Re: [RFC] [PATCH] Implement -ffortify for C/C++

[Dirk Mueller <dmueller at suse dot de>]

On Tuesday, 30. January 2007 17:45, Jakub Jelinek wrote:

> In glibc headers (as well as libssp headers) -D_FORTIFY_SOURCE=2
> disallows str*/stp* etc. to cross structure field boundaries,
> while mem* still can cross them

You're referring to __builtin_object_size(.., 0) vs __builtin_object_size(.., 
1), right?

I'm trying to do that via 

+      fn = build_bos_call (TREE_VALUE (params),
+                          bos && flag_fortify > 1 
+                          ? integer_one_node : integer_zero_node);

so it produces __builtin_object_size(.., 1) if it is a str*/stp* related 
function and fortify level is > 1. This is how I understood it from reading 
the glibc header file (I admit it was late and I was drunk). 

> , also %n in *printf is only supported 
> if format string is in read-only memory (string literal, _(string
> literal)). With -D_FORTIFY_SOURCE=1 that's all allowed.

I'm setting the flags argument of the printf*chk variants to fortify_flag - 1, 
so it should be allowed with -ffortify level 1 and not with level 2 and 
above. Where did  I make the mistake here? I definitely want it to behave the 
same. 


Thanks,
Dirk