1 files changed, 117 insertions, 0 deletions
diff --git a/src/VBox/Runtime/r3/win/RTTimeZoneGetCurrent-win.cpp b/src/VBox/Runtime/r3/win/RTTimeZoneGetCurrent-win.cpp
new file mode 100644
index 00000000..310d8507
--- /dev/null
+++ b/src/VBox/Runtime/r3/win/RTTimeZoneGetCurrent-win.cpp
@@ -0,0 +1,117 @@
+/* $Id: RTTimeZoneGetCurrent-win.cpp $ */
+/** @file
+ * IPRT - RTTimeZoneGetCurrent, generic.
+ */
+
+/*
+ * Copyright (C) 2017-2023 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+ * in the VirtualBox distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+ */
+
+
+/*********************************************************************************************************************************
+*   Header Files                                                                                                                 *
+*********************************************************************************************************************************/
+#include <iprt/time.h>
+#include "internal/iprt.h"
+
+#include <iprt/errcore.h>
+#include <iprt/env.h>
+#include <iprt/string.h>
+#include <iprt/utf16.h>
+#include <iprt/win/windows.h>
+#include "internal-r3-win.h"
+
+
+/*********************************************************************************************************************************
+*   Structures and Typedefs                                                                                                      *
+*********************************************************************************************************************************/
+typedef DWORD (WINAPI *PFNGETDYNAMICTIMEZONEINFORMATION)(PDYNAMIC_TIME_ZONE_INFORMATION);
+
+
+/*********************************************************************************************************************************
+*   Global Variables                                                                                                             *
+*********************************************************************************************************************************/
+/** Pointer to the GetDynamicTimeZoneInformation API if present. */
+static PFNGETDYNAMICTIMEZONEINFORMATION g_pfnGetDynamicTimeZoneInformation = NULL;
+/** Flipped after we've tried to resolve g_pfnGetDynamicTimeZoneInformation.  */
+static bool volatile                    g_fResolvedApi = false;
+
+
+RTDECL(int) RTTimeZoneGetCurrent(char *pszName, size_t cbName)
+{
+    AssertPtrReturn(pszName, VERR_INVALID_POINTER);
+    AssertReturn(cbName > 0, VERR_BUFFER_OVERFLOW);
+
+    /*
+     * Resolve API.
+     */
+    PFNGETDYNAMICTIMEZONEINFORMATION pfnApi;
+    if (g_fResolvedApi)
+        pfnApi = g_pfnGetDynamicTimeZoneInformation;
+    else
+    {
+        pfnApi = (PFNGETDYNAMICTIMEZONEINFORMATION)GetProcAddress(g_hModKernel32, "GetDynamicTimeZoneInformation");
+        g_pfnGetDynamicTimeZoneInformation = pfnApi;
+        g_fResolvedApi = true;
+    }
+
+    /*
+     * Call the API and convert the name we get.
+     */
+    union
+    {
+        TIME_ZONE_INFORMATION           Tzi;
+        DYNAMIC_TIME_ZONE_INFORMATION   DynTzi;
+    } uBuf;
+    RT_ZERO(uBuf);
+    DWORD     dwRc;
+    PCRTUTF16 pwszSrcName;
+    size_t    cwcSrcName;
+    if (pfnApi)
+    {
+        dwRc = pfnApi(&uBuf.DynTzi);
+        pwszSrcName = uBuf.DynTzi.TimeZoneKeyName;
+        cwcSrcName  = RT_ELEMENTS(uBuf.DynTzi.TimeZoneKeyName);
+    }
+    else
+    {
+        /* Not sure how helpful this fallback really is... */
+        dwRc = GetTimeZoneInformation(&uBuf.Tzi);
+        pwszSrcName = uBuf.Tzi.StandardName;
+        cwcSrcName  = RT_ELEMENTS(uBuf.Tzi.StandardName);
+    }
+    if (dwRc != TIME_ZONE_ID_INVALID)
+    {
+        Assert(*pwszSrcName != '\0');
+        return RTUtf16ToUtf8Ex(pwszSrcName, cwcSrcName, &pszName, cbName, &cbName);
+    }
+    return RTErrConvertFromWin32(GetLastError());
+}
+