callgraph.c

/*
 * callgraph.c
 *
 *      Subroutine-rich sample to help testing
 *      any type of analysis tooling involving callgraphs,
 *      whether static or dynamic.
 *
 *      Each function implements some type of edge case
 *      that one may want to consider covering in their tool,
 *      such as function pointers.
 */

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void start(int value);
void end(void);

void foo(int value);
void bar(int value);

void flop(void);
void flap(void);
void borp(int value);

/* Tests: deterministic control split */
void start(int value) {
    if (value < 42)
        foo(value);
    else
        bar(value);
}


/* Tests: nondeterministic control split */
void foo(int value)
{
    //srand(time(NULL));
    //int seed = rand() + value;

    if (value >= 12)
        flop();
    else
        flap();
}

/* Tests: function pointers and indirect calls */
void bar(int value)
{
    void (*p)();
    if (value != 1)
        p = flap;
    else
        p = flop;

    p();
}


/* Tests: back edge to parent (WARNING: infinite loop) */
void flop(void) 
{
    borp(0);
}

void flap(void)
{
    borp(1);
}

void borp(int value)
{
    if (value == 0)
        flop();
    else if (value == 1)
        flap();
}


/* Tests: imports */
void end(void)
{
    exit(0);
}

int main(int argc, char *argv[])
{
    if (argc < 2) {
        return -1;
    }
    int value = atoi(argv[1]);
    start(value);

    printf("Done! Ending...\n");
    end();
}