(when (probe-file #p"/dev/null")
(open-device-stream #p"/dev/null" :output))
)
+
+(defun un-unspecific (value)
+ "Convert :UNSPECIFIC to NIL."
+ (if (eq value :unspecific) nil value))
+
+(defun canonicalize-directory-name (filename)
+ (flet ((un-unspecific (value)
+ (if (eq value :unspecific) nil value)))
+ (let* ((path (pathname filename))
+ (name (un-unspecific (pathname-name path)))
+ (type (un-unspecific (pathname-type path)))
+ (new-dir
+ (cond ((and name type) (list (concatenate 'string name "." type)))
+ (name (list name))
+ (type (list type))
+ (t nil))))
+ (if new-dir
+ (make-pathname
+ :directory (append (un-unspecific (pathname-directory path))
+ new-dir)
+ :name nil :type nil :version nil :defaults path)
+ path))))
+
+(defun probe-directory (filename)
+ (let ((path (canonicalize-directory-name filename)))
+ #+allegro (excl:probe-directory path)
+ #+clisp (values
+ (ignore-errors
+ (#+lisp=cl ext:probe-directory #-lisp=cl lisp:probe-directory
+ path)))
+ #+(or cmu scl) (eq :directory (unix:unix-file-kind (namestring path)))
+ #+lispworks (lw:file-directory-p path)
+ #+sbcl (eq :directory (sb-unix:unix-file-kind (namestring path)))
+ #-(or allegro clisp cmu lispworks sbcl scl)
+ (probe-file path)))
+
+(defun directory-tree (filename)
+ "Returns a tree of pathnames for sub-directories of a directory"
+ (let* ((root (canonicalize-directory-name filename))
+ (subdirs (loop for path in (directory
+ (make-pathname :name :wild
+ :type :wild
+ :defaults root))
+ when (probe-directory path)
+ collect (canonicalize-directory-name path))))
+ (when (find nil subdirs)
+ (error "~A" subdirs))
+ (when (null root)
+ (error "~A" root))
+ (if subdirs
+ (cons root (mapcar #'directory-tree subdirs))
+ (if (probe-directory root)
+ (list root)
+ (error "root not directory ~A" root)))))
+
+