/*

 * Source file for missing WinCE functionality

 * Copyright © 2012 RealVNC Ltd.

 *

 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include "missing.h"

#include <config.h>

#include <libusbi.h>

#include <windows.h>

// The registry path to store environment variables

#define ENVIRONMENT_REG_PATH _T("Software\\libusb\\environment")

/* Workaround getenv not being available on WinCE.

 * Instead look in HKLM\Software\libusb\environment */

char *getenv(const char *name)

{

	static char value[MAX_PATH];

	TCHAR wValue[MAX_PATH];

	WCHAR wName[MAX_PATH];

	DWORD dwType, dwData;

	HKEY hkey;

	LONG rc;

	if (!name)

		return NULL;

	if (MultiByteToWideChar(CP_UTF8, 0, name, -1, wName, MAX_PATH) <= 0) {

		usbi_dbg("Failed to convert environment variable name to wide string");

		return NULL;

	}

	wName[MAX_PATH - 1] = 0; // Be sure it's NUL terminated

	rc = RegOpenKeyEx(HKEY_LOCAL_MACHINE, ENVIRONMENT_REG_PATH, 0, KEY_QUERY_VALUE, &hkey);

	if (rc != ERROR_SUCCESS) {

		usbi_dbg("Failed to open registry key for getenv with error %d", rc);

		return NULL;

	}

	// Attempt to read the key

	dwData = sizeof(wValue);

	rc = RegQueryValueEx(hkey, wName, NULL, &dwType,

		(LPBYTE)&wValue, &dwData);

	RegCloseKey(hkey);

	if (rc != ERROR_SUCCESS) {

		usbi_dbg("Failed to read registry key value for getenv with error %d", rc);

		return NULL;

	}

	if (dwType != REG_SZ) {

		usbi_dbg("Registry value was of type %d instead of REG_SZ", dwType);

		return NULL;

	}

	// Success in reading the key, convert from WCHAR to char

	if (WideCharToMultiByte(CP_UTF8, 0,

			wValue, dwData / sizeof(*wValue),

			value, MAX_PATH,

			NULL, NULL) <= 0) {

		usbi_dbg("Failed to convert environment variable value to narrow string");

		return NULL;

	}

	value[MAX_PATH - 1] = 0; // Be sure it's NUL terminated

	return value;

}