From 38bd273d234fa7e77aa7d6d1f9446d9984b5f906 Mon Sep 17 00:00:00 2001
From: JinmingHu <jinmhu@microsoft.com>
Date: Sun, 30 May 2021 10:36:49 +0800
Subject: [PATCH] fix read consistency issue (#2364)

---
 .../azure-storage-blobs/src/blob_client.cpp       | 15 +++------------
 .../src/share_file_client.cpp                     | 15 +++++++++++++--
 2 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/sdk/storage/azure-storage-blobs/src/blob_client.cpp b/sdk/storage/azure-storage-blobs/src/blob_client.cpp
index 5e0cb408c..baf0981cc 100644
--- a/sdk/storage/azure-storage-blobs/src/blob_client.cpp
+++ b/sdk/storage/azure-storage-blobs/src/blob_client.cpp
@@ -191,10 +191,7 @@ namespace Azure { namespace Storage { namespace Blobs {
         {
           newOptions.Range.Value().Length = options.Range.Value().Length.Value() - retryOffset;
         }
-        if (!newOptions.AccessConditions.IfMatch.HasValue())
-        {
-          newOptions.AccessConditions.IfMatch = eTag;
-        }
+        newOptions.AccessConditions.IfMatch = eTag;
         return std::move(Download(newOptions, context).Value.BodyStream);
       };
 
@@ -291,10 +288,7 @@ namespace Azure { namespace Storage { namespace Blobs {
             chunkOptions.Range = Core::Http::HttpRange();
             chunkOptions.Range.Value().Offset = offset;
             chunkOptions.Range.Value().Length = length;
-            if (!chunkOptions.AccessConditions.IfMatch.HasValue())
-            {
-              chunkOptions.AccessConditions.IfMatch = eTag;
-            }
+            chunkOptions.AccessConditions.IfMatch = eTag;
             auto chunk = Download(chunkOptions, context);
             int64_t bytesRead = chunk.Value.BodyStream->ReadToCount(
                 buffer + (offset - firstChunkOffset),
@@ -417,10 +411,7 @@ namespace Azure { namespace Storage { namespace Blobs {
             chunkOptions.Range = Core::Http::HttpRange();
             chunkOptions.Range.Value().Offset = offset;
             chunkOptions.Range.Value().Length = length;
-            if (!chunkOptions.AccessConditions.IfMatch.HasValue())
-            {
-              chunkOptions.AccessConditions.IfMatch = eTag;
-            }
+            chunkOptions.AccessConditions.IfMatch = eTag;
             auto chunk = Download(chunkOptions, context);
             bodyStreamToFile(
                 *(chunk.Value.BodyStream),
diff --git a/sdk/storage/azure-storage-files-shares/src/share_file_client.cpp b/sdk/storage/azure-storage-files-shares/src/share_file_client.cpp
index 405a83e02..d1a4639fa 100644
--- a/sdk/storage/azure-storage-files-shares/src/share_file_client.cpp
+++ b/sdk/storage/azure-storage-files-shares/src/share_file_client.cpp
@@ -272,8 +272,7 @@ namespace Azure { namespace Storage { namespace Files { namespace Shares {
         auto newResponse = Download(newOptions, context);
         if (eTag != newResponse.Value.Details.ETag)
         {
-          throw Azure::Core::RequestFailedException(
-              "File was changed during the download process.");
+          throw Azure::Core::RequestFailedException("file was modified in the middle of download");
         }
         return std::move(newResponse.Value.BodyStream);
       };
@@ -669,6 +668,7 @@ namespace Azure { namespace Storage { namespace Files { namespace Shares {
     }
 
     auto firstChunk = Download(firstChunkOptions, context);
+    const Azure::ETag etag = firstChunk.Value.Details.ETag;
 
     int64_t fileSize;
     int64_t fileRangeSize;
@@ -728,6 +728,11 @@ namespace Azure { namespace Storage { namespace Files { namespace Shares {
             {
               throw Azure::Core::RequestFailedException("error when reading body stream");
             }
+            if (chunk.Value.Details.ETag != etag)
+            {
+              throw Azure::Core::RequestFailedException(
+                  "file was modified in the middle of download");
+            }
 
             if (chunkId == numChunks - 1)
             {
@@ -774,6 +779,7 @@ namespace Azure { namespace Storage { namespace Files { namespace Shares {
     _internal::FileWriter fileWriter(fileName);
 
     auto firstChunk = Download(firstChunkOptions, context);
+    const Azure::ETag etag = firstChunk.Value.Details.ETag;
 
     int64_t fileSize;
     int64_t fileRangeSize;
@@ -840,6 +846,11 @@ namespace Azure { namespace Storage { namespace Files { namespace Shares {
             chunkOptions.Range.Value().Offset = offset;
             chunkOptions.Range.Value().Length = length;
             auto chunk = Download(chunkOptions, context);
+            if (chunk.Value.Details.ETag != etag)
+            {
+              throw Azure::Core::RequestFailedException(
+                  "file was modified in the middle of download");
+            }
             bodyStreamToFile(
                 *(chunk.Value.BodyStream),
                 fileWriter,