rewind and update error message

lib/private/connector/sabre/file.php

@@ -85,6 +85,7 @@ class File extends Node implements IFile {
 		if (is_string($data)) {
 			$stream = fopen('php://temp', 'r+');
 			fwrite($stream, $data);
+			fseek($stream, 0);
 			$data = $stream;
 		};
 		try {
@@ -121,7 +122,7 @@ class File extends Node implements IFile {
 		try {
 			$target = $storage->fopen($internalPartPath, 'wb');
 			if ($target === false) {
-				\OC_Log::write('webdav', '\OC\Files\Filesystem::file_put_contents() failed', \OC_Log::ERROR);
+				\OC_Log::write('webdav', '\OC\Files\Filesystem::fopen() failed', \OC_Log::ERROR);
 				$this->fileView->unlink($partFilePath);
 				// because we have no clue about the cause we can only throw back a 500/Internal Server Error
 				throw new Exception('Could not write file contents');