Back: A Simple GNU/Linux Module Loader
Forward: Using GNU libltdl
 
FastBack: Dynamic Loading
Up: Dynamic Loading
FastForward: Using GNU libltdl
Top: Autoconf, Automake, and Libtool
Contents: Table of Contents
Index: Index
About: About this document

17.5 A Simple GNU/Linux Dynamic Module


As an appetiser for working with dynamic loadable modules, here is a minimal module written for the interface used by the loader in the previous section:

 
#include <stdio.h>

int
run (const char *argument)
{
  printf ("Hello, %s!\n", argument);
  return 0;
}

Again, to compile on a GNU/Linux machine:

 
$ gcc -fPIC -c simple-module.c
$ gcc -shared -o simple-module.so

Having compiled both loader and module, a test run looks like this:

 
$ ./simple-loader simple-module World
Hello, World!
        => 0

If you have a GNU/Linux system, you should experiment with the simple examples from this chapter to get a feel for the relationship between a dynamic module loader and its modules -- tweak the interface a little; try writing another simple module. If you have a machine with a different dynamic loading API, try porting these examples to that machine to get a feel for the kinds of problems you would encounter if you wanted a module system that would work with both APIs.

The next chapter will do just that, and develop these examples into a fully portable module loading system with the aid of GNU Autotools. In 20.1 A Module Loading Subsystem, I will add a more realistic module loader into the Sic project last discussed in 12. A Large GNU Autotools Project.



This document was generated by Gary V. Vaughan on February, 8 2006 using texi2html