Malloc Debug Problem

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Bruno - 08 Sep 2005 02:48 GMT

Hi ,

Has anyone ever managed to use "MallocDebug" with a command line application
generated with CW9.3 ?
I am failing lamentably and getting a bit annoyed ...
Here is what i did : In CW, I created a sample C 'HelloWorld' program using
the 'C Console Mach-O' template and stripped out all the MSL references out
of it. I removed all the librairies in order to link only against the
'System' framework and crt1.o binary. Invariably , In 'MallocDebug' when I
click on "Launch", after a while, I get the following error message :
"Unable to read malloc information from (null)"...

Thanks

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Greg - 08 Sep 2005 12:22 GMT

> Hi ,
>
[quoted text clipped - 9 lines]
>
> Thanks

The "hello, world" console app just prints one line of text and exits.
To track memory leaks in an app, the app has to be running (and
preferably doing something).

It should not be necessary to remove any libraries from the program
being tested: just launch it within MallocDebug. MallocDebug will
ensure that the debug malloc library is loaded into the program's
space. All memory allocations end up calling the System's malloc
routine eventually; so if a program is leaking memory, MallocDebug will
show where the leaking allocations were made.

Greg

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Bruno - 08 Sep 2005 13:23 GMT

> The "hello, world" console app just prints one line of text and exits.
> To track memory leaks in an app, the app has to be running (and
> preferably doing something).

Understood ! that was a bit stupid of myself..., now I got it to do
something: create a memory leak and loop indefinitely. But still,
MallocDebug fails to detect the leak .... Any ideas why (see code below)

//
void leak(int size)
{
char *buff = malloc(size);
}

int main(int argc, char *argv[])
{
printf("Hello World, this is CodeWarrior!\n");

leak(100000);

// Do something ... Or at least pretend
do
{
;
}while(1);
return 0;
}
//

> It should not be necessary to remove any libraries from the program
> being tested: just launch it within MallocDebug.

True and false : if you link against 'MSL All Mach O.lib', you can't use
MallocDebug : you get an error because the _exit symbol if defined twice.
You need to use a combination of the 'MSL C++ - BSD -MachO.lib' and the 'BSD
Runtime.lib'.

>MallocDebug will
> ensure that the debug malloc library is loaded into the program's
> space. All memory allocations end up calling the System's malloc
> routine eventually; so if a program is leaking memory, MallocDebug will
> show where the leaking allocations were made.

I knew that , thanks.

> Greg

Bruno

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Ben Artin - 08 Sep 2005 23:45 GMT

> True and false : if you link against 'MSL All Mach O.lib', you can't use
> MallocDebug : you get an error because the _exit symbol if defined twice.
> You need to use a combination of the 'MSL C++ - BSD -MachO.lib' and the 'BSD
> Runtime.lib'.

True. (libgmalloc loses similarly)

Ben

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Eric Albert - 09 Sep 2005 04:06 GMT

> > True and false : if you link against 'MSL All Mach O.lib', you can't use
> > MallocDebug : you get an error because the _exit symbol if defined twice.
> > You need to use a combination of the 'MSL C++ - BSD -MachO.lib' and the 'BSD
> > Runtime.lib'.
>
> True. (libgmalloc loses similarly)

Is this still true on Tiger?

-Eric

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Eric Albert ejalbert@cs.stanford.edu
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Ben Artin - 09 Sep 2005 04:49 GMT

> > > True and false : if you link against 'MSL All Mach O.lib', you can't use
> > > MallocDebug : you get an error because the _exit symbol if defined twice.
[quoted text clipped - 5 lines]
>
> Is this still true on Tiger?

Haven't checked, and I am moving to Xcode anyway so I doubt I'll take the time
to do so :-)

Ben

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Eric Albert - 09 Sep 2005 18:23 GMT

> > > > True and false : if you link against 'MSL All Mach O.lib', you
> > > > can't use MallocDebug : you get an error because the _exit
[quoted text clipped - 7 lines]
> Haven't checked, and I am moving to Xcode anyway so I doubt I'll take
> the time to do so :-)

Which is pretty much the same reason why I haven't checked. :) But
libgmalloc and Malloc Debug were changed to work better in cases like
this for Tiger, so I wouldn't be surprised if it's fixed.

-Eric

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Mac Forum / Programming / CodeWarrior / September 2005

Malloc Debug Problem