util: never trigger any proxy traps using `format()`

PR-URL: https://github.com/nodejs/node/pull/30767
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

2 files changed, 10 insertions, 0 deletions

diff --git a/lib/internal/util/inspect.js b/lib/internal/util/inspect.js
index 4e6f967c6a..a4a9a05ece 100644
--- a/lib/internal/util/inspect.js
+++ b/lib/internal/util/inspect.js
@@ -1648,6 +1648,13 @@ function reduceToSingleString(
 }
 
 function hasBuiltInToString(value) {
+  // Prevent triggering proxy traps.
+  const getFullProxy = false;
+  const proxyTarget = getProxyDetails(value, getFullProxy);
+  if (proxyTarget !== undefined) {
+    value = proxyTarget;
+  }
+
   // Count objects that have no `toString` function as built-in.
   if (typeof value.toString !== 'function') {
     return true;
diff --git a/test/parallel/test-util-inspect-proxy.js b/test/parallel/test-util-inspect-proxy.js
index c684026b19..505503d579 100644
--- a/test/parallel/test-util-inspect-proxy.js
+++ b/test/parallel/test-util-inspect-proxy.js
@@ -41,6 +41,9 @@ proxyObj = new Proxy(target, handler);
 // Inspecting the proxy should not actually walk it's properties
 util.inspect(proxyObj, opts);
 
+// Make sure inspecting object does not trigger any proxy traps.
+util.format('%s', proxyObj);
+
 // getProxyDetails is an internal method, not intended for public use.
 // This is here to test that the internals are working correctly.
 let details = processUtil.getProxyDetails(proxyObj, true);