Keep copy-mode -c active for the entire visit

CHANGES

@@ -1,7 +1,6 @@
 CHANGES FROM 3.7c TO 3.8
 
-* Add copy-mode -c to start with the current cursor column as the preferred
+* Add copy-mode -c to disable end-of-line following during vertical movement.
-  column, rather than initially following line ends.
 
 * Many improvements to floating panes:
 

regress/copy-mode-entry-column.sh

@@ -179,6 +179,27 @@ for entry_line in 'prompt> ' '        '; do
 			fi
 			x cancel
 		done
+
+		# Returning to the entry mark must not reenable EOL following.
+		$TMUX copy-mode -c || fail "copy-mode -c failed"
+		x cursor-up
+		check_cursor 8,2
+		x jump-to-mark
+		check_cursor 8,3
+		$TMUX copy-mode || fail "second copy-mode failed"
+		x cursor-up
+		check_cursor 8,2
+		x cancel
+
+		# A new ordinary visit restores the default. Adding -c to an already
+		# active visit does not change its policy.
+		$TMUX copy-mode || fail "copy-mode failed"
+		$TMUX copy-mode -c || fail "second copy-mode -c failed"
+		x cursor-up
+		end=20
+		[ "$mode" = emacs ] || end=19
+		check_cursor "$end,2"
+		x cancel
 	done
 done
 

tmux.1

@@ -2616,9 +2616,9 @@ command is:
 Enter copy mode.
 .Pp
 .Fl c
-initializes the preferred cursor column to the column at which copy mode is
+disables end-of-line following during vertical movement for the duration of
-entered, rather than initially following the end of each line.
+copy mode.
-Subsequent cursor movements use the normal copy mode behaviour.
+Normal cursor limits and selection behaviour are unchanged.
 .Pp
 .Fl u
 enters copy mode and scrolls one page up and

window-copy.c

@@ -106,8 +106,6 @@ static int	window_copy_search_down(struct window_mode_entry *, int);
 static void	window_copy_goto_line(struct window_mode_entry *, const char *);
 static void	window_copy_update_cursor(struct window_mode_entry *, u_int,
 		    u_int);
-static void	window_copy_update_preferred_column(
-		    struct window_copy_mode_data *, u_int);
 static void	window_copy_start_selection(struct window_mode_entry *);
 static int	window_copy_mouse_in_selection(struct window_mode_entry *,
 		    u_int, u_int, int *, int *);
@@ -332,6 +330,7 @@ struct window_copy_mode_data {
 
 	u_int		 lastcx; 	/* position in last line w/ content */
 	u_int		 lastsx;	/* size of last line w/ content */
+	int		 columnflag;	/* do not follow line ends */
 
 	u_int		 mx;		/* mark position */
 	u_int		 my;
@@ -616,11 +615,9 @@ window_copy_init(struct window_mode_entry *wme,
 	window_copy_sync_snapshot(data, base->grid);
 
 	data->cx = cx;
-	if (args_has(args, 'c')) {
+	data->columnflag = args_has(args, 'c');
-		/* Preserve the entry column on the first vertical move. */
+	if (data->columnflag)
 		data->lastcx = cx;
-		data->lastsx = UINT_MAX;
-	}
 	if (cy < screen_hsize(data->backing)) {
 		data->cy = 0;
 		data->oy = screen_hsize(data->backing) - cy;
@@ -834,7 +831,10 @@ window_copy_scroll1(struct window_mode_entry *wme, struct window_pane *wp,
 	oy = screen_hsize(data->backing) + data->cy - data->oy;
 	ox = window_copy_find_length(wme, oy);
 
-	window_copy_update_preferred_column(data, ox);
+	if (data->cx != ox) {
+		data->lastcx = data->cx;
+		data->lastsx = ox;
+	}
 	data->cx = data->lastcx;
 
 	if (delta >= 0) {
@@ -865,8 +865,8 @@ window_copy_scroll1(struct window_mode_entry *wme, struct window_pane *wp,
 	if (data->screen.sel == NULL || !data->rectflag) {
 		py = screen_hsize(data->backing) + data->cy - data->oy;
 		px = window_copy_find_length(wme, py);
-		if ((data->cx >= data->lastsx && data->cx != px) ||
+		if ((!data->columnflag && data->cx >= data->lastsx &&
-		    data->cx > px)
+		    data->cx != px) || data->cx > px)
 			window_copy_cursor_end_of_line(wme);
 	}
 
@@ -898,7 +898,10 @@ window_copy_pageup1(struct window_mode_entry *wme, int half_page)
 	oy = screen_hsize(data->backing) + data->cy - data->oy;
 	ox = window_copy_find_length(wme, oy);
 
