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xemu/qemu-ga.c
Michael Roth 3cf0bed836 qemu-ga: add guest-sync-delimited 
guest-sync leaves it as an exercise to the user as to how to reliably
obtain the response to guest-sync if the client had previously read in a
partial response (due qemu-ga previously being restarted mid-"sentence"
due to reboot, forced restart, etc).

qemu-ga handles this situation on its end by having a client precede
their guest-sync request with a 0xFF byte (invalid UTF-8), which
qemu-ga/QEMU JSON parsers will treat as a flush event. Thus we can
reliably flush the qemu-ga parser state in preparation for receiving
the guest-sync request.

guest-sync-delimited provides the same functionality for a client: when
a guest-sync-delimited is issued, qemu-ga will precede it's response
with a 0xFF byte that the client can use as an indicator to flush its
buffer/parser state in preparation for reliably receiving the
guest-sync-delimited response.

It is also useful as an optimization for clients, since, after issuing a
guest-sync-delimited, clients can safely discard all stale data read
from the channel until the 0xFF is found.

More information available on the wiki:

http://wiki.qemu.org/Features/QAPI/GuestAgent#QEMU_Guest_Agent_Protocol

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2012-03-12 15:09:23 -05:00

660 lines
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/*
* QEMU Guest Agent
*
* Copyright IBM Corp. 2011
*
* Authors:
* Adam Litke <aglitke@linux.vnet.ibm.com>
* Michael Roth <mdroth@linux.vnet.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>
#include <glib.h>
#include <getopt.h>
#ifndef _WIN32
#include <syslog.h>
#include <sys/wait.h>
#endif
#include "json-streamer.h"
#include "json-parser.h"
#include "qint.h"
#include "qjson.h"
#include "qga/guest-agent-core.h"
#include "module.h"
#include "signal.h"
#include "qerror.h"
#include "error_int.h"
#include "qapi/qmp-core.h"
#include "qga/channel.h"
#ifdef _WIN32
#include "qga/service-win32.h"
#include <windows.h>
#endif
#ifndef _WIN32
#define QGA_VIRTIO_PATH_DEFAULT "/dev/virtio-ports/org.qemu.guest_agent.0"
#else
#define QGA_VIRTIO_PATH_DEFAULT "\\\\.\\Global\\org.qemu.guest_agent.0"
#endif
#define QGA_PIDFILE_DEFAULT "/var/run/qemu-ga.pid"
#define QGA_SENTINEL_BYTE 0xFF
struct GAState {
JSONMessageParser parser;
GMainLoop *main_loop;
GAChannel *channel;
bool virtio; /* fastpath to check for virtio to deal with poll() quirks */
GACommandState *command_state;
GLogLevelFlags log_level;
FILE *log_file;
bool logging_enabled;
#ifdef _WIN32
GAService service;
#endif
bool delimit_response;
};
struct GAState *ga_state;
#ifdef _WIN32
DWORD WINAPI service_ctrl_handler(DWORD ctrl, DWORD type, LPVOID data,
LPVOID ctx);
VOID WINAPI service_main(DWORD argc, TCHAR *argv[]);
#endif
static void quit_handler(int sig)
{
g_debug("received signal num %d, quitting", sig);
if (g_main_loop_is_running(ga_state->main_loop)) {
g_main_loop_quit(ga_state->main_loop);
}
}
#ifndef _WIN32
/* reap _all_ terminated children */
static void child_handler(int sig)
{
int status;
while (waitpid(-1, &status, WNOHANG) > 0) /* NOTHING */;
}
static gboolean register_signal_handlers(void)
{
