barf.c

#include <stdio.h>
#include <stdlib.h>
 
struct data_info
{
    void (*done_callback) (int status);
};
 
void done_handler(int status)
{
    printf("done_handler: status=%d\n", status);
}
 
void process(struct data_info* thing, int status)
{
    if (thing && thing->done_callback)
    thing->done_callback(status);
}
 
int main(int argc, char* argv[])
{
    struct data_info* test2;
    struct data_info test;
     
    test2 = malloc(sizeof(struct data_info));
    test2->done_callback = done_handler;
    process(test2, 2);
    free(test2);
 
    /*test2 = NULL; left dangling! */
     
    if (!test2 || !test2->done_callback)
    {
        puts("test2 bad, aborting");
        return -1;
    }
 
    test.done_callback = test2->done_callback;
    if (!test.done_callback)
        puts("no callback, aborting");
    process(&test, 1);
    return 0;
}