[Insight-developers] [Insight-users] 50 character limit in ITK on Win32?

Thu May 3 19:13:53 EDT 2012

On Thu, May 3, 2012 at 6:44 PM, Andras Lasso <lasso at cs.queensu.ca> wrote:
>> For those of us with vs2008, it's just fine to have a 66 character (or
> longer) path
>
> This is not always true. The maximum allowable path length is also dependent
> on length of the solution name, project names, and dependency between
> projects. See:
> http://social.msdn.microsoft.com/forums/en-US/csharpide/thread/d614d0ba-eea2
> -444b-9be8-7fe4fb85a226/
> http://support.microsoft.com/kb/2516078
>
> Andras
>

Thanks for the link. Another piece of evidence that reinforces my
"opinion." I will continue to strongly, strongly recommend keeping
file and directory names short for those that need to build on
Windows. :-)

> -----Original Message-----
> From: insight-developers-bounces at itk.org
> [mailto:insight-developers-bounces at itk.org] On Behalf Of Mark Roden
> Sent: Thursday, May 03, 2012 6:18 PM
> To: David Cole
> Cc: Insight Developers
> Subject: Re: [Insight-developers] [Insight-users] 50 character limit in ITK
> on Win32?
>
> Hi David,
>
> I am locally removing the check for now.  My concern was that I'm developing
> a deployment script where, rather than having to check binaries into source
> control, the script will sync to the itk repo, to a particular commit, and
> then build that commit, starting from scratch and checking the appropriate
> cmake options.  I just want to avoid having to remove the check in the
> script, since it seems superfluous to my build process anyway.
>
> I'd also suggest that there be a maximum character file name style
> convention along with all of the other style requirements that ITK has.  I
> don't think Windows' 255 character path limit is going away any time soon,
> and in light of that, using file names like
> ConstNeighborhoodIteratorGetBoundaryConditionChange.xml
> and
> itkLevelSetEvolutionNumberOfIterationsStoppingCriterionTest.cxx
> would invite this kind of problem, especially if the files are buried deep
> into several nested directories.
>
> I'll look out for CMake 2.8.9 and update to it once it's out.
>
> Thanks,
> Mark
>
>
> On Thu, May 3, 2012 at 3:04 PM, David Cole <david.cole at kitware.com> wrote:
>> On Thu, May 3, 2012 at 5:30 PM, Mark Roden <mmroden at gmail.com> wrote:
>>> Hi Cory,
>>>
>>> OK, I'll switch over to the developer's thread.
>>>
>>> But it appears that the 50 character limit (or 51 character limit, as
>>> reported by Alex Gouaillard) is only a problem with a particular
>>> combination of vs2010 and cmake 2.8.3.  For those of us with vs2008,
>>> it's just fine to have a 66 character (or longer) path.
>>>
>>> I would propose, then, that this error message not be for any and all
>>> versions of win32, but only for those compiler/cmake combinations
>>> where this bug exists.  Otherwise, this limit is just overly
>>> restrictive.
>>>
>>> Thanks,
>>> Mark
>>>
>>> On Thu, May 3, 2012 at 2:24 PM, Cory Quammen <cquammen at cs.unc.edu> wrote:
>>>> Mark,
>>>>
>>>> I think the path length choice was made conservatively because no
>>>> one had the patience to figure out the exact length where things go
> wrong.
>>>>
>>>> The depth of the source tree, especially with the third-party
>>>> libraries, is more of a problem that are the file name lengths in ITK.
>>>>
>>>> It might be more reasonable to issue a warning rather than halt with
>>>> an error. You may want to propose this to the developers list to see
>>>> what others think.
>>>>
>>>> - Cory
>>>>
>>>> On Thu, May 3, 2012 at 5:13 PM, Mark Roden <mmroden at gmail.com> wrote:
>>>>> But a path length of 66 works.
>>>>>
>>>>> It appears that this patch was for a particular compiler (vs2010)
>>>>> and a particular version of cmake (2.8.3).  That's a much more
>>>>> specific issue than all win32 platforms; I'm on vs2008, and as I
>>>>> said, 66 characters works just fine.
>>>>>
>>>>> And I would be strongly in favor of making this a warning, rather
>>>>> than hard limit, if it's difficult/impossible to detect that
>>>>> particular combination of compiler/cmake versions.  I don't, and
>>>>> never have had, an issue building in ITK in any random directory,
>>>>> regardless of path
>>>>> length-- maybe because I tend to keep my path lengths lower than
>>>>> 100 characters.
>>>>>
>>>>> But if this does continue to be an issue, is there some kind of
>>>>> style guide for path length?  I see some really absurdly long
>>>>> filenames in there, and if it really is an issue with vs2010, then
>>>>> maybe that style should be enforced (along with all of the other commit
> rules).
>>>>>
>>>>> On Thu, May 3, 2012 at 2:04 PM, Cory Quammen <cquammen at cs.unc.edu>
> wrote:
>>>>>> Mark,
>>>>>>
>>>>>> The limit is there to save your sanity :-)
