How to obtain direct access to raw HD data in C?

Question

I need to do a complete format on a USB stick (FAT16 or FAT32), put a file on the drive, then delete it and recover the file using a C program.

Could anyone give me a hint on what should I use to accomplish this?

I understand the layouts of the FAT16/32 filesystems, the problem is that I don't know how to access the raw HD data using C (since I can't use things like fopen or mmap because the file isn't there anymore).

I have set a bounty on a similar question [CreateFile: direct write operation to raw disk “Access is denied” - Vista, Win7](http://stackoverflow.com/q/8694713/341970). Could you help me? — Ali, Jan 03 '12 at 20:37

score 8 · Accepted Answer · edited Dec 17 '11 at 01:20

This is highly operating system specific.

For Linux, you would open the raw device /dev/sdxx. Note that there are privilege hoops to manage.

For Windows, you would use something like:

 HANDLE h = CreateFile ("\\\\.\\PhysicalDriveX", GENERIC_READ,
                    FILE_SHARE_READ | FILE_SHARE_WRITE, NULL,
                    OPEN_EXISTING,
                    FILE_FLAG_NO_BUFFERING | FILE_FLAG_RANDOM_ACCESS,
                    NULL);

where X depends on the device.

score 2 · Answer 2 · answered Dec 17 '11 at 01:06

2

Just use normal filesystem operations on the disk device.

This means you need to identify the disk device first, of course. But once opened, you can even mmap() it.

answered Dec 17 '11 at 01:06

fge

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" But once opened, you can even mmap() it." Can you please show a working example? mmap() - ing "\\\\.\\PhysicalDriveX" fails. – Laszlo Jan 19 '20 at 18:59

How to obtain direct access to raw HD data in C?

2 Answers2

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