Date:	Mon, 17 Apr 2000 13:28:28 +0200 (IST)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender:	eliz AT is
To:	Waldemar Schultz <schultz AT ma DOT tum DOT de>
cc:	djgpp AT delorie DOT com
Subject:	Re: alternative malloc
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On Mon, 17 Apr 2000, Waldemar Schultz wrote:

> > If your program has replacements for malloc, free, and realloc, then
> > the linker will use them instead of the versions in the library.
> > 
> > But you *must* implement all the 3 functions, since the library
> > version has them all on a single module.
> 
> and what about 'strdup' (? etc.)

There should be no problem with `strdup', or any other function that is 
defined on a seperate source file.  Calling `malloc' is not the problem: 
these calls will simply be passed to the replacement `malloc'.

The problem I was referring to is that the GNU linker cannot link parts of 
object files, it can only link each object file in its entirety.  Since 
malloc.c in the  library defines `malloc', `free', and `realloc' 
functions, they all need to be replaced at once.  Otherwise, if the 
program calls `realloc', the linker will link malloc.c from the library, 
and will then complain about multiple definitions of `malloc'.

Of course, I assume that the replacement `malloc' is functionally 
equivalent to the library version, albeit with different internal 
implementation.  If the replacement is not an equivalent, then the 
program will most likely crash right on startup (because the startup
code calls `malloc').

As an example, Emacs defines its own replacements for these functions, 
but leaves the rest of the library, including strdup, alone.  And it 
works.

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