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authorPhil Sainty <psainty@orcon.net.nz>2017-10-21 11:17:56 +0300
committerEli Zaretskii <eliz@gnu.org>2017-10-21 11:17:56 +0300
commit0d8e4f45d612ecd77f4997fae30e4d1591f9b8a6 (patch)
tree72c3d41f678300c07d799d7942ca6b2d8cce6d9d /lisp/term.el
parent79d57f4b7a8dc0d0cd213ce5989886cc9fc9b7f3 (diff)
downloademacs-0d8e4f45d612ecd77f4997fae30e4d1591f9b8a6.tar.gz
Avoid creating inconsistent buffer states in term-char-mode
* lisp/term.el (term-mode, term-char-mode, term-line-mode) (term-emulate-terminal): Make buffer read-only in 'term-char-mode', except for the process filter's output. Use 'read-only-mode-hook' to track and restore the user-set state of 'buffer-read-only' for 'term-line-mode'. (Bug#24837) (term-char-mode-buffer-read-only): New user option. (term-line-mode-buffer-read-only): New buffer-local variable. (term-line-mode-buffer-read-only-update): New function. (term-char-mode, term-line-mode): Use 'term-set-goto-process-mark' in pre-command-hook, and 'term-goto-process-mark-maybe' in post-command-hook to counter-act unexpected changes to point when using 'term-char-mode'. (term-char-mode-point-at-process-mark): New user option. (term-goto-process-mark): New buffer-local variable. (term-set-goto-process-mark): New function. (term-goto-process-mark-maybe): New function. (term-process-mark): New function. * etc/NEWS: Mention the new behavior and user options.
Diffstat (limited to 'lisp/term.el')
-rw-r--r--lisp/term.el98
1 files changed, 98 insertions, 0 deletions
diff --git a/lisp/term.el b/lisp/term.el
index c748c450206..2046578368c 100644
--- a/lisp/term.el
+++ b/lisp/term.el
@@ -427,6 +427,8 @@ by moving term-home-marker. It is set to t if there is a
(defvar term-old-mode-line-format) ; Saves old mode-line-format while paging.
(defvar term-pager-old-local-map nil "Saves old keymap while paging.")
(defvar term-pager-old-filter) ; Saved process-filter while paging.
+(defvar-local term-line-mode-buffer-read-only nil
+ "The `buffer-read-only' state to set in `term-line-mode'.")
(defcustom explicit-shell-file-name nil
"If non-nil, is file name to use for explicitly requested inferior shell."
@@ -487,6 +489,41 @@ This variable is buffer-local, and is a good thing to set in mode hooks."
:type 'boolean
:group 'term)
+(defcustom term-char-mode-buffer-read-only t
+ "If non-nil, only the process filter may modify the buffer in char mode.
+
+A non-nil value makes the buffer read-only in `term-char-mode',
+which prevents editing commands from making the buffer state
+inconsistent with the state of the terminal understood by the
+inferior process. Only the process filter is allowed to make
+changes to the buffer.
+
+Customize this option to nil if you want the previous behaviour."
+ :version "26.1"
+ :type 'boolean
+ :group 'term)
+
+(defcustom term-char-mode-point-at-process-mark t
+ "If non-nil, keep point at the process mark in char mode.
+
+A non-nil value causes point to be moved to the current process
+mark after each command in `term-char-mode' (provided that the
+pre-command point position was also at the process mark). This
+prevents commands that move point from making the buffer state
+inconsistent with the state of the terminal understood by the
+inferior process.
+
+Mouse events are not affected, so moving point and selecting text
+is still possible in char mode via the mouse, after which other
+commands can be invoked on the mouse-selected point or region,
+until the process filter (or user) moves point to the process
+mark once again.
+
+Customize this option to nil if you want the previous behaviour."
+ :version "26.1"
+ :type 'boolean
+ :group 'term)
+
(defcustom term-scroll-to-bottom-on-output nil
"Controls whether interpreter output causes window to scroll.
If nil, then do not scroll. If t or `all', scroll all windows showing buffer.
@@ -1105,6 +1142,8 @@ Entry to this mode runs the hooks on `term-mode-hook'."
