RE: Linking Cygwin & MSVC objects / libraries using MSVC linker

RE: Linking Cygwin & MSVC objects / libraries using MSVC linker

[Nicholas Peters]

>From: "Robert Collins" <robert.collins@itdomain.com.au>
>To: "Nicholas Peters" <nickapeters@hotmail.com>, <cygwin@cygwin.com>
>Subject: RE: Linking Cygwin & MSVC objects / libraries using MSVC linker
>Date: Tue, 24 Apr 2001 10:55:15 +1000
>
> > -----Original Message-----
> > From: Nicholas Peters [ mailto:nickapeters@hotmail.com ]
> > Sent: Tuesday, April 24, 2001 10:59 AM
> > To: cygwin@cygwin.com
> > Subject: Linking Cygwin & MSVC objects / libraries using MSVC linker
> >
> >
> > Is it possible to link Cygwin compiled objects and Microsoft
> > Visual C (not
> > C++) objects using the libcygwin.a and it's associated libraries  and
> > Microsofts various libraries (MSVCRT, etc).  I would very
> > much like to use
>
>lybcygwin.a is mainly an import lib for cygwin1.dll aka libm aka libc
>aka lpthread aka I'm not shure howmanyotherlibraries.
>
> > the MSVC linker for this (not ld) but am open to all ideas.
> > When I tried
> > to just flat out link (with MSVC linker) I got some errors
> > from libcygwin.a
> > stating it had undefined external references to data_start, data_end,
> > bss_start, bss_end.  After reading through some of the mail
> > archives for
> > this list I decided to throw in some null char declarations for those
> > references since I'm not using the fork functionality of
> > libcygwin.  I get
> > two warnings in the link, and the resulting exe crashes.
> >
> > The warnings are:
> > libcygwin.a : warning multiple ".idata" sections found with different
> > attributes.
> >
> > libcygwin.a : warning __fmode already defined in MSVCRT.LIB second
> > definition ignored.
> >
> > When I list libcygwin.a BEFORE MSVCRT in my link command
> > line, the second
> > warning changes to:
> >
> > MSVCRT.LIB : warning _atexit already defined in libcygwin.a second
> > definition ignored.
> >
> > Either way the the produced executable crashes with "The
> > instruction at
> > <address> referenced memory at <address>.  The memory could
> > not be "read". "
>
>AFAIK you cannot mix MSVCRT.LIB and libcygwin.a. They implement the same
>functions. What do you need from cygwin?

   I need mostly socket stuff, the link (with MSVC) without libcygwin.a 
produces:

: error LNK2001: unresolved external symbol _gethostname
: error LNK2001: unresolved external symbol _sleep
: error LNK2001: unresolved external symbol __imp___ctype_
: error LNK2001: unresolved external symbol _accept
: error LNK2001: unresolved external symbol _select
: error LNK2001: unresolved external symbol _listen
: error LNK2001: unresolved external symbol _bind
: error LNK2001: unresolved external symbol _setsockopt
: error LNK2001: unresolved external symbol _socket
: error LNK2001: unresolved external symbol _htons
: error LNK2001: unresolved external symbol _getservbyname
: error LNK2001: unresolved external symbol __impure_ptr
: error LNK2001: unresolved external symbol __impure_ptr

   From previous experience I believe I can safely ignore the impure_ptr 
errors (by forcing the link with /FORCE), and if you know what libraries to 
strip out of libcygwin to get the above symbols taken care of that would be 
great.  Thanks for responding.

                                           Nick
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Re: Linking Cygwin & MSVC objects / libraries using MSVC linker

[Jesper Eskilson]

"Nicholas Peters" <nickapeters@hotmail.com> writes:

>    I need mostly socket stuff, the link (with MSVC) without libcygwin.a
>    produces:

Note that there are no socket-stuff in MSVCRT.*, you need to link with
ws2_32.lib for that. You should be able to resolve most of your socket-calls
with the ones there.

/Jesper
-- 
-------------------------------------------------------------------------
Jesper Eskilson                                         jojo@virtutech.se
Virtutech                                         http://www.virtutech.se
-------------------------------------------------------------------------


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RE: Linking Cygwin & MSVC objects / libraries using MSVC linker

[Robert Collins]

> -----Original Message-----
> From: Nicholas Peters [ mailto:nickapeters@hotmail.com ]
> Sent: Tuesday, April 24, 2001 10:59 AM
> To: cygwin@cygwin.com
> Subject: Linking Cygwin & MSVC objects / libraries using MSVC linker
> 
> 
> Is it possible to link Cygwin compiled objects and Microsoft 
> Visual C (not 
> C++) objects using the libcygwin.a and it's associated libraries  and 
> Microsofts various libraries (MSVCRT, etc).  I would very 
> much like to use 

lybcygwin.a is mainly an import lib for cygwin1.dll aka libm aka libc
aka lpthread aka I'm not shure howmanyotherlibraries.

> the MSVC linker for this (not ld) but am open to all ideas.  
> When I tried  
> to just flat out link (with MSVC linker) I got some errors 
> from libcygwin.a 
> stating it had undefined external references to data_start, data_end, 
> bss_start, bss_end.  After reading through some of the mail 
> archives for 
> this list I decided to throw in some null char declarations for those 
> references since I'm not using the fork functionality of 
> libcygwin.  I get 
> two warnings in the link, and the resulting exe crashes.
> 
> The warnings are:
> libcygwin.a : warning multiple ".idata" sections found with different 
> attributes.
> 
> libcygwin.a : warning __fmode already defined in MSVCRT.LIB second 
> definition ignored.
> 
> When I list libcygwin.a BEFORE MSVCRT in my link command 
> line, the second 
> warning changes to:
> 
> MSVCRT.LIB : warning _atexit already defined in libcygwin.a second 
> definition ignored.
> 
> Either way the the produced executable crashes with "The 
> instruction at 
> <address> referenced memory at <address>.  The memory could 
> not be "read". "

AFAIK you cannot mix MSVCRT.LIB and libcygwin.a. They implement the same
functions. What do you need from cygwin?

Rob

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Linking Cygwin & MSVC objects / libraries using MSVC linker

[Nicholas Peters]

Is it possible to link Cygwin compiled objects and Microsoft Visual C (not 
C++) objects using the libcygwin.a and it's associated libraries  and 
Microsofts various libraries (MSVCRT, etc).  I would very much like to use 
the MSVC linker for this (not ld) but am open to all ideas.  When I tried  
to just flat out link (with MSVC linker) I got some errors from libcygwin.a 
stating it had undefined external references to data_start, data_end, 
bss_start, bss_end.  After reading through some of the mail archives for 
this list I decided to throw in some null char declarations for those 
references since I'm not using the fork functionality of libcygwin.  I get 
two warnings in the link, and the resulting exe crashes.

The warnings are:
libcygwin.a : warning multiple ".idata" sections found with different 
attributes.

libcygwin.a : warning __fmode already defined in MSVCRT.LIB second 
definition ignored.

When I list libcygwin.a BEFORE MSVCRT in my link command line, the second 
warning changes to:

MSVCRT.LIB : warning _atexit already defined in libcygwin.a second 
definition ignored.

Either way the the produced executable crashes with "The instruction at 
<address> referenced memory at <address>.  The memory could not be "read". "

A message in the archives had a similar problem:

http://sources.redhat.com/ml/cygwin/1997-12/msg00071.html

but the author didn't get a reply as far as I can tell, so I thought I'd try 
my luck. If you need more info just let me know, any help is appreciated.

                                      Nick Peters

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