struct sigaction sigact, sigact_chld;
int ret;
memset(&sigact, 0, sizeof(struct sigaction));
sigact.sa_handler = quit_handler;
ret = sigaction(SIGINT, &sigact, NULL);
if (ret == -1) {
g_error("error configuring signal handler: %s", strerror(errno));
return false;
}
ret = sigaction(SIGTERM, &sigact, NULL);
if (ret == -1) {
g_error("error configuring signal handler: %s", strerror(errno));
return false;
}
memset(&sigact_chld, 0, sizeof(struct sigaction));
sigact_chld.sa_handler = child_handler;
sigact_chld.sa_flags = SA_NOCLDSTOP;
ret = sigaction(SIGCHLD, &sigact_chld, NULL);
if (ret == -1) {
g_error("error configuring signal handler: %s", strerror(errno));
}
return true;
}
#endif
static void usage(const char *cmd)
{
printf(
"Usage: %s -c <channel_opts>\n"
"QEMU Guest Agent %s\n"
"\n"
" -m, --method transport method: one of unix-listen, virtio-serial, or\n"
" isa-serial (virtio-serial is the default)\n"
" -p, --path device/socket path (%s is the default for virtio-serial)\n"
" -l, --logfile set logfile path, logs to stderr by default\n"
" -f, --pidfile specify pidfile (default is %s)\n"
" -v, --verbose log extra debugging information\n"
" -V, --version print version information and exit\n"
" -d, --daemonize become a daemon\n"
#ifdef _WIN32
" -s, --service service commands: install, uninstall\n"
#endif
" -b, --blacklist comma-separated list of RPCs to disable (no spaces, \"?\""
" to list available RPCs)\n"
" -h, --help display this help and exit\n"
"\n"
"Report bugs to <mdroth@linux.vnet.ibm.com>\n"
, cmd, QGA_VERSION, QGA_VIRTIO_PATH_DEFAULT, QGA_PIDFILE_DEFAULT);
}
static const char *ga_log_level_str(GLogLevelFlags level)
{
switch (level & G_LOG_LEVEL_MASK) {
case G_LOG_LEVEL_ERROR:
return "error";
case G_LOG_LEVEL_CRITICAL:
return "critical";
case G_LOG_LEVEL_WARNING:
return "warning";
case G_LOG_LEVEL_MESSAGE:
return "message";
case G_LOG_LEVEL_INFO:
return "info";
case G_LOG_LEVEL_DEBUG:
return "debug";
default:
return "user";
}
}
bool ga_logging_enabled(GAState *s)
{
return s->logging_enabled;
}
void ga_disable_logging(GAState *s)
{
s->logging_enabled = false;
}
void ga_enable_logging(GAState *s)
{
s->logging_enabled = true;
}
static void ga_log(const gchar *domain, GLogLevelFlags level,
const gchar *msg, gpointer opaque)
{
GAState *s = opaque;
GTimeVal time;
const char *level_str = ga_log_level_str(level);
if (!ga_logging_enabled(s)) {
return;
}
level &= G_LOG_LEVEL_MASK;
#ifndef _WIN32
if (domain && strcmp(domain, "syslog") == 0) {
syslog(LOG_INFO, "%s: %s", level_str, msg);
} else if (level & s->log_level) {
#else
if (level & s->log_level) {
#endif
g_get_current_time(&time);
fprintf(s->log_file,
"%lu.%lu: %s: %s\n", time.tv_sec, time.tv_usec, level_str, msg);
fflush(s->log_file);
}
}
void ga_set_response_delimited(GAState *s)
{
s->delimit_response = true;
}
#ifndef _WIN32
static void become_daemon(const char *pidfile)
{
pid_t pid, sid;
int pidfd;
char *pidstr = NULL;
pid = fork();
if (pid < 0) {
exit(EXIT_FAILURE);
}
if (pid > 0) {
exit(EXIT_SUCCESS);
}
pidfd = open(pidfile, O_CREAT|O_WRONLY|O_EXCL, S_IRUSR|S_IWUSR);
if (pidfd == -1) {
g_critical("Cannot create pid file, %s", strerror(errno));
exit(EXIT_FAILURE);
}
if (asprintf(&pidstr, "%d", getpid()) == -1) {
