qga-win: add logging to Windows event log

This commit allows QGA to write to Windows event log using Win32 API's
ReportEvent() [1], much like syslog() under *nix guests.

In order to generate log message definitions we use a very basic message
text file [2], so that every QGA's message gets ID 1.  The tools
"windmc" and "windres" respectively are used to generate ".rc" file and
COFF object file, and then the COFF file is linked into qemu-ga.exe.

[1] https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-reporteventa
[2] https://learn.microsoft.com/en-us/windows/win32/eventlog/message-text-files

Originally-by: Yuri Pudgorodskiy <yur@virtuozzo.com>
Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Konstantin Kostiuk <kkostiuk@redhat.com>
Tested-by: Konstantin Kostiuk <kkostiuk@redhat.com>
Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>

1 files changed, 13 insertions, 3 deletions

diff --git a/qga/main.c b/qga/main.c
index 0865c992f0..1463a1c170 100644
--- a/qga/main.c
+++ b/qga/main.c
@@ -83,6 +83,7 @@ struct GAState {
 #ifdef _WIN32
     GAService service;
     HANDLE wakeup_event;
+    HANDLE event_log;
 #endif
     bool delimit_response;
     bool frozen;
@@ -324,13 +325,14 @@ static void ga_log(const gchar *domain, GLogLevelFlags level,
     }
 
     level &= G_LOG_LEVEL_MASK;
-#ifndef _WIN32
     if (g_strcmp0(domain, "syslog") == 0) {
+#ifndef _WIN32
         syslog(LOG_INFO, "%s: %s", level_str, msg);
-    } else if (level & s->log_level) {
 #else
-    if (level & s->log_level) {
+        ReportEvent(s->event_log, EVENTLOG_INFORMATION_TYPE,
+                    0, 1, NULL, 1, 0, &msg, NULL);
 #endif
+    } else if (level & s->log_level) {
         g_autoptr(GDateTime) now = g_date_time_new_now_utc();
         g_autofree char *nowstr = g_date_time_format(now, "%s.%f");
         fprintf(s->log_file, "%s: %s: %s\n", nowstr, level_str, msg);
@@ -1286,6 +1288,13 @@ static GAState *initialize_agent(GAConfig *config, int socket_activation)
     g_debug("Guest agent version %s started", QEMU_FULL_VERSION);
 
 #ifdef _WIN32
+    s->event_log = RegisterEventSource(NULL, "qemu-ga");
+    if (!s->event_log) {
+        g_autofree gchar *errmsg = g_win32_error_message(GetLastError());
+        g_critical("unable to register event source: %s", errmsg);
+        return NULL;
+    }
+
     /* On win32 the state directory is application specific (be it the default
      * or a user override). We got past the command line parsing; let's create
      * the directory (with any intermediate directories). If we run into an
@@ -1377,6 +1386,7 @@ static void cleanup_agent(GAState *s)
 {
 #ifdef _WIN32
     CloseHandle(s->wakeup_event);
+    CloseHandle(s->event_log);
 #endif
     if (s->command_state) {
         ga_command_state_cleanup_all(s->command_state);