Fix several mostly Windows related phpdbg bugs

* Properly initialize PHPDBG_G(watch_tmp)

  Otherwise that may cause segfaults in ZTS builds.

* Deactivate potentially remaining watchpoints after REPL

  Otherwise the memory could still be protected, resulting in segfaults
  during shutdown.

* NULL zend_handlers_table after freeing

  As of commit 4130fe4[1], the `zend_handlers_table` is explicitly
  freed in the `zend_vm_dtor()`.  Since phpdbg (and maybe some other
  SAPIs) may restart the engine afterwards, we have to make sure that
  the table is also NULLed.

* Only set context option if there is a context

  In other words, we must not follow the null pointer.

* Cater to file handles without attached console

  File handles do not necessarily have an attached console (for
  instance, pipes do not), in which case `GetConsoleScreenBufferInfo()`
  fails.  In this case we set a default value (`40`) for lines like on
  other systems.

[1] <http://git.php.net/?p=php-src.git;a=commit;h=4130fe437a5db7ead1444d3748bd0fbad9829cb2>

7 files changed, 29 insertions, 6 deletions

diff --git a/NEWS b/NEWS
index c7b5542554..9093eb7308 100644
--- a/NEWS
+++ b/NEWS
@@ -7,6 +7,7 @@ PHP                                                                        NEWS
 
 - phpdbg:
   . Fixed bug #73926 (phpdbg will not accept input on restart execution). (cmb)
+  . Fixed several mostly Windows related phpdbg bugs. (cmb)
 
 11 Jun 2020, PHP 7.4.7
 
diff --git a/Zend/zend_vm_execute.h b/Zend/zend_vm_execute.h
index 13d55291f9..7af6b31501 100644
--- a/Zend/zend_vm_execute.h
+++ b/Zend/zend_vm_execute.h
@@ -61348,6 +61348,7 @@ void zend_vm_dtor(void)
 	if (zend_handlers_table) {
 		zend_hash_destroy(zend_handlers_table);
 		free(zend_handlers_table);
+		zend_handlers_table = NULL;
 	}
 }
 
diff --git a/Zend/zend_vm_execute.skl b/Zend/zend_vm_execute.skl
index 3e520e9bac..170fc300bb 100644
--- a/Zend/zend_vm_execute.skl
+++ b/Zend/zend_vm_execute.skl
@@ -75,6 +75,7 @@ void zend_vm_dtor(void)
 	if (zend_handlers_table) {
 		zend_hash_destroy(zend_handlers_table);
 		free(zend_handlers_table);
+		zend_handlers_table = NULL;
 	}
 }
 
diff --git a/sapi/phpdbg/phpdbg.c b/sapi/phpdbg/phpdbg.c
index 8207e36540..0f1f03625c 100644
--- a/sapi/phpdbg/phpdbg.c
+++ b/sapi/phpdbg/phpdbg.c
@@ -1341,10 +1341,12 @@ php_stream *phpdbg_stream_url_wrap_php(php_stream_wrapper *wrapper, const char *
 	if (!strncasecmp(path, "stdin", 6) && PHPDBG_G(stdin_file)) {
 		php_stream *stream = php_stream_fopen_from_fd(dup(fileno(PHPDBG_G(stdin_file))), "r", NULL);
 #ifdef PHP_WIN32
-		zval *blocking_pipes = php_stream_context_get_option(context, "pipe", "blocking");
-		if (blocking_pipes) {
-			convert_to_long(blocking_pipes);
-			php_stream_set_option(stream, PHP_STREAM_OPTION_PIPE_BLOCKING, Z_LVAL_P(blocking_pipes), NULL);
+		if (context != NULL) {
+			zval *blocking_pipes = php_stream_context_get_option(context, "pipe", "blocking");
+			if (blocking_pipes) {
+				convert_to_long(blocking_pipes);
+				php_stream_set_option(stream, PHP_STREAM_OPTION_PIPE_BLOCKING, Z_LVAL_P(blocking_pipes), NULL);
+			}
 		}
 #endif
 		return stream;
@@ -2059,6 +2061,8 @@ phpdbg_out:
 phpdbg_out:
 #endif
 
+		phpdbg_purge_watchpoint_tree();
+
 		if (first_command) {
 			free(first_command);
 			first_command = NULL;
diff --git a/sapi/phpdbg/phpdbg_utils.c b/sapi/phpdbg/phpdbg_utils.c
index 857b5e3311..dca70deb8f 100644
--- a/sapi/phpdbg/phpdbg_utils.c
+++ b/sapi/phpdbg/phpdbg_utils.c
@@ -357,8 +357,11 @@ PHPDBG_API int phpdbg_get_terminal_height(void) /* {{{ */
 #ifdef _WIN32
 	CONSOLE_SCREEN_BUFFER_INFO csbi;
 
-	GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &csbi);
-	lines = csbi.srWindow.Bottom - csbi.srWindow.Top + 1;
+	if (GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &csbi)) {
+		lines = csbi.srWindow.Bottom - csbi.srWindow.Top + 1;
+	} else {
+		lines = 40;
+	}
 #elif defined(HAVE_SYS_IOCTL_H) && defined(TIOCGWINSZ)
 	struct winsize w;
 
diff --git a/sapi/phpdbg/phpdbg_watch.c b/sapi/phpdbg/phpdbg_watch.c
index d9f9f8673f..317aa9666a 100644
--- a/sapi/phpdbg/phpdbg_watch.c
+++ b/sapi/phpdbg/phpdbg_watch.c
@@ -1406,6 +1406,8 @@ void phpdbg_setup_watchpoints(void) {
 	zend_hash_init(PHPDBG_G(watchlist_mem), phpdbg_pagesize / (sizeof(Bucket) + sizeof(uint32_t)), NULL, NULL, 1);
 	PHPDBG_G(watchlist_mem_backup) = malloc(phpdbg_pagesize > sizeof(HashTable) ? phpdbg_pagesize : sizeof(HashTable));
 	zend_hash_init(PHPDBG_G(watchlist_mem_backup), phpdbg_pagesize / (sizeof(Bucket) + sizeof(uint32_t)), NULL, NULL, 1);
+
+	PHPDBG_G(watch_tmp) = NULL;
 }
 
 void phpdbg_destroy_watchpoints(void) {
@@ -1433,3 +1435,13 @@ void phpdbg_destroy_watchpoints(void) {
 	zend_hash_destroy(PHPDBG_G(watchlist_mem_backup));
 	free(PHPDBG_G(watchlist_mem_backup));
 }
+
+void phpdbg_purge_watchpoint_tree(void) {
+	phpdbg_btree_position pos;
+	phpdbg_btree_result *res;
+
+	pos = phpdbg_btree_find_between(&PHPDBG_G(watchpoint_tree), 0, -1);
+	while ((res = phpdbg_btree_next(&pos))) {
+		phpdbg_deactivate_watchpoint(res->ptr);
+	}
+}
diff --git a/sapi/phpdbg/phpdbg_watch.h b/sapi/phpdbg/phpdbg_watch.h
index 313df624ea..9814d78e2e 100644
--- a/sapi/phpdbg/phpdbg_watch.h
+++ b/sapi/phpdbg/phpdbg_watch.h
@@ -119,6 +119,7 @@ typedef struct {
 
 void phpdbg_setup_watchpoints(void);
 void phpdbg_destroy_watchpoints(void);
+void phpdbg_purge_watchpoint_tree(void);
 
 #ifndef _WIN32
 int phpdbg_watchpoint_segfault_handler(siginfo_t *info, void *context);