Hi Christian,
On Nov 5 16:45, Christian Franke wrote:
> Corinna Vinschen wrote:
> > Do we really still need IOCTL_DISK_GET_DRIVE_LAYOUT w/o _EX?
>
> Possibly not. I borrowed this code from code behind /proc/partitions.
>
> > fhandler_proc still uses it, too, but the EX variation is available
> > since XP. I can't imagine that a fallback to the non-EX-version is still
> > necessary. If you like you could drop it immediately, or we can drop
> > both usages as a followup patch.
>
> Old IOCTL dropped and code simplified.
Great. I pushed your patch.
However, while I was just happily removing the non-EX ioctl's from
fhandler/proc.cc I found that this isn't feasible:
The EX calls are not supported by the floppy driver. D'uh.
So for /proc/partitions emulation we still need them.
> > Last, but not least, do you see a chance to add any other /dev/disk
> > subdir? by-partuuid, perhaps?
>
> Possibly, but not very soon. I'm not yet sure which API functions could be
> used.
> Some early draft ideas:
>
> /dev/disk/by-partuid (Partition UUID -> device)
> GPT_PART_UUID -> ../../sdXN (GPT partition UUID)
> MBR_SERIAL-partN -> ../../sdYM (Fake UUID for MBR)
That should only require IOCTL_DISK_GET_PARTITION_INFO_EX, I think.
> /dev/disk/by-uuid (Windows Volume UUID -> device)
> Vol_UUID1 -> ../../sdXN (disk volume)
> Vol_UUID2 -> ../../scd0 (CD/DVD drive volume)
> Vol_UUID3 -> /proc/sys/GLOBAL??/Volume{UUID} (others, e.g. VeraCrypt
> volume)
Yeah, tricky. These are not the partition GUIDs but the filesystem
GUIDs or serial numbers. AFAICS, Windows filesystems (FAT*, NTFS)
don't maintain a filesystem GUID, as, e. g., ext4 or xfs, but only
serial numbers you can fetch via NtQueryVolumeInformationFile.
A Linux example of that is the serial number from a FAT32 filesytem
as the EFI boot partition in by-uuid:
lrwxrwxrwx 1 root root 10 Oct 30 10:20 DC38-0407 -> ../../sda1
On second thought, maybe that's sufficient for our by-uuid emulation.
> /dev/disk/by-drive (Cygwin specific: drive letter -> volume)
> c -> ../by-uuid/UUID (if UUID available)
> x -> /proc/sys/DosDevices/X: (others, e.g. Network, "mounted" Volume
> Shadow Copy)
Ah, good idea. That's what my extension in /proc/partition already
provides, but a /dev/disk/by-drive sounds like a great idea.
Thanks,
Corinna
