[PATCH] Cygwin: Fix access to block devices below /proc/sys.

[Christian Franke]

Corinna Vinschen wrote:
> On Nov 28 22:59, Christian Franke wrote:
>> ...
>> The attached experimental patch does not fix the lseek() (sorry), but
>> handles such block devices with fhandler_dev_floppy instead. Tested with
>> above use cases.
>>
>> I'm not sure whether this could break access to other /proc/sys block
>> devices. This would happen if fh->exists() returns virt_blk for devices
>> which do not support IOCTL_DISK_GET_DRIVE_GEOMETRY* or
>> IOCTL_DISK_GET_PARTITION_INFO*.
> Pushed, becasue it's a nice idea.  The above problem shouldn't happen,
> in theory, but I'm not sure.  virt_blk is generated for devices types
>
>    FILE_DEVICE_DISK
>    FILE_DEVICE_CD_ROM
>    FILE_DEVICE_VIRTUAL_DISK
>    FILE_DEVICE_DFS
>    FILE_DEVICE_NETWORK_FILE_SYSTEM
>
> FILE_DEVICE_DFS or FILE_DEVICE_NETWORK_FILE_SYSTEM might be a problem,
> but there should be a way to workaround that, if necessary, isn't it?
> Maybe it's a bad idea to treat those as blk devices at all?

Could anything be read from such a node? If yes, treat as character device?

If no and /proc/sys/foo/bar/some/path allows access to /some/path behind 
DFS/NFS node /proc/sys/foo/bar, then treat as directory?

This is already the case for SMB shares:

$ ls -ld /proc/sys/DosDevices/X:
lr-------- 1 ... 0 Nov 30 13:10 /proc/sys/DosDevices/X: ->
   /proc/sys/Device/LanmanRedirector/;X:..../127.0.0.1/Share

$ ls -lLd /proc/sys/DosDevices/X:
drwxr-xr-x 1 ... 0 Nov 14 09:06 /proc/sys/DosDevices/X:

$ ls -L /proc/sys/DosDevices/X:
... files on this share

Thanks,
Christian