3 files changed, 23 insertions, 2 deletions
diff --git a/CONTRIBUTORS.txt b/CONTRIBUTORS.txt
index 136d0eb8..5bb109f4 100644
--- a/CONTRIBUTORS.txt
+++ b/CONTRIBUTORS.txt
@@ -78,3 +78,5 @@ Patch contributors:
     * Detect whether zlib is new enough in configure script.
   Evan Jones <evanj@mit.edu>
     * Optimize Java serialization code when writing a small message to a stream.
+  Michael Kucharski <m.kucharski@gmail.com>
+    * Added CodedInputStream.getTotalBytesRead().
diff --git a/java/src/main/java/com/google/protobuf/CodedInputStream.java b/java/src/main/java/com/google/protobuf/CodedInputStream.java
index 9125957d..f339c00e 100644
--- a/java/src/main/java/com/google/protobuf/CodedInputStream.java
+++ b/java/src/main/java/com/google/protobuf/CodedInputStream.java
@@ -467,7 +467,9 @@ public final class CodedInputStream {
   /**
    * The total number of bytes read before the current buffer.  The total
    * bytes read up to the current position can be computed as
-   * {@code totalBytesRetired + bufferPos}.
+   * {@code totalBytesRetired + bufferPos}.  This value may be negative if
+   * reading started in the middle of the current buffer (e.g. if the
+   * constructor that takes a byte array and an offset was used).
    */
   private int totalBytesRetired;
 
@@ -489,6 +491,7 @@ public final class CodedInputStream {
     this.buffer = buffer;
     bufferSize = off + len;
     bufferPos = off;
+    totalBytesRetired = -off;
     input = null;
   }
 
@@ -496,6 +499,7 @@ public final class CodedInputStream {
     buffer = new byte[BUFFER_SIZE];
     bufferSize = 0;
     bufferPos = 0;
+    totalBytesRetired = 0;
     this.input = input;
   }
 
@@ -546,7 +550,7 @@ public final class CodedInputStream {
    * Resets the current size counter to zero (see {@link #setSizeLimit(int)}).
    */
   public void resetSizeCounter() {
-    totalBytesRetired = 0;
+    totalBytesRetired = -bufferPos;
   }
 
   /**
@@ -616,6 +620,14 @@ public final class CodedInputStream {
   }
 
   /**
+   * The total bytes read up to the current position. Calling
+   * {@link #resetSizeCounter()} resets this value to zero.
+   */
+  public int getTotalBytesRead() {
+      return totalBytesRetired + bufferPos;
+  }
+
+  /**
    * Called with {@code this.buffer} is empty to read more bytes from the
    * input.  If {@code mustSucceed} is true, refillBuffer() gurantees that
    * either there will be at least one byte in the buffer when it returns
diff --git a/java/src/test/java/com/google/protobuf/CodedInputStreamTest.java b/java/src/test/java/com/google/protobuf/CodedInputStreamTest.java
index 850b8aa7..a75a400b 100644
--- a/java/src/test/java/com/google/protobuf/CodedInputStreamTest.java
+++ b/java/src/test/java/com/google/protobuf/CodedInputStreamTest.java
@@ -434,6 +434,7 @@ public class CodedInputStreamTest extends TestCase {
         new SmallBlockInputStream(new byte[256], 8));
     input.setSizeLimit(16);
     input.readRawBytes(16);
+    assertEquals(16, input.getTotalBytesRead());
 
     try {
       input.readRawByte();
@@ -443,7 +444,10 @@ public class CodedInputStreamTest extends TestCase {
     }
 
     input.resetSizeCounter();
+    assertEquals(0, input.getTotalBytesRead());
     input.readRawByte();  // No exception thrown.
+    input.resetSizeCounter();
+    assertEquals(0, input.getTotalBytesRead());
 
     try {
       input.readRawBytes(16);  // Hits limit again.
@@ -477,10 +481,13 @@ public class CodedInputStreamTest extends TestCase {
   public void testReadFromSlice() throws Exception {
     byte[] bytes = bytes(0, 1, 2, 3, 4, 5, 6, 7, 8, 9);
     CodedInputStream in = CodedInputStream.newInstance(bytes, 3, 5);
+    assertEquals(0, in.getTotalBytesRead());
     for (int i = 3; i < 8; i++) {
       assertEquals(i, in.readRawByte());
+      assertEquals(i-2, in.getTotalBytesRead());
     }
     // eof
     assertEquals(0, in.readTag());
+    assertEquals(5, in.getTotalBytesRead());
   }
 }