Re: Reading MBR from disk

From:

Barry Schwarz <schwarzb@dqel.com>

Newsgroups:

microsoft.public.vc.language,microsoft.public.windows.file_system

Date:

Mon, 02 Jun 2008 04:53:04 -0700

Message-ID:

<00n7441ehimnvekcjc0ggisfeufnb3dgb5@4ax.com>

On Mon, 2 Jun 2008 01:21:00 -0700, JY <sd@nospamgroup.com> wrote:

Hi,

I'm trying to use _read to get the MBR information from the 1st sector of a
disk.
The code is shown below:

int main( void )
{
    char *pDisk = "\\\\.\\PhysicalDrive1";

    int fdDisk0 = _open(pDisk, _O_RDONLY | _O_BINARY);

    if (fdDisk0 != -1)
    {
                               //MasterBootRecord is a struct in a header.
        MasterBootRecord mbrDisk0;
        memset(&mbrDisk0, '\0', sizeof(MasterBootRecord));
        int nReadBytes = 0;
        nReadBytes = _read(fdDisk0, &mbrDisk0, sizeof(MasterBootRecord));

        _close(fdDisk0);
    }

    return 0;
}

Somehow, nReadBytes returns -1. I'm not sure what is wrong, could someone
please help.

The help for _read says it returns -1 when the handle is invalid, the
file is not open for reading, or the file is locked. You check the
handle so it should be valid. You specified read in the call to
_open. That leaves the file is locked. Is the MBR protected? Do you
need administrator authority to read it?

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