binder_ndk: sanitize binder descriptor for logging

Invalid char in a string causes "implicit-conversion" ubsan error.
So, when printing "read" binder descriptor for log, sanitize it by
replacing invalid char with '?'.

Bug: n/a
Test: binder_parcel_fuzzer
Change-Id: I51f806ff28ccc52f9b3da328ace4ca8c348483ba
diff --git a/libs/binder/ndk/ibinder.cpp b/libs/binder/ndk/ibinder.cpp
index 8ffa735..6949c2c 100644
--- a/libs/binder/ndk/ibinder.cpp
+++ b/libs/binder/ndk/ibinder.cpp
@@ -104,6 +104,17 @@
     return {};
 }
 
+// b/175635923 libcxx causes "implicit-conversion" with a string with invalid char
+static std::string SanitizeString(const String16& str) {
+    std::string sanitized{String8(str)};
+    for (auto& c : sanitized) {
+        if (!isprint(c)) {
+            c = '?';
+        }
+    }
+    return sanitized;
+}
+
 bool AIBinder::associateClass(const AIBinder_Class* clazz) {
     if (clazz == nullptr) return false;
 
@@ -118,7 +129,7 @@
     if (descriptor != newDescriptor) {
         if (getBinder()->isBinderAlive()) {
             LOG(ERROR) << __func__ << ": Expecting binder to have class '" << newDescriptor
-                       << "' but descriptor is actually '" << descriptor << "'.";
+                       << "' but descriptor is actually '" << SanitizeString(descriptor) << "'.";
         } else {
             // b/155793159
             LOG(ERROR) << __func__ << ": Cannot associate class '" << newDescriptor