Re: Building boost on the RC_1_28_0 branch

From: Markus Schöpflin (markus.schoepflin_at_[hidden])
Date: 2002-05-15 09:16:40

David Abrahams wrote:
> 
> ----- Original Message -----
> From: "Markus Schöpflin" <markus.schoepflin_at_[hidden]>
> 
> You can work around your problem by using -sALL_LOCATE_TARGET=... to build
> > > to a top-level directory (map a drive letter if neccessary)
> >
> > Unfortunaltely not. ".\bjam -sALL_LOCATE_TARGET=c:\" still gives
> > an error.
> 
> The same error?

Yes, but one or two directories further down.

> > > In Boost.Build v2 we can try to work around this problem by making the
> > > mkdir rule CD to the parent directory, if neccessary.
> >
> > Won't help. I tried repeatedly to "mkdir 0123456789 && cd 0123456789"
> > and it still fails when reaching a limit somewhere near 256 chars.
> 
> Where would the 256 characters be? the point is that each directory being
> created would be reached through a sequence of "cd" commands to reach an
> appropriate depth.
> 
> Or are you saying that absolute paths cannot be longer than 256 characters,
> no matter how they are formed?

Exactly. Try it for yourself. Just repeat the mkdir && cd command sequence
and you will encounter an error sooner or later.

> > Looks like we have to use the native WIN32 API to solve this. I could
> > offer to venture a look at the jam sources if this is feasible.
> 
> I don't see how that would help, but maybe you do. So feel free to look at
> it.

If have the hope that the native WIN32 API doesn't have this limit when
used with a file system that supports longer path names. I have the
feeling I'm hitting a limit within cmd.exe. So instead of calling mkdir
maybe using CreateDir() from the API would help.

I just found something in the CreateDir() documentation:

<quote>
There is a default string size limit for paths of 248 characters.
This limit is related to how the CreateDirectory function parses paths.

Windows NT/2000/XP: To extend this limit to nearly 32,000 wide
characters, call the Unicode version of the function and prepend
"\\?\" to the path. For more information, see File Name Conventions. 
</quote>

Markus