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.] _______________________________________________ asdf-devel mailing list asdf-devel@common-lisp.net http://common-lisp.net/cgi-bin/mailman/listinfo/asdf-devel
