Search Results for "ReadFile" in kernel32

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    private static extern bool ReadFile(IntPtr handle,

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        // first read the data into an internal buffer since ReadFile cannot read into a buf at

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        bool f = ReadFile(_handle, buf, (uint)count, ref read, IntPtr.Zero);

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        throw new Win32Exception(Marshal.GetLastWin32Error(), "ReadFile failed");

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   if (!Win32.ReadFile(handle, data, length, out len, IntPtr.Zero))

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     FsctlReadFileUsnData = (EFileDevice.FileSystem << 16) | (58 << 2) | EMethod.Neither | (0 << 14),

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    private void ReadFile() {

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Warning! GetOverlappedResult writes to the address of the buffer specified in the ORIGINAL OPERATION (ie/ ReadFile or WriteFile). .NET may move the address of the buffer before GetOverlappedResult returns, resulting in a buffer overflow. Use AllocHGlobal and FreeHGlobal or otherwise ensure the buffer is pinned between the two calls.

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Summary

The ReadFile API

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static extern bool ReadFile(IntPtr hFile, [Out] byte[] lpBuffer,

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static extern unsafe int ReadFile(IntPtr handle, IntPtr bytes, uint numBytesToRead,

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static extern bool ReadFile(IntPtr hFile, [Out] byte[] lpBuffer, uint nNumberOfBytesToRead,

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static extern unsafe bool ReadFile(

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  Private Shared Function ReadFile(ByVal hFile As IntPtr, ByVal Buffer As IntPtr, _

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<DllImport("kernel32.dll")> Friend Shared Function ReadFile( _

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The documentation states that if using unbuffered IO, the memory must be "storage aligned" (aligned to the sector size of the storage device). Either this is not enforced, or managed allocations (specifically byte arrays) are automatically storage aligned because there seems to be no problem using it. Note that storage aligned and page aligned are not the same, and managed allocations are not in general page aligned (required for ReadFileScatter).

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Regarding the above note, my experience shows that failing to provide a storage-aligned buffer causes ReadFile to perform all IO synchronously. I.e. it always blocks until the operation is complete and never returns ERROR_IO_PENDING.

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Warning! GetOverlappedResult writes to the address of the buffer specified in the ORIGINAL OPERATION (ie/ ReadFile or WriteFile). .NET may move the address of the buffer before GetOverlappedResult returns, resulting in a buffer overflow. Use AllocHGlobal and FreeHGlobal or otherwise ensure the buffer is pinned between the two calls. The same applies to the overlapped structure.

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    If ReadFile(hDriver, ip, Marshal.SizeOf(erg), dwBytesReceived, Nothing) Then

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        public unsafe byte[] CT_ReadFile(int InputReportByteLength)

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            if (ReadFile(HidHandle, BufBytes, InputReportByteLength, ref BytesRead, null))

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WriteFile, WriteFileGather, ReadFileScatter

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Documentation

[ReadFile] on MSDN

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Summary

The ReadFileEx API

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static extern bool ReadFileEx(IntPtr hFile, [Out] byte [] lpBuffer,

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ReadFileCompletionDelegate <- need to define this

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Documentation

[ReadFileEx] on MSDN

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Summary

The ReadFileScatter API

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static extern bool ReadFileScatter(IntPtr hFile, FILE_SEGMENT_ELEMENT []

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Documentation

[ReadFileScatter] on MSDN

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Warning! GetOverlappedResult writes to the address of the buffer specified in the ORIGINAL OPERATION (ie/ ReadFile or WriteFile). .NET may move the address of the buffer before GetOverlappedResult returns, resulting in a buffer overflow. Use AllocHGlobal and FreeHGlobal or otherwise ensure the buffer is pinned between the two calls.

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ReadFile, WriteFileGather, ReadFileScatter

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ReadFileScatter