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 in

Answer 1

With the GNU C Library, you can use the backtrace module. Here is an example for that:

#include 
#include 
#include 


void handler(char *caller) {
  void *array[10];
  size_t size;
  printf("Stack Trace Start for %s\n",caller);
  size = backtrace(array, 10);
  backtrace_symbols_fd(array, size, 2);
  printf("Stack Trace End\n");
}

void car() {
    handler("car()");
    printf("Continue Execution");
}
void baz() {car(); }

void bar() { baz(); }
void foo() { bar(); }


int main(int argc, char **argv) {
  foo(); 
}

compile with -g -rdynamic compiler option to load the symbols

gcc -g -rdynamic Test1.c -o Test

You will see an output similar to

Stack Trace Start for car()
./Test(handler+0x2d)[0x80486f1]
./Test(car+0x12)[0x804872e]
./Test(baz+0xb)[0x8048747]
./Test(bar+0xb)[0x8048754]
./Test(foo+0xb)[0x8048761]
./Test(main+0xb)[0x804876e]
/lib/i386-linux-gnu/libc.so.6(__libc_start_main+0xe7)[0x126e37]
./Test[0x8048631]
Stack Trace End
Continue Execution in car

You can write this handler function and call from anywhere in your program at any number of time. Remember to increase the array size as required.