[PATCH] PR21482: long paths on Windows

[Robinson, Paul]

New patch attached.  Threw together . and .. elimination for Michael.
Extra test for Rafael, although I had to #include <windows.h> in the
unittest to make the necessary Windows APIs available. (Testing a relative
path requires setting the current directory to a known writeable place, 
which means calling Windows APIs because path/fs don't have them.)  If it's 
going overboard to do that, let me know and I can take the relative-path
test back out; but actually I think it's useful to have it.
--paulr

> -----Original Message-----
> From: llvm-commits-bounces at cs.uiuc.edu [mailto:llvm-commits-
> bounces at cs.uiuc.edu] On Behalf Of Robinson, Paul
> Sent: Tuesday, November 11, 2014 2:13 PM
> To: Michael Spencer
> Cc: llvm-commits at cs.uiuc.edu; Aaron Ballman
> Subject: RE: [PATCH] PR21482: long paths on Windows
> 
> > -----Original Message-----
> > From: Michael Spencer [mailto:bigcheesegs at gmail.com]
> > Sent: Tuesday, November 11, 2014 12:36 PM
> > To: Robinson, Paul
> > Cc: Aaron Ballman; Rafael Espíndola; llvm-commits at cs.uiuc.edu
> > Subject: Re: [PATCH] PR21482: long paths on Windows
> >
> > On Tue, Nov 11, 2014 at 7:27 AM, Robinson, Paul
> > <Paul_Robinson at playstation.sony.com> wrote:
> > > New patch attached.
> > >
> > > I ended up not using make_absolute because it caused more string
> > copying.
> > > If there's some reason to consider it safer than current_path and
> doing
> > > my own pasting, I can do that instead, but only if y'all think it has
> > > actual value.
> > >
> > > This changed the specific error returned by another fs test, which
> > > seems reasonable.
> > > --paulr
> >
> > This patch doesn't seem to be able to handle "..\foo". \\?\ disables
> > expansion of . and ..
> 
> Feh.
> 
> I'm not able to find a pre-Windows8 API that does this canonicalization
> on sufficiently long path names.  If anybody else has one I'm all ears.
> Otherwise I guess I have to write my own.
> --paulr
> 
> >
> > Other than that it looks fine.
> >
> > - Michael Spencer
> >
> > >
> > >> -----Original Message-----
> > >> From: Michael Spencer [mailto:bigcheesegs at gmail.com]
> > >> Sent: Monday, November 10, 2014 4:04 PM
> > >> To: Robinson, Paul
> > >> Cc: Aaron Ballman; Rafael Espíndola; llvm-commits at cs.uiuc.edu
> > >> Subject: Re: [PATCH] PR21482: long paths on Windows
> > >>
> > >> On Mon, Nov 10, 2014 at 3:05 PM, Robinson, Paul
> > >> <Paul_Robinson at playstation.sony.com> wrote:
> > >> >> -----Original Message-----
> > >> >> From: Aaron Ballman [mailto:aaron.ballman at gmail.com]
> > >> >> Sent: Monday, November 10, 2014 2:47 PM
> > >> >> To: Rafael Espíndola
> > >> >> Cc: Robinson, Paul; llvm-commits at cs.uiuc.edu
> > >> >> Subject: Re: [PATCH] PR21482: long paths on Windows
> > >> >>
> > >> >> On Mon, Nov 10, 2014 at 5:43 PM, Rafael Espíndola
> > >> >> <rafael.espindola at gmail.com> wrote:
> > >> >> > static std::error_code widen_path(const Twine &Path8,
> > >> >> >
> > >> >> > widenPath
> > >> >> >
> > >> >> > Using  '\\?\'  also disables using / as a path separator, no?
> > Don't
> > >> we
> > >> >> > have to check/assert that there is no / in Path8?
> > >> >
> > >> > So for paranoia I should translate all / to \ in the widened path?
> I
> > >> don't
> > >> > see any existing utility to do that, but easy enough to invent one.
> > >>
> > >> sys::path::native(). in Path.h
> > >>
> > >> We also have make_absolute in FileSystem.h
> > >>
> > >> - Michael Spencer
> > >>
> > >> >
> > >> >> >
> > >> >> > +  size_t NLevels = ((248 - TmpLen) / 10) + 1;
> > >> >> > +  const char *OneDir = "\\123456789";
> > >> >> >
> > >> >> > Use the size of OneDir instead of hard codding the 10.
> > >> >> >
> > >> >> > Aaron, this only uses '\\?\' to create long paths. They can
> still
> > be
> > >> >> > accessed by regular tools by changing the current directory, no?
> > >> >>
> > >> >> Yes, relative paths aren't an issue. Just tools using absolute
> paths
> > >> >> that don't support the extended path namespace (which can happen
> if
> > >> >> the app assumes MAX_PATH is actually the max).
> > >> >>
> > >> >> ~Aaron
> > >> >>
> > >> >> >
> > >> >> > On 10 November 2014 16:01, Robinson, Paul
> > >> >> > <Paul_Robinson at playstation.sony.com> wrote:
> > >> >> >> Support directory names longer than 248 characters on Windows.
> > >> >> >>
> > >> >> >> The normal Windows path limit is 260 characters; the limit for
> > >> >> directory
> > >> >> >> names is 248, to leave room for an 8.3 filename at the end.
> > Adding
> > >> the
> > >> >> >> '\\?\' prefix greatly expands these limits.  Intercept path
> names
> > >> that
> > >> >> >> we are about to pass to the Windows APIs and add the prefix if
> > >> >> necessary.
> > >> >> >>
> > >> >> >> Also correct the comment about the state of the temporary
> > directory
> > >> >> used
> > >> >> >> by the Support unittests.
> > >> >> >> --paulr
> > >> >> >>
> > >> >> >>
> > >> >> >> _______________________________________________
> > >> >> >> llvm-commits mailing list
> > >> >> >> llvm-commits at cs.uiuc.edu
> > >> >> >> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> > >> >> >>
> > >> >
> > >> > _______________________________________________
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> > >> > llvm-commits at cs.uiuc.edu
> > >> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> 
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