odd behavior of symlinks on Win XP SP2

odd behavior of symlinks on Win XP SP2

[Jeff.Hodges]

I've searched this list and googled and all, and can't find anything about 
this issue, so perhaps it's some cockpit error on my part. Anyways, here's the 
issue/question...

  cygwin symlinks (aka cygwin-created windows shortcuts) seem to work 
  differently, and incorrectly, from the windows perspective, on Win XP SP2
  than they did on (say) Win 2000 Pro. 

On Win2k, I got into the habit of creating many of my symlinks/shortcuts via 
Cygwin ("ln -s" of course) because then they were available, and worked 
correctly, from both the Cygwin and windows perspectives.

Mostly these are symlinks to directories which I use to more conveniently 
traipse around my filesystem. This was true of all my cygwin install/upgrades 
on Win2k from say 1999 thru 2004. The native Win filesystem has been NTFS in 
all cases, fwiw.

However, now on Win XP SP2 (professional) -- I moved to XP SP2 from Win2k in 
Nov-2004 -- I notice the following behavior with both existing 
symlinks/shortcuts copied over to XP from my Win2k box and with new symlinks 
I've created with my newly-upgraded (27-Dec-2004) cygwin install (on XP)...

1. cygwin-created (via "ln -s") symlinks/shortcuts pointing to a directory are 
displayed in windows file dialogs with the windows default "funky file" icon 
(I dunno what it's actual name is) rather than the windows folder icon as used 
to be the case on win2k/cygwin.

2. cygwin-created (via "ln -s") symlinks/shortcuts pointing to a directory are 
displayed in some windows file-open or file-save dialogs, but not in others. 
On win2k/cygwin, they were always displayed and always behaved exactly like 
windows-created shortcuts pointing to a directory. In terms of how they are 
behaving on WinXP/cygwin..

2.1. In the cases where they *are* displayed in windows file-open or file-save 
dialogs, e.g. using windows version of OpenOffice 1.1.3, the program in 
question attempts to either open the symlink/shortcut file itself or overwrite 
it, respectively.

2.2. In the cases where they "are not* displayed in the windows dialog 
(whether open or save), e.g. as done by Firefox 1.0 in the file-save case, 
well, the symlink/shortcut simply isn't listed in the dialog, when on 
win2k/cygwin they were displayed (and behaved) just fine.


I suspect either there's some cockpit error I've committed (or am committing) 
either or both on the Win XP side or the Cygwin side, OR, there's something 
different with Win XP SP2 wrt shortcuts that's causing this.

I do have a symlink or two that I'd created on win2k/cygwin that I copied over 
to the WinXP/cygwin machine (as a part of a  copied-over filesystem subtree) 
that behaves (on XP) as it did on win2k. Yet there are other 
symlinks/shortcuts in the same filesystem subtree that now work incorrectly.

Has anyone else noticed this behavior? If so do you have any ideas on how to 
get it rectified?

thanks,

JeffH





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Re: odd behavior of symlinks on Win XP SP2

[Igor Pechtchanski]

On Fri, 14 Jan 2005, Jeff.Hodges wrote:

> I've searched this list and googled and all, and can't find anything
> about this issue, so perhaps it's some cockpit error on my part.
> Anyways, here's the issue/question...
>
>   cygwin symlinks (aka cygwin-created windows shortcuts) seem to work
>   differently, and incorrectly, from the windows perspective, on Win XP
>   SP2 than they did on (say) Win 2000 Pro.
>
> On Win2k, I got into the habit of creating many of my symlinks/shortcuts
> via Cygwin ("ln -s" of course) because then they were available, and
> worked correctly, from both the Cygwin and windows perspectives.
>
> Mostly these are symlinks to directories which I use to more
> conveniently traipse around my filesystem. This was true of all my
> cygwin install/upgrades on Win2k from say 1999 thru 2004. The native Win
> filesystem has been NTFS in all cases, fwiw.
>
> However, now on Win XP SP2 (professional) -- I moved to XP SP2 from
> Win2k in Nov-2004 -- I notice the following behavior with both existing
> symlinks/shortcuts copied over to XP from my Win2k box and with new
> symlinks I've created with my newly-upgraded (27-Dec-2004) cygwin
> install (on XP)...
>
> 1. cygwin-created (via "ln -s") symlinks/shortcuts pointing to a
> directory are displayed in windows file dialogs with the windows default
> "funky file" icon (I dunno what it's actual name is) rather than the
> windows folder icon as used to be the case on win2k/cygwin.
>
> 2. cygwin-created (via "ln -s") symlinks/shortcuts pointing to a
> directory are displayed in some windows file-open or file-save dialogs,
> but not in others. On win2k/cygwin, they were always displayed and
> always behaved exactly like windows-created shortcuts pointing to a
> directory. In terms of how they are behaving on WinXP/cygwin..
>
> 2.1. In the cases where they *are* displayed in windows file-open or
> file-save dialogs, e.g. using windows version of OpenOffice 1.1.3, the
> program in question attempts to either open the symlink/shortcut file
> itself or overwrite it, respectively.
>
> 2.2. In the cases where they "are not* displayed in the windows dialog
> (whether open or save), e.g. as done by Firefox 1.0 in the file-save
> case, well, the symlink/shortcut simply isn't listed in the dialog, when
> on win2k/cygwin they were displayed (and behaved) just fine.

