Re: [pph/libcpp] Allow include callback to not read the file (issue4388057)

[Lawrence Crowl <crowl at google dot com>]

This change is not source compatible with existing code using
the callbacks (which may not be in the gcc svn).  Perhaps a new
callback is needed?

On 4/12/11, Diego Novillo <dnovillo@google.com> wrote:
>
> During pph processing, when we find an included file that we are going
> to instantiate from an image, we don't want libcpp to stack and read
> it.
>
> I've implemented this by allowing the 'include' callback to return a
> boolean value.  If it returns true, then we call _cpp_stack_include.
> Otherwise, the file is ignored.
>
> Tom, I believe this is the right approach, but I'm not sure.  It does
> what I want, though.
>
>
> Thanks.  Diego.
>
> libcpp/ChangeLog.pph
> 2011-04-12  Diego Novillo  <dnovillo@google.com>
>
> 	* directives.c (do_include_common): If the callback
> 	pfile->cb.include returns falose do not call
> 	_cpp_stack_include.
> 	* include/cpplib.h (struct cpp_callbacks): Change return
> 	type of field 'include' to bool.
>
> gcc/cp/ChangeLog.pph
> 2011-04-12  Diego Novillo  <dnovillo@google.com>
>
> 	* pph.c (pth_include_handler): Return true.
> 	(pph_include_handler): If the header file exists as a PPH
> 	image, return false.
>
> diff --git a/gcc/cp/pph.c b/gcc/cp/pph.c
> index 74d1d50..6584e72 100644
> --- a/gcc/cp/pph.c
> +++ b/gcc/cp/pph.c
> @@ -1984,9 +2008,10 @@ pph_read_file (const char *filename)
>      error ("Cannot open PPH file for reading: %s: %m", filename);
>  }
>
> +
>  /* Record a #include or #include_next for PTH.  */
>
> -static void
> +static bool
>  pth_include_handler (cpp_reader *reader ATTRIBUTE_UNUSED,
>  	             location_t loc ATTRIBUTE_UNUSED,
>  	             const unsigned char *dname,
> @@ -2012,11 +2037,14 @@ pth_include_handler (cpp_reader *reader
> ATTRIBUTE_UNUSED,
>
>    state->new_angle_brackets = angle_brackets;
>    state->new_iname = name;
> +
> +  return true;
>  }
>
> +
>  /* Record a #include or #include_next for PPH.  */
>
> -static void
> +static bool
>  pph_include_handler (cpp_reader *reader,
>                       location_t loc ATTRIBUTE_UNUSED,
>                       const unsigned char *dname,
> @@ -2025,6 +2053,7 @@ pph_include_handler (cpp_reader *reader,
>                       const cpp_token **tok_p ATTRIBUTE_UNUSED)
>  {
>    const char *pph_file;
> +  bool read_text_file_p;
>
>    if (flag_pph_debug >= 1)
>      {
> @@ -2034,9 +2063,15 @@ pph_include_handler (cpp_reader *reader,
>        fprintf (pph_logfile, "%c\n", angle_brackets ? '>' : '"');
>      }
>
> +  read_text_file_p = true;
>    pph_file = query_pph_include_map (name);
>    if (pph_file != NULL && !cpp_included_before (reader, name,
> input_location))
> -    pph_read_file (pph_file);
> +    {
> +      pph_read_file (pph_file);
> +      read_text_file_p = false;
> +    }
> +
> +  return read_text_file_p;
>  }
>
>
> diff --git a/libcpp/directives.c b/libcpp/directives.c
> index 7812b57..09c7686 100644
> --- a/libcpp/directives.c
> +++ b/libcpp/directives.c
> @@ -788,15 +788,19 @@ do_include_common (cpp_reader *pfile, enum
> include_type type)
>      cpp_error (pfile, CPP_DL_ERROR, "#include nested too deeply");
>    else
>      {
> +      bool do_stack_include;
> +
>        /* Get out of macro context, if we are.  */
>        skip_rest_of_line (pfile);
>
> +      do_stack_include = true;
>        if (pfile->cb.include)
> -	pfile->cb.include (pfile, pfile->directive_line,
> -			   pfile->directive->name, fname, angle_brackets,
> -			   buf);
> +	do_stack_include = pfile->cb.include (pfile, pfile->directive_line,
> +					      pfile->directive->name,
> +					      fname, angle_brackets, buf);
>
> -      _cpp_stack_include (pfile, NULL, fname, angle_brackets, type);
> +      if (do_stack_include)
> +	_cpp_stack_include (pfile, NULL, fname, angle_brackets, type);
>      }
>
>    XDELETEVEC (fname);
> diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
> index 3dc4139..c9f3dfb 100644
> --- a/libcpp/include/cpplib.h
> +++ b/libcpp/include/cpplib.h
> @@ -480,7 +480,9 @@ struct cpp_callbacks
>    void (*file_change) (cpp_reader *, const struct line_map *);
>
>    void (*dir_change) (cpp_reader *, const char *);
> -  void (*include) (cpp_reader *, unsigned int, const unsigned char *,
> +  /* Called when processing a #include directive.  If the handler
> +     returns false, the file will not be read.  */
> +  bool (*include) (cpp_reader *, unsigned int, const unsigned char *,
>  		   const char *, int, const cpp_token **);
>    void (*define) (cpp_reader *, unsigned int, cpp_hashnode *);
>    void (*undef) (cpp_reader *, unsigned int, cpp_hashnode *);
>
> --
> This patch is available for review at http://codereview.appspot.com/4388057
>


-- 
Lawrence Crowl