stack smash protection])
+	xiph_stack_check_old_cflags="$CFLAGS"
+	SSP_FLAGS="-fstack-protector --param ssp-buffer-size=4"
+	CFLAGS=$SSP_FLAGS
+	AC_TRY_LINK([
+			#include <stdio.h>
+			],
+		[puts("Hello, World!"); return 0;],
+		AC_MSG_RESULT([yes])
+			CFLAGS="$xiph_stack_check_old_cflags $SSP_FLAGS",
+		AC_MSG_RESULT([no])
+			CFLAGS="$xiph_stack_check_old_cflags"
+		)
+])# XIPH_GCC_STACK_PROTECTOR
+
+AC_DEFUN([XIPH_GXX_STACK_PROTECTOR],
+[AC_LANG_PUSH([C++])
+	AC_MSG_CHECKING([if $CXX supports stack smash protection])
+	xiph_stack_check_old_cflags="$CFLAGS"
+	SSP_FLAGS="-fstack-protector --param ssp-buffer-size=4"
+	CFLAGS=$SSP_FLAGS
+	AC_TRY_LINK([
+			#include <cstdio>
+			],
+		[puts("Hello, World!"); return 0;],
+		AC_MSG_RESULT([yes])
+			CFLAGS="$xiph_stack_check_old_cflags $SSP_FLAGS",
+		AC_MSG_RESULT([no])
+			CFLAGS="$xiph_stack_check_old_cflags"
+		)
+	AC_LANG_POP([C++])
+])# XIPH_GXX_STACK_PROTECTOR