Linking pthread.dll to another dll

Linking pthread.dll to another dll

[Erik Hensema]

Hi,

I'm porting a shared library from Unix to NT, and I'm using pthread.dll for
the multithreaded support.
I'm having trouble using errno and the lib. Using the debugger, I can see
that errno seems to be a function (huh? why does errno = x; work???). In my
source, errno is a variable. Obiviously, errno doesn't change after a call
to a pthread function.

What can I do to make errno work? And, how is errno implemented in the
pthread dll? Is it some C++ syntax or something? My source is Ansi C.

I'm using MSVC 6.0 from the command line, and I'm using this line to link my
dll:

cl /Fehic.dll /LDd /Zi /MTd $(OBJ) \
   hic.def \
   pthread.lib \
   thread.lib \
   ws2_32.lib \
   nt-support.lib \
   mvxutil.lib \
   mon.lib

I've tried to use the way pthread.dll is linked, however, I get an
unresolved symbol "errno" when I try that. Should I include some file to
make it work?
Please note there's nothing in the online help about errno being a function
or something.

-- 
Erik Hensema
Work: erik.hensema@group2000.nl
Home: erik@hensema.xs4all.nl

Re: Linking pthread.dll to another dll

[Mumit Khan]

Erik Hensema <erik.hensema@group2000.nl> writes:
> Hi,
> 
> I'm porting a shared library from Unix to NT, and I'm using pthread.dll for
> the multithreaded support.
> I'm having trouble using errno and the lib. Using the debugger, I can see
> that errno seems to be a function (huh? why does errno = x; work???). In my
> source, errno is a variable. Obiviously, errno doesn't change after a call
> to a pthread function.
> 
> What can I do to make errno work? And, how is errno implemented in the
> pthread dll? Is it some C++ syntax or something? My source is Ansi C.


The errno is implemented as a macro on (most, if not all of the) MT
capable runtime libraries, and you need to be careful not to make the 
usual mistake that's in lots of code developed under older varieties 
of Unix:
  
  extern int errno;
  /* use errno. */

The correct form is:

  #include <errno.h>
  /* use errno. */

Regards,
Mumit