Hmm, interesting.  I've never noticed this, but your mail prompted me to
look on my own machine.  And, lo and behold, on a plain WinXP SP1 (note,
no SP2) I get the same behavior.

> I suspect either there's some cockpit error I've committed (or am
> committing) either or both on the Win XP side or the Cygwin side, OR,
> there's something different with Win XP SP2 wrt shortcuts that's causing
> this.

I'd say the latter (except it applies to WinXP in general, not just SP2).

> I do have a symlink or two that I'd created on win2k/cygwin that I
> copied over to the WinXP/cygwin machine (as a part of a copied-over
> filesystem subtree) that behaves (on XP) as it did on win2k. Yet there
> are other symlinks/shortcuts in the same filesystem subtree that now
> work incorrectly.
>
> Has anyone else noticed this behavior? If so do you have any ideas on
> how to get it rectified?

I've noticed this.  Further, after a quick look at the structure of the
symlinks[*] shows that the shortcuts created by WinXP have much more stuff
in them (513 bytes vs. 115 bytes), and they seem to have most of the stuff
(comments and paths) in Unicode.  I suspect that WinXP doesn't really deal
well with non-Unicode shortcuts.

Perhaps an update to Cygwin's symlink() implementation is in order?  The
one that's there now actually has the structure of a Windows symlink
hard-coded in (which apparently fails on XP).  See path.cc in
src/winsup/cygwin.  <http://cygwin.com/acronyms/#PTC>.
HTH,
	Igor
[*] BTW, if you have a symlink named "foo", run "attrib -R foo.lnk" to be
able to view (and maybe even edit, if you know what you're doing) the
contents in vi, and then "attrib +R foo.lnk" to turn it back to a symlink.
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Re: odd behavior of symlinks on Win XP SP2

[Corinna Vinschen]

On Jan 14 20:05, Igor Pechtchanski wrote:
> On Fri, 14 Jan 2005, Jeff.Hodges wrote:
> > Mostly these are symlinks to directories which I use to more
> > conveniently traipse around my filesystem. This was true of all my
> > cygwin install/upgrades on Win2k from say 1999 thru 2004. The native Win
> > filesystem has been NTFS in all cases, fwiw.

2001.  The shortcuts have been added to Cygwin in 2001.

> > 1. cygwin-created (via "ln -s") symlinks/shortcuts pointing to a
> > directory are displayed in windows file dialogs with the windows default
> > "funky file" icon (I dunno what it's actual name is) rather than the
> > windows folder icon as used to be the case on win2k/cygwin.
> > 
> > 2. cygwin-created (via "ln -s") symlinks/shortcuts pointing to a
> > directory are displayed in some windows file-open or file-save dialogs,
> > but not in others. On win2k/cygwin, they were always displayed and
> > always behaved exactly like windows-created shortcuts pointing to a
> > directory. In terms of how they are behaving on WinXP/cygwin..
> >
> > 2.1. In the cases where they *are* displayed in windows file-open or
> > file-save dialogs, e.g. using windows version of OpenOffice 1.1.3, the
> > program in question attempts to either open the symlink/shortcut file
> > itself or overwrite it, respectively.
> >
> > 2.2. In the cases where they "are not* displayed in the windows dialog
> > (whether open or save), e.g. as done by Firefox 1.0 in the file-save
> > case, well, the symlink/shortcut simply isn't listed in the dialog, when
> > on win2k/cygwin they were displayed (and behaved) just fine.
> 
> Hmm, interesting.  I've never noticed this, but your mail prompted me to
> look on my own machine.  And, lo and behold, on a plain WinXP SP1 (note,
> no SP2) I get the same behavior.

