[asdf-devel] bug in new ASDF
Robert Goldman
rpgoldman at sift.info
Mon Jul 13 18:37:30 UTC 2009
Richard M Kreuter wrote:
> Gary King writes:
>
>>> OK, I /have/ misdiagnosed this. The logic seems actually busted in
>>> directory-pathname-p. The problem is that, at least on allegro, you
>>> can get a valid directory pathname whose name component is neither
>>> NIL, nor :unspecific, but "" (the empty string).
>> Ugh,
>>
>>> (member (pathname-name pathname) (list nil "" :unspecific) :test
>>> 'equal)
>>
>> A source of the problem are pathnames that arise from things like this:
>>
>> > (make-pathname :name "" :directory '(:absolute "tmp"))
>> #p"/tmp/"
>> > (pathname-name *)
>> ""
>>
>> Added a call to namestring seems to be another way to canonical things
>> so I think this will also work and feels (to me) a bit more portable:
>>
>> (defun directory-pathname-p (pathname)
>> (let ((pathname (namestring pathname)))
>> (and (member (pathname-name pathname) (list nil :unspecific))
>> (member (pathname-type pathname) (list nil :unspecific)))))
>
> I see two problems:
>
> (1) If the the host component of *DEFAULT-PATHNAME-DEFAULTS* is
> different than the host component of PATHNAME, the parse might fail
> or come out wrong.
>
> (2) Pathnames with "" for the name component don't have namestrings
> under SBCL. (IIUC, the intent there is to try to have namestring
> parsing and unparsing be non-lossy.)
>
> I think it might do just as well to say that "" for the name counts the
> same as NIL or :UNSPECIFIC for DIRECTORY-PATHNAME-P, unless somebody
> knows of implementations that don't work that way.
>
The problem with this is that it is open to the kind of attacks that
Andreas and Zach propose. Note that those already break the existing
directory-pathname-p assumption that one can check the name and type
components separately....
[I am pleased to reveal that ACL, at least, throws away name fields of
"."... Haven't checked SBCL, nor have I yet checked to see if these are
acceptable name components.]
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