+(defun git-setup-commit-buffer (commit)
+ "Setup the commit buffer with the contents of COMMIT."
+ (let (author-name author-email subject date msg)
+ (with-temp-buffer
+ (let ((coding-system (git-get-logoutput-coding-system)))
+ (git-call-process-env t nil "log" "-1" commit)
+ (goto-char (point-min))
+ (when (re-search-forward "^Author: *\\(.*\\) <\\(.*\\)>$" nil t)
+ (setq author-name (match-string 1))
+ (setq author-email (match-string 2)))
+ (when (re-search-forward "^Date: *\\(.*\\)$" nil t)
+ (setq date (match-string 1)))
+ (while (re-search-forward "^ \\(.*\\)$" nil t)
+ (push (match-string 1) msg))
+ (setq msg (nreverse msg))
+ (setq subject (pop msg))
+ (while (and msg (zerop (length (car msg))) (pop msg)))))
+ (git-setup-log-buffer (get-buffer-create "*git-commit*")
+ author-name author-email subject date
+ (mapconcat #'identity msg "\n"))))
+
+(defun git-get-commit-files (commit)
+ "Retrieve the list of files modified by COMMIT."
+ (let (files)
+ (with-temp-buffer
+ (git-call-process-env t nil "diff-tree" "-r" "-z" "--name-only" "--no-commit-id" commit)
+ (goto-char (point-min))
+ (while (re-search-forward "\\([^\0]*\\)\0" nil t 1)
+ (push (match-string 1) files)))
+ files))
+
+(defun git-amend-commit ()
+ "Undo the last commit on HEAD, and set things up to commit an
+amended version of it."
+ (interactive)
+ (unless git-status (error "Not in git-status buffer."))
+ (when (git-empty-db-p) (error "No commit to amend."))
+ (let* ((commit (git-rev-parse "HEAD"))
+ (files (git-get-commit-files commit)))
+ (git-call-process-env nil nil "reset" "--soft" "HEAD^")
+ (git-update-status-files (copy-sequence files) 'uptodate)
+ (git-mark-files git-status files)
+ (git-refresh-files)
+ (git-setup-commit-buffer commit)
+ (git-commit-file)))
+