But they work in Windows Explorer, nevertheless.  We're not in control
of the icon used by Windows.  As soon as we do, the shortcut is not a
Cygwin shortcut anymore and it's saved by tar as a file rather than a
symlink.

> I've noticed this.  Further, after a quick look at the structure of the
> symlinks[*] shows that the shortcuts created by WinXP have much more stuff
> in them (513 bytes vs. 115 bytes), and they seem to have most of the stuff
> (comments and paths) in Unicode.  I suspect that WinXP doesn't really deal
> well with non-Unicode shortcuts.
> 
> Perhaps an update to Cygwin's symlink() implementation is in order?  The
> one that's there now actually has the structure of a Windows symlink
> hard-coded in (which apparently fails on XP).  See path.cc in
> src/winsup/cygwin.  <http://cygwin.com/acronyms/#PTC>.

It has been done so for speed.  And it doesn't really fail.  The shortcut
is still a shortcut in Windows Explorer.  I'm wondering if it's really 
the Unicodeness of the shortcut which makes the difference.  Usually
shortcuts generated in Windows Explorer are much longer anyway.


Corinna

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Re: odd behavior of symlinks on Win XP SP2

[Jeff.Hodges]

Thanks for looking at this Igor. Glad to know it isn't just me. 

pechtcha@cs.nyu.edu said:
>  And, lo and behold, on a plain WinXP SP1 (note, no SP2) I get the
> same behavior.

aha. innaresting. Well, I installed vanilla XP and then copied over a buncha 
directories from my old Win2k box, including \cygwin, and didn't play with it 
much before I upgraded to SP2. So I didn't really note anything while it was 
pre-SP2.

> Perhaps an update to Cygwin's symlink() implementation is in order? 

that's what I'm thinking.


corinna-cygwin@cygwin.com said:
> 2001.  The shortcuts have been added to Cygwin in 2001. 

ah, ok. I guess I didn't really start playing/using Cygwin in somewhat ernest 
until around then anyway.


corinna-cygwin@cygwin.com said:
> And it doesn't really fail.  The shortcut is still a shortcut in
> Windows Explorer.

Well, I claim that it *does* "really fail" because they (cygwin-created 
shortcut/symlinks) no longer -- on XP as compared to Win2k -- behave as they 
did. One uses file open/save dialogs very often when using windoze and on XP 
the cygwin-created shortcut/symlinks no longer behave as-documented (or 
as-in-an-explorer-window). So they don't "fail in all use cases", rather they 
"fail in some often-exercised use cases".


Seems to me we ought to see if we can't update the symlink() impl such that 
this is addressed. I'm betting there's some new attributes or whatever (as 
Igor notes) that've been added to symlinks in XP and if we can figure out what 
that is, and figure out what the minimum is we need to change in our 
cygwin-created .lnk files, we can perhaps (likely?) fix this without adversely 
affecting performance. Maybe there's some new system call on XP that we can 
use to create these buggers (if we're lucky)? After all, AFAIK, all cygwin 
cares about is the cygwin path being in the .lnk file's "comment" 
attribute/field, yes?

thanks again for looking into this,

JeffH



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Re: odd behavior of symlinks on Win XP SP2

[Corinna Vinschen]

On Jan 15 08:17, Jeff.Hodges@KingsMountain.com wrote:
> Seems to me we ought to see if we can't update the symlink() impl such that 
> this is addressed. I'm betting there's some new attributes or whatever (as 
> Igor notes) that've been added to symlinks in XP and if we can figure out what 
> that is, and figure out what the minimum is we need to change in our 
> cygwin-created .lnk files, we can perhaps (likely?) fix this without adversely 
> affecting performance. Maybe there's some new system call on XP that we can 
> use to create these buggers (if we're lucky)? After all, AFAIK, all cygwin 
> cares about is the cygwin path being in the .lnk file's "comment" 
> attribute/field, yes?

