Cygwin making files inaccessible?

[Andrey Repin]

Greetings, Jay K!

> I looked at this a while. I tried various recent cygwin1.dlls as there were two ACL changes recently.
> I tried building cygwin1.dll with those changes reverted, but failed to build it. 
> For one thing it took me a while to find shilka..it is in cocom, but that wasn't the entire problem.

> Eventually.. I noticed the behavior was not the same for every
> file/directory/volume. Sometimes it worked ok.
> Though I think the ACLs still get changed quite a bit: "full" expands to "many".
> Of course it has worked plenty for me and everyone else.

> Eventually I tried chmod -R 777 * and this seems to have worked.

> I speculate that some "bad" Cygwin ACLs got created at some point.
>  And maybe cacls wasn't deleting them?? That parts seems wierd. Maybe on directories?
> Possibly due to those two recent changes, or maybe user error, I don't know.

This may happen outside Cygwin tree, when initial ACL's are set in some
interesting way.
One possible solution is to tweak /cygdrive mount point to include "noacl"
flag, deferring all ACL modifications to Windows.

(Please bottom post in this list. Thank you.)


> From: Jay K
> Sent: Saturday, February 5, 2022 12:16 PM
> To: cygwin@cygwin.com <cygwin@cygwin.com>
> Subject: Cygwin making files inaccessible? 
>  
> Cygwin making files inaccessible?
> i.e. when Cygwin copies or writes to them, not random files.

> C:\t>dir /s/b/a

> C:\t>dir /q .

> 02/05/2022  04:11 AM    <DIR>          BUILTIN\Administrators .
> 02/05/2022  04:11 AM    <DIR>          NT SERVICE\TrustedInsta..

> C:\t>cacls .
> C:\t Everyone:(OI)(CI)F

> C:\t>echo > 1.txt

> C:\t>cacls 1.txt
> C:\t\1.txt Everyone:F

> C:\t>copy 1.txt 2.txt
>         1 file(s) copied.

> C:\t>cacls 2.txt
> C:\t\2.txt Everyone:F

> C:\t>del 2.txt

> C:\t>uname -a
> CYGWIN_NT-10.0-WOW DESKTOP-BCFUMJ4 3.3.4(0.341/5/3) 2022-01-31 19:31 i686 Cygwin

> C:\t>cp 1.txt 2.txt

> C:\t>which cp
> /usr/bin/cp

> C:\t>cacls 2.txt
> C:\t\2.txt NULL SID:(DENY)(special access:)
>                     READ_CONTROL

>            DESKTOP-BCFUMJ4\jay:(DENY)(special access:)
>                                FILE_READ_DATA
>                                FILE_READ_EA
>                                FILE_EXECUTE

>            DESKTOP-BCFUMJ4\jay:(special access:)
>                                STANDARD_RIGHTS_ALL
>                                DELETE
>                                READ_CONTROL
>                                WRITE_DAC
>                                WRITE_OWNER
>                                SYNCHRONIZE
>                                STANDARD_RIGHTS_REQUIRED
>                                FILE_READ_ATTRIBUTES
>                                FILE_WRITE_ATTRIBUTES

>            DESKTOP-BCFUMJ4\None:R
>            Everyone:R


> C:\t>more 1.txt
> ECHO is on.

> C:\t>more 2.txt
> Cannot access file C:\t\2.txt

> Same behavior from cygwin64.

> C:\t>\cygwin64\bin\uname -a
> CYGWIN_NT-10.0 DESKTOP-BCFUMJ4 3.3.3(0.341/5/3) 2021-12-03 16:35 x86_64 Cygwin

> Huh?

> I would hope Cygwin could/would just copy the ACLs asis.
> I am guessing there is some failed attempt to translate them
> to an internal form and then back to NT form.

> My real scenario was open/write/read, not cp.exe.

>  - Jay



-- 
With best regards,
Andrey Repin
Monday, February 7, 2022 9:59:12

Sorry for my terrible english...