Re: [PATCH 1/4] enhance overflow and truncation detection in strncpy and strncat (PR 81117)

[Jeff Law <law@redhat.com>]

On 08/06/2017 02:07 PM, Martin Sebor wrote:
> The attached patch adds support for a new GCC format specifier,
> G, that behaves like %K but accepts a gcall* argument.  This
> makes it possible to provide inlining context for "artificial"
> inline functions like strncpy (with _FORTIFY_SOURCE) in
> diagnostics issued from the middle end.
> 
> Martin
> 
> gcc-81117-1.diff
> 
> 
> PR c/81117 - Improve buffer overflow checking in strncpy
> 
> gcc/ChangeLog:
> 
> 	PR c/81117
> 	* tree-diagnostic.c (default_tree_printer): Handle %G.
> 	* tree-pretty-print.h (percent_G_format): Declare new function.
> 	* tree-pretty-print.c (percent_K_format): Define a static overload.
> 	(percent_G_format): New function.
> 
> gcc/c/ChangeLog:
> 
> 	PR c/81117
> 	* c-objc-common.c (c_objc_common_init): Handle 'G'.
> 
> gcc/c-family/ChangeLog:
> 
> 	* c-format.h (T89_G): New macro.
> 	* c-format.c (local_gcall_ptr_node): New variable.
> 	(init_dynamic_diag_info): Initialize it.
> 
> gcc/cp/ChangeLog:
> 
> 	PR c/81117
> 	* error.c (cp_printer): Handle 'G'.
> 
> gcc/testsuite/ChangeLog:
> 
> 	PR c/81117
> 	* gcc.dg/format/gcc_diag-10.c: Exercise %G.
> 
> diff --git a/gcc/tree-diagnostic.c b/gcc/tree-diagnostic.c
> index 52b7e7f..ad58b69 100644
> --- a/gcc/tree-diagnostic.c
> +++ b/gcc/tree-diagnostic.c
> @@ -275,6 +275,10 @@ default_tree_printer (pretty_printer *pp, text_info *text, const char *spec,
>        t = va_arg (*text->args_ptr, tree);
>        break;
>  
> +    case 'G':
> +      percent_G_format (text);
> +      return true;
> +
>      case 'K':
>        percent_K_format (text);
>        return true;
> diff --git a/gcc/tree-pretty-print.c b/gcc/tree-pretty-print.c
> index 4d8177c..7c4c805 100644
> --- a/gcc/tree-pretty-print.c
> +++ b/gcc/tree-pretty-print.c
> @@ -33,6 +33,7 @@ along with GCC; see the file COPYING3.  If not see
>  #include "dumpfile.h"
>  #include "internal-fn.h"
>  #include "gomp-constants.h"
> +#include "gimple.h"
This is an indication you're probably putting the 'G' handling in the
wrong place.  Wouldn't gimple-pretty-print.c be more correct?

That's my only objection to this patch, so if it moves trivially, then
it's pre-approved.  If it's non-trivial, then we'll want another iteration.

jeff