Fix ByteCountingInputStream when reading past EOF

dd-java-agent/agent-profiling/profiling-uploader/src/main/java/com/datadog/profiling/uploader/ByteCountingInputStream.java

@@ -15,7 +15,9 @@ final class ByteCountingInputStream extends InputStream {
   @Override
   public int read() throws IOException {
     int data = source.read();
-    readBytes++;
+    if (data >= 0) {
+      readBytes++;
+    }
     return data;
   }
 

dd-java-agent/agent-profiling/profiling-uploader/src/test/java/com/datadog/profiling/uploader/ByteCountingInputStreamTest.java

@@ -0,0 +1,26 @@
+package com.datadog.profiling.uploader;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import org.junit.jupiter.api.Test;
+
+public class ByteCountingInputStreamTest {
+
+  @Test
+  public void testDoesNotCountAfterEof() throws IOException {
+    byte[] data = {1, 2, 3};
+
+    ByteCountingInputStream in = new ByteCountingInputStream(new ByteArrayInputStream(data));
+    for (byte datum : data) {
+      int b = in.read();
+      assertEquals(datum, b);
+    }
+    assertEquals(data.length, (int) in.getReadBytes());
+
+    // read past EOF
+    assertEquals(-1, in.read());
+    assertEquals(data.length, (int) in.getReadBytes());
+  }
+}