how to trace function call in C?

Question

Without modifying the source code, how can i trace which functions are called and with what parameters, when some function(say func100 in the following example) is invoked. I would like the output to be as follows:

enter func100(p1001=xxx,p1002=xxx)
        enter func110(p1101=xxx,p1102=xxx)
        exit  func110(p1101=xxx,p1102=xxx)
        enter func120(p1201=xxx,p1202=xxx,p1203=xxx)
                enter func121(p1211=xxx)
                exit  func121(p1211=xxx)
        exit  func120(p1201=xxx,p1202=xxx,p1203=xxx)
exit  func100(p1001=xxx,p1002=xxx)

is this doable? or what's the solution with minimum modification of source code?

Answer 1

Use a debugger to set breakpoints with associated actions. For example, in gdb you could set a breakpoint at the beginning and end of each of the functions you want to trace. You can give each of those breakpoints a command to execute, such as:

printf("Enter func100(p1001=%d, p1002=%d)", p1001, p1002)

Then, when you run the program (in the debugger) it'll print the text from each of your commands along with the associated parameters.

Take a look at the relevant documentation for gdb.

Answer 2

If you use dynamic modules you can get this info with the command ltrace. You can even specify the watched library with the -l flag