[cygwin] Cygwin's git says "error: failed to read delta-pack base object"

[Corinna Vinschen]

On Dec  4 22:42, Adam Dinwoodie wrote:
> On Thu, Dec 04, 2014 at 04:27:51PM -0500, Dave Lindbergh wrote:
> > You are more than welcome to read the strace output if that'll give
> > you a clue (it doesn't give me one). All 1.7 MBytes of it are at
> > http://nerdfever.com/files/strace.txt
> > 
> > (That comes from "strace git clone
> > https://github.com/nerdfever/pic32mx-bmf >strace.txt")
> > 
> > I'm still stumped.
> 
> Okay, I'm looking through this trace in the hope of finding something.
> The below looks suspicious, but I'm not sufficiently familiar with
> either Git or Cygwin internals to know (a) whether this is a problem at
> all or (b) if it is a problem, whether it's a symptom of an earlier
> problem I haven't spotted on my brief skim.
> 
>       616 12330609 [main] git 2348 unlink_nt: Trying to delete \??\Z:\pic32mx-bmf\.git\objects\30, isdir = 1
>      3190 12333799 [main] git 2348 unlink_nt: Setting delete disposition on \??\Z:\pic32mx-bmf\.git\objects\30 failed, status = 0xC0000101
>      6362 12340161 [main] git 2348 unlink_nt: Try-to-bin \??\Z:\pic32mx-bmf\.git\objects\30
>     24341 12364502 [main] git 2348 try_to_bin: \??\Z:\pic32mx-bmf\.git\objects\30, return bin_status 3
>       645 12365147 [main] git 2348 unlink_nt: Try \??\Z:\pic32mx-bmf\.git\objects\30 again
>     12250 12377397 [main] git 2348 unlink_nt: Setting delete disposition on \??\Z:\pic32mx-bmf\.git\objects\30 failed, status = 0xC0000101
>     22680 12400077 [main] git 2348 unlink_nt: Try \??\Z:\pic32mx-bmf\.git\objects\30 again
>      8487 12408564 [main] git 2348 unlink_nt: Setting delete disposition on \??\Z:\pic32mx-bmf\.git\objects\30 failed, status = 0xC0000101
>      1903 12410467 [main] git 2348 unlink_nt: Try \??\Z:\pic32mx-bmf\.git\objects\30 again
>     <above two lines repeated several more times>

First a sharing violation (not visible in the above snippet), then
directory not empty.

This seems to be the result of an earlier problem.  What I found in
the strace is this:

- Create file Z:\pic32mx-bmf\.git\objects\30\tmp_obj_YljwNZ

- open file, write something, close file.

- link (Z:\pic32mx-bmf\.git\objects\30\tmp_obj_YljwNZ,
	Z:\pic32mx-bmf\.git\objects\30\0bdeb2fd209d24afb865584da10b78aa8fefc4)
  succeeds.

- unlink (Z:\pic32mx-bmf\.git\objects\30\tmp_obj_YljwNZ) succeeds

- Trying to open
  Z:\pic32mx-bmf\.git\objects\30\0bdeb2fd209d24afb865584da10b78aa8fefc4
  but the file doesn't exist and NtCreateFile fails with status
  0xC0000034, STATUS_OBJECT_NAME_NOT_FOUND --> ENOENT.

- Subsequent unlink (Z:\pic32mx-bmf\.git\objects\30) fails with a
  STATUS_DIRECTORY_NOT_EMPTY --> ENOTEMPTY.

- git seems to be prepared for such a case, the parent process calls
  opendir/readdir on the directory.  Enumerating the files in
  Z:\pic32mx-bmf\.git\objects\30 shows the entries ".", ".." and
  "0bdeb2fd209d24afb865584da10b78aa8fefc4".

- Then git calls lstat on the file, which results in NtOpenFile
  returning status STATUS_OBJECT_NAME_NOT_FOUND again.

- From a POSIX POV this means "somebody else" deleted the file,
  so the dir is empty now.  Git tries to delete the directory again,
  which again results in STATUS_DIRECTORY_NOT_EMPTY --> ENOTEMPTY
  and, internally, a sharing violation which disallows to move the
  directory out of the way.

This looks suspiciously like a bug in the remote filesystem.  Link
succeeded, so there are two links to the same file in the directory.
Unlinking link 1 succeeds, so there's still one link to the file in the
directory, but link 2 is inaccessible as if the file has been deleted
completely.  Thus, a full POSIX git on this drive is broken.

Can you please run

  /usr/lib/csih/getVolInfo /cygdrive/z

and paste the output here?  Maybe I can workaround this in the next
Cygwin version.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 819 bytes
Desc: not available
URL: <http://cygwin.com/pipermail/cygwin/attachments/20141205/9e73101f/attachment.sig>