Method and apparatus for modifying relocatable object code files and monitoring programs

A computer program product stored on a computer readable medium that stores computer codes for equipping a computer program with an interceptor function for being executed in place of an intercepted function, said computer program having a plurality of object code files including a first object code file containing a definition of said intercepted function and a second object code file including a first structure identifying said intercepted function definition by an original intercepted function name, said computer program product comprising:

• computer code that modifies said first structure to identify said intercepted function definition by a modified intercepted function name, whereby a modified second object code file is produced;
• computer code that provides a third object code file containing a definition of said interceptor function and a second structure identifying said interceptor function definition by said original intercepted function name;
• and
• computer code that links at least said modified first object code file, said second object code file and said third object code file to produce a modified computer program whereby a first call causes execution of said interceptor function.