cmdctl.c

/*-
 * Copyright (c) 2014 Unknown
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/prctl.h>
#include <sys/wait.h>
#include <poll.h>

struct cmdctl {
    pid_t       pid;
    pthread_t   tp;
    int     fds[6];
    const char  *prefix;
};
static struct cmdctl *cmdctl;

static int
CMD_nonblocking(int sock)
{
        int i, j;

        i = 1;
        j = ioctl(sock, FIONBIO, &i);
    assert(j == 0);
        return (j);
}

static void *
CMD_thread(void *priv)
{
    struct cmdctl *v;
    struct pollfd *fds, fd;
    char buf[8 * 1024];
    int i;

    v = priv;
    CMD_nonblocking(v->fds[0]);
    while (1) {
        fds = &fd;
        memset(fds, 0, sizeof *fds);
        fds->fd = v->fds[0];
        fds->events = POLLIN;
        i = poll(fds, 1, 1000);
        if (i == 0)
            continue;
        if (fds->revents & (POLLERR|POLLHUP))
            break;
        i = read(v->fds[0], buf, sizeof buf - 1);
        if (i <= 0)
            break;
        buf[i] = '\0';
        printf("%s%s", v->prefix, buf);
    }
    return (NULL);
}

static void
CMD_RunChild(void)
{
    struct pollfd *fds, fd;
    int error, i, l, offset = 0;
    char buf[8 * 1024], *p, *q;
    char msg[1024];

    error = prctl(PR_SET_PDEATHSIG, SIGHUP);
    if (error != 0)
        printf("prctl(2) failed: %d %s.", errno,
            strerror(errno));

    assert(dup2(cmdctl->fds[0], 0) == 0);
    assert(dup2(cmdctl->fds[3], 1) == 1);
    assert(dup2(1, 2) == 2);
    assert(dup2(cmdctl->fds[4], 3) == 3);
    AZ(close(cmdctl->fds[0]));
    AZ(close(cmdctl->fds[1]));
    AZ(close(cmdctl->fds[2]));
    AZ(close(cmdctl->fds[3]));
    setbuf(stdout, NULL);
    setbuf(stderr, NULL);
    CMD_nonblocking(cmdctl->fds[4]);
        while (1) {
                fds = &fd;
                memset(fds, 0, sizeof *fds);
                fds->fd = cmdctl->fds[4];
                fds->events = POLLIN;
                i = poll(fds, 1, 1000);
                if (i == 0)
                        continue;
                if (fds->revents & (POLLERR|POLLHUP))
                        break;
                i = read(cmdctl->fds[4], buf + offset, sizeof buf - 1 - offset);
                if (i <= 0)
                        break;
                buf[i] = '\0';
        p = buf;
        while (1) {
            q = strchr(p, '\n');
            if (q == NULL) {
                offset = &buf[i] - p;
                memmove(buf, p, offset);
                break;
            }
            offset = 0;
            *q = '\0';
            {
                struct cmdctl _v, *v = &_v;
                void *pp;
                int status, r;

                AZ(pipe(&v->fds[0]));
                AZ(pipe(&v->fds[2]));
                v->prefix = "";
                v->pid = fork();
                assert(v->pid >= 0);
                if (v->pid == 0) {
                    assert(dup2(v->fds[0], 0) == 0);
                    assert(dup2(v->fds[3], 1) == 1);
                    assert(dup2(1, 2) == 2);
                    AZ(close(v->fds[0]));
                    AZ(close(v->fds[1]));
                    AZ(close(v->fds[2]));
                    AZ(close(v->fds[3]));
                    for (i = 3; i <getdtablesize(); i++)
                        (void)close(i);
                    printf("Executing %s\n", p);
                    AZ(execl("/bin/sh", "/bin/sh", "-c",
                        p, NULL));
                    exit(1);
                }
                AZ(close(v->fds[0]));
                AZ(close(v->fds[3]));
                v->fds[0] = v->fds[2];
                v->fds[2] = v->fds[3] = -1;
                AZ(pthread_create(&v->tp, NULL, CMD_thread, v));

                /* May already have been closed */
                (void)close(v->fds[1]);
                AZ(pthread_join(v->tp, &pp));
                AZ(close(v->fds[0]));
                r = wait4(v->pid, &status, 0, NULL);
                v->pid = 0;
                l = snprintf(msg, sizeof(msg),
                    "R %d Status: %04x", r, status);
                if (!WIFEXITED(status) ||
                    WEXITSTATUS(status) != 0) {
                    l += snprintf(msg + l, sizeof(msg) - l,
                        " Bad exit code: %04x sig %x"
                        " exit %x",
                        status, WTERMSIG(status),
                        WEXITSTATUS(status));
                }
                l += snprintf(msg + l, sizeof(msg) - l, "\n");
                printf("%s", msg);
            }
            p = q + 1;
        }
        }
    printf("Command controller exited.\n");
    exit(1);
}

void
CMD_Execute(const char *fmt, ...)
{
    va_list ap;
    ssize_t l;
    int buflen;
    char buf[BUFSIZ];

    va_start(ap, fmt);
    buflen = vsnprintf(buf, sizeof(buf), fmt, ap);
    va_end(ap);
    assert(buflen < sizeof(buf));

    l = write(cmdctl->fds[5], buf, buflen);
    if (l == -1) {
        printf(
            "write(2) error for command \"%s\": %d %s\n", buf,
            errno, strerror(errno));
        return;
    }
    /* XXX no wait until it finishes? */
}

static void
CMD_Run(void)
{

    cmdctl = calloc(1, sizeof(*cmdctl));
    AN(cmdctl);
    cmdctl->prefix = "Child said: ";
    AZ(pipe(&cmdctl->fds[0]));
    AZ(pipe(&cmdctl->fds[2]));
    AZ(pipe(&cmdctl->fds[4]));
    cmdctl->pid = fork();
    assert(cmdctl->pid >= 0);
    if (cmdctl->pid == 0)
        CMD_RunChild();
    AZ(close(cmdctl->fds[0]));
    AZ(close(cmdctl->fds[3]));
    AZ(close(cmdctl->fds[4]));
    cmdctl->fds[0] = cmdctl->fds[2];
    cmdctl->fds[2] = cmdctl->fds[3] = -1;
    AZ(pthread_create(&cmdctl->tp, NULL, CMD_thread, cmdctl));
}

static void
CMD_Fini(void)
{

    if (cmdctl->pid >= 0)
        kill(cmdctl->pid, SIGTERM);
}

#ifdef TEST
int
main(void)
{
    CMD_Run();
    CMD_Execute("blah");
    CMD_Fini();
}