Calling Global Constructors: Difference between revisions

To understand this apparent complexity, consider a program consisting of <tt>foo.o</tt> and <tt>bar.o</tt> that is being linked:

 

 

The compiler will rewrite the command line and pass it to the linker as:

 

 

The idea is that the these files together form the <tt>_init</tt> and <tt>_fini</tt> functions during the linking. This is done by storing the <tt>_init</tt> function in the <tt>.init</tt> section, and the <tt>_fini</tt> function in the <tt>.fini section</tt>. Each file then contributes a bit to these sections and the linker makes glues together the fragments in the code specified on the command line. <tt>crti.o</tt> provides the function header, <tt>crtbegin.o</tt> and <tt>crtend.o</tt> provide the body, and <tt>crtn.o</tt> provide the footer (return statement). It is important to understand that the link order matters and strange things may happen if the objects is not exactly linked in this order.