(term-reset-size (cdr size) (car size)))
size))
+ (add-hook 'read-only-mode-hook #'term-line-mode-buffer-read-only-update nil t)
+
(easy-menu-add term-terminal-menu)
(easy-menu-add term-signals-menu)
(or term-input-ring
@@ -1246,6 +1285,13 @@ intervention from Emacs, except for the escape character (usually C-c)."
(easy-menu-add term-terminal-menu)
(easy-menu-add term-signals-menu)
+ ;; Don't allow changes to the buffer or to point which are not
+ ;; caused by the process filter.
+ (when term-char-mode-buffer-read-only
+ (setq buffer-read-only t))
+ (add-hook 'pre-command-hook #'term-set-goto-process-mark nil t)
+ (add-hook 'post-command-hook #'term-goto-process-mark-maybe nil t)
+
;; Send existing partial line to inferior (without newline).
(let ((pmark (process-mark (get-buffer-process (current-buffer))))
(save-input-sender term-input-sender))
@@ -1265,9 +1311,20 @@ This means that Emacs editing commands work as normally, until
you type \\[term-send-input] which sends the current line to the inferior."
(interactive)
(when (term-in-char-mode)
+ (when term-char-mode-buffer-read-only
+ (setq buffer-read-only term-line-mode-buffer-read-only))
+ (remove-hook 'pre-command-hook #'term-set-goto-process-mark t)
+ (remove-hook 'post-command-hook #'term-goto-process-mark-maybe t)
(use-local-map term-old-mode-map)
(term-update-mode-line)))
+(defun term-line-mode-buffer-read-only-update ()
+ "Update the user-set state of `buffer-read-only' in `term-line-mode'.
+
+Called as a buffer-local `read-only-mode-hook' function."
+ (when (term-in-line-mode)
+ (setq term-line-mode-buffer-read-only buffer-read-only)))
+
(defun term-update-mode-line ()
(let ((term-mode
(if (term-in-char-mode)
@@ -2711,6 +2768,7 @@ See `term-prompt-regexp'."
count-bytes ; number of bytes
decoded-substring
save-point save-marker old-point temp win
+ (inhibit-read-only t)
(buffer-undo-list t)
(selected (selected-window))
last-win
@@ -3109,6 +3167,46 @@ See `term-prompt-regexp'."
(when (get-buffer-window (current-buffer))
(redisplay))))
+(defvar-local term-goto-process-mark t
+ "Whether to reset point to the current process mark after this command.
+
+Set in `pre-command-hook' in char mode by `term-set-goto-process-mark'.")
+
+(defun term-set-goto-process-mark ()
+ "Sets `term-goto-process-mark'.
+
+Always set to nil if `term-char-mode-point-at-process-mark' is nil.
+
+Called as a buffer-local `pre-command-hook' function in
+`term-char-mode' so that when point is equal to the process mark
+at the pre-command stage, we know to restore point to the process
+mark at the post-command stage.
+
+See also `term-goto-process-mark-maybe'."
+ (setq term-goto-process-mark
+ (and term-char-mode-point-at-process-mark
+ (eq (point) (marker-position (term-process-mark))))))
+
+(defun term-goto-process-mark-maybe ()
+ "Move point to the term buffer's process mark upon keyboard input.
+
+Called as a buffer-local `post-command-hook' function in
+`term-char-mode' to prevent commands from putting the buffer into
+an inconsistent state by unexpectedly moving point.
+
+Mouse events are ignored so that mouse selection is unimpeded.
+
+Only acts when the pre-command position of point was equal to the
+process mark, and the `term-char-mode-point-at-process-mark'
+option is enabled. See `term-set-goto-process-mark'."
+ (when term-goto-process-mark
+ (unless (mouse-event-p last-command-event)
+ (goto-char (term-process-mark)))))
+
+(defun term-process-mark ()
+ "The current `process-mark' for the term buffer process."
+ (process-mark (get-buffer-process (current-buffer))))
+
(defun term-handle-deferred-scroll ()
(let ((count (- (term-current-row) term-height)))
(when (>= count 0)