Cannot create empty file - breaks WooCommerce Admin compatibility

[marsjaninzmarsa]

Hi, there is a compatibility issue between your plugin and WooCommerce Admin reports export functionality. Basically, your stream wrapper, even when running on filesystem locally, using fopen and whole rest of the team, doesn't preserve its behavior when it comes to handling empty files, preventing it from being created at all and silently breaking whole export functionality, which depends on handling previously created, empty files to write to.

Steps to reproduce:

1. Have existing running WooCommerce store with WooCommerce Admin and some transactions history for export (more than 25/one page) to trigger multipass export flow
2. Go to Statistics, click "export"
3. Observe empty uploads/woocommerce_uploads/reports/index.html not being created (serious security risk) and .csvs not being generated at all, besides of properly generated and saved, not-empty .htaccess, and link to non-existing file being emailed to your user email.

or, if you don't have a shop running, just run this code from your functions/mu-plugin to test just it:

<?php
$upload_dir = wp_upload_dir();
$reports_dir =  trailingslashit( $upload_dir['basedir'] ) . 'woocommerce_uploads/reports/';
$files = array(
    array(
        'base'    => $reports_dir,
        'file'    => '.htaccess',
        'content' => 'DirectoryIndex index.php index.html' . PHP_EOL . 'deny from all',
    ),
    array(
        'base'    => $reports_dir,
        'file'    => 'index.html',
        'content' => '',
    ),
);


foreach ( $files as $file ) {
    if ( ! file_exists( trailingslashit( $file['base'] ) ) ) {
        wp_mkdir_p( $file['base'] );
    }
    if ( ! file_exists( trailingslashit( $file['base'] ) . $file['file'] ) ) {
        $file_handle = @fopen( trailingslashit( $file['base'] ) . $file['file'], 'wb' ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged, WordPress.WP.AlternativeFunctions.file_system_read_fopen
        if ( $file_handle ) {
            fwrite( $file_handle, $file['content'] ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_read_fwrite
            fclose( $file_handle ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_read_fclose
        }
    }
}

(based on woocommerce/packages/woocommerce-admin/src/ReportCSVExporter.php:maybe_create_directory, entry point for export functionality)

Tested on v0.5.3 and v0.7.0, breaks just the same.