[gtk-vnc] meson: enable stack protector on freebsd and windows

[Daniel P. Berrange <dberrange src gnome org>]

commit 077b8b22fc1cf5440aad03b84cc84e51466023b0
Author: Daniel P. Berrangé <dan berrange com>
Date:   Wed Aug 19 18:56:13 2020 +0100

    meson: enable stack protector on freebsd and windows
    
    Fedora 33 rawhide no longer successfully builds GTK-VNC on mingw using
    fortify source, without also having stack protector flags enabled/
    
    Signed-off-by: Daniel P. Berrangé <berrange redhat com>

 meson.build | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)
---
diff --git a/meson.build b/meson.build
index 79ebb2d..70b9494 100644
--- a/meson.build
+++ b/meson.build
@@ -231,12 +231,6 @@ check_cflags = [
   '-Wno-suggest-attribute=pure',
   '-Wno-suggest-attribute=const',
 ]
-if host_machine.system() == 'linux'
-  check_cflags += [
-    '-fstack-protector-all',
-    '--param=ssp-buffer-size=4',
-  ]
-endif
 
 cflags = []
 foreach cflag: check_cflags
@@ -246,6 +240,21 @@ foreach cflag: check_cflags
 endforeach
 
 
+if host_machine.system() in [ 'linux', 'freebsd', 'windows' ]
+  # we prefer -fstack-protector-strong but fallback to -fstack-protector-all
+  fstack_cflags = cc.first_supported_argument([
+    '-fstack-protector-strong',
+    '-fstack-protector-all',
+  ])
+  cflags += fstack_cflags
+
+  # When building with mingw using -fstack-protector requires libssp library
+  # which is included by using -fstack-protector with linker.
+  if fstack_cflags.length() == 1 and host_machine.system() == 'windows'
+    add_project_link_arguments(fstack_cflags, language: 'c')
+  endif
+endif
+
 add_project_arguments(cflags, language: 'c')
 
 gtk_vnc_prefix = get_option('prefix')