2 files changed, 69 insertions, 1 deletions

diff --git a/core/java/android/util/JsonReader.java b/core/java/android/util/JsonReader.java
index 132b595..09ce8e4 100644
--- a/core/java/android/util/JsonReader.java
+++ b/core/java/android/util/JsonReader.java
@@ -196,6 +196,12 @@ public final class JsonReader implements Closeable {
     private int pos = 0;
     private int limit = 0;
 
+    /*
+     * The offset of the first character in the buffer.
+     */
+    private int bufferStartLine = 1;
+    private int bufferStartColumn = 1;
+
     private final List<JsonScope> stack = new ArrayList<JsonScope>();
     {
         push(JsonScope.EMPTY_DOCUMENT);
@@ -711,6 +717,16 @@ public final class JsonReader implements Closeable {
      * false.
      */
     private boolean fillBuffer(int minimum) throws IOException {
+        // Before clobbering the old characters, update where buffer starts
+        for (int i = 0; i < pos; i++) {
+            if (buffer[i] == '\n') {
+                bufferStartLine++;
+                bufferStartColumn = 1;
+            } else {
+                bufferStartColumn++;
+            }
+        }
+
         if (limit != pos) {
             limit -= pos;
             System.arraycopy(buffer, pos, buffer, 0, limit);
@@ -729,6 +745,28 @@ public final class JsonReader implements Closeable {
         return false;
     }
 
+    private int getLineNumber() {
+        int result = bufferStartLine;
+        for (int i = 0; i < pos; i++) {
+            if (buffer[i] == '\n') {
+                result++;
+            }
+        }
+        return result;
+    }
+
+    private int getColumnNumber() {
+        int result = bufferStartColumn;
+        for (int i = 0; i < pos; i++) {
+            if (buffer[i] == '\n') {
+                result = 1;
+            } else {
+                result++;
+            }
+        }
+        return result;
+    }
+
     private int nextNonWhitespace() throws IOException {
         while (pos < limit || fillBuffer(1)) {
             int c = buffer[pos++];
@@ -1107,7 +1145,8 @@ public final class JsonReader implements Closeable {
      * with this reader's content.
      */
     private IOException syntaxError(String message) throws IOException {
-        throw new MalformedJsonException(message + " near " + getSnippet());
+        throw new MalformedJsonException(message
+                + " at line " + getLineNumber() + " column " + getColumnNumber());
     }
 
     private CharSequence getSnippet() {
diff --git a/core/tests/coretests/src/android/util/JsonReaderTest.java b/core/tests/coretests/src/android/util/JsonReaderTest.java
index b5c2c27..440aeb5 100644
--- a/core/tests/coretests/src/android/util/JsonReaderTest.java
+++ b/core/tests/coretests/src/android/util/JsonReaderTest.java
@@ -856,4 +856,33 @@ public final class JsonReaderTest extends TestCase {
         } catch (IOException expected) {
         }
     }
+
+    public void testFailWithPosition() throws IOException {
+        testFailWithPosition("Expected literal value at line 6 column   3",
+                "[\n\n\n\n\n0,}]");
+    }
+
+    public void testFailWithPositionGreaterThanBufferSize() throws IOException {
+        String spaces = repeat(' ', 8192);
+        testFailWithPosition("Expected literal value at line 6 column 3",
+                "[\n\n" + spaces + "\n\n\n0,}]");
+    }
+
+    private void testFailWithPosition(String message, String json) throws IOException {
+        JsonReader reader = new JsonReader(new StringReader(json));
+        reader.beginArray();
+        reader.nextInt();
+        try {
+            reader.peek();
+            fail();
+        } catch (IOException expected) {
+            assertEquals(message, expected.getMessage());
+        }
+    }
+
+    private String repeat(char c, int count) {
+        char[] array = new char[count];
+        Arrays.fill(array, c);
+        return new String(array);
+    }
 }