dll: add FSP_SERVICE and EventLog functionality

src/dll/eventlog.c

@@ -0,0 +1,56 @@
+/**
+ * @file dll/eventlog.c
+ *
+ * @copyright 2015-2016 Bill Zissimopoulos
+ */
+/*
+ * This file is part of WinFsp.
+ *
+ * You can redistribute it and/or modify it under the terms of the
+ * GNU Affero General Public License version 3 as published by the
+ * Free Software Foundation.
+ *
+ * Licensees holding a valid commercial license may use this file in
+ * accordance with the commercial license agreement provided with the
+ * software.
+ */
+
+#include <dll/library.h>
+#include <stdarg.h>
+
+static HANDLE FspEventLogHandle;
+static INIT_ONCE FspEventLogInitOnce = INIT_ONCE_STATIC_INIT;
+static BOOL WINAPI FspEventLogRegisterEventSource(
+    PINIT_ONCE InitOnce, PVOID Parameter, PVOID *Context);
+
+FSP_API VOID FspEventLog(ULONG Type, PWSTR Format, ...)
+{
+    va_list ap;
+
+    va_start(ap, Format);
+    FspEventLogV(Type, Format, ap);
+    va_end(ap);
+}
+
+FSP_API VOID FspEventLogV(ULONG Type, PWSTR Format, va_list ap)
+{
+    InitOnceExecuteOnce(&FspEventLogInitOnce, FspEventLogRegisterEventSource, 0, 0);
+    if (0 == FspEventLogHandle)
+        return;
+
+    WCHAR Buf[1024], *Strings[1];
+        /* wvsprintfW is only safe with a 1024 WCHAR buffer */
+
+    wvsprintfW(Buf, Format, ap);
+    Buf[(sizeof Buf / sizeof Buf[0]) - 1] = L'\0';
+
+    Strings[0] = Buf;
+    ReportEventW(FspEventLogHandle, (WORD)Type, 0, 1, 0, 1, 0, Strings, 0);
+}
+
+static BOOL WINAPI FspEventLogRegisterEventSource(
+    PINIT_ONCE InitOnce, PVOID Parameter, PVOID *Context)
+{
+    FspEventLogHandle = RegisterEventSourceW(0, L"" LIBRARY_NAME);
+    return TRUE;
+}