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cygwin: unlink: workaround NFS non-ability to move file in certain cases 

Under some not quite clear conditions, NFS fails to use its
unlink workaround to rename a file to ".nfsXYZ".  The problem has been
reproduced with the GAWK testext.awk testcase.  To workaround this in
Cygwin, we now call try_to_bin on NFS, too.  For some reason NFS doesn't
fail to rename the .cygXYZ file to .nfsXYZ after this Cygwin rename.
Fix comment in unlink_nt accordingly.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2017-10-18 16:27:17 +02:00
parent 5b7921523d
commit 88cfcda06b
1 changed files with 43 additions and 8 deletions
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51
winsup/cygwin/syscalls.cc
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@ -501,8 +501,11 @@ try_to_bin (path_conv &pc, HANDLE &fh, ACCESS_MASK access, ULONG flags)
Otherwise the below code closes the handle to allow replacing the file. */
status = NtSetInformationFile (fh, &io, &disp, sizeof disp,
FileDispositionInformation);
if (status == STATUS_DIRECTORY_NOT_EMPTY)
switch (status)
{
case STATUS_SUCCESS:
break;
case STATUS_DIRECTORY_NOT_EMPTY:
/* Uh oh! This was supposed to be avoided by the check_dir_not_empty
test in unlink_nt, but given that the test isn't atomic, this *can*
happen. Try to move the dir back ASAP. */
@ -522,6 +525,34 @@ try_to_bin (path_conv &pc, HANDLE &fh, ACCESS_MASK access, ULONG flags)
}
debug_printf ("Renaming dir %S back to %S failed, status = %y",
&recycler, pc.get_nt_native_path (), status);
break;
case STATUS_FILE_RENAMED:
/* On NFS, the subsequent request to set the delete disposition fails
with STATUS_FILE_RENAMED. We have to reopen the file, close the
original handle, and set the delete disposition on the reopened
handle to make sure setting delete disposition works. */
InitializeObjectAttributes (&attr, &ro_u_empty, 0, fh, NULL);
status = NtOpenFile (&tmp_fh, access, &attr, &io,
FILE_SHARE_VALID_FLAGS, flags);
if (!NT_SUCCESS (status))
debug_printf ("NtOpenFile (%S) for reopening in renamed case failed, "
"status = %y", pc.get_nt_native_path (), status);
else
{
NtClose (fh);
fh = tmp_fh;
status = NtSetInformationFile (fh, &io, &disp, sizeof disp,
FileDispositionInformation);
if (!NT_SUCCESS (status))
debug_printf ("Setting delete disposition %S (%S) in renamed "
"case failed, status = %y",
&recycler, pc.get_nt_native_path (), status);
}
break;
default:
debug_printf ("Setting delete disposition on %S (%S) failed, status = %y",
&recycler, pc.get_nt_native_path (), status);
break;
}
/* In case of success, restore R/O attribute to accommodate hardlinks.
That leaves potentially hardlinks around with the R/O bit suddenly
@ -759,15 +790,19 @@ retry_open:
{
debug_printf ("Sharing violation when opening %S",
pc.get_nt_native_path ());
/* We never call try_to_bin on NFS and NetApp for the follwing reasons:
/* We never call try_to_bin on NetApp. Netapp filesystems don't
understand the "move and delete" method at all and have all kinds
of weird effects. Just setting the delete dispositon usually
works fine, though.
NFS implements its own mechanism to remove in-use files, which looks
quite similar to what we do in try_to_bin for remote files.
Netapp filesystems don't understand the "move and delete" method
at all and have all kinds of weird effects. Just setting the delete
dispositon usually works fine, though. */
if (!pc.fs_is_nfs () && !pc.fs_is_netapp ())
quite similar to what we do in try_to_bin for remote files. However,
apparently it doesn't work as desired in all cases. This has been
observed when running the gawk 4.1.62++ testcase "testext.awk" under
Windows 10. So for NFS we still call try_to_bin to rename the file,
at least to make room for subsequent creation of a file with the
same filename. */
if (!pc.fs_is_netapp ())
bin_stat = move_to_bin;
/* If the file is not a directory, of if we didn't set the move_to_bin
flag, just proceed with the FILE_SHARE_VALID_FLAGS set. */