Re: [Boost-users] [filesystem] filesystem::absolute() doesn't work with ../relative_path or ./relative_path

Subject: Re: [Boost-users] [filesystem] filesystem::absolute() doesn't work with ../relative_path or ./relative_path
From: Lars Viklund (zao_at_[hidden])
Date: 2011-10-07 05:13:52

On Fri, Oct 07, 2011 at 09:52:32AM +0530, Sachin Garg wrote:
> In boost 1.47.0 filesystem v3, boost::filesystem::absolute only appends the
> relative path to base path. It should also remove "./" from relative paths
> and "backtrack" on base path if relative path contains "../../" etc.

That is outside the scope of the function.

In order to properly handle `..`, it would have to hit the filesystem
to find out the information needed to canonicalize the path, as you
cannot naïvely assume that a `..` is equivalent to removing parts of the
path. Thanks to symlinks and hardlinks, you can find yourself in a
completely different area of the filesystems. Resolving paths is
something that functions that need to resolve paths do, not a simple
mechanical absolute().

If the function did this (which it shouldn't), it would be completely
unusable if the path does not represent assets on the local machine,
assets rooted somewhere else, assets in a virtual filesystem, and so on.

It would also have a lot more error cases, like not being able to
traverse the directory hierarchy.

All in all, the behaviour is a feature, not a bug.

In any way, the documentation explains exactly how the resulting path is
composed:
http://www.boost.org/doc/libs/1_47_0/libs/filesystem/v3/doc/reference.html#absolute

-- 
Lars Viklund | zao_at_[hidden]