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digitalmars.D.bugs - [Issue 8967] New: dirEntries throws when encountering a "long path" on windows

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=8967

           Summary: dirEntries throws when encountering a "long path" on
                    windows
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody puremagic.com
        ReportedBy: regan netmail.co.nz


--- Comment #0 from Regan Heath <regan netmail.co.nz> 2012-11-06 09:56:10 PST
---
Exception thrown:

Bypasses std.file.FileException std\file.d(2434)
=== Bypassed ===
std.file.FileException std\file.d(2434):
E:\basic\2012-10-16_0\abcdefghi1abcdefghi2abcdefghi3abcdefghi4abcdefghi5abcdefghi6abcdefghi7abcdefghi8abcdefghi9abcdefg
hi0\abcdefghi1abcdefghi2abcdefghi3abcdefghi4abcdefghi5abcdefghi6abcdefghi7abcdefghi8abcdefghi9abcdefghi0\abcdefghi1abcdefghi2abcdefghi3abcdefghi4abcdefghi5abcde
fghi6abcdefghi7abcdefghi8abcdefghi9abcdefghi0: The system cannot find the path
specified.

The solution is simple/trivial.  FindFirstFileW will handle "long paths" in the
following format:

  \\?\<path>

where <path> may be C:\folder\... or \\host\share\...

So, the simplest fix is to alter DirIteratorImpl.stepIn, line:
  string search_pattern = buildPath(directory, "*.*");
to read:
  string search_pattern = r"\\?\" ~ buildPath(directory, "*.*");

(I have tried/tested this fix and it works for me)

Alternately (better) have buildPath (on windows) detect paths longer than 256
characters and automatically pre-pend \\?\ itself.  

This should work ok as long as W functions are used, but will cause issues when
some A functions, and other windows functions are used as long paths are not
supported throughout.  

But, in those cases a too long short path would error - just in a different
way.

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next sibling parent d-bugmail puremagic.com writes:
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Regan Heath <regan netmail.co.nz> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         OS/Version|All                         |Windows


--- Comment #1 from Regan Heath <regan netmail.co.nz> 2012-11-06 10:01:39 PST
---
I should add, the call to direntries used SpanMode.depth, and was passed a
short path which contained the long path shown in the exception.

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prev sibling parent d-bugmail puremagic.com writes:
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Vladimir Panteleev <thecybershadow gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |thecybershadow gmail.com


--- Comment #2 from Vladimir Panteleev <thecybershadow gmail.com> 2012-12-21
21:24:30 PST ---
I'm not sure whether the standard library should be adding the \\?\ prefix
internally. If we are to change dirEntries, then we should also change all I/O
routines that deal with paths. And even then, the resulting paths may not be
usable by other components (used directly in the user's program), such as OS or
C functions, and external programs.

To work around this problem, the user could also use a function such as the one
here [1], and pass path strings through it at the point where they enter the
program's I/O logic layer.

  [1]: https://github.com/CyberShadow/RABCDAsm/blob/master/common.d#L25

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