Am 26.03.2020 um 20:56 schrieb Corinna Vinschen:
Brian and Thomas,
Thanks to both of you for providing this info.
On Mar 26 13:12, Brian Inglis wrote:
On 2020-03-26 05:00, Corinna Vinschen wrote:
On Mar 26 10:00, Thomas Wolff wrote:
A symbolic link created with WSL is neither interpreted in cygwin nor can it
be deleted:
touch file
wsl ln -s file link
wsl ls -l link
lrwxrwxrwx 1 towo towo 1 Mar 26 08:56 link -> file
ls -l link
-rw-r----- 1 Unknown+User Unknown+Group 0 Mar 26 00:00 link
What kind of file are they in the real world? Reparse points? If so,
what content do they have? I attached a Q&D source from my vault
of old test apps to check on reparse point content. Please compile with
gcc -g ../src/rd-reparse.c -o rd-reparse -lntdll
It takes a single native NT path as parameter, kind of like this:
./rd-reparse '\??\C:\cygwin64\home\corinna\link'
They should be WSL or Windows mklink (soft) links, and the reason why mklink was
allowed unelevated in Windows 10 with Developer mode.
In an *elevated* shell:
$ ls -dln u
-rw-r----- 1 4294967295 4294967295 0 Nov 9 06:09 u
$ getfacl u
getfacl: u: Permission denied
$ icacls u
u NULL SID:(DENY)(Rc,S,REA,WEA,X,DC)
$HOSTNAME\$USER:(F)
$HOSTNAME\$USER:(RX,W,DC)
BUILTIN\Users:(Rc,S,RA)
BUILTIN\Administrators:(RX,W,DC)
BUILTIN\Users:(DENY)(S,RD,REA,X)
Everyone:(RX)
NT AUTHORITY\SYSTEM:(I)(F)
BUILTIN\Administrators:(I)(F)
$HOSTNAME\$USER:(I)(F)
Successfully processed 1 files; Failed processing 0 files
$ ./rd-reparse '\??\C:\...\u'
ReparseTag: 0xa000001d
^^^^^^^^^^
This is a reparse point tag different from the normal Windows symlink
reparse point tag, 0xa000000c. Searching for this value shows this
is defined in ntifs.h as IO_REPARSE_TAG_LX_SYMLINK.
Unfortunately I don't see a definition of the reparse point data for
that reparse point type.
In your examples the data part looks like a 4 byte int value, being 2 in
both of your examples, maybe a file type, followed by the path in
multibyte, no trailing \0.
Unfortunately, in both cases the path is relative, just the file name it
points to. To get more information, could one of you two please create
a few more symlinks?
- A symlink pointing to a local path, given in absolute path syntax.
I assume the path will be in POSIX syntax, contain slashes, but it
would be helpful to see it.
- A symlink with a target path pointing to a remote file (what syntax
does this use?)
- Last but not least, could you please create a symlink pointing to a
target with a non-ASCII char, e. g., some german umlaut?
Not sure what kind of remote you'd like to see. I have a 'net use'
(cifs/smbfs) mounted drive but couldn't mount it in WSL. Otherwise:
> wsl -d Ubuntu ls -l link*
lrwxrwxrwx 1 towo towo 4 Mar 27 00:31 link -> file
lrwxrwxrwx 1 towo towo 15 Mar 27 00:31 link-abs -> /mnt/c/tmp/file
lrwxrwxrwx 1 towo towo 5 Mar 27 00:39 link-foo -> föö
lrwxrwxrwx 1 towo towo 16 Mar 27 00:39 link-foo-abs -> /mnt/c/tmp/föö
> rd-reparse '\??\C:\tmp\link' ; echo
ReparseTag: 0xa000001d
ReparseDataLength: 8
Reserved: 0
02 00 00 00 66 69 6c 65
> rd-reparse '\??\C:\tmp\link-abs' ; echo
ReparseTag: 0xa000001d
ReparseDataLength: 19
Reserved: 0
02 00 00 00 2f 6d 6e 74 2f 63 2f 74 6d 70 2f 66
69 6c 65
> rd-reparse '\??\C:\tmp\link-foo' ; echo
ReparseTag: 0xa000001d
ReparseDataLength: 9
Reserved: 0
02 00 00 00 66 c3 b6 c3 b6
> rd-reparse '\??\C:\tmp\link-foo-abs' ; echo
ReparseTag: 0xa000001d
ReparseDataLength: 20
Reserved: 0
02 00 00 00 2f 6d 6e 74 2f 63 2f 74 6d 70 2f 66
c3 b6 c3 b6
>
If the link name itself contains non-ASCII, rd-reparse fails with
NtOpenFile: C0000034
It's questionable if supporting this new symlink type makes sense, but
taking a closer look doesn't hurt, I guess.
Well, at least they should be deletable, I think.
Thomas
Thanks,
Corinna
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