Wrapper program to make general applications into erlang ports.

port_adaptor.c

/*
 * Wrapper program to make general applications into erlang ports.
 */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sysexits.h>
#include <sys/wait.h>

#include <assert.h>

static int caught = 0;
static int grace = 0;

static void caught_signal(int which)
{
    caught = which;
}

static int wait_for_process(pid_t pid)
{
    int rv = EX_SOFTWARE;
    int stats = 0;
    int i = 0;
    struct sigaction sig_handler;
    char buf[256];

    sig_handler.sa_handler = caught_signal;
    sig_handler.sa_flags = 0;

    sigaction(SIGALRM, &sig_handler, NULL);
    sigaction(SIGHUP, &sig_handler, NULL);
    sigaction(SIGINT, &sig_handler, NULL);
    sigaction(SIGTERM, &sig_handler, NULL);
    sigaction(SIGPIPE, &sig_handler, NULL);
    sigaction(SIGCHLD, &sig_handler, NULL);

    fgets(buf, sizeof(buf), stdin);
    if (caught != SIGCHLD) {
        if (kill(pid, SIGTERM) < 0) {
            perror("Failed to kill my child.");
            exit(EX_SOFTWARE);
        }
    }

    /* Loop forever waiting for the process to quit */
    for (i = 0; ;i++) {
        sleep(grace);
        pid_t p = waitpid(pid, &stats, WNOHANG);
        if (p == pid) {
            /* child exited.  Let's get out of here */
            rv = WIFEXITED(stats) ?
                WEXITSTATUS(stats) :
                (0x80 | WTERMSIG(stats));
            break;
        } else {
            printf("Undead, sending sig N9NE\n");
            if (kill(pid, SIGKILL) < 0) {
                /* Kill failed.  Must have lost the process. :/ */
                perror("lost child when trying to kill");
                exit(EX_SOFTWARE);
            }
        }
    }
    return rv;
}

static int spawn_and_wait(int argc, char **argv)
{
    int rv = EX_SOFTWARE;
    pid_t pid = fork();

    assert(argc > 0);

    switch (pid) {
    case -1:
        perror("fork");
        rv = EX_OSERR;
        break; /* NOTREACHED */
    case 0:
        execvp(argv[0], argv);
        perror("exec");
        rv = EX_SOFTWARE;
        break; /* NOTREACHED */
    default:
        printf("%d\n", pid);
        fflush(stdout);
        rv = wait_for_process(pid);
    }
    return rv;
}

int main(int argc, char **argv)
{
    assert(argc > 2);
    grace = atoi(argv[1]);
    return spawn_and_wait(argc-2, argv+2);
}