[PATCH 01/11] syscalls.cc: unlink_nt: Try FILE_DISPOSITION_IGNORE_READONLY_ATTRIBUTE first
Corinna Vinschen
corinna-cygwin@cygwin.com
Mon Jan 18 10:45:34 GMT 2021
Hi Ben,
after venting that I missed this flag, back to the patch itself:
On Jan 15 14:45, Ben Wijen wrote:
> ---
> winsup/cygwin/ntdll.h | 3 ++-
> winsup/cygwin/syscalls.cc | 20 ++++++++++++++++----
> 2 files changed, 18 insertions(+), 5 deletions(-)
>
> diff --git a/winsup/cygwin/ntdll.h b/winsup/cygwin/ntdll.h
> index d4f6aaf45..7eee383dd 100644
> --- a/winsup/cygwin/ntdll.h
> +++ b/winsup/cygwin/ntdll.h
> @@ -497,7 +497,8 @@ enum {
> FILE_DISPOSITION_DELETE = 0x01,
> FILE_DISPOSITION_POSIX_SEMANTICS = 0x02,
> FILE_DISPOSITION_FORCE_IMAGE_SECTION_CHECK = 0x04,
> - FILE_DISPOSITION_ON_CLOSE = 0x08
> + FILE_DISPOSITION_ON_CLOSE = 0x08,
> + FILE_DISPOSITION_IGNORE_READONLY_ATTRIBUTE = 0x10,
> };
>
> enum
> diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
> index 525efecf3..ce4e9c65c 100644
> --- a/winsup/cygwin/syscalls.cc
> +++ b/winsup/cygwin/syscalls.cc
> @@ -709,11 +709,23 @@ _unlink_nt (path_conv &pc, bool shareable)
> flags);
> if (!NT_SUCCESS (status))
> goto out;
> - /* Why didn't the devs add a FILE_DELETE_IGNORE_READONLY_ATTRIBUTE
> - flag just like they did with FILE_LINK_IGNORE_READONLY_ATTRIBUTE
> - and FILE_LINK_IGNORE_READONLY_ATTRIBUTE???
> + /* Try FILE_DISPOSITION_IGNORE_READONLY_ATTRIBUTE first
> + it was added with Redstone 5 (Win10 18_09) (as were POSIX rename semantics)
> + If it fails: fall-back to usual trickery */
> + if (wincap.has_posix_rename_semantics ())
> + {
> + fdie.Flags = FILE_DISPOSITION_DELETE | FILE_DISPOSITION_POSIX_SEMANTICS;
> + fdie.Flags|= FILE_DISPOSITION_IGNORE_READONLY_ATTRIBUTE;
> + status = NtSetInformationFile (fh, &io, &fdie, sizeof fdie,
> + FileDispositionInformationEx);
> + if (NT_SUCCESS (status))
> + {
> + NtClose (fh);
> + goto out;
> + }
> + }
Rather than calling NtSetInformationFile here again, we should rather
just skip the transaction stuff on 1809 and later. I'd suggest adding
another wincap flag like, say, "has_posix_ro_override", being true
for 1809 and later. Then we can skip the transaction handling if
wincap.has_posix_ro_override () and just add the
FILE_DISPOSITION_IGNORE_READONLY_ATTRIBUTE flag to fdie.Flags, if
it's available.
Thanks,
Corinna
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