Fix for an ArrayIndexOutOfBoundsException.

The `fillBuffer` method changes `pos`, so it is incorrect to cache
its previous value.

gson/src/main/java/com/google/gson/stream/JsonReader.java

@@ -228,13 +228,14 @@ public class JsonReader implements Closeable {
   /** True to accept non-spec compliant JSON */
   private boolean lenient = false;
 
+  static final int BUFFER_SIZE = 1024;
   /**
    * Use a manual buffer to easily read and unread upcoming characters, and
    * also so we can create strings without an intermediate StringBuilder.
    * We decode literals directly out of this buffer, so it must be at least as
    * long as the longest token that can be reported as a number.
    */
-  private final char[] buffer = new char[1024];
+  private final char[] buffer = new char[BUFFER_SIZE];
   private int pos = 0;
   private int limit = 0;
 
@@ -1604,11 +1605,11 @@ public class JsonReader implements Closeable {
     nextNonWhitespace(true);
     pos--;
 
-    int p = pos;
-    if (p + 5 > limit && !fillBuffer(5)) {
+    if (pos + 5 > limit && !fillBuffer(5)) {
       return;
     }
 
+    int p = pos;
     char[] buf = buffer;
     if(buf[p] != ')' || buf[p + 1] != ']' || buf[p + 2] != '}' || buf[p + 3] != '\'' || buf[p + 4] != '\n') {
       return; // not a security token!

gson/src/test/java/com/google/gson/stream/JsonReaderTest.java

@@ -1730,6 +1730,21 @@ public final class JsonReaderTest extends TestCase {
     }
   }
 
+  /**
+   * Regression test for an issue with buffer filling and consumeNonExecutePrefix.
+   */
+  public void testReadAcrossBuffers() throws IOException {
+    StringBuilder sb = new StringBuilder('#');
+    for (int i = 0; i < JsonReader.BUFFER_SIZE - 3; i++) {
+      sb.append(' ');
+    }
+    sb.append("\n)]}'\n3");
+    JsonReader reader = new JsonReader(reader(sb.toString()));
+    reader.setLenient(true);
+    JsonToken token = reader.peek();
+    assertEquals(JsonToken.NUMBER, token);
+  }
+
   private void assertDocument(String document, Object... expectations) throws IOException {
     JsonReader reader = new JsonReader(reader(document));
     reader.setLenient(true);