Enable compiler stack protection flags

ChangeLog

+Wed Mar 21 10:52:06 EST 2007 Daniel P. Berrange <berrange@redhat.com>
+
+	* acinclude.m4: Always use -Wp,-D_FORTIFY_SOURCE=2 -fexceptions
+	-fstack-protector --param=ssp-buffer-size=4
+	-fasynchronous-unwind-tables if supported by the compiler. Check
+	all warnings flags for compiler support
+
 Tue Mar 20 10:00:06 EST 2007 Daniel P. Berrange <berrange@redhat.com>
 
 	* qemud/conf.c: Fixed buffer overflow in code building up

acinclude.m4

@@ -12,57 +12,54 @@ AC_DEFUN([LIBVIRT_COMPILE_WARNINGS],[
     AC_ARG_ENABLE(compile-warnings,
                   AC_HELP_STRING([--enable-compile-warnings=@<:@no/minimum/yes/maximum/error@:>@],
                                  [Turn on compiler warnings]),,
-                  [enable_compile_warnings="m4_default([$1],[yes])"])
+                  [enable_compile_warnings="m4_default([$1],[maximum])"])
 
     warnCFLAGS=
-    if test "x$GCC" != xyes; then
-	enable_compile_warnings=no
-    fi
 
-    warning_flags=
-    realsave_CFLAGS="$CFLAGS"
+    try_compiler_flags="-Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -fasynchronous-unwind-tables"
 
     case "$enable_compile_warnings" in
     no)
-	warning_flags=
 	;;
     minimum)
-	warning_flags="-Wall"
+	try_compiler_flags="$try_compiler_flags -Wall"
 	;;
     yes)
-	warning_flags="-Wall -Wmissing-prototypes"
+	try_compiler_flags="$try_compiler_flags -Wall -Wmissing-prototypes"
 	;;
     maximum|error)
-	warning_flags="-Wall -Wmissing-prototypes -Wnested-externs -Wpointer-arith"
-        warning_flags="$warning_flags -Wextra -Wshadow -Wcast-align -Wwrite-strings -Waggregate-return -Wstrict-prototypes -Winline -Wredundant-decls"
-	CFLAGS="$warning_flags $CFLAGS"
-	for option in -Wno-sign-compare; do
-		SAVE_CFLAGS="$CFLAGS"
-		CFLAGS="$CFLAGS $option"
-		AC_MSG_CHECKING([whether gcc understands $option])
-		AC_TRY_COMPILE([], [],
-			has_option=yes,
-			has_option=no,)
-		CFLAGS="$SAVE_CFLAGS"
-		AC_MSG_RESULT($has_option)
-		if test $has_option = yes; then
-		  warning_flags="$warning_flags $option"
-		fi
-		unset has_option
-		unset SAVE_CFLAGS
-	done
-	unset option
+	try_compiler_flags="$try_compiler_flags -Wall -Wmissing-prototypes -Wnested-externs -Wpointer-arith"
+        try_compiler_flags="$try_compiler_flags -Wextra -Wshadow -Wcast-align -Wwrite-strings -Waggregate-return"
+	try_compiler_falgs="$try_compiler_flags -Wstrict-prototypes -Winline -Wredundant-decls -Wno-sign-compare"
 	if test "$enable_compile_warnings" = "error" ; then
-	    warning_flags="$warning_flags -Werror"
+	    try_compiler_flags="$try_compiler_flags -Werror"
 	fi
 	;;
     *)
 	AC_MSG_ERROR(Unknown argument '$enable_compile_warnings' to --enable-compile-warnings)
 	;;
     esac
+
+    compiler_flags=
+    for option in $try_compiler_flags; do
+	SAVE_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $option"
+	AC_MSG_CHECKING([whether gcc understands $option])
+	AC_TRY_COMPILE([], [],
+		has_option=yes,
+		has_option=no,)
+	CFLAGS="$SAVE_CFLAGS"
+	AC_MSG_RESULT($has_option)
+	if test $has_option = yes; then
+	  compiler_flags="$compiler_flags $option"
+	fi
+	unset has_option
+	unset SAVE_CFLAGS
+    done
+    unset option
+    unset try_compiler_flags
+
     CFLAGS="$realsave_CFLAGS"
-    AC_MSG_CHECKING(what warning flags to pass to the C compiler)
-    AC_MSG_RESULT($warning_flags)
 
     AC_ARG_ENABLE(iso-c,
                   AC_HELP_STRING([--enable-iso-c],
@@ -85,6 +82,6 @@ AC_DEFUN([LIBVIRT_COMPILE_WARNINGS],[
     fi
     AC_MSG_RESULT($complCFLAGS)
 
-    WARN_CFLAGS="$warning_flags $complCFLAGS"
+    WARN_CFLAGS="$compiler_flags $complCFLAGS"
     AC_SUBST(WARN_CFLAGS)
 ])