Windows: fix EFI DcsProp rewrite handling

Ensure ESP file writes have true replace semantics even when the operation is delegated to the elevated COM helper. This prevents shorter edits of EFI\VeraCrypt\DcsProp from leaving stale bytes at the end of the file.

Also XML-escape decoded EFI boot configuration values before serializing them, preserving values containing characters such as <, > and & during EfiBootConf save/update paths.

Fixes #954.

src/Common/BootEncryption.cpp

@@ -443,6 +443,30 @@ namespace VeraCrypt
 			}
 		}
 
+		static void FastFileResize (const wstring &filePath, __int64 fileSize)
+		{
+			Elevate();
+
+			DWORD result;
+			CComBSTR fileBstr;
+			BSTR bstr = W2BSTR(filePath.c_str());
+			if (bstr)
+			{
+				fileBstr.Attach (bstr);
+				result = ElevatedComInstance->FastFileResize (fileBstr, fileSize);
+			}
+			else
+			{
+				result = ERROR_OUTOFMEMORY;
+			}
+
+			if (result != ERROR_SUCCESS)
+			{
+				SetLastError (result);
+				throw SystemException(SRC_POS);
+			}
+		}
+
 		static BOOL DeviceIoControl (BOOL readOnly, BOOL device, const wstring &filePath, DWORD dwIoControlCode, LPVOID input, DWORD inputSize, 
 												LPVOID output, DWORD outputSize)
 		{
@@ -759,6 +783,7 @@ namespace VeraCrypt
 		static void Release () { }
 		static void SetDriverServiceStartType (DWORD startType) { throw ParameterIncorrect (SRC_POS); }
 		static void GetFileSize (const wstring &filePath, unsigned __int64 *pSize) { throw ParameterIncorrect (SRC_POS); }
+		static void FastFileResize (const wstring &filePath, __int64 fileSize) { throw ParameterIncorrect (SRC_POS); }
 		static BOOL DeviceIoControl (BOOL readOnly, BOOL device, const wstring &filePath, DWORD dwIoControlCode, LPVOID input, DWORD inputSize, LPVOID output, DWORD outputSize) { throw ParameterIncorrect (SRC_POS); }
 		static void InstallEfiBootLoader (bool preserveUserConfig, bool hiddenOSCreation, int pim, int hashAlg) { throw ParameterIncorrect (SRC_POS); }
 		static void BackupEfiSystemLoader () { throw ParameterIncorrect (SRC_POS); }
@@ -896,6 +921,27 @@ namespace VeraCrypt
 		}
 	}
 
+	void File::SetEnd ()
+	{
+		if (!FileOpen)
+		{
+			SetLastError (LastError);
+			throw SystemException (SRC_POS);
+		}
+
+		if (Elevated)
+		{
+			if (FilePointerPosition > 0x7fffffffffffffffULL)
+				throw ParameterIncorrect (SRC_POS);
+
+			Elevator::FastFileResize (Path, (int64) FilePointerPosition);
+		}
+		else
+		{
+			throw_sys_if (!SetEndOfFile (Handle));
+		}
+	}
+
 	void File::GetFileSize (unsigned __int64& size)
 	{
 		if (!FileOpen)
@@ -2299,6 +2345,22 @@ namespace VeraCrypt
 		}
 	}
 
+	static string XmlQuoteConfigValue (const char *configValue)
+	{
+		if (!configValue)
+			return string();
+
+		size_t valueLen = strlen (configValue);
+		if (valueLen > (INT_MAX - 2) / 5)
+			throw ParameterIncorrect (SRC_POS);
+
+		vector<char> quotedValue (valueLen * 5 + 2);
+		if (!XmlQuoteText (configValue, quotedValue.data(), (int) quotedValue.size()))
+			throw ParameterIncorrect (SRC_POS);
+
+		return string (quotedValue.data());
+	}
+
 	BOOL EfiBootConf::WriteConfigString (FILE* configFile, char* configContent, const char *configKey, const char *configValue)
 	{
 		
@@ -2314,9 +2376,10 @@ namespace VeraCrypt
 					c[1] = '!';
 			}
 
+			string quotedValue = XmlQuoteConfigValue (configValue);
 			if ( 0 != fwprintf (
 					configFile, L"\n\t\t<config key=\"%hs\">%hs</config>",
-					configKey, configValue))
+					configKey, quotedValue.c_str()))
 			{
 				bRet = TRUE;
 			}
@@ -2444,7 +2507,8 @@ namespace VeraCrypt
 			XmlGetAttributeText (xml, "key", key, sizeof (key));
 			XmlGetNodeText (xml, value, sizeof (value));
 
-			fwprintf (configFile, L"\n\t\t<config key=\"%hs\">%hs</config>", key, value);
+			string quotedValue = XmlQuoteConfigValue (value);
+			fwprintf (configFile, L"\n\t\t<config key=\"%hs\">%hs</config>", key, quotedValue.c_str());
 			xml++;
 		}
 
@@ -3148,6 +3212,7 @@ namespace VeraCrypt
 
 		File f(pathESP + szFilePath, false, true);
 		f.Write(fileContent.data(), dwSize);
+		f.SetEnd();
 		f.Close();
 
 	}
@@ -3622,6 +3687,7 @@ namespace VeraCrypt
 		{
 			File f(path, false, true);
 			f.Write(data, size);
+			f.SetEnd();
 			f.Close();
 		}
 	}

src/Common/BootEncryption.h

@@ -44,6 +44,7 @@ namespace VeraCrypt
 		DWORD Read (uint8 *buffer, DWORD size);
 		void Write (uint8 *buffer, DWORD size);
 		void SeekAt (int64 position);
+		void SetEnd ();
 		void GetFileSize (unsigned __int64& size);
 		void GetFileSize (DWORD& dwSize);
       bool IoCtl(DWORD code, void* inBuf, DWORD inBufSize, void* outBuf, DWORD outBufSize);