ssh.el

(require 'cl)

(defun set-env-in-subshells (varname value)

  (let ((shell-command (concat "export "
                               (shell-quote-argument varname)
                               "="
                               (let ((v (shell-quote-argument value)))
                                 (if (and (equal varname "PATH") running-on-windows)
                                     (let ((cygpath-command  (format "cygpath --path %s" v)))
                                       (shell-quote-argument (car (split-string (shell-command-to-string cygpath-command)))))

                                   v))
                               "\n")))

    (mapcar (lambda (b)
              (with-current-buffer b
                (case major-mode
                  ((eshell-mode)
                   (setenv varname value))
                  ((shell-mode)
                   ;; of course we're assuming it's Bash here.
                   (let ((proc (get-buffer-process b)))
                     (when proc
                       (comint-send-string proc shell-command)))))))

            (buffer-list))))

(defun happy ()
  (= 0
     (call-process
      "ssh-add"
      nil               ;;input
      nil               ;; output
      nil               ;;do redisplay
      "-l")))

(defun snarf-ssh-auth-stuff ()
  "Snarf agent data from keychain or some file, and set
environment variables appropriately"
  (interactive)
  (when (executable-find "ssh-add")

    (when (not (happy))
      (some (lambda (fn)
              (with-temp-buffer
                (and (file-readable-p fn)
                     (equal (user-uid) (elt (file-attributes fn) 2))
                     (progn
                       (insert-file-contents fn)
                       (goto-char (point-min))
                       (save-excursion
                         (while (search-forward ";" (point-max) t)
                           (replace-match "\n")
                           ))
                       (keep-lines "=")
                       (while (not (eobp))
                         (when (looking-at (rx (and
                                                (submatch (+? (not (any "="))))
                                                "="
                                                (submatch (+ (not (any ";\n"))))
                                                )))
                           (let ((varname  (match-string 1))
                                 (value    (match-string 2)))
                             (setenv               varname value)
                             (set-env-in-subshells varname value)
                             ))
                         (forward-line 1))

                       (or (happy)
                           (progn
                             (if (fboundp 'lwarn)
                                 (lwarn
                                  'stale-ssh-auth-data
                                  :warning
                                  "The data in %s don't appear to point to a working ssh-agent"
                                  fn)
                               (error fn
                                      "The data don't appear to point to a working ssh-agent"))
                             nil))))))
            (cons
             (expand-file-name "~/ssh-auth-stuff")
             (condition-case error-descr
                 (directory-files
                  "~/.keychain/"
                  t
                  (rx (and "-sh" (zero-or-one (and "-" (any "A-Za-z0-9"))))))
               (file-error (progn (message (error-message-string error-descr))
                                  nil))))))

    (if (happy)
        (message "Hooray: %s"
                 (replace-regexp-in-string
                  "\n" ""
                  (shell-command-to-string "ssh-add -l")))
      (message "Oh darn, couldn't load any SSH auth data."))))
(provide 'ssh)