Sleepless: symbol hijacking example

• Assume we have some program that uses some symbols (let's say the sleep function) from some shared library (the GNU C library, as an example.)

• We want to hijack the symbol such as that every time the program will call the 'sleep' it will call our provided version of it and not the original.

• What our 'sleep' function will do is print 'sleep less, do more' and then call the original sleep function but with half the sleep time requested.