Date: Tue, 17 Nov 1998 08:48:40 -0500 (EST) From: Thomas David Rivers <rivers@dignus.com> To: hackers@FreeBSD.ORG, nate@mt.sri.com Subject: Re: Wrapping a function Message-ID: <199811171348.IAA11670@lakes.dignus.com> In-Reply-To: <199811170517.WAA22627@mt.sri.com>
next in thread | previous in thread | raw e-mail | index | archive | help
>
> Does anyone have an easy way of 'wrapping' an already existing library
> function so that any programs linked against your .o will call your
> function, but so your function can call the 'real' library function?
>
> Example:
>
> my_malloc.c:
>
> void *malloc(size_t size)
> {
> void *ret;
>
> printf("Calling malloc\n");
> ret = REALMALLOC(size);
> printf("Leaving malloc\n");
> return ret;
> }
>
> Ignoring all of the functions where there is loss of errno and such, are
> they any good ideas? Note, the use of the dl* functions is explicitly
> not allowed since those happen to be the functions I want to wrap in
> this case.
>
> I'm at a loss here how to do this in C, so any good hacks are welcomed.
>
>
> Nate
>
> To Unsubscribe: send mail to majordomo@FreeBSD.org
> with "unsubscribe freebsd-hackers" in the body of the message
>
I don't know about our linker (gnu-ld) - but many UNIX linkers (and other
systems as well) have a way to re-name identifiers.
The standard trick would be to pre-link the malloc code from the library;
renaming the malloc entry there - to say, MALLOC. (ld -r is how you
prelink.)
Then, you can link your code with that.
- Dave Rivers -
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199811171348.IAA11670>