Catch potential exceptions during to string conversion

As of PHP 7.4.0, exceptions are allowed to be thrown from inside
`__toString()` methods; we have to cater to that, and catch these
exceptions early.

Closes GH-6042

3 files changed, 34 insertions, 11 deletions

diff --git a/ext/com_dotnet/com_com.c b/ext/com_dotnet/com_com.c
index b61cb265e3..ce4bca9d87 100644
--- a/ext/com_dotnet/com_com.c
+++ b/ext/com_dotnet/com_com.c
@@ -85,7 +85,9 @@ PHP_FUNCTION(com_create_instance)
 
 		if (NULL != (tmp = zend_hash_str_find(Z_ARRVAL_P(server_params),
 				"Server", sizeof("Server")-1))) {
-			convert_to_string_ex(tmp);
+			if (!try_convert_to_string(tmp)) {
+				return;
+			}
 			server_name = Z_STRVAL_P(tmp);
 			server_name_len = Z_STRLEN_P(tmp);
 			ctx = CLSCTX_REMOTE_SERVER;
@@ -93,21 +95,27 @@ PHP_FUNCTION(com_create_instance)
 
 		if (NULL != (tmp = zend_hash_str_find(Z_ARRVAL_P(server_params),
 				"Username", sizeof("Username")-1))) {
-			convert_to_string_ex(tmp);
+			if (!try_convert_to_string(tmp)) {
+				return;
+			}
 			user_name = Z_STRVAL_P(tmp);
 			user_name_len = Z_STRLEN_P(tmp);
 		}
 
 		if (NULL != (tmp = zend_hash_str_find(Z_ARRVAL_P(server_params),
 				"Password", sizeof("Password")-1))) {
-			convert_to_string_ex(tmp);
+			if (!try_convert_to_string(tmp)) {
+				return;
+			}
 			password = Z_STRVAL_P(tmp);
 			password_len = Z_STRLEN_P(tmp);
 		}
 
 		if (NULL != (tmp = zend_hash_str_find(Z_ARRVAL_P(server_params),
 				"Domain", sizeof("Domain")-1))) {
-			convert_to_string_ex(tmp);
+			if (!try_convert_to_string(tmp)) {
+				return;
+			}
 			domain_name = Z_STRVAL_P(tmp);
 			domain_name_len = Z_STRLEN_P(tmp);
 		}
@@ -720,7 +728,9 @@ PHP_FUNCTION(com_event_sink)
 		if ((tmp = zend_hash_index_find(Z_ARRVAL_P(sink), 1)) != NULL && Z_TYPE_P(tmp) == IS_STRING)
 			dispname = Z_STRVAL_P(tmp);
 	} else if (sink != NULL) {
-		convert_to_string(sink);
+		if (!try_convert_to_string(sink)) {
+			return;
+		}
 		dispname = Z_STRVAL_P(sink);
 	}
 
diff --git a/ext/com_dotnet/com_handlers.c b/ext/com_dotnet/com_handlers.c
index d42e7453f8..2a1740e01e 100644
--- a/ext/com_dotnet/com_handlers.c
+++ b/ext/com_dotnet/com_handlers.c
@@ -38,9 +38,11 @@ static zval *com_property_read(zval *object, zval *member, int type, void **cahc
 	obj = CDNO_FETCH(object);
 
 	if (V_VT(&obj->v) == VT_DISPATCH) {
-		VariantInit(&v);
+		if (!try_convert_to_string(member)) {
+			return rv;
+		}
 
-		convert_to_string_ex(member);
+		VariantInit(&v);
 
 		res = php_com_do_invoke(obj, Z_STRVAL_P(member), Z_STRLEN_P(member),
 				DISPATCH_METHOD|DISPATCH_PROPERTYGET, &v, 0, NULL, 1);
@@ -66,9 +68,12 @@ static zval *com_property_write(zval *object, zval *member, zval *value, void **
 	obj = CDNO_FETCH(object);
 
 	if (V_VT(&obj->v) == VT_DISPATCH) {
+		if (!try_convert_to_string(member)) {
+			return value;
+		}
+
 		VariantInit(&v);
 
-		convert_to_string_ex(member);
 		if (SUCCESS == php_com_do_invoke(obj, Z_STRVAL_P(member), Z_STRLEN_P(member),
 				DISPATCH_PROPERTYPUT|DISPATCH_PROPERTYPUTREF, &v, 1, value, 0)) {
 			VariantClear(&v);
@@ -205,7 +210,9 @@ static int com_property_exists(zval *object, zval *member, int check_empty, void
 	obj = CDNO_FETCH(object);
 
 	if (V_VT(&obj->v) == VT_DISPATCH) {
-		convert_to_string_ex(member);
+		if (!try_convert_to_string(member)) {
+			return 0;
+		}
 		if (SUCCEEDED(php_com_get_id_of_name(obj, Z_STRVAL_P(member), Z_STRLEN_P(member), &dispid))) {
 			/* TODO: distinguish between property and method! */
 			return 1;
diff --git a/ext/com_dotnet/com_saproxy.c b/ext/com_dotnet/com_saproxy.c
index 8369a4bcdd..eec6e2998e 100644
--- a/ext/com_dotnet/com_saproxy.c
+++ b/ext/com_dotnet/com_saproxy.c
@@ -108,7 +108,10 @@ static zval *saproxy_read_dimension(zval *object, zval *offset, int type, zval *
 		}
 		ZVAL_COPY_VALUE(&args[i-1], offset);
 
-		convert_to_string(&proxy->indices[0]);
+		if (!try_convert_to_string(&proxy->indices[0])) {
+			efree(args);
+			return rv;
+		}
 		VariantInit(&v);
 
 		res = php_com_do_invoke(proxy->obj, Z_STRVAL(proxy->indices[0]),
@@ -223,7 +226,10 @@ static void saproxy_write_dimension(zval *object, zval *offset, zval *value)
 		ZVAL_COPY_VALUE(&args[i-1], offset);
 		ZVAL_COPY_VALUE(&args[i], value);
 
-		convert_to_string(&proxy->indices[0]);
+		if (!try_convert_to_string(&proxy->indices[0])) {
+			efree(args);
+			return;
+		}
 		VariantInit(&v);
 		if (SUCCESS == php_com_do_invoke(proxy->obj, Z_STRVAL(proxy->indices[0]),
 					Z_STRLEN(proxy->indices[0]), DISPATCH_PROPERTYPUT, &v, proxy->dimensions + 1,