g_critical("Cannot allocate memory");
goto fail;
}
if (write(pidfd, pidstr, strlen(pidstr)) != strlen(pidstr)) {
free(pidstr);
g_critical("Failed to write pid file");
goto fail;
}
umask(0);
sid = setsid();
if (sid < 0) {
goto fail;
}
if ((chdir("/")) < 0) {
goto fail;
}
close(STDIN_FILENO);
close(STDOUT_FILENO);
close(STDERR_FILENO);
free(pidstr);
return;
fail:
unlink(pidfile);
g_critical("failed to daemonize");
exit(EXIT_FAILURE);
}
#endif
static int send_response(GAState *s, QObject *payload)
{
const char *buf;
QString *payload_qstr, *response_qstr;
GIOStatus status;
g_assert(payload && s->channel);
payload_qstr = qobject_to_json(payload);
if (!payload_qstr) {
return -EINVAL;
}
if (s->delimit_response) {
s->delimit_response = false;
response_qstr = qstring_new();
qstring_append_chr(response_qstr, QGA_SENTINEL_BYTE);
qstring_append(response_qstr, qstring_get_str(payload_qstr));
QDECREF(payload_qstr);
} else {
response_qstr = payload_qstr;
}
qstring_append_chr(response_qstr, '\n');
buf = qstring_get_str(response_qstr);
status = ga_channel_write_all(s->channel, buf, strlen(buf));
QDECREF(response_qstr);
if (status != G_IO_STATUS_NORMAL) {
return -EIO;
}
return 0;
}
static void process_command(GAState *s, QDict *req)
{
QObject *rsp = NULL;
int ret;
g_assert(req);
g_debug("processing command");
rsp = qmp_dispatch(QOBJECT(req));
if (rsp) {
ret = send_response(s, rsp);
if (ret) {
g_warning("error sending response: %s", strerror(ret));
}
qobject_decref(rsp);
} else {
g_warning("error getting response");
}
}
/* handle requests/control events coming in over the channel */
static void process_event(JSONMessageParser *parser, QList *tokens)
{
GAState *s = container_of(parser, GAState, parser);
QObject *obj;
QDict *qdict;
Error *err = NULL;
int ret;
g_assert(s && parser);
g_debug("process_event: called");
obj = json_parser_parse_err(tokens, NULL, &err);
if (err || !obj || qobject_type(obj) != QTYPE_QDICT) {
qobject_decref(obj);
qdict = qdict_new();
if (!err) {
g_warning("failed to parse event: unknown error");
error_set(&err, QERR_JSON_PARSING);
} else {
g_warning("failed to parse event: %s", error_get_pretty(err));
}
qdict_put_obj(qdict, "error", error_get_qobject(err));
error_free(err);
} else {
qdict = qobject_to_qdict(obj);
}
g_assert(qdict);
/* handle host->guest commands */
if (qdict_haskey(qdict, "execute")) {
process_command(s, qdict);
} else {
if (!qdict_haskey(qdict, "error")) {
QDECREF(qdict);
qdict = qdict_new();
g_warning("unrecognized payload format");
error_set(&err, QERR_UNSUPPORTED);
qdict_put_obj(qdict, "error", error_get_qobject(err));
error_free(err);
}
ret = send_response(s, QOBJECT(qdict));
if (ret) {
g_warning("error sending error response: %s", strerror(ret));
}
}
QDECREF(qdict);
}
/* false return signals GAChannel to close the current client connection */
static gboolean channel_event_cb(GIOCondition condition, gpointer data)
{
GAState *s = data;
gchar buf[QGA_READ_COUNT_DEFAULT+1];
gsize count;
GError *err = NULL;
GIOStatus status = ga_channel_read(s->channel, buf, QGA_READ_COUNT_DEFAULT, &count);
if (err != NULL) {
g_warning("error reading channel: %s", err->message);
g_error_free(err);
return false;
}
switch (status) {
case G_IO_STATUS_ERROR:
