Define _POSIX_SOURCE in cygwin's features.h?

Christopher Faylor cgf-no-personal-reply-please@cygwin.com
Thu Jan 12 17:59:00 GMT 2006


On Thu, Jan 12, 2006 at 05:40:35PM -0000, Dave Korn wrote:
>Christopher Faylor wrote:
>>Someone on the cygwin irc channel had a problem building a package
>>which would have been solved if Cygwin defined _POSIX_SOURCE.
>>
>>I know that Cygwin is not fully POSIX compliant (I really really do)
>>but I'm wondering if setting _POSIX_SOURCE in the cygwin headers
>>wouldn't solve more porting problems than it creates.
>>
>>Any opinions on this?  Eric?
>>
>>P.S.  I know that Cygwin isn't fully compliant with POSIX
>>specifications.
>
>As far as I can tell by googling, _POSIX_SOURCE, despite the leading
>underscore, is in fact a user-land feature test macro that it is up to
>each individual application to decide whether to switch it on or not
>according to whether the application itself is compliant or not.

No need to use google.  Just grep for it in /usr/include on linux.

_POSIX_SOURCE is defined in features.h on linux under control of the
_GNU_SOURCE macro.

  /* If _GNU_SOURCE was defined by the user, turn on all the other features.  */
  #ifdef _GNU_SOURCE
  # undef  _ISOC99_SOURCE
  # define _ISOC99_SOURCE 1
  # undef  _POSIX_SOURCE
  # define _POSIX_SOURCE  1
  # undef  _POSIX_C_SOURCE
  # define _POSIX_C_SOURCE        199506L
  # undef  _XOPEN_SOURCE
  # define _XOPEN_SOURCE  600
  # undef  _XOPEN_SOURCE_EXTENDED
  # define _XOPEN_SOURCE_EXTENDED 1
  # undef  _LARGEFILE64_SOURCE
  # define _LARGEFILE64_SOURCE    1
  # undef  _BSD_SOURCE
  # define _BSD_SOURCE    1
  # undef  _SVID_SOURCE
  # define _SVID_SOURCE   1
  #endif

So, let me clarify.  Should we define _POSIX_SOURCE similarly to the way
that linux does it?  This may mean that we have to define _GNU_SOURCE
also and maybe that's not a good idea but, again, it might solve more
problems than it causes.

cgf

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