I'm glad that you're talking about "us" as a group.  Anybody interested
in tracking that down?


Corinna

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Re: odd behavior of symlinks on Win XP SP2

[Jeff.Hodges]

> I'm glad that you're talking about "us" as a group.  Anybody interested
> in tracking that down?

I'm not in a position to hack code on this unfortunately, but I can offer to 
test.

I suspect it's important in the longer term to track this down because they 
(MSFT) ~could~ make further changes down the road that break cygwin-created 
symlinks altogether (from the windoze perspective), which'd more than just 
"annoying".

JeffH



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Re: odd behavior of symlinks on Win XP SP2

[Christopher Faylor]

On Mon, Jan 17, 2005 at 08:25:26AM -0800, Jeff.Hodges@KingsMountain.com wrote:
>> I'm glad that you're talking about "us" as a group.  Anybody interested
>> in tracking that down?
>
>I'm not in a position to hack code on this unfortunately, but I can offer to 
>test.
>
>I suspect it's important in the longer term to track this down because they 
>(MSFT) ~could~ make further changes down the road that break cygwin-created 
>symlinks altogether (from the windoze perspective), which'd more than just 
>"annoying".

No, Microsoft is not going to break things so that cygwin's symlinks no
longer operate.  Cygwin understands its own version of symlinks very well.

cgf

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Re: odd behavior of symlinks on Win XP SP2

[Sven Köhler]

>>I suspect it's important in the longer term to track this down because they 
>>(MSFT) ~could~ make further changes down the road that break cygwin-created 
>>symlinks altogether (from the windoze perspective), which'd more than just 
>>"annoying".
> 
> No, Microsoft is not going to break things so that cygwin's symlinks no
> longer operate.  Cygwin understands its own version of symlinks very well.

This comment is ridiculous. He clearly complained about MS-Software that 
cannot handle cygwin-created links, and you're talking about cygwin 
understand its own symlinks - well, think about it again.


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Re: odd behavior of symlinks on Win XP SP2

[Christopher Faylor]

On Mon, Jan 17, 2005 at 10:33:47PM +0100, Sven K?hler wrote:
>>>I suspect it's important in the longer term to track this down because 
>>>they (MSFT) ~could~ make further changes down the road that break 
>>>cygwin-created symlinks altogether (from the windoze perspective), 
>>>which'd more than just "annoying".
>>
>>No, Microsoft is not going to break things so that cygwin's symlinks no
>>longer operate.  Cygwin understands its own version of symlinks very well.
>
>This comment is ridiculous. He clearly complained about MS-Software that 
>cannot handle cygwin-created links, and you're talking about cygwin 
>understand its own symlinks - well, think about it again.

Apologies.  I took the word "altogether" to mean "completely" but
obviously missed the meaning implied by "from the windoze perspective".

cgf

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Re: odd behavior of symlinks on Win XP SP2

[Jeff.Hodges]

skoehler@upb.de said:
> He clearly complained about MS-Software that  cannot handle
> cygwin-created links, and you're talking about cygwin  understand its
> own symlinks

correct. thanks.


cgf-no-personal-reply-please@cygwin.com said:
> Apologies.  I took the word "altogether" to mean "completely" but
> obviously missed the meaning implied by "from the windoze
> perspective".

accepted & understood. thanks.


So, again, from the perspective of having cygwin-created symlinks that 
transparently behave as windows shortcuts, they (cygwin-created symlinks) are 
presently half-broken on XP.  And if MSFT were to for some reason align their 
explorer code to match their Open-Save dialog code wrt how they treat (and 
discriminate between) shortcuts, cygwin-created symlink/shortcuts would likely 
quit working entirely *in the windows world* (they'd of course likely to 
continue to work fine in the cygwin world). If this were to come to pass and 
not be addressed by the cygwin community, then it wouldn't make any sense to 
have the the default (or even option) of creating cygwin symlinks as 
"winsymlinks". This would be a loose, imv.

thanks,

JeffH



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Re: odd behavior of symlinks on Win XP SP2

[Jeff.Hodges]

Jeff.Hodges@KingsMountain.com said:
> If this were to come to pass and  not be addressed by the cygwin
> community, then it wouldn't make any sense to  have the the default
> (or even option) of creating cygwin symlinks as  "winsymlinks".

oops. add "...on XP and possibly derivatives thereof."

JeffH



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