g_warning("error reading channel");
return false;
case G_IO_STATUS_NORMAL:
buf[count] = 0;
g_debug("read data, count: %d, data: %s", (int)count, buf);
json_message_parser_feed(&s->parser, (char *)buf, (int)count);
break;
case G_IO_STATUS_EOF:
g_debug("received EOF");
if (!s->virtio) {
return false;
}
case G_IO_STATUS_AGAIN:
/* virtio causes us to spin here when no process is attached to
* host-side chardev. sleep a bit to mitigate this
*/
if (s->virtio) {
usleep(100*1000);
}
return true;
default:
g_warning("unknown channel read status, closing");
return false;
}
return true;
}
static gboolean channel_init(GAState *s, const gchar *method, const gchar *path)
{
GAChannelMethod channel_method;
if (method == NULL) {
method = "virtio-serial";
}
if (path == NULL) {
if (strcmp(method, "virtio-serial") != 0) {
g_critical("must specify a path for this channel");
return false;
}
/* try the default path for the virtio-serial port */
path = QGA_VIRTIO_PATH_DEFAULT;
}
if (strcmp(method, "virtio-serial") == 0) {
s->virtio = true; /* virtio requires special handling in some cases */
channel_method = GA_CHANNEL_VIRTIO_SERIAL;
} else if (strcmp(method, "isa-serial") == 0) {
channel_method = GA_CHANNEL_ISA_SERIAL;
} else if (strcmp(method, "unix-listen") == 0) {
channel_method = GA_CHANNEL_UNIX_LISTEN;
} else {
g_critical("unsupported channel method/type: %s", method);
return false;
}
s->channel = ga_channel_new(channel_method, path, channel_event_cb, s);
if (!s->channel) {
g_critical("failed to create guest agent channel");
return false;
}
return true;
}
#ifdef _WIN32
DWORD WINAPI service_ctrl_handler(DWORD ctrl, DWORD type, LPVOID data,
LPVOID ctx)
{
DWORD ret = NO_ERROR;
GAService *service = &ga_state->service;
switch (ctrl)
{
case SERVICE_CONTROL_STOP:
case SERVICE_CONTROL_SHUTDOWN:
quit_handler(SIGTERM);
service->status.dwCurrentState = SERVICE_STOP_PENDING;
SetServiceStatus(service->status_handle, &service->status);
break;
default:
ret = ERROR_CALL_NOT_IMPLEMENTED;
}
return ret;
}
VOID WINAPI service_main(DWORD argc, TCHAR *argv[])
{
GAService *service = &ga_state->service;
service->status_handle = RegisterServiceCtrlHandlerEx(QGA_SERVICE_NAME,
service_ctrl_handler, NULL);
if (service->status_handle == 0) {
g_critical("Failed to register extended requests function!\n");
return;
}
service->status.dwServiceType = SERVICE_WIN32;
service->status.dwCurrentState = SERVICE_RUNNING;
service->status.dwControlsAccepted = SERVICE_ACCEPT_STOP | SERVICE_ACCEPT_SHUTDOWN;
service->status.dwWin32ExitCode = NO_ERROR;
service->status.dwServiceSpecificExitCode = NO_ERROR;
service->status.dwCheckPoint = 0;
service->status.dwWaitHint = 0;
SetServiceStatus(service->status_handle, &service->status);
g_main_loop_run(ga_state->main_loop);
service->status.dwCurrentState = SERVICE_STOPPED;
SetServiceStatus(service->status_handle, &service->status);
}
#endif
int main(int argc, char **argv)
{
const char *sopt = "hVvdm:p:l:f:b:s:";
const char *method = NULL, *path = NULL, *pidfile = QGA_PIDFILE_DEFAULT;
const char *log_file_name = NULL;
#ifdef _WIN32
const char *service = NULL;
#endif
const struct option lopt[] = {
{ "help", 0, NULL, 'h' },
{ "version", 0, NULL, 'V' },
{ "logfile", 1, NULL, 'l' },
