// dynhello: the smallest honest test of dynamic linking.
//
// Linked against libc.so and libdynhello.so, with /lib/ld-musl-x86_64.so.1 as
// its interpreter, so nothing here works unless the kernel loaded the
// interpreter and the interpreter mapped both libraries. It then checks the
// three things a dynamic program leans on that a static one hides: thread-
// local storage (errno), the heap, and a fork whose child still has its
// libraries.

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <unistd.h>

int dynhello_greet(const char *who);

int
main(int argc, char **argv)
{
    int bad = 0;

    dynhello_greet(argc > 1 ? argv[1] : "world");

    errno = 0;
    if (close(-1) == 0 || errno != EBADF) {
        printf("dynhello: FAIL errno is %d, not EBADF\n", errno);
        bad++;
    }

    char *p = malloc(1 << 20);
    if (!p) {
        printf("dynhello: FAIL malloc\n");
        bad++;
    } else {
        memset(p, 0x5a, 1 << 20);
        free(p);
    }

    pid_t pid = fork();
    if (pid == 0) {
        dynhello_greet("child");
        _exit(0);
    }
    int st = 0;
    if (pid < 0 || waitpid(pid, &st, 0) != pid || !WIFEXITED(st) ||
        WEXITSTATUS(st) != 0) {
        printf("dynhello: FAIL fork child status %d\n", st);
        bad++;
    }

    printf("dynhello: %s\n", bad ? "FAILED" : "ok");
    return bad != 0;
}