Allow openInputStream to succeed on blob snapshots (#255)

Allow openInputStream to succeed on blob snapshots

Author: mirobers

ChangeLog.txt

@@ -2,6 +2,7 @@ XXXX.XX.XX Version X.X.X
  * Improved performance of blob uploadFromFile APIs to avoid unnecessary buffering.
  * Improved performance when streaming directly from a FileInputStream to avoid unnecessary buffering.
  * Switched to using fixed length streaming mode in the HTTP client to avoid unnecessary buffering.
+ * Fixed a bug preventing openInputStream from working on a blob snapshot.
 
 2017.11.01 Version 6.1.0
  * Added support for the last time the tier was modified.

microsoft-azure-storage-test/src/com/microsoft/azure/storage/blob/CloudBlockBlobTests.java

@@ -44,6 +44,7 @@
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.net.HttpURLConnection;
 import java.net.URI;
 import java.net.URISyntaxException;
@@ -657,6 +658,10 @@ public void testBlobSnapshotValidationTest() throws StorageException, URISyntaxE
         byte[] retrievedBuff = outStream.toByteArray();
         assertEquals(length, retrievedBuff.length);
 
+        InputStream inputStream = blobSnapshot.openInputStream();
+        retrievedBuff = inputStream.readAllBytes();
+        assertEquals(length, retrievedBuff.length);
+
         // Read operation should work fine.
         blobSnapshot.downloadAttributes();
 
@@ -667,6 +672,11 @@ public void testBlobSnapshotValidationTest() throws StorageException, URISyntaxE
         blobSnapshotUsingRootUri.download(outStream);
         retrievedBuff = outStream.toByteArray();
         assertEquals(length, retrievedBuff.length);
+
+        inputStream = blobSnapshotUsingRootUri.openInputStream();
+        retrievedBuff = inputStream.readAllBytes();
+        assertEquals(length, retrievedBuff.length);
+
         assertEquals(blobSnapshot.getSnapshotID(), blobSnapshotUsingRootUri.getSnapshotID());
 
         // Expect an IllegalArgumentException from upload.
@@ -707,6 +717,33 @@ public void testBlobSnapshotValidationTest() throws StorageException, URISyntaxE
         catch (IllegalArgumentException e) {
             assertEquals("Cannot perform this operation on a blob representing a snapshot.", e.getMessage());
         }
+
+        // Expect an IllegalArgumentException from openOutputStream.
+        try {
+            blobSnapshotUsingRootUri.openOutputStream();
+            fail("Expect an IllegalArgumentException from openOutputStream");
+        }
+        catch (IllegalArgumentException e) {
+            assertEquals("Cannot perform this operation on a blob representing a snapshot.", e.getMessage());
+        }
+
+        // Expect an IllegalArgumentException from uploadBlock.
+        try {
+            blobSnapshotUsingRootUri.uploadBlock("foo", new ByteArrayInputStream(new byte[0]), 0);
+            fail("Expect an IllegalArgumentException from uploadBlock");
+        }
+        catch (IllegalArgumentException e) {
+            assertEquals("Cannot perform this operation on a blob representing a snapshot.", e.getMessage());
+        }
+
+        // Expect an IllegalArgumentException from commitBlockList.
+        try {
+            blobSnapshotUsingRootUri.commitBlockList(new ArrayList<BlockEntry>());
+            fail("Expect an IllegalArgumentException from commitBlockList");
+        }
+        catch (IllegalArgumentException e) {
+            assertEquals("Cannot perform this operation on a blob representing a snapshot.", e.getMessage());
+        }
     }
 
     /**

microsoft-azure-storage/src/com/microsoft/azure/storage/blob/CloudBlob.java

@@ -2375,8 +2375,6 @@ public final BlobInputStream openInputStream(final AccessCondition accessConditi
             opContext = new OperationContext();
         }
 
-        assertNoWriteOperationForSnapshot();
-
         options = BlobRequestOptions.populateAndApplyDefaults(options, this.properties.getBlobType(), this.blobServiceClient, 
                 false /* setStartTime */);