[PATCH] Cygwin: Add /dev/disk/by-id symlinks

[Corinna Vinschen]

Hi Christian,

On Oct  3 14:39, Christian Franke wrote:
> Christian Franke wrote:
> > This is a first attempt to partly emulate the Linux directory
> > /dev/disk/by-id. Useful to make sure the correct device is accessed in
> > conjunction with dd, ddrescue, fdisk, ....
> 
> Attached is the second attempt.
> 
> 
> > The additional '*-partN' links to partitions are not yet included.
> 
> These are now included.
> 
> 
> > This only works properly if Win32 path '\\.\PhysicalDriveN' is always
> > trivially mapped to NT path '\Device\HarddiskN\Partition0'.
> > IOCTL_STORAGE_QUERY_PROPERTY with a handle from NtOpenFile(.,
> > READ_CONTROL,...) instead of CreateFile(., 0, ...) did not work with all
> > drivers. With stornvme.sys, it fails with permission denied. Perhaps
> > other permission bits are required for NtOpenFile(). Thanks for any info
> > regarding this.
> 
> According to NtQueryObject(., ObjectBasicInformation, ...), using
> NtOpenFile(., MAXIMUM_ALLOWED, ...) without admin rights sets GrantedAccess
> to 0x001200a0 (FILE_EXECUTE|FILE_READ_ATTRIBUTES|READ_CONTROL|SYNCHRONIZE).
> For some unknown reason, NVMe drives behind stornvme.sys additionally
> require SYNCHRONIZE to use IOCTL_STORAGE_QUERY_PROPERTY. Possibly a harmless
> bug in the access check somewhere in the NVMe stack.
> 
> The disk scanning from the first patch has been reworked based on code
> borrowed from proc.cc:format_proc_partitions(). For the longer term, it may
> make sense to provide one flexible scanning function for /dev/sdXN,
> /proc/partitions and /proc/disk/by-id.

I applied your patch locally (patch looks pretty well, btw) but found
that /dev/disk/by-id is empty, even when running with admin rights.

I ran this on Windows 11 and Windows 2K19 in a QEMU/KVM VM.  A
\Device\Harddisk0\Partition0 symlink pointing to \Device\Harddisk0\DR0
exists in both cases.  I straced it, and found the following debug
output:

  1015 1155432 [main] ls 361 stordesc_to_id_name: Harddisk0\Partition0: 'Red_Hat' 'VirtIO' '' (ignored)

Is that really desired?


Thanks,
Corinna