Merge pull request #745 from square/eric.incorrect-skipValue

Fix infinite loop when calling skipValue at the end an object or array.

moshi/src/main/java/com/squareup/moshi/JsonUtf8Reader.java

@@ -957,11 +957,19 @@ final class JsonUtf8Reader extends JsonReader {
         pushScope(JsonScope.EMPTY_OBJECT);
         count++;
       } else if (p == PEEKED_END_ARRAY) {
-        stackSize--;
         count--;
+        if (count < 0) {
+          throw new JsonDataException(
+              "Expected a value but was " + peek() + " at path " + getPath());
+        }
+        stackSize--;
       } else if (p == PEEKED_END_OBJECT) {
-        stackSize--;
         count--;
+        if (count < 0) {
+          throw new JsonDataException(
+              "Expected a value but was " + peek() + " at path " + getPath());
+        }
+        stackSize--;
       } else if (p == PEEKED_UNQUOTED_NAME || p == PEEKED_UNQUOTED) {
         skipUnquotedValue();
       } else if (p == PEEKED_DOUBLE_QUOTED || p == PEEKED_DOUBLE_QUOTED_NAME) {
@@ -970,6 +978,9 @@ final class JsonUtf8Reader extends JsonReader {
         skipQuotedValue(SINGLE_QUOTE_OR_SLASH);
       } else if (p == PEEKED_NUMBER) {
         buffer.skip(peekedNumberLength);
+      } else if (p == PEEKED_EOF) {
+        throw new JsonDataException(
+            "Expected a value but was " + peek() + " at path " + getPath());
       }
       peeked = PEEKED_NONE;
     } while (count != 0);

moshi/src/main/java/com/squareup/moshi/JsonValueReader.java

@@ -308,6 +308,9 @@ final class JsonValueReader extends JsonReader {
 
     Object skipped = stackSize != 0 ? stack[stackSize - 1] : null;
 
+    if (skipped instanceof JsonIterator) {
+      throw new JsonDataException("Expected a value but was " + peek() + " at path " + getPath());
+    }
     if (skipped instanceof Map.Entry) {
       // We're skipping a name. Promote the map entry's value.
       Map.Entry<?, ?> entry = (Map.Entry<?, ?>) stack[stackSize - 1];
@@ -315,6 +318,8 @@ final class JsonValueReader extends JsonReader {
     } else if (stackSize > 0) {
       // We're skipping a value.
       remove();
+    } else {
+      throw new JsonDataException("Expected a value but was " + peek() + " at path " + getPath());
     }
   }
 

moshi/src/test/java/com/squareup/moshi/JsonReaderTest.java

@@ -988,6 +988,44 @@ public final class JsonReaderTest {
     assertThat(reader.hasNext()).isFalse();
   }
 
+  @Test public void skipValueAtEndOfObjectFails() throws IOException {
+    JsonReader reader = newReader("{}");
+    reader.beginObject();
+    try {
+      reader.skipValue();
+      fail();
+    } catch (JsonDataException expected) {
+      assertThat(expected).hasMessage("Expected a value but was END_OBJECT at path $.");
+    }
+    reader.endObject();
+    assertThat(reader.peek()).isEqualTo(JsonReader.Token.END_DOCUMENT);
+  }
+
+  @Test public void skipValueAtEndOfArrayFails() throws IOException {
+    JsonReader reader = newReader("[]");
+    reader.beginArray();
+    try {
+      reader.skipValue();
+      fail();
+    } catch (JsonDataException expected) {
+      assertThat(expected).hasMessage("Expected a value but was END_ARRAY at path $[0]");
+    }
+    reader.endArray();
+    assertThat(reader.peek()).isEqualTo(JsonReader.Token.END_DOCUMENT);
+  }
+
+  @Test public void skipValueAtEndOfDocumentFails() throws IOException {
+    JsonReader reader = newReader("1");
+    reader.nextInt();
+    try {
+      reader.skipValue();
+      fail();
+    } catch (JsonDataException expected) {
+      assertThat(expected).hasMessage("Expected a value but was END_DOCUMENT at path $");
+    }
+    assertThat(reader.peek()).isEqualTo(JsonReader.Token.END_DOCUMENT);
+  }
+
   @Test public void basicPeekJson() throws IOException {
     JsonReader reader = newReader("{\"a\":12,\"b\":[34,56],\"c\":78}");
     reader.beginObject();