Enhance ScopedUtfChars to include the null check most callers were missing.

Also switch most non-users over to ScopedUtfChars.

Also ensure all users check that ScopedUtfChars was successful in getting the
chars.

Also rewrite ObjectInputStream and ObjectOutputStream without duplication.

Change-Id: I929d00fe3ff50b303cba4a2cf2269355e9fef5f9

1 files changed, 15 insertions, 2 deletions

diff --git a/include/ScopedUtfChars.h b/include/ScopedUtfChars.h
index bfe9bb9..3051d3b 100644
--- a/include/ScopedUtfChars.h
+++ b/include/ScopedUtfChars.h
@@ -20,12 +20,25 @@
 #include "JNIHelp.h"
 
 // A smart pointer that provides read-only access to a Java string's UTF chars.
+// Unlike GetStringUTFChars, we throw NullPointerException rather than abort if
+// passed a null jstring, and c_str will return NULL.
+// This makes the correct idiom very simple:
+//
+//   ScopedUtfChars name(env, javaName);
+//   if (name.c_str() == NULL) {
+//       return NULL;
+//   }
 class ScopedUtfChars {
 public:
     ScopedUtfChars(JNIEnv* env, jstring s)
-    : mEnv(env), mString(s), mUtfChars(NULL)
+    : mEnv(env), mString(s)
     {
-        mUtfChars = env->GetStringUTFChars(s, NULL);
+        if (s == NULL) {
+            mUtfChars = NULL;
+            jniThrowNullPointerException(env, NULL);
+        } else {
+            mUtfChars = env->GetStringUTFChars(s, NULL);
+        }
     }
 
     ~ScopedUtfChars() {