phpdbg: Backport watchpoint fixes to PHP-8.4

NEWS

@@ -121,6 +121,10 @@ PHP                                                                        NEWS
 
 - Phpdbg:
   . Fix wrong command names. (ndossche, Weilin Du)
+  . Fixed bug GH-22480 (Use-after-free when re-watching an already-watched
+    variable). (Ilia Alshanetsky)
+  . Fixed over-read when watching a packed array element. (Ilia Alshanetsky)
+  . Fixed double free of watch element chains. (Arnaud)
 
 - Readline:
   . Fixed a crash in readline_info() when completion_append_character

sapi/phpdbg/phpdbg.c

@@ -241,6 +241,13 @@ static PHP_RSHUTDOWN_FUNCTION(phpdbg) /* {{{ */
 	return SUCCESS;
 } /* }}} */
 
+static ZEND_MODULE_POST_ZEND_DEACTIVATE_D(phpdbg) /* {{{ */
+{
+	phpdbg_release_watch_elements();
+
+	return SUCCESS;
+} /* }}} */
+
 /* {{{ Attempt to set the execution context for phpdbg
 	If the execution context was set previously it is returned
 	If the execution context was not set previously boolean true is returned
@@ -688,7 +695,9 @@ static zend_module_entry sapi_phpdbg_module_entry = {
 	PHP_RSHUTDOWN(phpdbg),
 	NULL,
 	PHPDBG_VERSION,
-	STANDARD_MODULE_PROPERTIES
+	NO_MODULE_GLOBALS,
+	ZEND_MODULE_POST_ZEND_DEACTIVATE_N(phpdbg),
+	STANDARD_MODULE_PROPERTIES_EX
 };
 
 static inline int php_sapi_phpdbg_module_startup(sapi_module_struct *module) /* {{{ */

sapi/phpdbg/phpdbg_btree.c

@@ -158,13 +158,18 @@ int phpdbg_btree_insert_or_update(phpdbg_btree *tree, zend_ulong idx, void *ptr,
 		}
 
 		{
-			phpdbg_btree_branch *memory = *branch = pemalloc((i + 2) * sizeof(phpdbg_btree_branch), tree->persistent);
+			phpdbg_btree_branch *memory = pemalloc((i + 2) * sizeof(phpdbg_btree_branch), tree->persistent);
+			phpdbg_btree_branch *node = memory;
 			do {
-				(*branch)->branches[!((idx >> i) % 2)] = NULL;
-				branch = &(*branch)->branches[(idx >> i) % 2];
-				*branch = ++memory;
+				node->branches[!((idx >> i) % 2)] = NULL;
+				node->branches[(idx >> i) % 2] = node + 1;
+				node++;
 			} while (i--);
+			node->result.idx = idx;
+			node->result.ptr = ptr;
+			*branch = memory;
 			tree->count++;
+			return SUCCESS;
 		}
 	} else if (!(flags & PHPDBG_BTREE_UPDATE)) {
 		return FAILURE;