Re: GSoC ShlibMemLoad

> >> > (**) In (one of) the other test libraries you are using a
> for-loop and
> >> >     write to print the pid. If you encapsulate that into a function
> >> >     FOO to generally print unsigned numbers and then put FOO into the
> >> >     libprintf code you can print any number you need, like function
> >> >     addresses.  Inside of rtld itself it is of course possible to use
> >> >     the working printf to print its address.
> >
> >> Because I have already studied this whole code for quite a long time
> >> and have not came up with any solution I am thinking of writing an
> >> email to John Polstra who is an author of the rtld for
> >> FreeBSD. Maybe he will be able to help out. Do you think it is a
> >> good idea?
> >
> > Yes. Getting the help of (one of) the original authors of some code is
> > (in my opinion) a good idea. He should know the intricacies of the
> > code.
>
> I wrote the email today in the morning.

> >
> >> Today I also wrote a simple program which generates defs.h file.
> >
> > That note I did not understand. Can you explain a bit more?
>
> I committed make_defs.c file which automatically generates file
> elf-defs.h (the same as defs.h).
> An argument for this program should be the program itself, like
> ./make_defs make_defs

Hm. Ok, the defs.h file is the header which contains all the definitions

	#define Elf_Half Elf32_Half
	#define Elf_Addr Elf32_Addr
	#define Elf_Rel Elf32_Rel

etc. From the contents of the generator file make_defs.c I infer that you
doing this to switch the code between 32 and 64 bit ELF systems (and
possibly other ). Is that right ?

What are (dis)advantages of this approach compared to the alternative of
using a single defs.h file and preprocessor conditionals to switch between
the possibilities ?

I.e have one defs.h file containing, roughly:

	#ifdef USE_ELF_64 /* Or whatever other name sounds more appropriate */

	#  define Elf_Half Elf64_Half
	#  define Elf_Addr Elf64_Addr
	#  define Elf_Rel Elf64_Rel
	[...]

	#else /* 32 bit / default branch */
	#  define Elf_Half Elf32_Half
	#  define Elf_Addr Elf32_Addr
	#  define Elf_Rel Elf32_Rel
	[...]
	#endif

and then using it like so

	gcc -DUSE_ELF_64 foo.c ...	// on 64bit elf systems
and	gcc              foo.c ...	// on 32bit elf systems

--
	Andreas Kupries <andreask@...>
	Developer @ http://www.ActiveState.com
	Tel: +1 778-786-1122

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