Comment by josefx
4 years ago
> Your code snippet assumes that your C compiler is just a high-level assembler. But it's not - it executes against a theoretical C virtual machine that doesn't know about about forking.
Luckily a C compiler that doesn't know about concepts outside of the C Virtual machine will not be able to compile a Linux executable or even dynamically load a library that exposes the vfork call (let alone try to execute the underlying system call directly).
That doesn't make sense. The C VM only affects how C code is understood by the compiler, in particular what optimisations are allowed. It doesn't stop the compiler from generating an executable or linking to libraries.
> It doesn't stop the compiler from generating an executable or linking to libraries.
The C standard claims multiple definitions result in undefined behavior. Dynamic libraries are filled to the brim with copies of symbols because it is impossible to tell in which library a symbol should be stored. Linking against a dynamic standard library cannot end well.