Question

I am writing a C program with POSIX API and using Linux.
I compiled and ran it on a friend’s Mac OSX PC and there was a small error, but I did not use Linux specific features.

I will use some specific features that Linux adds to the API. I will also use specific POSIX extensions for Mac Os X and FreeBSD.
I will use conditional compilation to choose the code. If the OS is none of those, I will use generic POSIX code.

I do not own Darwin/Mac OSX and FreeBSD, Linux is the only OS that I have in my PC. I cannot download and install FreeBSD, because it is more than 500 MB.
I want to know a way to test if the program will compile and behave as expected on other POSIX systems.
I wonder if there is a POSIX simulator and compiler to do tests.
The tests are simple, they do not use GUI and drivers, they are only command line.

I will need to do 3 tests: FreeBSD, Mac OSX/Darwin and Generic POSIX, but I do not have the tools.

EDIT

Is there a minimal version of FreeBSD and Darwin without GUI, but with GCC/G++ and ssh/scp? Darwin is free, is not it?
My PC is old, but I think I can install them in a virtual machine, create a virtual network and use ssh/scp to transfer and test the programs.

Answer 1

One simple way is to compile your program with the proper feature test macros. For example if you define _POSIX_C_SOURCE to the target version of POSIX (currently 200809L), you will request the system headers expose to your program nothing except what’s needed/allowed by POSIX base. This can be done via the command line CFLAGS with -D_POSIX_C_SOURCE=200809L. If you want the XSI option (full Single Unix Standard functionality, which is a superset of POSIX base) then use -D_XOPEN_SOURCE=700 instead.

This will not help you detect problems that come from either certain systems lacking POSIX functionality (for example, OSX is broken and lacks a working sem_init last I checked, even though it’s mandatory in POSIX), or from writing code that depends on non-standard behavior in the POSIX-standard interfaces (for example, using GNU regex extensions in the expressions you pass to regcomp) but it will help you catch any accidental usage of interfaces not in the standard.