>>>>>>
>>>>>> Did you try to compile with a path length of 100 characters? When
>>>>>> I did, I ran into a file-not-found complaint by the compiler when
>>>>>> compiling GDCM. Then I checked to see that the file it is
>>>>>> complaining about does indeed exist.
>>>>>>
>>>>>> See the long email thread that led to this restriction here:
>>>>>>
>>>>>> http://www.itk.org/pipermail/insight-developers/2011-June/019268.h
>>>>>> tml
>>>>>>
>>>>>> Basically, the relative paths generated by CMake and limitations
>>>>>> in the length of paths in Visual Studio lead to this limit.
>>>>>>
>>>>>> Cory
>>>>>>
>>>>>> On Thu, May 3, 2012 at 4:49 PM, Mark Roden <mmroden at gmail.com> wrote:
>>>>>>> Hi all,
>>>>>>>
>>>>>>> I've just recompiled itk 4.0, and found that there's a 50
>>>>>>> character path limit for win32.
>>>>>>>
>>>>>>> What's the logic behind this?  I comment out that line, and
>>>>>>> everything works perfectly fine.
>>>>>>>
>>>>>>> The filename limit for windows is 255 (260 including the drive
>>>>>>> letter and trailing null), but each component of the path can be
>>>>>>> 255 characters long.  MacOS has the same limit for HFS+, where
>>>>>>> each element is locked to 255, but the total path has to be 1024 or
> lower.
>>>>>>> (source:
>>>>>>> http://en.wikipedia.org/wiki/Comparison_of_file_systems).  If
>>>>>>> you're not using windows-specific programming, but just treating the
> path as a string, there's a 255 character limit.
>>>>>>>
>>>>>>> With my base file path that's 66 characters long, the longest
>>>>>>> filename I can find is 146:
>>>>>>>
>>>>>>> C:\Users\mmroden\Documents\src\MyProjectsinQT\ExternalLibs\itk\IT
>>>>>>> K\Documentation\Migration\ConstNeighborhoodIteratorGetBoundaryCon
>>>>>>> ditionChange.xml
>>>>>>>
>>>>>>> That's a far cry from 255.
>>>>>>>
>>>>>>> Just how deep are the paths in ITK anyway?  Is the directory tree
>>>>>>> really 205 characters long?  Or is this just someone guessing
>>>>>>> without actually checking?
>>>>>>>
>>>>>>> The problem with this is that I want to incorporate ITK building
>>>>>>> as part of a build script, rather than having to checkin binary
>>>>>>> images into a repo.  I'd have to add a portion to the script to
>>>>>>> remove the limit.
>>>>>>>
>>>>>>> What if it were just set to 100?
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Mark
>>>>>>> _____________________________________
>>>>>>> Powered by www.kitware.com
>>>>>>>
>>>>>>> Visit other Kitware open-source projects at
>>>>>>> http://www.kitware.com/opensource/opensource.html
>>>>>>>
>>>>>>> Kitware offers ITK Training Courses, for more information visit:
>>>>>>> http://www.kitware.com/products/protraining.php
>>>>>>>
>>>>>>> Please keep messages on-topic and check the ITK FAQ at:
>>>>>>> http://www.itk.org/Wiki/ITK_FAQ
>>>>>>>
>>>>>>> Follow this link to subscribe/unsubscribe:
>>>>>>> http://www.itk.org/mailman/listinfo/insight-users
>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Cory Quammen
>>>>>> Research Associate
>>>>>> Department of Computer Science
>>>>>> The University of North Carolina at Chapel Hill
>>>>
>>>>
>>>>
>>>> --
>>>> Cory Quammen
>>>> Research Associate
>>>> Department of Computer Science
>>>> The University of North Carolina at Chapel Hill
>>> _______________________________________________
>>> Powered by www.kitware.com
>>>
>>> Visit other Kitware open-source projects at
>>> http://www.kitware.com/opensource/opensource.html
>>>
>>> Kitware offers ITK Training Courses, for more information visit:
>>> http://kitware.com/products/protraining.php
>>>
>>> Please keep messages on-topic and check the ITK FAQ at:
>>> http://www.itk.org/Wiki/ITK_FAQ
>>>
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>>
>>
>> This commit that Brad King made recently in CMake (and it will appear
>> in the 2.8.9 release in a couple months) does exactly that: it warns
>> when it encounters a path that's too long, and only on Visual Studio
>> 10.
>>
>>
>> http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=d931ce9fe0c26cfddb7
>> 66901cfd1ccbc9def71c7
>>
>> I'd strongly, strongly encourage you to keep your Windows root path
>> for ITK source and build trees to be as short as possible anyhow.
>>
>> So, after CMake 2.8.9 is required (or at least detected) we can modify
>> the ITK CMakeLists to eliminate / conditionalize that chunk.
>>
>> We could turn it into a warning.... but would people pay attention and
>> move things when they hit it, or would they plow through, and then hit
>> a much later build error and then be mad that they wasted their time?
>>
>> You can certainly make it a warning, make it conditional on VS10, or
>> just eliminate it locally.
>>
>>
>> David
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>
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>