如何使用 CreateFile 在 UnBuffered 模式下追加 Windows 中的文件
How to append in file in Windows in UnBuffered mode using CreateFile
每次调用我的函数时,它都会覆盖文件。请注意,我使用以下标志以无缓冲模式打开文件。
FILE_FLAG_NO_BUFFERING | FILE_FLAG_WRITE_THROUGH
如果我使用简单的缓冲模式,它工作正常。
FILE_ATTRIBUTE_NORMAL
我在非缓冲模式下遇到以下错误。
** ERROR ** CreateFile failed: The parameter is incorrect.
请在下面找到代码片段。这段代码被调用了很多次。
HANDLE hFile;
LPCWSTR file_path = convertCharArrayToLPCWSTR(UNBUFFERED_FILE);
hFile = CreateFile(file_path,
FILE_APPEND_DATA,
FILE_SHARE_WRITE,
NULL,
OPEN_ALWAYS,
FILE_FLAG_NO_BUFFERING | FILE_FLAG_WRITE_THROUGH,
NULL
);
if (hFile == INVALID_HANDLE_VALUE)
{
std::cout << "Unable to open/create file for writing" << std::endl;
PrintError(TEXT("CreateFile failed"));
}
Data *data = new Data();
DWORD dwBytesToWrite = sizeof(Data);
DWORD dwBytesWritten = 0;
BOOL bErrorFlag = FALSE;
bErrorFlag = WriteFile(
hFile, // open file handle
data, // start of data to write
dwBytesToWrite, // number of bytes to write
&dwBytesWritten, // number of bytes that were written
NULL);
if (bErrorFlag == FALSE)
{
std::cout << "Unable to write to file" << std::endl;
PrintError(TEXT("Unable to write to file"));
}
if (dwBytesToWrite != dwBytesWritten)
{
std::cout << "Error in writing: Whole data not written" << std::endl;
PrintError(TEXT("Error in writing: Whole data not written"));
}
CloseHandle(hFile);
。
如果有任何替代想法,请提出建议。
来自 NtCreateFile
FILE_NO_INTERMEDIATE_BUFFERING
The file cannot be cached or buffered in a driver's internal
buffers. This flag is incompatible with the DesiredAccess
parameter's FILE_APPEND_DATA
flag.
所以当你打电话给
CreateFile(file_path,
FILE_APPEND_DATA, // !!
FILE_SHARE_WRITE,
NULL,
OPEN_ALWAYS,
FILE_FLAG_NO_BUFFERING /*!!*/| FILE_FLAG_WRITE_THROUGH,
NULL
);
您将 FILE_FLAG_NO_BUFFERING
(映射到 FILE_NO_INTERMEDIATE_BUFFERING
)与 FILE_APPEND_DATA
一起使用 - 您必须得到 ERROR_INVALID_PARAMETER
。你需要删除一个标志。我建议删除 FILE_FLAG_NO_BUFFERING
标志,因为有了它你只能写扇区大小的整数。
每次调用我的函数时,它都会覆盖文件。请注意,我使用以下标志以无缓冲模式打开文件。
FILE_FLAG_NO_BUFFERING | FILE_FLAG_WRITE_THROUGH
如果我使用简单的缓冲模式,它工作正常。
FILE_ATTRIBUTE_NORMAL
我在非缓冲模式下遇到以下错误。
** ERROR ** CreateFile failed: The parameter is incorrect.
请在下面找到代码片段。这段代码被调用了很多次。
HANDLE hFile;
LPCWSTR file_path = convertCharArrayToLPCWSTR(UNBUFFERED_FILE);
hFile = CreateFile(file_path,
FILE_APPEND_DATA,
FILE_SHARE_WRITE,
NULL,
OPEN_ALWAYS,
FILE_FLAG_NO_BUFFERING | FILE_FLAG_WRITE_THROUGH,
NULL
);
if (hFile == INVALID_HANDLE_VALUE)
{
std::cout << "Unable to open/create file for writing" << std::endl;
PrintError(TEXT("CreateFile failed"));
}
Data *data = new Data();
DWORD dwBytesToWrite = sizeof(Data);
DWORD dwBytesWritten = 0;
BOOL bErrorFlag = FALSE;
bErrorFlag = WriteFile(
hFile, // open file handle
data, // start of data to write
dwBytesToWrite, // number of bytes to write
&dwBytesWritten, // number of bytes that were written
NULL);
if (bErrorFlag == FALSE)
{
std::cout << "Unable to write to file" << std::endl;
PrintError(TEXT("Unable to write to file"));
}
if (dwBytesToWrite != dwBytesWritten)
{
std::cout << "Error in writing: Whole data not written" << std::endl;
PrintError(TEXT("Error in writing: Whole data not written"));
}
CloseHandle(hFile);
。 如果有任何替代想法,请提出建议。
来自 NtCreateFile
FILE_NO_INTERMEDIATE_BUFFERING
The file cannot be cached or buffered in a driver's internal buffers. This flag is incompatible with the DesiredAccess parameter's
FILE_APPEND_DATA
flag.
所以当你打电话给
CreateFile(file_path,
FILE_APPEND_DATA, // !!
FILE_SHARE_WRITE,
NULL,
OPEN_ALWAYS,
FILE_FLAG_NO_BUFFERING /*!!*/| FILE_FLAG_WRITE_THROUGH,
NULL
);
您将 FILE_FLAG_NO_BUFFERING
(映射到 FILE_NO_INTERMEDIATE_BUFFERING
)与 FILE_APPEND_DATA
一起使用 - 您必须得到 ERROR_INVALID_PARAMETER
。你需要删除一个标志。我建议删除 FILE_FLAG_NO_BUFFERING
标志,因为有了它你只能写扇区大小的整数。