How do I reimplement (or wrap) a syscall function on Linux?

Question

Suppose I want to completely take over the open() system call, maybe to wrap the actual syscall and perform some logging. One way to do this is to use LD_PRELOAD to load a (

Answer 1

Symbols are resolved by the linker in the order you list them on the command line so if you listed your library before the standard library you'd have precidence. For gcc you'd need to specify

gcc  -nodefaultlibs  -lYOUR_LIB 

This way your libraries would be searched and found first.