-	window_copy_update_preferred_column(data, ox);
+	if (data->cx != ox) {
+		data->lastcx = data->cx;
+		data->lastsx = ox;
+	}
 	data->cx = data->lastcx;
 
 	n = 1;
@@ -921,8 +924,8 @@ window_copy_pageup1(struct window_mode_entry *wme, int half_page)
 	if (data->screen.sel == NULL || !data->rectflag) {
 		py = screen_hsize(data->backing) + data->cy - data->oy;
 		px = window_copy_find_length(wme, py);
-		if ((data->cx >= data->lastsx && data->cx != px) ||
+		if ((!data->columnflag && data->cx >= data->lastsx &&
-		    data->cx > px)
+		    data->cx != px) || data->cx > px)
 			window_copy_cursor_end_of_line(wme);
 	}
 
@@ -954,7 +957,10 @@ window_copy_pagedown1(struct window_mode_entry *wme, int half_page,
 	oy = screen_hsize(data->backing) + data->cy - data->oy;
 	ox = window_copy_find_length(wme, oy);
 
-	window_copy_update_preferred_column(data, ox);
+	if (data->cx != ox) {
+		data->lastcx = data->cx;
+		data->lastsx = ox;
+	}
 	data->cx = data->lastcx;
 
 	n = 1;
@@ -977,8 +983,8 @@ window_copy_pagedown1(struct window_mode_entry *wme, int half_page,
 	if (data->screen.sel == NULL || !data->rectflag) {
 		py = screen_hsize(data->backing) + data->cy - data->oy;
 		px = window_copy_find_length(wme, py);
-		if ((data->cx >= data->lastsx && data->cx != px) ||
+		if ((!data->columnflag && data->cx >= data->lastsx &&
-		    data->cx > px)
+		    data->cx != px) || data->cx > px)
 			window_copy_cursor_end_of_line(wme);
 	}
 
@@ -6310,22 +6316,6 @@ window_copy_find_length(struct window_mode_entry *wme, u_int py)
 	return (grid_line_length(data->backing->grid, py));
 }
 
-static void
-window_copy_update_preferred_column(struct window_copy_mode_data *data,
-    u_int sx)
-{
-	if (data->lastsx == UINT_MAX) {
-		/* Treat the entry column as inside a line. */
-		data->lastsx = data->lastcx + 1;
-		if (data->cx == data->lastcx)
-			return;
-	}
-	if (data->cx != sx) {
-		data->lastcx = data->cx;
-		data->lastsx = sx;
-	}
-}
-
 static u_int
 window_copy_cursor_limit(struct window_mode_entry *wme, u_int py,
     int allow_onemore)
@@ -6512,8 +6502,10 @@ window_copy_cursor_up(struct window_mode_entry *wme, int scroll_only)
 	norectsel = data->screen.sel == NULL || !data->rectflag;
 	oy = screen_hsize(data->backing) + data->cy - data->oy;
 	ox = window_copy_find_length(wme, oy);
-	if (norectsel)
+	if (norectsel && data->cx != ox) {
-		window_copy_update_preferred_column(data, ox);
+		data->lastcx = data->cx;
+		data->lastsx = ox;
+	}
 
 	if (data->lineflag == LINE_SEL_LEFT_RIGHT && oy == data->sely)
 		window_copy_other_end(wme);
@@ -6550,8 +6542,8 @@ window_copy_cursor_up(struct window_mode_entry *wme, int scroll_only)
 	if (norectsel) {
 		py = screen_hsize(data->backing) + data->cy - data->oy;
 		px = window_copy_find_length(wme, py);
-		if ((data->cx >= data->lastsx && data->cx != px) ||
+		if ((!data->columnflag && data->cx >= data->lastsx &&
-		    data->cx > px)
+		    data->cx != px) || data->cx > px)
 		{
 			window_copy_update_cursor(wme, px, data->cy);
 			if (window_copy_update_selection(wme, 1, 0))
@@ -6590,8 +6582,10 @@ window_copy_cursor_down(struct window_mode_entry *wme, int scroll_only)
 	norectsel = data->screen.sel == NULL || !data->rectflag;
 	oy = screen_hsize(data->backing) + data->cy - data->oy;
 	ox = window_copy_find_length(wme, oy);
-	if (norectsel)
+	if (norectsel && data->cx != ox) {
-		window_copy_update_preferred_column(data, ox);
+		data->lastcx = data->cx;
+		data->lastsx = ox;
+	}
 
 	if (data->lineflag == LINE_SEL_RIGHT_LEFT && oy == data->endsely)
 		window_copy_other_end(wme);
@@ -6620,8 +6614,8 @@ window_copy_cursor_down(struct window_mode_entry *wme, int scroll_only)
 	if (norectsel) {
 		py = screen_hsize(data->backing) + data->cy - data->oy;
 		px = window_copy_find_length(wme, py);
-		if ((data->cx >= data->lastsx && data->cx != px) ||
+		if ((!data->columnflag && data->cx >= data->lastsx &&
-		    data->cx > px)
+		    data->cx != px) || data->cx > px)
 		{
 			window_copy_update_cursor(wme, px, data->cy);
 			if (window_copy_update_selection(wme, 1, 0))