Re: missing prototypes in io.h

[Mumit Khan <khan at NanoTech dot Wisc dot EDU>]

Jimen Ching <jching@flex.com> writes:
> 
> I wrote a program that uses the cygwin UNIX layer.  I need to link this
> application to a library that was written for Win32.
> 
> My program compiles with cygwin, no problems.  When I tried to compile the
> library using cygwin, it includes io.h and wants the 'access' function
> prototype.  But io.h (non-mingw32 version) has almost nothing in it.

And it shouldn't. It's a platform specific header, and is not required
to have anything more than what's needed for *that* platform.

> I'm compiling the source of both without the mingw32 option.  Thus, gcc
> does not look into the mingw32 header directory.  Am I supposed to compile
> the library using mingw32, and my program with non-mingw32?  I was under
> the impression that I can write an application that uses both the Win32
> API _and_ the cygwin UNIX layer.  But the header files seem to stand in
> the way...

I do this all the time, and just do the right thing depending on the 
platform. Most of my code is configure driven, so it's a bit different,
but the basic idea is the following:
  
  /* Get access() prototype. */
  #ifdef __MINGW32__
  # include <io.h>
  #elif HAVE_UNISTD_H
  # include <unistd.h>
  #else
  # /* do something to declare access() on systems that lack unistd.h.
  #endif

Where HAVE_UNISTD_H is probed for by configure. If you know your target
Unix/Cygwin system already has unistd.h, you can always do the following:

  /* Get access() prototype. */
  #ifdef __MINGW32__
  # include <io.h>
  #else
  # include <unistd.h>
  #endif

Regards,
Mumit


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