我正在直接使用C#从磁盘读取并使用kernel32 ReadFile方法。我只想读取特定扇区以节省时间,但ReadFile从第一个扇区读取到N个扇区。如何选择只能读取自己的扇区?
[StructLayout(LayoutKind.Sequential)]
public struct OVERLAPPED
{
public uint Internal;
public uint InternalHigh;
public uint Offset;
public uint OffsetHigh;
public int hEvent;
}
[DllImport("kernel32", SetLastError = true)]
static extern int CreateFile(string filename, uint desiredAccess, uint shareMode, IntPtr attributes, uint creationDisposition, uint flagsAndAttributes, IntPtr templateFile);
[DllImport("kernel32", SetLastError = true)]
public static extern Boolean CloseHandle(int handle);
[DllImport("kernel32.dll", SetLastError = true)]
public static extern Boolean ReadFile(IntPtr hFile, Byte[] buffer, UInt32 BytesToRead, ref UInt32 BytedRead, OVERLAPPED OverLapped);
static int EIGHT_K = 8192;
static int FIVE_TWELVE_BYTES = 512;
static uint GENERIC_READ = 0x80000000;
static uint OPEN_EXISTING = 3;
static uint FILE_SHARE_READ = 1;
static uint FILE_SHARE_WRITE = 2;
[STAThread]
private void button1_Click(object sender, EventArgs e)
{
int fileHandle = 0;
bool returnVal = true;
try
{
// Open the device specified (Using the boot partition)
string deviceName = @"\\.\f:";
fileHandle = CreateFile(deviceName, GENERIC_READ,FILE_SHARE_READ | FILE_SHARE_WRITE, (IntPtr)0, OPEN_EXISTING, 0,(IntPtr)0);
if (fileHandle != -1)
{
Byte[] sector = new Byte[EIGHT_K];
UInt32 bytesRead = (uint)EIGHT_K;
OVERLAPPED ol = new OVERLAPPED();
// Can't get a FileStream ctor to work so I am using Win32 API ReadFile
bool worked = ReadFile((IntPtr)fileHandle, sector, (uint)EIGHT_K, ref bytesRead, ol);
return;
}
}
catch (Exception ex)
{
return;
}
finally
{
CloseHandle(fileHandle);
}
return;
}
我要标记DVD,直到需要原始DVD才能运行该程序。
最佳答案
您的OVERLAPPED
结构声明不正确,并且在64位进程中不正确。但是无论如何您都不需要它。您没有执行重叠的I / O。这也是因为ReadFile
的声明不正确。该函数需要一个指向OVERLAPPED
结构的指针。您通过值传递它。
无论如何,您只需要考虑重叠的I / O。因此,通过从代码中删除OVERLAPPED
结构声明来解决此问题。并这样声明ReadFile
:
[DllImport("kernel32.dll", SetLastError = true)]
public static extern Boolean ReadFile(IntPtr hFile, Byte[] buffer,
UInt32 BytesToRead, out UInt32 BytedRead, IntPtr Overlapped);
传递
IntPtr.Zero
作为Overlapped
参数。并确保您检查ReadFile
的返回值是否有错误。下一步是寻找文件中的位置。为此使用
SetFilePointerEx
。DllImport("kernel32.dll")]
static extern bool SetFilePointerEx(IntPtr hFile, long liDistanceToMove,
out long lpNewFilePointer, uint dwMoveMethod);
请查阅
SetFilePointerEx
的文档,以了解如何调用此函数。由于您使用的是直接磁盘访问,因此您当然需要将读取与扇区边界对齐。
关于c# - 用C#读取Pinvoke的DVD的特定扇区,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/24746540/