Adding support for uploading empty 0 byte files through DataLakeFileClient.uploadFromFile() (#37863)

Author: ibrahimrabab

sdk/storage/azure-storage-file-datalake/CHANGELOG.md

@@ -7,6 +7,7 @@
 ### Breaking Changes
 
 ### Bugs Fixed
+- Fixed a bug that did not allow uploading an empty 0 byte file with `DataLakeFileClient.uploadFromFile()`.
 
 ### Other Changes
 

sdk/storage/azure-storage-file-datalake/assets.json

@@ -2,5 +2,5 @@
   "AssetsRepo": "Azure/azure-sdk-assets",
   "AssetsRepoPrefixPath": "java",
   "TagPrefix": "java/storage/azure-storage-file-datalake",
-  "Tag": "java/storage/azure-storage-file-datalake_ab160ac82f"
+  "Tag": "java/storage/azure-storage-file-datalake_0fffe56fda"
 }

sdk/storage/azure-storage-file-datalake/src/main/java/com/azure/storage/file/datalake/DataLakeFileAsyncClient.java

@@ -870,8 +870,8 @@ public Mono<Response<PathInfo>> uploadFromFileWithResponse(String filePath, Para
                         long fileSize = channel.size();
 
                         if (fileSize == 0) {
-                            throw LOGGER.logExceptionAsError(new IllegalArgumentException("Size of the file must be "
-                                + "greater than 0."));
+                            // if file size is 0, create the file but do not upload data.
+                            return createWithResponse(null, null, headers, metadata, validatedRequestConditions);
                         }
 
                         // By default, if the file is larger than 100 MB chunk it and append it in stages.

sdk/storage/azure-storage-file-datalake/src/test/java/com/azure/storage/file/datalake/FileApiTest.java

@@ -2377,6 +2377,22 @@ public void uploadFromFileWithResponse(int dataSize, long singleUploadSize, Long
         assertEquals(dataSize, fc.getProperties().getFileSize());
     }
 
+    @Test
+    public void uploadFromFileEmptyFile() {
+        File file = getRandomFile(0);
+        file.deleteOnExit();
+        createdFiles.add(file);
+
+        Response<PathInfo> response = fc.uploadFromFileWithResponse(file.toPath().toString(), null, null, null, null,
+            null, null);
+        // uploadFromFileWithResponse will return 200 for a non-empty file, but since we are uploading an empty file,
+        // it will return 201 since only createWithResponse gets called
+        assertEquals(201, response.getStatusCode());
+        assertNotNull(response.getValue().getETag());
+
+        assertEquals(0, fc.getProperties().getFileSize());
+    }
+
     private static void compareListToBuffer(List<ByteBuffer> buffers, ByteBuffer result) {
         result.position(0);
         for (ByteBuffer buffer : buffers) {

sdk/storage/azure-storage-file-datalake/src/test/java/com/azure/storage/file/datalake/FileAsyncApiTests.java

@@ -2844,6 +2844,24 @@ public void uploadFromFileWithResponse(int dataSize, long singleUploadSize, Long
             .verifyComplete();
     }
 
+    @Test
+    public void uploadFromFileEmptyFile() {
+        File file = getRandomFile(0);
+        file.deleteOnExit();
+        createdFiles.add(file);
+
+        StepVerifier.create(fc.uploadFromFileWithResponse(file.toPath().toString(), null, null, null, null))
+            .assertNext(r -> {
+                // uploadFromFileWithResponse will return 200 for a non-empty file, but since we are uploading an empty
+                // file, it will return 201 since only createWithResponse gets called
+                assertEquals(201, r.getStatusCode());
+                assertNotNull(r.getValue().getETag());
+            }).then(() -> StepVerifier.create(fc.getProperties())
+                .assertNext(r -> assertEquals(0, r.getFileSize()))
+                .verifyComplete())
+            .verifyComplete();
+    }
+
     @EnabledIf("com.azure.storage.file.datalake.DataLakeTestBase#isLiveMode")
     @Test
     public void asyncBufferedUploadEmpty() {