libvirt/src/qemu/qemu_monitor.c

/*
 * qemu_monitor.c: interaction with QEMU monitor console
 *
 * Copyright (C) 2006-2009 Red Hat, Inc.
 * Copyright (C) 2006 Daniel P. Berrange
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
 *
 * Author: Daniel P. Berrange <berrange@redhat.com>
 */

#include <config.h>

#include <poll.h>
#include <sys/un.h>
#include <unistd.h>
#include <fcntl.h>

#include "qemu_monitor.h"
#include "qemu_conf.h"
#include "event.h"
#include "virterror_internal.h"
#include "memory.h"
#include "logging.h"

#define VIR_FROM_THIS VIR_FROM_QEMU

struct _qemuMonitor {
    int fd;
    int watch;
    int hasSendFD;

    virDomainObjPtr vm;

    qemuMonitorEOFNotify eofCB;
};

/* Return -1 for error, 1 to continue reading and 0 for success */
typedef int qemuMonitorHandleOutput(virDomainObjPtr vm,
                                    const char *output);

/*
 * Returns -1 for error, 0 on end-of-file, 1 for success
 */
static int
qemuMonitorReadOutput(virDomainObjPtr vm,
                      int fd,
                      char *buf,
                      size_t buflen,
                      qemuMonitorHandleOutput func,
                      const char *what,
                      int timeout)
{
    size_t got = 0;
    buf[0] = '\0';
    timeout *= 1000; /* poll wants milli seconds */

    /* Consume & discard the initial greeting */
    while (got < (buflen-1)) {
        ssize_t ret;

        ret = read(fd, buf+got, buflen-got-1);

        if (ret < 0) {
            struct pollfd pfd = { .fd = fd, .events = POLLIN };
            if (errno == EINTR)
                continue;

            if (errno != EAGAIN) {
                virReportSystemError(NULL, errno,
                                     _("Failure while reading %s startup output"),
                                     what);
                return -1;
            }

            ret = poll(&pfd, 1, timeout);
            if (ret == 0) {
                qemudReportError(NULL, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
                                 _("Timed out while reading %s startup output"), what);
                return -1;
            } else if (ret == -1) {
                if (errno != EINTR) {
                    virReportSystemError(NULL, errno,
                                         _("Failure while reading %s startup output"),
                                         what);
                    return -1;
                }
            } else {
                /* Make sure we continue loop & read any further data
                   available before dealing with EOF */
                if (pfd.revents & (POLLIN | POLLHUP))
                    continue;

                qemudReportError(NULL, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
                                 _("Failure while reading %s startup output"), what);
                return -1;
            }
        } else if (ret == 0) {
            return 0;
        } else {
            got += ret;
            buf[got] = '\0';
            ret = func(vm, buf);
            if (ret == -1)
                return -1;
            if (ret == 1)
                continue;
            return 1;
        }
    }

    qemudReportError(NULL, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
                     _("Out of space while reading %s startup output"), what);
    return -1;

}

static int
qemuMonitorCheckPrompt(virDomainObjPtr vm ATTRIBUTE_UNUSED,
                       const char *output)
{
    if (strstr(output, "(qemu) ") == NULL)
        return 1; /* keep reading */

    return 0;
}

static int
qemuMonitorOpenCommon(virDomainObjPtr vm,
                      int monfd,
                      int reconnect)
{
    char buf[1024];
    int ret;

    if (virSetCloseExec(monfd) < 0) {
        qemudReportError(NULL, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
                         "%s", _("Unable to set monitor close-on-exec flag"));
        return -1;
    }
    if (virSetNonBlock(monfd) < 0) {
        qemudReportError(NULL, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
                         "%s", _("Unable to put monitor into non-blocking mode"));
        return -1;
    }

    if (!reconnect) {
        if (qemuMonitorReadOutput(vm, monfd,
                                  buf, sizeof(buf),
                                  qemuMonitorCheckPrompt,
                                  "monitor", 10) <= 0)
            ret = -1;
        else
            ret = 0;
    } else {
        ret = 0;
    }

    return ret;
}

static int
qemuMonitorOpenUnix(virDomainObjPtr vm,
                    const char *monitor,
                    int reconnect)
{
    struct sockaddr_un addr;
    int monfd;
    int timeout = 3; /* In seconds */
    int ret, i = 0;

    if ((monfd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
        virReportSystemError(NULL, errno,
                             "%s", _("failed to create socket"));
        return -1;
    }

    memset(&addr, 0, sizeof(addr));
    addr.sun_family = AF_UNIX;
    if (virStrcpyStatic(addr.sun_path, monitor) == NULL) {
        qemudReportError(NULL, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
                         _("Monitor path %s too big for destination"), monitor);
        goto error;
    }

    do {
        ret = connect(monfd, (struct sockaddr *) &addr, sizeof(addr));

        if (ret == 0)
            break;

        if (errno == ENOENT || errno == ECONNREFUSED) {
            /* ENOENT       : Socket may not have shown up yet
             * ECONNREFUSED : Leftover socket hasn't been removed yet */
            continue;
        }

        virReportSystemError(NULL, errno, "%s",
                             _("failed to connect to monitor socket"));
        goto error;

