(call-process ...) hangs in emacs

[Ken Brown]

On 8/26/2014 2:55 PM, Achim Gratz wrote:
> Ken Brown writes:
>> It looks like my idea is going to work, but it needs testing to make
>> sure I've implemented it correctly.  If anyone is willing to test it,
>> you can download emacs-24.3.93-2 from my personal Cygwin repository:
>>
>>    http://sanibeltranquility.com/cygwin/
>>
>> Instructions can be found at that URL.
>
> I've switched to this version today.
>
> I've noticed that two bugs are still present at least in the emacs-w32
> version:
>
> 1) When showing the Windows desktop with Win-D and then restoring it
> (including Emacs) with Win-D again, the cursor becomes a hollow
> rectangle that doesn't blink.  To get the normal cursor behaviour back
> you have to minimize and restore the Emacs window in the "normal" way.

This one has nothing to do with emacs.  I see the same thing in mintty, 
with just a shell prompt (bash in my case).

> 2) Files that have no POSIX permissions (filemode 0000) and where access
> is granted via ACL only get always opened as "read-only" and you have to
> C-x C-q them before saving.  It appears that this is Cygwin specific
> since on Linux the same version copes with that situation correctly
> (however, the mask bits in the ACL get displayed in the group portion of
> the file mode, which I've never seen happen on Cygwin, so this may be
> something that Cygwin needs to do -- maybe that'd even solve the
> problems that Perl has in the same situation).

AFAICT, emacs decides whether the file is writable via the system call 
faccessat.  (See the function 'check_writable' in src/fileio.c.)  This 
is not Cygwin specific.  So faccessat must be returning failure in the 
scenario you described.  I don't know if that's a Cygwin bug or not.

BTW, emacs on Cygwin doesn't directly check ACLs, because the relevant 
configure test fails.  That would explain the ACL display you see on 
Linux but not on Cygwin.  But I think this is a separate matter, not 
related to the bug you're reporting.

Ken

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