credentials.lisp

   1 ;;;;
   2 ;;;; Copyright (c) 2008 Zachary Beane, All Rights Reserved
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  27 ;;;;
  28 ;;;; credentials.lisp
  29
  30 (in-package #:zs3)
  31
  32 (defvar *credentials* nil
  33   "Used as the default initarg value of :CREDENTIALS when creating a
  34 request.")
  35
  36 (define-condition unsupported-credentials (error)
  37   ((object
  38     :initarg :object
  39     :accessor unsupported-credentials-object))
  40   (:report (lambda (c s)
  41              (format s "The value ~A is unsupported as S3 credentials. (Did you set *CREDENTIALS*?)~@
  42                          See http://www.xach.com/lisp/zs3/#*credentials* ~
  43                          for supported credentials formats."
  44                      (unsupported-credentials-object c)))))
  45
  46 (defgeneric access-key (credentials)
  47   (:method (object)
  48     (error 'unsupported-credentials :object object))
  49   (:method ((list cons))
  50     (first list)))
  51
  52 (defgeneric secret-key (credentials)
  53   (:method (object)
  54     (error 'unsupported-credentials :object object))
  55   (:method ((list cons))
  56     (second list)))
  57
  58
  59 ;;; Lazy-loading credentials
  60
  61 (defclass lazy-credentials-mixin () ())
  62
  63 (defmethod slot-unbound ((class t) (credentials lazy-credentials-mixin)
  64                          (slot (eql 'access-key)))
  65   (nth-value 0 (initialize-lazy-credentials credentials)))
  66
  67 (defmethod slot-unbound ((class t) (credentials lazy-credentials-mixin)
  68                          (slot (eql 'secret-key)))
  69   (nth-value 1 (initialize-lazy-credentials credentials)))
  70
  71
  72 ;;; Loading credentials from a file
  73
  74 (defclass file-credentials (lazy-credentials-mixin)
  75   ((file
  76     :initarg :file
  77     :accessor file)
  78    (access-key
  79     :accessor access-key)
  80    (secret-key
  81     :accessor secret-key)))
  82
  83 (defgeneric initialize-lazy-credentials (credentials)
  84   (:method ((credentials file-credentials))
  85     (with-open-file (stream (file credentials))
  86       (values (setf (access-key credentials) (read-line stream))
  87               (setf (secret-key credentials) (read-line stream))))))
  88
  89 (defun file-credentials (file)
  90   (make-instance 'file-credentials
  91                  :file file))