From 0ea182d0faa35c726dcb37249d48786bfc8ca04c Mon Sep 17 00:00:00 2001
From: Steve Loughran <stevel@apache.org>
Date: Tue, 28 Nov 2017 11:52:59 +0000
Subject: [PATCH] HADOOP-15042. Azure PageBlobInputStream.skip() can return
 negative value when numberOfPagesRemaining is 0. Contributed by Rajesh
 Balamohan

---
 .../java/org/apache/hadoop/fs/azure/PageBlobInputStream.java  | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azure/PageBlobInputStream.java b/hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azure/PageBlobInputStream.java
index 097201b2af3..aaac4904133 100644
--- a/hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azure/PageBlobInputStream.java
+++ b/hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azure/PageBlobInputStream.java
@@ -343,9 +343,9 @@ final class PageBlobInputStream extends InputStream {
 
     // Skip over whole pages as necessary without retrieving them from the
     // server.
-    long pagesToSkipOver = Math.min(
+    long pagesToSkipOver = Math.max(0, Math.min(
         n / PAGE_DATA_SIZE,
-        numberOfPagesRemaining - 1);
+        numberOfPagesRemaining - 1));
     numberOfPagesRemaining -= pagesToSkipOver;
     currentOffsetInBlob += pagesToSkipOver * PAGE_SIZE;
     skipped += pagesToSkipOver * PAGE_DATA_SIZE;