harddog_user.c

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/*
 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <os.h>

struct dog_data {
    int stdin;
    int stdout;
    int close_me[2];
};

static void pre_exec(void *d)
{
    struct dog_data *data = d;

    dup2(data->stdin, 0);
    dup2(data->stdout, 1);
    dup2(data->stdout, 2);
    close(data->stdin);
    close(data->stdout);
    close(data->close_me[0]);
    close(data->close_me[1]);
}

int start_watchdog(int *in_fd_ret, int *out_fd_ret, char *sock)
{
    struct dog_data data;
    int in_fds[2], out_fds[2], pid, n, err;
    char pid_buf[sizeof("nnnnnnn\0")], c;
    char *pid_args[] = { "/usr/bin/uml_watchdog", "-pid", pid_buf, NULL };
    char *mconsole_args[] = { "/usr/bin/uml_watchdog", "-mconsole", NULL,
                  NULL };
    char **args = NULL;

    err = os_pipe(in_fds, 1, 0);
    if (err < 0) {
        printk("harddog_open - os_pipe failed, err = %d\n", -err);
        goto out;
    }

    err = os_pipe(out_fds, 1, 0);
    if (err < 0) {
        printk("harddog_open - os_pipe failed, err = %d\n", -err);
        goto out_close_in;
    }

    data.stdin = out_fds[0];
    data.stdout = in_fds[1];
    data.close_me[0] = out_fds[1];
    data.close_me[1] = in_fds[0];

    if (sock != NULL) {
        mconsole_args[2] = sock;
        args = mconsole_args;
    }
    else {
        /* XXX The os_getpid() is not SMP correct */
        sprintf(pid_buf, "%d", os_getpid());
        args = pid_args;
    }

    pid = run_helper(pre_exec, &data, args);

    close(out_fds[0]);
    close(in_fds[1]);

    if (pid < 0) {
        err = -pid;
        printk("harddog_open - run_helper failed, errno = %d\n", -err);
        goto out_close_out;
    }

    n = read(in_fds[0], &c, sizeof(c));
    if (n == 0) {
        printk("harddog_open - EOF on watchdog pipe\n");
        helper_wait(pid);
        err = -EIO;
        goto out_close_out;
    }
    else if (n < 0) {
        printk("harddog_open - read of watchdog pipe failed, "
               "err = %d\n", errno);
        helper_wait(pid);
        err = n;
        goto out_close_out;
    }
    *in_fd_ret = in_fds[0];
    *out_fd_ret = out_fds[1];
    return 0;

 out_close_in:
    close(in_fds[0]);
    close(in_fds[1]);
 out_close_out:
    close(out_fds[0]);
    close(out_fds[1]);
 out:
    return err;
}

void stop_watchdog(int in_fd, int out_fd)
{
    close(in_fd);
    close(out_fd);
}

int ping_watchdog(int fd)
{
    int n;
    char c = '\n';

    n = write(fd, &c, sizeof(c));
    if (n != sizeof(c)) {
        printk("ping_watchdog - write failed, ret = %d, err = %d\n",
               n, errno);
        if (n < 0)
            return n;
        return -EIO;
    }
    return 1;

}