How to have cmake unpack my compiler

Question

In order to ensure that my Linux builds are identical regardless of the distribution the build host uses, I have packaged up my compiler and the sysroot files into a relocatable tar file and checked that into source control.

So the first step in any build (or at least, a step that must be invoked before any compile step) must be to extract this tar file.

If I was using a makefile, this would be simple to do. However, the project is using cmake and I can't figure out any way to do it with cmake. It might even be that I need this extract step invoked before cmake starts to detect the compiler: I can hard-code the compiler name but if cmake fails if it can't find the compiler then I need the unpack to happen before that test.

Is this possible with cmake?

Answer 1

You can use execute_process to invoke cmake's cross-platform command mode (cmake -E tar). The command would be something like:

execute_process(COMMAND ${CMAKE_COMMAND} -E tar xvf MyCompiler.bz2)

The command which causes CMake to check for a valid compiler is project, so as long as you have your execute_process call before the project call, the unpacking will be done before the compiler check.