does LD_PRELOAD work under cygwin?

[basic]

Hi,
  Does LD_PRELOAD work under cygwin? I've tried the following without success:

gcc test.c
gcc -shared testlib.c -o testlib.dll

LD_PRELOAD=$HOME/testlib.dll ./a.exe

where test.c is:

#include 

int main()
{
open("", 1);
return 0;
}


and testlib.c is:

#include 

int open(const char *s, int i, ...)
{
puts("test");
return 0;
}

Is there anything I'm doing wrong? Or is it just not supported?

--
basic



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Re: R: does LD_PRELOAD work under cygwin?

[basic]

On 12/04/2009 03:05 PM, Marco Atzeri wrote:
> --- Ven 4/12/09, basic  ha scritto:
>
>> Hi,
>>   Does LD_PRELOAD work under cygwin? I've tried the
>> following without success:
>
> LDPRELOAD works with few peculiarites for multiple dll's
> but this is not your case.
>
>>
>> gcc test.c
>> gcc -shared testlib.c -o testlib.dll
>
> see documentation
> http://cygwin.com/cygwin-ug-net/dll.html
> on how to build and link dll's
I've read the document, but I do not see what I'm doing is any different from 
it. Any hints?

>
>>
>> LD_PRELOAD=$HOME/testlib.dll ./a.exe
>>
>> where test.c is:
>>
>> #include 
>>
>> int main()
>> {
>> open("", 1);
>> return 0;
>> }
>>
>>
>> and testlib.c is:
>>
>> #include 
>>
>> int open(const char *s, int i, ...)
>> {
>> puts("test");
>> return 0;
>> }
>>
>> Is there anything I'm doing wrong? Or is it just not
>> supported?
>>
>> --
>> basic
>>
> regards
> Marco
>
>
>
>


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Re: R: does LD_PRELOAD work under cygwin? (solved)

[basic]

On 12/04/2009 04:57 PM, basic wrote:
> On 12/04/2009 03:05 PM, Marco Atzeri wrote:
>> --- Ven 4/12/09, basic  ha scritto:
>>
>>> Hi,
>>>   Does LD_PRELOAD work under cygwin? I've tried the
>>> following without success:
>>
>> LDPRELOAD works with few peculiarites for multiple dll's
>> but this is not your case.
>>
>>>
>>> gcc test.c
>>> gcc -shared testlib.c -o testlib.dll
>>
>> see documentation
>> http://cygwin.com/cygwin-ug-net/dll.html
>> on how to build and link dll's
> I've read the document, but I do not see what I'm doing is any different from 
> it. Any hints?
After searching the mailing lists more, I found
http://sourceware.org/ml/cygwin/2008-03/msg00547.html

I got it to work by adding a call to cygwin_internal (CW_HOOK, "open", open); 
to a DllMain
function in testlib.c.

> 
>>
>>>
>>> LD_PRELOAD=$HOME/testlib.dll ./a.exe
>>>
>>> where test.c is:
>>>
>>> #include 
>>>
>>> int main()
>>> {
>>> open("", 1);
>>> return 0;
>>> }
>>>
>>>
>>> and testlib.c is:
>>>
>>> #include 
>>>
>>> int open(const char *s, int i, ...)
>>> {
>>> puts("test");
>>> return 0;
>>> }
>>>
>>> Is there anything I'm doing wrong? Or is it just not
>>> supported?
>>>
>>> --
>>> basic
>>>
>> regards
>> Marco
>>
>>
>>
>>
> 
> 
> --
> basic
> 
> --
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> 


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