{ "pidfile", 1, NULL, 'f' },
{ "verbose", 0, NULL, 'v' },
{ "method", 1, NULL, 'm' },
{ "path", 1, NULL, 'p' },
{ "daemonize", 0, NULL, 'd' },
{ "blacklist", 1, NULL, 'b' },
#ifdef _WIN32
{ "service", 1, NULL, 's' },
#endif
{ NULL, 0, NULL, 0 }
};
int opt_ind = 0, ch, daemonize = 0, i, j, len;
GLogLevelFlags log_level = G_LOG_LEVEL_ERROR | G_LOG_LEVEL_CRITICAL;
FILE *log_file = stderr;
GAState *s;
module_call_init(MODULE_INIT_QAPI);
while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
switch (ch) {
case 'm':
method = optarg;
break;
case 'p':
path = optarg;
break;
case 'l':
log_file_name = optarg;
log_file = fopen(log_file_name, "a");
if (!log_file) {
g_critical("unable to open specified log file: %s",
strerror(errno));
return EXIT_FAILURE;
}
break;
case 'f':
pidfile = optarg;
break;
case 'v':
/* enable all log levels */
log_level = G_LOG_LEVEL_MASK;
break;
case 'V':
printf("QEMU Guest Agent %s\n", QGA_VERSION);
return 0;
case 'd':
daemonize = 1;
break;
case 'b': {
char **list_head, **list;
if (*optarg == '?') {
list_head = list = qmp_get_command_list();
while (*list != NULL) {
printf("%s\n", *list);
g_free(*list);
list++;
}
g_free(list_head);
return 0;
}
for (j = 0, i = 0, len = strlen(optarg); i < len; i++) {
if (optarg[i] == ',') {
optarg[i] = 0;
qmp_disable_command(&optarg[j]);
g_debug("disabling command: %s", &optarg[j]);
j = i + 1;
}
}
if (j < i) {
qmp_disable_command(&optarg[j]);
g_debug("disabling command: %s", &optarg[j]);
}
break;
}
#ifdef _WIN32
case 's':
service = optarg;
if (strcmp(service, "install") == 0) {
return ga_install_service(path, log_file_name);
} else if (strcmp(service, "uninstall") == 0) {
return ga_uninstall_service();
} else {
printf("Unknown service command.\n");
return EXIT_FAILURE;
}
break;
#endif
case 'h':
usage(argv[0]);
return 0;
case '?':
g_print("Unknown option, try '%s --help' for more information.\n",
argv[0]);
return EXIT_FAILURE;
}
}
#ifndef _WIN32
if (daemonize) {
g_debug("starting daemon");
become_daemon(pidfile);
}
#endif
s = g_malloc0(sizeof(GAState));
s->log_file = log_file;
s->log_level = log_level;
g_log_set_default_handler(ga_log, s);
g_log_set_fatal_mask(NULL, G_LOG_LEVEL_ERROR);
s->logging_enabled = true;
s->command_state = ga_command_state_new();
ga_command_state_init(s, s->command_state);
ga_command_state_init_all(s->command_state);
json_message_parser_init(&s->parser, process_event);
ga_state = s;
#ifndef _WIN32
if (!register_signal_handlers()) {
g_critical("failed to register signal handlers");
goto out_bad;
}
#endif
s->main_loop = g_main_loop_new(NULL, false);
if (!channel_init(ga_state, method, path)) {
g_critical("failed to initialize guest agent channel");
goto out_bad;
}
#ifndef _WIN32
g_main_loop_run(ga_state->main_loop);
#else
if (daemonize) {
SERVICE_TABLE_ENTRY service_table[] = {
{ (char *)QGA_SERVICE_NAME, service_main }, { NULL, NULL } };
StartServiceCtrlDispatcher(service_table);
} else {
g_main_loop_run(ga_state->main_loop);
}
#endif
ga_command_state_cleanup_all(ga_state->command_state);
ga_channel_free(ga_state->channel);
if (daemonize) {
unlink(pidfile);
}
return 0;
out_bad:
if (daemonize) {
unlink(pidfile);
}
return EXIT_FAILURE;
}
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