bug#41463: 27.0.91; ACL error on Windows when trying to save file

bug#41463: 27.0.91; ACL error on Windows when trying to save file

[Lars Ljung]

I get the following error when trying to save a specific file:

Saving file h:/some/file.txt...
file-extended-attributes: Getting ACLs: Input/output error, h:/some/file.txt

This is unexpected since both Emacs 26.3 and notepad.exe are able to
write to this file. Even though I also get an error when using the
Get-Acl command in PowerShell.

In GNU Emacs 27.0.91 (build 2, x86_64-w64-mingw32)
Repository revision: 4b9fbdb5a713745dfdb13042e33ba2345e6860e1
Repository branch: emacs-27
Windowing system distributor 'Microsoft Corp.', version 10.0.18363
System Description: Microsoft Windows 10 Enterprise (v10.0.1909.18363.836)

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
 'configure --prefix=/c/emacs/emacs-27.1 --without-compress-install
 --disable-build-details --without-pop LDFLAGS=-shared-libgcc'

Configured features:
XPM JPEG TIFF GIF PNG RSVG SOUND DBUS NOTIFY W32NOTIFY ACL GNUTLS
LIBXML2 HARFBUZZ ZLIB TOOLKIT_SCROLL_BARS MODULES THREADS JSON PDUMPER
LCMS2 GMP

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: cp1252

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t

bug#41463: 27.0.91; ACL error on Windows when trying to save file

[Eli Zaretskii]

> From: Lars Ljung <lars@matholka.se>
> Date: Fri, 22 May 2020 19:47:39 +0200
> 
> I get the following error when trying to save a specific file:
> 
> Saving file h:/some/file.txt...
> file-extended-attributes: Getting ACLs: Input/output error, h:/some/file.txt
> 
> This is unexpected since both Emacs 26.3 and notepad.exe are able to
> write to this file. Even though I also get an error when using the
> Get-Acl command in PowerShell.

Please report all the details: the ACLs and the owner of that file,
and your user's name and group.  It is impossible to investigate this
without those details.

There was no change in handling of ACLs between Emacs 26 and 27, but
some file-related operations now signal an error instead of silently
failing.  I'm guessing you bumped into one such situation.

Thanks.

bug#41463: 27.0.91; ACL error on Windows when trying to save file

[Lars Ljung]

Den 2020-05-22 kl. 21:08, skrev Eli Zaretskii:
> Please report all the details: the ACLs and the owner of that file,
> and your user's name and group.  It is impossible to investigate this
> without those details.
> 
> There was no change in handling of ACLs between Emacs 26 and 27, but
> some file-related operations now signal an error instead of silently
> failing.  I'm guessing you bumped into one such situation.

Now I think that this happens because H: is a network drive that is
marked as "available offline". The problem goes away if I reconnect to
the company network, and it comes back when I go offline again.

I traced this to acl_get_file() in w32.c where GetLastError() returns
50, i.e. ERROR_NOT_SUPPORTED.

I hope this helps.