Waiter program that waits on a sleeping child

waiter.cpp

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

extern char** environ;

int main(int argc, char* argv[])
{
    if (argc != 3) {
        puts("Usage: waiter <seconds to wait on child> <options>");
        return 1;
    }

    char* fake_argv[] = {const_cast<char*>("/bin/sleep"), argv[1], nullptr}; 
    pid_t child = fork();
    if (!child) {
        int rc = execve(fake_argv[0], const_cast<char* const*>(fake_argv), environ);
        if (rc < 0) {
            if (errno == ENOENT)
                fprintf(stderr, "%s: Command not found.\n", argv[0]);
            else
                fprintf(stderr, "execvp(%s): %s\n", argv[0], strerror(errno));
            _exit(1);
        }
        assert(false);
    }
    int wstatus = 0;
    int options = atoi(argv[2]);

    while(true) {
        int rc = waitpid(child, &wstatus, options);
        if (rc < 0 && errno != EINTR) {
            if (errno != ECHILD)
                perror("waitpid");
            break;
        }
        if (WIFEXITED(wstatus)) {
            if (WEXITSTATUS(wstatus) != 0)
                printf("waiter : sleep(%d) exited with status %d", child, WEXITSTATUS(wstatus));
        } else if (WIFSTOPPED(wstatus)) {
            fprintf(stderr, "waiter: sleep(%d) stoped with signal %s\n", child, strsignal(WSTOPSIG(wstatus)));
        } else {
            if (WIFSIGNALED(wstatus)) {
                printf("waiter: sleep(%d) exited due to signal '%s'\n", child, strsignal(WTERMSIG(wstatus)));
            } else {
                // Should use WIFCONTINUED but that's not supported in serenity :(
                //printf("waiter: sleep(%d) %s\n", child, WIFCONTINUED(wstatus) ? "continued" : "funny business");
                printf("waiter: sleep(%d) something else happened\n", child);
            }
        }
        sleep(1);
    }
    return 0;
}