From:	stephensk AT acm DOT org (Kurt A. Stephens)
Subject:	malloc() indirection
10 Jul 1998 08:21:59 -0700 :
Message-ID:	<35A55F3D.614D7803.cygnus.gnu-win32@acm.org>
Mime-Version:	1.0
To:	gnu-win32 AT cygnus DOT com

I'd like to propose a change to the cygwin32.dll.
The goal is to allow user defined functions for malloc(), realloc(), and
free() can be used
instead of the standard allocator.

For example: a conservative garbage collector or debugging allocator
might be nice.

This can easily be done on most real UNIX systems by linking in a
different malloc() before
the system libraries.  I found this will not work with Windows .dlls.

/*  malloc.c */
/* Rename standard malloc(), realloc(), free() as follows */
void* _cygwin32_malloc(size_t size) ...
void* _cygwin32_realloc(void *ptr, size_t size) ...
void _cygwin32_free(void*ptr)...
/* or */
#define malloc _cygwin32_malloc
#define realloc _cygwin32_realloc
#define free _cygwin32_free

/* umalloc.c */
void *(*_cygwin32_malloc_func)(size_t ) = _cygwin32_malloc;
void *(*_cygwin32_realloc_func)(void*, size_t ) = _cygwin32_realloc;
void (*_cygwin32_free_func)(void*) = _cygwin32_free;

void *malloc(size_t s) { return (*_cygwin32_malloc_func)(s); }
void *realloc(void *p, size_t s) { return (*_cygwin32_realloc_func)(p,
s); }
void free(void *p) { return (*_cygwin32_free_func)(p, s); }

I'd implement this myself but I don't want to download all the source,
etc.   It might be nice
if this could be implemented in the next release -- it's a small but
very useful change.

Thanks,
Please post AND reply directly,
Kurt A. Stephens

P.S. I'm so glad that sbrk() was implemented!



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