Waiter program that waits on a sleeping child (Serenity only)

watier.cpp

#include <AK/Assertions.h>
#include <AK/LogStream.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_NOT_REACHED();
    }
    int wstatus = 0;
    int options = atoi(argv[2]);

    do {
        int rc = waitpid(child, &wstatus, options);
        if (rc < 0 && errno != EINTR) {
            if (errno != ECHILD)
                perror("waitpid");
            break;
        }
        if (WIFEXITED(wstatus)) {
            if (WEXITSTATUS(wstatus) != 0)
                dbg() << "waiter : sleep(" << child << ") exited with status " << WEXITSTATUS(wstatus);
        } else if (WIFSTOPPED(wstatus)) {
            fprintf(stderr, "watier: 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 {
                printf("waiter: sleep(%d) exited abnormally\n", child);
            }
        }
    } while (errno == EINTR);

    return 0;
}