    } while ((++i <= timeout*5) && (usleep(.2 * 1000000) <= 0));

    if (ret != 0) {
        virReportSystemError(NULL, errno, "%s",
                             _("monitor socket did not show up."));
        goto error;
    }

    if (qemuMonitorOpenCommon(vm, monfd, reconnect) < 0)
        goto error;

    return monfd;

error:
    close(monfd);
    return -1;
}

static int
qemuMonitorOpenPty(virDomainObjPtr vm,
                   const char *monitor,
                   int reconnect)
{
    int monfd;

    if ((monfd = open(monitor, O_RDWR)) < 0) {
        qemudReportError(NULL, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
                         _("Unable to open monitor path %s"), monitor);
        return -1;
    }

    if (qemuMonitorOpenCommon(vm, monfd, reconnect) < 0)
        goto error;

    return monfd;

error:
    close(monfd);
    return -1;
}


static void
qemuMonitorIO(int watch, int fd, int events, void *opaque) {
    qemuMonitorPtr mon = opaque;
    int quit = 0, failed = 0;

    if (mon->fd != fd || mon->watch != watch) {
        VIR_ERROR0(_("event from unexpected fd/watch"));
        failed = 1;
    } else {
        if (events & (VIR_EVENT_HANDLE_HANGUP | VIR_EVENT_HANDLE_ERROR))
            quit = 1;
        else {
            VIR_ERROR(_("unhandled fd event %d for monitor fd %d"),
                      events, mon->fd);
            failed = 1;
        }
    }

    mon->eofCB(mon, mon->vm, failed);
}





qemuMonitorPtr
qemuMonitorOpen(virDomainObjPtr vm,
                int reconnect,
                qemuMonitorEOFNotify eofCB)
{
    qemuMonitorPtr mon;

    if (VIR_ALLOC(mon) < 0) {
        virReportOOMError(NULL);
        return NULL;
    }

    mon->fd = -1;
    mon->vm = vm;
    mon->eofCB = eofCB;

    switch (vm->monitor_chr->type) {
    case VIR_DOMAIN_CHR_TYPE_UNIX:
        mon->hasSendFD = 1;
        mon->fd = qemuMonitorOpenUnix(vm, vm->monitor_chr->data.nix.path,
                                      reconnect);
        break;

    case VIR_DOMAIN_CHR_TYPE_PTY:
        mon->fd = qemuMonitorOpenPty(vm, vm->monitor_chr->data.file.path,
                                     reconnect);
        break;

    default:
        qemudReportError(NULL, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
                         _("unable to handle monitor type: %s"),
                         virDomainChrTypeToString(vm->monitor_chr->type));
        goto cleanup;
    }

    if ((mon->watch = virEventAddHandle(mon->fd,
                                        VIR_EVENT_HANDLE_HANGUP | VIR_EVENT_HANDLE_ERROR,
                                        qemuMonitorIO,
                                        mon, NULL)) < 0) {
        qemudReportError(NULL, NULL, NULL, VIR_ERR_INTERNAL_ERROR, "%s",
                         _("unable to register monitor events"));
        goto cleanup;
    }

    return mon;

cleanup:
    qemuMonitorClose(mon);
    return NULL;
}


void qemuMonitorClose(qemuMonitorPtr mon)
{
    if (!mon)
        return;

    if (mon->watch)
        virEventRemoveHandle(mon->watch);

    if (mon->fd != -1)
        close(mon->fd);
    VIR_FREE(mon);
}


int qemuMonitorWrite(qemuMonitorPtr mon,
                     const char *data,
                     size_t len)
{
    return safewrite(mon->fd, data, len);
}

int qemuMonitorWriteWithFD(qemuMonitorPtr mon,
                           const char *data,
                           size_t len,
                           int fd)
{
    struct msghdr msg;
    struct iovec iov[1];
    ssize_t ret;
    char control[CMSG_SPACE(sizeof(int))];
    struct cmsghdr *cmsg;

    if (!mon->hasSendFD) {
        errno = EINVAL;
        return -1;
    }

    memset(&msg, 0, sizeof(msg));

    iov[0].iov_base = (void *)data;
    iov[0].iov_len = len;

    msg.msg_iov = iov;
    msg.msg_iovlen = 1;

    msg.msg_control = control;
    msg.msg_controllen = sizeof(control);

    cmsg = CMSG_FIRSTHDR(&msg);
    cmsg->cmsg_len = CMSG_LEN(sizeof(int));
    cmsg->cmsg_level = SOL_SOCKET;
    cmsg->cmsg_type = SCM_RIGHTS;
    memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));

    do {
        ret = sendmsg(mon->fd, &msg, 0);
    } while (ret < 0 && errno == EINTR);

    return ret == len ? 0 : -1;
}

int qemuMonitorRead(qemuMonitorPtr mon,
                    char *data,
                    size_t len)
{
    return read(mon->fd, data, len);
}

int qemuMonitorWaitForInput(qemuMonitorPtr mon)
{
    struct pollfd fd = { mon->fd, POLLIN | POLLERR | POLLHUP, 0 };

retry:
    if (poll(&fd, 1, -1) < 0) {
        if (errno == EINTR)
            goto retry;
        return -1;
    }
    return 0;
}