perl-Win32-API package problem

perl-Win32-API package problem

[SJ Luo]

Hi,

  I have a small Perl program that utilize module
Win32::API::Callback. This module works properly if I downloaded this
module from CPAN and compile by myself. There occurs a problem if I
get it from binary package perl-Win32-API downloaded by Cygwin setup
program. I then tried to figure this problem out by downloading source
module and compile by myself. I found a simple flow to duplicate the
fail with the following sequence.

----- Cut here -----
% cd /usr/src/perl-Win32-API-0.84-1.src
% cygport perl-Win32-API.cygport prep compile
    :
% cd perl-Win32-API-0.84-1.x86_64/build/
% mv API_test64.dll API_test64.dll.lnk; cp API_test64.dll.lnk API_test64.dll
% mv rtc64.dll rtc64.dll.lnk; cp rtc64.dll.lnk rtc64.dll
% cd Callback
% make test
    :
    (Failed test 'callback function works' at t/02_Callback.t line 58.)
    :
% touch Callback.c
% make
% make test
    :
    (All tests passed)
    :
----- Cut here -----

  The two lines of commands "mv xxxx; cp xxx" are to dereference the
symbolic links of testing-needed dll files because
Win32::API::LoadLibrary() seems not be able to resolve Cygwin symbolic
link.
  Two "make test" commands are shown above. The first test fails at
02_Callback.t line 75. After fail, a force recompile of the
Callback.dll module is done by touch and make. Doing "make test"
again, this time all test items passed.

  By checking the gcc compile option, I found there is a gcc option
"-fno-stack-protector" provided when I compile this module by myself,
while the option is removed when I compile with cygport. If I try
manually compiling without this option, the same problem occurs.

The host system is Windows7. Cygwin dll is 64bit version 2.10.0-1.
wish it can be solved soon in next package release.

Thanks,
SJ
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Re: perl-Win32-API package problem

[Achim Gratz]

SJ Luo writes:
>   The two lines of commands "mv xxxx; cp xxx" are to dereference the
> symbolic links of testing-needed dll files because
> Win32::API::LoadLibrary() seems not be able to resolve Cygwin symbolic
> link.

You'd need to use native symlinks for that to work, yes.

>   By checking the gcc compile option, I found there is a gcc option
> "-fno-stack-protector" provided when I compile this module by myself,
> while the option is removed when I compile with cygport. If I try
> manually compiling without this option, the same problem occurs.

I don't know enough of how the stack protector actually is implemented
to understand why it would work without the protector and stop working
with.

> The host system is Windows7. Cygwin dll is 64bit version 2.10.0-1.
> wish it can be solved soon in next package release.

I'll see if it's possible to remove the option from within cygport, if
yo I'll have to think about any ramifications that might have.


Regards,
Achim.
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Re: perl-Win32-API package problem

[Achim Gratz]

SJ Luo writes:
>   I have a small Perl program that utilize module
> Win32::API::Callback.

Sorry that it took so long, but the problem should be fixed with the new
release of that package.  Please confirm that it works for your
application when you get the chance to test, thank you.


Regards,
Achim.
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Re: perl-Win32-API package problem

[S.J. Luo]

Hi Achim,

> >   By checking the gcc compile option, I found there is a gcc option
> > "-fno-stack-protector" provided when I compile this module by myself,
> > while the option is removed when I compile with cygport. If I try
> > manually compiling without this option, the same problem occurs.
>
> I don't know enough of how the stack protector actually is implemented
> to understand why it would work without the protector and stop working
> with.
>
> I'll see if it's possible to remove the option from within cygport, if
> yo I'll have to think about any ramifications that might have.

Thanks for the responding. I just learned that stack protector is
trying to prevent against buffer overflow/stack-corruption based
attacks. It might not be a big issue. A crack-aware program shall
simply avoid this module.

And yes I believe it is complex that how stack protector have
influence on this Perl module. But I think this option is just
necessary. The Makefile.PL explicitly applies -fno-stack-protector
option on non-MSVC compilers with 64bit target:

https://metacpan.org/source/BULKDD/Win32-API-0.84/Makefile.PL#L149

SJ

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