Thread: C++ - Trying to use SetFilePointer & SetFilePointerEx to read USB device

Hello,

Windows 10
gcc 5.3.0

I'm opening a USB memory stick for read.
I can read the beginning of the stick ok, then I try to reset
the file pointer to another position and fail.
What am I doing wrong?
Thanks.

Regards

Code:

    DWORD dwCurrentFilePosition = SetFilePointer(
                hdisk, // must have GENERIC_READ and/or GENERIC_WRITE
                0,     // do not move pointer
                NULL,  // hdisk is not large enough in needing this pointer
                FILE_CURRENT); // provides offset from current position
    printf("Current file pointer position: %lu\n", dwCurrentFilePosition);

Code:

    // position is a LARGE_INTEGER
    position.QuadPart = (__int64)1024;
    printf("LowPart:%lu HighPart:%lu\n", position.LowPart, position.HighPart);

    dwCurrentFilePosition = SetFilePointerEx(
                hdisk,    // must have GENERIC_READ and/or GENERIC_WRITE
                position, // new position
                NULL,     // hdisk is not large enough to need this pointer
                FILE_CURRENT); //provides offset from current position
    printf("New file pointer position: %lu\n", dwCurrentFilePosition);

Code:

Current file pointer position: 512 // this is correct, from previous read
LowPart:1024 HighPart:0
New file pointer position: 1 // should be 1024