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[[meta copyright="Copyright © 2008, 2009 Free Software Foundation, Inc."]]
[[meta license="""[[toggle id="license" text="GFDL 1.2+"]][[toggleable
id="license" text="Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License, Version 1.2 or
any later version published by the Free Software Foundation; with no Invariant
Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license
is included in the section entitled
[[GNU_Free_Documentation_License|/fdl]]."]]"""]]
[[meta title="Lexical .. Resolution"]]
For historical reasons, [[UNIX]] filesystems have a real (hard) `..` link from each
directory pointing to its parent. However, this is problematic, because the
meaning of "parent" really depends on context. If you have a symlink for
example, you can reach a certain node in the filesystem by a different path. If
you go to `..` from there, UNIX will traditionally take you to the hard-coded
parent node -- but this is usually not what you want. Usually you want to go
back to the logical parent from which you came. That is called "lexical"
resolution.
Some application already use lexical resolution internally for that reason. It
is generally agreed that many problems could be avoided if the standard
filesystem lookup calls used lexical resolution as well. The compatibility
problems probably would be negligable.
The goal of this project is to modify the filename lookup mechanism in the Hurd
to use lexical resolution, and to check that the system is still fully
functional afterwards. This task requires understanding the filename resolution
mechanism.
See also [[GNU_Savannah_bug 17133]].
Possible mentors: ?
Exercise: This project requires changes to the name lookup mechanism in the
Hurd-related glibc parts, as well as the Hurd servers. Thus, the exercise task
should involve hacking glibc or Hurd servers, or even both. Fixing the bug in
the client-side nfs translator (/hurd/nfs) that makes "rmdir foo/" fail while
"rmdir foo" works, seems a good candidate.
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