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Re: [Caml-list] Segfault using malloc within stubs
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Date: 2005-02-06 (14:01)
From: julius <flute@n...>
Subject: Re: [Caml-list] Segfault using malloc within stubs
Actually, this is just un exemple that illustrates the real function I 
used. We can add some use of the test pointer and result value but it 
changes nothing: in this function you can't do anything that someway 
malloc the test pointer.
As you say it's very weird and much disapointing :)


PS: In my implementation, test is given to a function that use it to 
stock its result (after malloc it), and result is a caml value pointing 
to some calculus result. The end is same: segfault...

Remi Vanicat wrote:

> On Sun, 06 Feb 2005 08:38:06 +0100, julius <> wrote:
>> Hello,
>> I have this strange problem with my stubs, I wrote this function but it
>> leads to a segfault:
>> CAMLprim value foo(value v)
>> {
>>    CAMLparam1(v);
>>    CAML(result);
>>    char** test;
>>    test=(char**)malloc(4*sizeof(char*));
>>    CAMLreturn(result);
>> }
>> After much tests, it seems that malloc is not allowed when using Caml
>> data types or when trying to register data to the ocaml garbage
>> collector... But I don't understand why as C heap and OCaml heap are
>> distinct :-/
> It seem weird. First of all, mallocs are explicitly allowed in the
> doc. So the problem must be somewhere else. I see that in this code,
> the test pointer is never used, but throw away, and this could lead to
> a memory leak. Also the result variable is never set, so this is
> probably the problem. Try to add a result=Val_unit; somewhere in your
> code to see if the problem goes away. I forget : I don't know what
> CAML(result) mean. Did you want to use CAML_local1(result) ? may be
> this is the problem.