From: Andrey Repin <anrdaemon@yandex.ru>
To: Corinna Vinschen <cygwin@cygwin.com>
Subject: Re: (call-process ...) hangs in emacs
Date: Thu, 28 Aug 2014 13:35:00 -0000 [thread overview]
Message-ID: <187704841.20140828172337@yandex.ru> (raw)
In-Reply-To: <20140828100112.GQ20700@calimero.vinschen.de>
Greetings, Corinna Vinschen!
>> > faccessat/access/eaccess don't try to be intelligent by themselves.
>> > Rather they just call a Windows function if the filesystem is mounted
>> > with "acl" mount flags:
>>
>> > - Fetch file's security descriptor
>> > - Create process impersonation token.
>> > - Call NtAccessCheck
>> > - If NtAccessCheck returns "not allowed", check for backup/restore
>> > privileges via NtPrivilegeCheck.
>>
>> > In "noacl" mode or on filesystems not supporting ACLs, access uses the
>> > st_mode flags from stat() to figure out the permissions.
>>
>> I'm not very much into Cygwin internals, so beg pardon if I got something
>> wrong here... But reading this makes my internal sanity checker go into red
>> alarm state.
>>
>> Here's why:
>>
>> When Cygwin mount a filesystem with 'acl' flag set, it mangles current ACL's
>> set on the files to produce something that can be understood as basic POSIX
>> 'ugly'...erm, 'ugo' permissions. Behavior least desirable in many cases.
>> You say, it will then use native functions to determine access rights... No
>> wonder they will work, since you already mangled them to suit your needs.
>>
>> When Cygwin mount a filesystem with 'noacl' flag, thus let OS use true ACL's
>> (a feature Windows implemented surprisingly fast, while *NIX was only
>> proposing it... for far too long without any result in sight), it is then
>> followed by some magic and guesswork on Cygwin's end to find out access
>> rights.
>>
>> If you ask me, something isn't quite right here. Or something is missing.
> It's what "acl" means on Cygwin. "acl" means that Windowsd ACLs are used
> and permissions are handled and converted to and from POSIX permissions.
> "noacl" means, Cygwin ignores all ACLs and fakes ownership and POSIX
> permissions only based only on filetype and DOS R/O attribute, as it has
> to on filesystems not supporting ACLs, like FAT/FAT32.
Got it.
It seems, Cygwin need a middle groung between these two for cases, where FS
support access control, but don't want to be mangled.
--
WBR,
Andrey Repin (anrdaemon@yandex.ru) 28.08.2014, <17:22>
Sorry for my terrible english...
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next prev parent reply other threads:[~2014-08-28 13:35 UTC|newest]
Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-01 12:51 Angelo Graziosi
2014-08-01 13:17 ` Peter Hull
2014-08-01 13:32 ` Corinna Vinschen
2014-08-04 1:03 ` Ken Brown
2014-08-04 8:00 ` Corinna Vinschen
2014-08-04 13:34 ` Ken Brown
2014-08-04 13:45 ` Corinna Vinschen
2014-08-05 12:21 ` Ken Brown
2014-08-05 13:33 ` Peter Hull
2014-08-05 13:59 ` Peter Hull
2014-08-05 13:58 ` Corinna Vinschen
2014-08-05 17:55 ` Ken Brown
2014-08-05 18:40 ` Corinna Vinschen
2014-08-07 11:52 ` Ken Brown
2014-08-07 12:51 ` Corinna Vinschen
2014-08-07 18:54 ` Ken Brown
2014-08-07 15:30 ` Eric Blake
2014-08-07 18:54 ` Ken Brown
2014-08-07 21:42 ` Eric Blake
2014-08-08 13:27 ` Ken Brown
2014-08-08 15:39 ` Peter Hull
2014-08-09 1:38 ` Ken Brown
2014-08-18 12:28 ` Ken Brown
2014-08-18 14:58 ` Peter Hull
2014-08-18 15:03 ` Larry Hall (Cygwin)
2014-08-25 19:00 ` Ken Brown
2014-08-26 9:13 ` Peter Hull
2014-08-26 18:55 ` Achim Gratz
2014-08-26 22:13 ` Ken Brown
2014-08-27 8:42 ` Corinna Vinschen
2014-08-27 12:53 ` Ken Brown
2014-08-27 13:47 ` Corinna Vinschen
2014-08-27 14:40 ` Eric Blake
2014-08-27 17:15 ` Ken Brown
2014-08-27 15:15 ` Achim Gratz
2014-08-28 7:25 ` Achim Gratz
2014-08-28 9:55 ` Corinna Vinschen
2014-08-28 13:18 ` Corinna Vinschen
2014-08-28 15:04 ` Achim Gratz
2014-08-28 15:10 ` Corinna Vinschen
2014-08-28 15:27 ` Achim Gratz
2014-08-29 9:59 ` Achim Gratz
2014-08-29 11:09 ` Corinna Vinschen
2014-08-29 18:08 ` Ken Brown
2014-08-29 19:23 ` Achim Gratz
2014-08-29 19:36 ` Ken Brown
2014-08-29 20:00 ` Achim Gratz
2014-08-29 21:38 ` Ken Brown
2014-08-29 20:05 ` Andrey Repin
2014-08-29 21:43 ` Corinna Vinschen
2014-08-29 23:35 ` Andrey Repin
2014-09-01 11:47 ` Corinna Vinschen
2014-09-01 11:57 ` Corinna Vinschen
2014-09-01 17:38 ` Achim Gratz
2014-09-02 8:32 ` Corinna Vinschen
2014-09-02 17:29 ` Achim Gratz
2014-09-02 19:19 ` Corinna Vinschen
2014-09-02 19:42 ` Achim Gratz
2014-09-02 20:09 ` Corinna Vinschen
2014-09-02 20:23 ` Achim Gratz
2014-09-03 13:04 ` Corinna Vinschen
2014-09-03 17:59 ` Achim Gratz
2014-08-28 10:34 ` Eric Blake
2014-08-27 21:05 ` Andrey Repin
2014-08-28 10:01 ` Corinna Vinschen
2014-08-28 13:35 ` Andrey Repin [this message]
2014-08-28 14:10 ` Corinna Vinschen
2014-08-28 17:05 ` ACL behavior in Cygwin // " Andrey Repin
2014-08-28 18:29 ` Achim Gratz
2014-08-29 8:29 ` Corinna Vinschen
2014-08-28 18:38 ` Achim Gratz
2014-08-28 19:50 ` Andrey Repin
2014-08-06 2:30 ` Katsumi Yamaoka
2014-08-06 8:48 ` Corinna Vinschen
2014-08-06 23:41 ` Katsumi Yamaoka
2014-08-07 0:35 ` Andrey Repin
2014-08-04 8:05 ` Peter Hull
2014-08-04 13:36 ` Ken Brown
-- strict thread matches above, loose matches on Subject: below --
2014-08-06 0:15 Angelo Graziosi
2014-07-31 14:51 Peter Hull
2014-07-31 17:35 ` Ken Brown
2014-08-01 7:36 ` Peter Hull
2014-08-01 10:22 ` Katsumi Yamaoka
2014-08-01 11:33 ` Peter Hull
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