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https://gitlab.freedesktop.org/xorg/lib/libx11/-/commit/a9e845809bcaae22496bc8aa3ca252b410d5f39b
https://bugs.gentoo.org/862115
From a9e845809bcaae22496bc8aa3ca252b410d5f39b Mon Sep 17 00:00:00 2001
From: Matthieu Herrb <matthieu@herrb.eu>
Date: Fri, 11 Nov 2022 18:55:23 +0100
Subject: [PATCH] Fix 797755 Allow X*IfEvent() to reenter libX11
- the activation logic is reversed
- there is also _XInternalLockDisplay() that needs protection
- I've found cases (in fvwm2) where the callback calls XCheckIfEvent()
recursively. So the flag needs to be a counter.
Reviewed-by: Adam Jackson <ajax@redhat.com>
--- a/include/X11/Xlibint.h
+++ b/include/X11/Xlibint.h
@@ -207,7 +207,7 @@ struct _XDisplay
XIOErrorExitHandler exit_handler;
void *exit_handler_data;
- Bool in_ifevent;
+ CARD32 in_ifevent;
};
#define XAllocIDs(dpy,ids,n) (*(dpy)->idlist_alloc)(dpy,ids,n)
--- a/src/ChkIfEv.c
+++ b/src/ChkIfEv.c
@@ -49,8 +49,8 @@ Bool XCheckIfEvent (
unsigned long qe_serial = 0;
int n; /* time through count */
+ dpy->in_ifevent++;
LockDisplay(dpy);
- dpy->in_ifevent = True;
prev = NULL;
for (n = 3; --n >= 0;) {
for (qelt = prev ? prev->next : dpy->head;
@@ -80,7 +80,7 @@ Bool XCheckIfEvent (
/* another thread has snatched this event */
prev = NULL;
}
- dpy->in_ifevent = False;
+ dpy->in_ifevent--;
UnlockDisplay(dpy);
return False;
}
--- a/src/IfEvent.c
+++ b/src/IfEvent.c
@@ -48,8 +48,8 @@ XIfEvent (
register _XQEvent *qelt, *prev;
unsigned long qe_serial = 0;
+ dpy->in_ifevent++;
LockDisplay(dpy);
- dpy->in_ifevent = True;
prev = NULL;
while (1) {
for (qelt = prev ? prev->next : dpy->head;
@@ -60,7 +60,7 @@ XIfEvent (
*event = qelt->event;
_XDeq(dpy, prev, qelt);
_XStoreEventCookie(dpy, event);
- dpy->in_ifevent = False;
+ dpy->in_ifevent--;
UnlockDisplay(dpy);
return 0;
}
--- a/src/OpenDis.c
+++ b/src/OpenDis.c
@@ -189,7 +189,7 @@ XOpenDisplay (
dpy->xcmisc_opcode = 0;
dpy->xkb_info = NULL;
dpy->exit_handler_data = NULL;
- dpy->in_ifevent = False;
+ dpy->in_ifevent = 0;
/*
* Setup other information in this display structure.
--- a/src/PeekIfEv.c
+++ b/src/PeekIfEv.c
@@ -49,8 +49,8 @@ XPeekIfEvent (
register _XQEvent *prev, *qelt;
unsigned long qe_serial = 0;
+ dpy->in_ifevent++;
LockDisplay(dpy);
- dpy->in_ifevent = True;
prev = NULL;
while (1) {
for (qelt = prev ? prev->next : dpy->head;
@@ -64,7 +64,7 @@ XPeekIfEvent (
_XStoreEventCookie(dpy, ©);
*event = copy;
}
- dpy->in_ifevent = False;
+ dpy->in_ifevent--;
UnlockDisplay(dpy);
return 0;
}
--- a/src/locking.c
+++ b/src/locking.c
@@ -465,17 +465,33 @@ static void _XIfEventLockDisplay(
/* assert(dpy->in_ifevent); */
}
+static void _XInternalLockDisplay(
+ Display *dpy,
+ Bool wskip
+ XTHREADS_FILE_LINE_ARGS
+ );
+
+static void _XIfEventInternalLockDisplay(
+ Display *dpy,
+ Bool wskip
+ XTHREADS_FILE_LINE_ARGS
+ )
+{
+ /* assert(dpy->in_ifevent); */
+}
+
static void _XIfEventUnlockDisplay(
Display *dpy
XTHREADS_FILE_LINE_ARGS
)
{
- if (dpy->in_ifevent)
+ if (dpy->in_ifevent == 0) {
+ dpy->lock_fns->lock_display = _XLockDisplay;
+ dpy->lock_fns->unlock_display = _XUnlockDisplay;
+ dpy->lock->internal_lock_display = _XInternalLockDisplay;
+ UnlockDisplay(dpy);
+ } else
return;
-
- dpy->lock_fns->lock_display = _XLockDisplay;
- dpy->lock_fns->unlock_display = _XUnlockDisplay;
- UnlockDisplay(dpy);
}
static void _XLockDisplay(
@@ -507,6 +523,7 @@ static void _XLockDisplay(
if (dpy->in_ifevent) {
dpy->lock_fns->lock_display = _XIfEventLockDisplay;
dpy->lock_fns->unlock_display = _XIfEventUnlockDisplay;
+ dpy->lock->internal_lock_display = _XIfEventInternalLockDisplay;
}
}
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