[hackers] [st][PATCH] Fix MODE_MOUSEMOTION reporting

From: robert <robertrussell.72001_AT_gmail.com>
Date: Fri, 7 Jan 2022 15:33:34 -0800

Prior to this commit, mousereport tracks the previous button
press/release in the oldbutton variable. When MODE_MOUSEMOTION is set,
mouse reports should be sent for motion events only if a mouse button is
held down, and mousereport uses oldbutton to decide if a button is
pressed. But this is buggy; e.g., try the following in st:
    1. Run "echo '\e[?1002h'" and "cat -v".
    2. Press buttons 1 and 2 and move your pointer around in st. Observe
       that st sends mouse reports.
    3. Release button 2 and move your pointer around in st. Observe that
       st is no longer sending mouse reports, despite button 1 still
       being pressed.
    4. Interrupt cat and run "echo '\e[?1002l'" to disable mouse
       reporting.
(You can also try this in xterm to see the proper behaviour.)

The fix is simply to remove oldbutton. When MODE_MOUSEMOTION is set, the
window event_mask is set such that st receives MotionNotify events only
with at least one button pressed, so nothing more is required.

Incidentally, oldbutton was used in one other way in mousereport: it was
added to the event code for motion events, so that motion reports had
the same two most significant bits and the same two least significant
bits as the previous button press/release report, but this seems
pointless, because the terminal client should ignore these bits for
motion events.

---
 x.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/x.c b/x.c
index 8a16faa..c31057f 100644
--- a/x.c
+++ b/x.c
_AT_@ -252,8 +252,6 @@ static char *opt_line  = NULL;
 static char *opt_name  = NULL;
 static char *opt_title = NULL;
 
-static int oldbutton = 3; /* button event on startup: 3 = release */
-
 void
 clipcopy(const Arg *dummy)
 {
_AT_@ -375,11 +373,8 @@ mousereport(XEvent *e)
 			return;
 		if (!IS_SET(MODE_MOUSEMOTION) && !IS_SET(MODE_MOUSEMANY))
 			return;
-		/* MOUSE_MOTION: no reporting if no button is pressed */
-		if (IS_SET(MODE_MOUSEMOTION) && oldbutton == 3)
-			return;
 
-		button = oldbutton + 32;
+		button = 32;
 		ox = x;
 		oy = y;
 	} else {
_AT_@ -393,11 +388,9 @@ mousereport(XEvent *e)
 				button += 64 - 3;
 		}
 		if (e->xbutton.type == ButtonPress) {
-			oldbutton = button;
 			ox = x;
 			oy = y;
 		} else if (e->xbutton.type == ButtonRelease) {
-			oldbutton = 3;
 			/* MODE_MOUSEX10: no button release reporting */
 			if (IS_SET(MODE_MOUSEX10))
 				return;
-- 
2.17.1

Received on Sat Jan 08 2022 - 00:33:34 CET