somewhat off topic: managing Win32 limits in WebDAV

[Mark Phillips-4]

I would be most grateful for information and/or links to articles that describe how others have dealt with the 260 character path limit in Windows. The product manager I work with feels we must support Windows as a backend for the DAV enable product we are developing. Testing with a few clients has exposed the Win32 limitation in a rather stark way.

Thank you, in advance.

Mark Phillips

[Julian Reschke]

Mark Phillips wrote:
>   I would be most grateful for information and/or links to articles that
> describe how others have dealt with the 260 character path limit in
> Windows. The product manager I work with feels we must support Windows
> as a backend for the DAV enable product we are developing. Testing with
> a few clients has exposed the Win32 limitation in a rather stark way.
>
> Thank you, in advance.
>
> Mark Phillips

Hi Mark,

it seems to be you selected a non-optimal list for this question :-) --
w3c-dist-auth@... (the generic WebDAV mailing list) seems to be a
better choice.

That being said -- are you referring to a limit on the client or on the
server?

In general, Windows can deal with longer paths, you just need to use the
correct API for that. If course, many Windows *applications*, such as
Explorer, don't.

BR, Julian

[Mark Phillips-4]

I need to join the other list.

I am dealing with a server side limitation. Our set up is Apache 2.2 on
Windows XP Pro for the moment. We wrote our own client and the URL limit is
10,000,000. Probably excessive but there you go.

In our tests, Apache reports a 403 error but that appears to be misleading.
Further testing reveals a "magic" limit where URI's between 249 and 260
characters in length fail on the MKCOL command.

So our supposition is the ever-popular MAX_PATH constraint. Of course, that
may not be the issue and we open to new info.

thanks for the reply,

 - Mark




On 12/10/08 9:33 AM, "Julian Reschke" <julian.reschke@...> wrote:

>
> Mark Phillips wrote:
>>   I would be most grateful for information and/or links to articles that
>> describe how others have dealt with the 260 character path limit in
>> Windows. The product manager I work with feels we must support Windows
>> as a backend for the DAV enable product we are developing. Testing with
>> a few clients has exposed the Win32 limitation in a rather stark way.
>>
>> Thank you, in advance.
>>
>> Mark Phillips
>
> Hi Mark,
>
> it seems to be you selected a non-optimal list for this question :-) --
> w3c-dist-auth@... (the generic WebDAV mailing list) seems to be a
> better choice.
>
> That being said -- are you referring to a limit on the client or on the
> server?
>
> In general, Windows can deal with longer paths, you just need to use the
> correct API for that. If course, many Windows *applications*, such as
> Explorer, don't.
>
> BR, Julian
>
>

[Julian Reschke]

Mark Phillips wrote:

> I need to join the other list.
>
> I am dealing with a server side limitation. Our set up is Apache 2.2 on
> Windows XP Pro for the moment. We wrote our own client and the URL limit is
> 10,000,000. Probably excessive but there you go.
>
> In our tests, Apache reports a 403 error but that appears to be misleading.
> Further testing reveals a "magic" limit where URI's between 249 and 260
> characters in length fail on the MKCOL command.
>
> So our supposition is the ever-popular MAX_PATH constraint. Of course, that
> may not be the issue and we open to new info.
> ...

I guess it depends on what APR (Apache Portable Runtime) supports on
Windows. It's quite possible that it doesn't take advantage of the more
modern Windows APIs that do not suffer from these length restrictions.

BR, Julian

[Bjoern Hoehrmann]

* Julian Reschke wrote:

>Mark Phillips wrote:
>> I need to join the other list.
>>
>> I am dealing with a server side limitation. Our set up is Apache 2.2 on
>> Windows XP Pro for the moment. We wrote our own client and the URL limit is
>> 10,000,000. Probably excessive but there you go.
>>
>> In our tests, Apache reports a 403 error but that appears to be misleading.
>> Further testing reveals a "magic" limit where URI's between 249 and 260
>> characters in length fail on the MKCOL command.
>>
>> So our supposition is the ever-popular MAX_PATH constraint. Of course, that
>> may not be the issue and we open to new info.
>> ...
>
>I guess it depends on what APR (Apache Portable Runtime) supports on
>Windows. It's quite possible that it doesn't take advantage of the more
>modern Windows APIs that do not suffer from these length restrictions.

If APR is compiled with APR_HAS_UNICODE_FS it supports APR_PATH_MAX long
paths on Windows, the latter being set to 8192 by default. Note that the
individual components have file system specific limits, as I recall, and
as http://en.wikipedia.org/wiki/NTFS seems to confirm, it's 255 for NTFS
so you cannot have file names or directory names longer than that. Other
systems http://en.wikipedia.org/wiki/Comparison_of_file_systems#Limits
tend to have similar limits, so I am not sure that is the problem here.
The httpd also has its own limits for e.g. request header line length.
--
Björn Höhrmann · mailto:bjoern@... · http://bjoern.hoehrmann.de
Am Badedeich 7 · Telefon: [phone] · http://www.bjoernsworld.de
25899 Dagebüll · PGP Pub. KeyID: 0xA4357E78 · http://www.websitedev.de/ 

[Mark Phillips-4]

On 12/11/08 1:18 AM, "Bjoern Hoehrmann" <derhoermi@...> wrote:

>
> * Julian Reschke wrote:
>> Mark Phillips wrote:
>>> I am dealing with a server side limitation. Our set up is Apache 2.2 on
>>> Windows XP Pro for the moment.
>>>
>>> In our tests, Apache reports a 403 error but that appears to be misleading.
>>> Further testing reveals a "magic" limit where URI's between 249 and 260
>>> characters in length fail on the MKCOL command.
>>
>> I guess it depends on what APR (Apache Portable Runtime) supports on
>> Windows. It's quite possible that it doesn't take advantage of the more
>> modern Windows APIs that do not suffer from these length restrictions.
>
> If APR is compiled with APR_HAS_UNICODE_FS it supports APR_PATH_MAX long
> paths on Windows, the latter being set to 8192 by default. Note that the
> individual components have file system specific limits, as I recall, and
> as http://en.wikipedia.org/wiki/NTFS seems to confirm, it's 255 for NTFS
> so you cannot have file names or directory names longer than that.

As a follow up, the issue appears to be addressed in Apache 2.2.6, in which
a modification to the apr library enforces the use of the unicode path
scheme. Refer to <http://marc.info/?l=apr-dev&m=120084184128491&w=2> for
more information.

Thank you for your comments; they definitely helped us get closer to a
resolution.

 - Mark