[PATCH] Check for existence of the path before processing '..'

[Christopher Faylor]

On Tue, Jun 11, 2013 at 05:08:13PM +0400, Fedin Pavel wrote:
> Hello!
>
> Some time ago i reported ability to access things like
>"/usr/nonexistent/..bin". I still had this problem and i tried my hands on
>fixing it.
> The patch works by checking the actual existence of the path before
>removing the last component from it. For performance reasons, only one check
>is done for things like "../..". Because, obviously, if "/foo/bar/baz"
>exists, then "/foo/bar" exists too. Also, the check is done only after some
>components have been added to the path. So, for example, current directory
>(obtained when processing relative paths), will not be checked.
> I tried to add a similar test also to normalize_win32_path() function,
>however this broke things like "cd /usr/src/..". For some reason, a POSIX
>version of the path (but with reversed slashes) is passed to this routine
>when expanding mount points, so, consequently, test for "\usr\src" using
>GetFileType() fails.
> I think it's ok, at least POSIX paths now behave in POSIX way. I have
>tested against performance, there is some loss (~0.2 seconds), but only for
>referencing '..'.
> With this patch i am able to compile the latest version of glibc with no
>problems.

You introduce a check_parent flag which is set every time a non-slash
character is found.  That doesn't seem right.  It seems like it should
be set whenever you see a slash.

Also you are calling path_conv recursively.  I assume that is where you
are seeing a performance hit.

cgf

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