Windows核心编程 -- 错误处理

DWORD GetLastError( )函数是用来返回由上一个函数调用设置的线程32位错误代码，WinError.h头文件里包含了Microsoft定义的错误代码，如下所示：

#define ERROR_SUCCESS                    0L

#define NO_ERROR 0L                                                 // dderror
#define SEC_E_OK                         ((HRESULT)0x00000000L)

//
// MessageId: ERROR_INVALID_FUNCTION
//
// MessageText:
//
// Incorrect function.
//
#define ERROR_INVALID_FUNCTION           1L    // dderror

//
// MessageId: ERROR_FILE_NOT_FOUND
//
// MessageText:
//
// The system cannot find the file specified.
//
#define ERROR_FILE_NOT_FOUND             2L

//
// MessageId: ERROR_PATH_NOT_FOUND
//
// MessageText:
//
// The system cannot find the path specified.
//
#define ERROR_PATH_NOT_FOUND             3L

//
// MessageId: ERROR_TOO_MANY_OPEN_FILES
//
// MessageText:
//
// The system cannot open the file.
//
#define ERROR_TOO_MANY_OPEN_FILES        4L

//
// MessageId: ERROR_ACCESS_DENIED
//
// MessageText:
//
// Access is denied.
//
#define ERROR_ACCESS_DENIED              5L

//
// MessageId: ERROR_INVALID_HANDLE
//
// MessageText:
//
// The handle is invalid.
//
#define ERROR_INVALID_HANDLE             6L

//
// MessageId: ERROR_ARENA_TRASHED
//
// MessageText:
//
// The storage control blocks were destroyed.
//
#define ERROR_ARENA_TRASHED              7L

//
// MessageId: ERROR_NOT_ENOUGH_MEMORY
//
// MessageText:
//
// Not enough storage is available to process this command.
//
#define ERROR_NOT_ENOUGH_MEMORY          8L    // dderror

//
// MessageId: ERROR_INVALID_BLOCK
//
// MessageText:
//
// The storage control block address is invalid.
//
#define ERROR_INVALID_BLOCK              9L

//
// MessageId: ERROR_BAD_ENVIRONMENT
//
// MessageText:
//
// The environment is incorrect.
//
#define ERROR_BAD_ENVIRONMENT            10L

在这里，我写了一个小程序，先创建一个文件，以打开的模式创建，如果不存在该文件，会返回错误代码，代码以及输出结果如下所示；

	HANDLE hFile = CreateFile(TEXT("d:\\wang"),0,0,NULL,OPEN_EXISTING,0,NULL ) ;
	DWORD dwRet = GetLastError();
	_tprintf(TEXT("dwRet = %u\n"), dwRet );
	CloseHandle( hFile );

dwRet =2 查找对应的错误原因，可知是ERROR_FILE_NOT_FOUND。可通过FormatMessage对错误代码进行格式化，使错误简洁明了，代码如下：

HANDLE hFile = CreateFile(TEXT("d:\\wang"),0,0,NULL,OPEN_EXISTING,0,NULL ) ;
	DWORD dwRet = GetLastError();
	_tprintf(TEXT("dwRet = %u\n"), dwRet );

	LPVOID lpDisplayBuf;

	LPVOID lpMsgBuf ;
	DWORD systemLocal = MAKELANGID(LANG_NEUTRAL,SUBLANG_DEFAULT );
	BOOL bOk = FormatMessage(
		FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS 
		| FORMAT_MESSAGE_ALLOCATE_BUFFER,NULL,dwRet,systemLocal,(LPTSTR)&lpMsgBuf,0,NULL  );
	if ( !bOk )
	{
		HMODULE hmDll = LoadLibraryEx( TEXT("netmsg.dll"), NULL, DONT_RESOLVE_DLL_REFERENCES );
		if( hmDll != NULL )
		{
			bOk = FormatMessage(
				FORMAT_MESSAGE_FROM_HMODULE | FORMAT_MESSAGE_IGNORE_INSERTS 
				| FORMAT_MESSAGE_ALLOCATE_BUFFER,hmDll,dwRet,systemLocal,(LPTSTR)&lpMsgBuf,0,NULL  );
			FreeLibrary( hmDll );
		}
	}

	lpDisplayBuf = (LPVOID)LocalAlloc(LMEM_ZEROINIT, 
		(lstrlen((LPCTSTR)lpMsgBuf)+40)*sizeof(TCHAR)); 
	StringCchPrintf((LPTSTR)lpDisplayBuf, 
		LocalSize(lpDisplayBuf),
		TEXT("failed with error %d: %s"), 
		dwRet, lpMsgBuf); 

	if( bOk && ( lpMsgBuf != NULL ) )
	{
		_tprintf(TEXT("%s\n"), (LPCTSTR)lpDisplayBuf );
		LocalFree( lpMsgBuf );
		LocalFree( lpDisplayBuf );
	}
	else
	{
		_tprintf( TEXT(" No text found for this error number\n"));
	}
	CloseHandle( hFile );

lpDisplayBuf就是显示的错误信息。