how about little improve "stat" function for virtual cloned drisk on windows ?

how about little improve "stat" function for virtual cloned drisk on windows ?

[dreverser]

hello, i have issue for using stat for virtual cloned disk on windows/vmware
st_dev give me the the same serial number
and diff util doest work, because thinking path the same and there are
no files for diff

iam propose improve winsup\cygwin\mount.c
by add disk letter to st_dev

at this line
https://github.com/cygwin/cygwin/blob/367c1ae16185e7a81aea5bcc2388e4a7a473c92e/winsup/cygwin/mount.cc#L266

sernum = ffvi_buf.ffvi.VolumeSerialNumber;

after add disk letter to sernum
stat will give more unique st_dev
and as less diff will work

Re: how about little improve "stat" function for virtual cloned drisk on windows ?

[Brian Inglis]

On 2021-04-29 09:29, dreverser--- via Cygwin wrote:
> hello, i have issue for using stat for virtual cloned disk on windows/vmware
> st_dev give me the the same serial number
> and diff util doest work, because thinking path the same and there are
> no files for diff
> 
> iam propose improve winsup\cygwin\mount.c
> by add disk letter to st_dev
> 
> at this line
> https://github.com/cygwin/cygwin/blob/367c1ae16185e7a81aea5bcc2388e4a7a473c92e/winsup/cygwin/mount.cc#L266
> 
> sernum = ffvi_buf.ffvi.VolumeSerialNumber;
> 
> after add disk letter to sernum
> stat will give more unique st_dev
> and as less diff will work

To provide more information, please run and post results of commands below: e.g.

$ head /proc/version
CYGWIN_NT-10.0-19042 version 3.2.0-340.x86_64 (corinna@calimero) (gcc version 
9.3.0 20200312 (Fedora Cygwin 9.3.0-1) (GCC) ) 2021-03-29 08:42 UTC
$ stat /proc/cygdrive/?
   File: /proc/cygdrive/c
   Size: 0               Blocks: 8          IO Block: 65536  directory
Device: ee454341h/3997516609d   Inode: 1407374883553285  Links: 1
Access: (0050/d---r-x---)  Uid: (328384/NT SERVICE+TrustedInstaller)   Gid: 
(328384/NT SERVICE+TrustedInstaller)
Access: 2021-04-29 10:00:59.850885200 -0600
Modify: 2021-04-24 21:37:53.292164400 -0600
Change: 2021-04-24 21:37:53.292164400 -0600
  Birth: 2019-03-18 22:37:21.986161300 -0600
   File: /proc/cygdrive/d
   Size: 0               Blocks: 8          IO Block: 65536  directory
Device: 6b8d438h/112776248d     Inode: 1407374883553285  Links: 1
Access: (0050/d---r-x---)  Uid: (328384/NT SERVICE+TrustedInstaller)   Gid: 
(328384/NT SERVICE+TrustedInstaller)
Access: 2021-04-24 15:14:10.005696600 -0600
Modify: 2021-04-24 15:14:10.005696600 -0600
Change: 2021-04-24 15:14:10.005696600 -0600
  Birth: 2009-07-13 20:38:56.526817600 -0600

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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too much technical detail. Reader discretion is advised.
[Data in binary units and prefixes, physical quantities in SI.]

Re: how about little improve "stat" function for virtual cloned drisk on windows ?

[Corinna Vinschen]

On Apr 29 18:29, dreverser--- via Cygwin wrote:
> hello, i have issue for using stat for virtual cloned disk on windows/vmware
> st_dev give me the the same serial number
> and diff util doest work, because thinking path the same and there are
> no files for diff
> 
> iam propose improve winsup\cygwin\mount.c
> by add disk letter to st_dev
> 
> at this line
> https://github.com/cygwin/cygwin/blob/367c1ae16185e7a81aea5bcc2388e4a7a473c92e/winsup/cygwin/mount.cc#L266
> 
> sernum = ffvi_buf.ffvi.VolumeSerialNumber;
> 
> after add disk letter to sernum
> stat will give more unique st_dev
> and as less diff will work

Unfortunately it's not that easy, because it's not just one drive letter
mounted filesystem vs. the virtual clone.  What if the filesystem is not
mounted with a drive letter but into a directory instead?  What if the
same filesystem has been mounted multiple times?  Especially the latter
case is a problem because it's the same filesystem in a very real sense.


Corinna