// trace_hook.c — intercept signal handler to log VM state
#define _GNU_SOURCE
#include <signal.h>
#include <stdio.h>
#include <dlfcn.h>

static FILE *trace;

int sigaction(int signum, const struct sigaction *act,
              struct sigaction *oldact) {
    // Log which signals are being registered
    if (!trace) trace = fopen("/tmp/vm_trace.txt", "w");
    fprintf(trace, "sigaction(%d)\n", signum);
    fflush(trace);

    // Call real sigaction
    int (*real)(int, const struct sigaction*, struct sigaction*) =
        dlsym(RTLD_NEXT, "sigaction");
    return real(signum, act, oldact);
}