Hook call vs hook function

[thawalrus]

Hello,

I was interested in how libcod does the hooking. Now I see that there are two functions that are very much alike: cracking_hook_function and cracking_hook_call. One is inserting a JMP instruction, the other is not.

Now, my question is: How does the function without the JMP instruction work? My assumption is that hooking always needs a JMP instruction.

Thanks in advance.

Regards,
Walrus