RE: Confusing problem with FSMountLocalVolumeSync
RE: Confusing problem with FSMountLocalVolumeSync
- Subject: RE: Confusing problem with FSMountLocalVolumeSync
- From: "David Hazel" <email@hidden>
- Date: Mon, 20 Nov 2006 16:34:38 -0000
- Importance: Normal
Title: Re: Confusing problem with FSMountLocalVolumeSync
Yes,
that works fine. In fact, so far I've been remounting the device by manually
unplugging it and plugging it back in, after the error.
What
I'm writing to the device at this point is an exact backup taken of its contents
at some point in the past when it was known to have valid data. The backup is
exactly correct (as I can verify by running a Windows version of the same
software and restoring the backup).
The
function that works fully does almost the same thing, but writes zeros
everywhere except the MBR and then overwrites the FAT tables with data that
means "this device is empty". The only difference, therefore, between what works
and what gives an error is that the erroring function writes non-zero data to
the device (and reads data from a normal file during the process, but I've not
been able to establish any connection between that and the
error).
By the
way, after looking yet again at the documentation for FSMountLocalVolumeSync, I
think the error I'm getting is simply "I/O error", rather than anything more
specific. I was assuming that errno gets set by this function, but I don't think
it does.
At 15:50 +0000 20/11/06, David Hazel wrote:
Are there any known
circumstances when FSMountVolumeSync will fail, possibly related to an error
during a write operation?
The obvious suggestion is that you've corrupted the logical volume format
on the device, and that's causing the failure.
In the debugger, set a breakpoint just before you call FSMountVolumeSync
and then try to mount the device from the command line. For example, if
the disk ID is "disk2", you'd do the following:
$ mkdir mountpoint
$ mount_msdos /dev/disk2 mountpoint
Does that work?
S+E
--
Quinn "The
Eskimo!"
<http://www.apple.com/developer/>
Apple Developer Relations,
Developer Technical Support, Core OS/Hardware
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