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Date: Thu, 5 Nov 2009 18:22:18 +0000
Message-ID: <416096c60911051022obc335ceu15dc7ee0e487cb66@mail.gmail.com>
Subject: Re: malloc overrides
From: Andy Koppe <andy DOT koppe AT gmail DOT com>
To: cygwin AT cygwin DOT com
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2009/11/5 Yaakov (Cygwin/X):
>>> extern void _exit (int);
>>> extern char* strdup (const char*);
>>
>> =C2=A0 static int are_we_stuck =3D 1;
>>>
>>> char* malloc(unsigned n) {
>>
>> =C2=A0 =C2=A0 =C2=A0 are_we_stuck =3D 0;
>>>
>>> =C2=A0 =C2=A0 return 0;
>>> }
>>>
>>> int main(void) {
>>> =C2=A0 =C2=A0 strdup("yo");
>>
>> =C2=A0 =C2=A0 =C2=A0 _exit (are_we_stuck);
>>>
>>> }
>>
>> =C2=A0 FTFY.
>
> Funny, as I went to sleep last night I thought of just that solution. In
> practice, though, while it doesn't hang, it doesn't give the correct answ=
er
> either. =C2=A0 As Corinna said, the malloc override needs to be functiona=
l, in
> that it allocates memory which can then be free()d. =C2=A0So this isn't g=
oing to
> be quite so simple. :-(

Does the memory actually need to be freed?

The simplest implementation of malloc() simply advances a pointer into
an array (taking alignment into account), and the simplest
implementation of free() does nothing.

Andy

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