[njs] Fixed backtraces while traversing imported user modules.

[Dmitry Volyntsev]

details:   https://hg.nginx.org/njs/rev/bede4b8a693a
branches:  
changeset: 1823:bede4b8a693a
user:      Dmitry Volyntsev <xeioex at nginx.com>
date:      Mon Feb 14 14:10:04 2022 +0000
description:
Fixed backtraces while traversing imported user modules.

Previously, njs_builtin_match_native_function(), which is used to build a
backtrace for an exception, assumed that user modules always return
object values, which is not the case.  As a result, njs_object_traverse()
may receive incorrect pointer.

This fix is to only traverse object values.

diffstat:

 src/njs_builtin.c                           |  12 +++++++-----
 test/js/import_native_module_exception.t.js |  12 ++++++++++++
 2 files changed, 19 insertions(+), 5 deletions(-)

diffs (40 lines):

diff -r 4d38ea471228 -r bede4b8a693a src/njs_builtin.c
--- a/src/njs_builtin.c	Thu Jan 27 13:01:55 2022 +0000
+++ b/src/njs_builtin.c	Mon Feb 14 14:10:04 2022 +0000
@@ -761,13 +761,15 @@ njs_builtin_match_native_function(njs_vm
             break;
         }
 
-        ctx.match = module->name;
+        if (njs_is_object(&module->value)) {
+            ctx.match = module->name;
 
-        ret = njs_object_traverse(vm, njs_object(&module->value), &ctx,
-                                  njs_builtin_traverse);
+            ret = njs_object_traverse(vm, njs_object(&module->value), &ctx,
+                                      njs_builtin_traverse);
 
-        if (ret == NJS_DONE) {
-            goto found;
+            if (ret == NJS_DONE) {
+                goto found;
+            }
         }
     }
 
diff -r 4d38ea471228 -r bede4b8a693a test/js/import_native_module_exception.t.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/js/import_native_module_exception.t.js	Mon Feb 14 14:10:04 2022 +0000
@@ -0,0 +1,12 @@
+/*---
+includes: []
+flags: []
+paths: [test/js/module, test/js/module/libs]
+negative:
+  phase: runtime
+---*/
+
+import fs from 'fs';
+import lib from 'lib3.js';
+
+fs.readFileSync({}.a.a);