open-file-in-github.el

(defun depth-from-git-root ()
  (length (split-string
           (shell-command-to-string "git rev-parse --show-cdup")
           "/")))

(defun relative-file-name ()
  (mapconcat 'identity (last
              (split-string (buffer-file-name) "/")
              (depth-from-git-root))
             "/"))

(defun my-filter (condp lst)
  (delq nil
        (mapcar (lambda (x) (and (funcall condp x) x)) lst)))

(defun current-branchp (branch)
  (if (string-match "^\\* " branch)
      t nil))

(defun current-git-branch ()
  (substring
   (car (my-filter 'current-branchp
                   (split-string (shell-command-to-string "git branch") "\n")))
   2))

(defun github-repo ()
  (substring
   (replace-regexp-in-string
    ".*:" ""
    (shell-command-to-string "git config remote.origin.url"))
   0 -5))

(defun github-url ()
  (concat
   "http://github.com/" (github-repo) "/blob/"
   (current-git-branch) "/" (relative-file-name)))

(defun open-file-in-github ()
  (interactive)
  (browse-url (github-url)))