fix: Add an exception to zero byte uploads on CreateFrom (#2342)

* fix: Add an exception to zero byte uploads on CreateFrom

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google-cloud-storage/src/main/java/com/google/cloud/storage/StorageImpl.java

@@ -230,6 +230,10 @@ public Blob createFrom(BlobInfo blobInfo, Path path, int bufferSize, BlobWriteOp
     if (Files.isDirectory(path)) {
       throw new StorageException(0, path + " is a directory");
     }
+    long size = Files.size(path);
+    if (size == 0L) {
+      return create(blobInfo, null, options);
+    }
     Opts<ObjectTargetOpt> opts = Opts.unwrap(options).resolveFrom(blobInfo);
     final Map<StorageRpc.Option, ?> optionsMap = opts.getRpcOptions();
     BlobInfo.Builder builder = blobInfo.toBuilder().setMd5(null).setCrc32c(null);
@@ -251,7 +255,6 @@ public Blob createFrom(BlobInfo blobInfo, Path path, int bufferSize, BlobWriteOp
             getOptions().asRetryDependencies(),
             retryAlgorithmManager.idempotent(),
             jsonResumableWrite);
-    long size = Files.size(path);
     HttpContentRange contentRange =
         HttpContentRange.of(ByteRangeSpec.relativeLength(0L, size), size);
     ResumableOperationResult<StorageObject> put =

google-cloud-storage/src/test/java/com/google/cloud/storage/it/ITObjectTest.java

@@ -74,10 +74,12 @@
 import com.google.common.primitives.Ints;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
+import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.ByteBuffer;
 import java.nio.channels.Channels;
+import java.nio.file.Paths;
 import java.security.Key;
 import java.util.Arrays;
 import java.util.HashMap;
@@ -197,6 +199,21 @@ public void testCreateEmptyBlob() {
     assertArrayEquals(new byte[0], readBytes);
   }
 
+  @Test
+  public void testZeroByteFileUpload() throws Exception {
+    String blobName = generator.randomObjectName();
+    BlobId blobId = BlobId.of(bucket.getName(), blobName);
+    BlobInfo blobInfo = BlobInfo.newBuilder(blobId).build();
+
+    File zeroByteFile = File.createTempFile("zerobyte", null);
+    zeroByteFile.deleteOnExit();
+
+    storage.createFrom(blobInfo, Paths.get(zeroByteFile.getAbsolutePath()));
+
+    byte[] readBytes = storage.readAllBytes(bucket.getName(), blobName);
+    assertArrayEquals(new byte[0], readBytes);
+  }
+
   @Test
   @SuppressWarnings({"unchecked", "deprecation"})
   public void testCreateBlobStream() {