I know it is a Macro we are passing to a function. How do you explain what is the use of this macro, and in which scenario i have to use this ?.
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I know it is a Macro we are passing to a function. How do you explain what is the use of this macro, and in which scenario i have to use this ?.
Whereas applications developed conforming to POSIX.1 – (IEEE 1003.1-2008, ISO/IEC 9945:2009) and / or Single Unix Specification 2008 (ISO/IEC 9945:2009 with X/Open Curses) help ensure how portable your application is. The
_GNU_SOURCEwill most likely limits source code usage to GNU/Linux and GNU/Hurd systems, unless additional work is done to address the non-portability of such functionality on other platforms.Some companies, and government / military contracts may require certain platform standards to be used.
If you are developing an Open Source / Free Software application that you wish to be available on multiple Unix and Unix-like systems (including Microsoft Windows NT, 2000, and newer which have a POSIX compatibility available) then limiting your development to POSIX.1 library functions makes this an easier task. Other targets include the free/open BSD platforms NetBSD, FreeBSD, OpenBSD, DragonflyBSD, as well as the commercial Unix systems (Solaris, AIX, HP/UX, etc.) that do not include
_GNU_SOURCEfunctionality.If you use an altered functionality of a portable function, I can’t think of an example but I believe they do exist, it may create subtle bugs in non-GNU platforms.
So in general, if your development is already locked into GNU / Linux and GNU / Hurd then feel free to use such extensions, but avoid such usages for any applications that may be deployed on other Unix and Unix-like operating systems.
I do work on a large-ish code base that has been ported from two other Unix platforms to Linux, and we do use
_GNU_SOURCEextensions sparingly, though most of the development is limited to modern POSIX or IEEE 1003.1 / Single Unix Spec and C99 (Standard C Library) standards for future compatibility.