Automattic / jetpack

		if($fullpath && ($fsize = filesize($fullpath)) !== false) {

			// IE8 can't handle data uris larger than 32KB

			if($fsize/1024 < 32) {

				if(is_null($mime)) {

					if(class_exists('finfo')) { // php 5.3+

						$finfo = new finfo(FILEINFO_MIME);

						$mime = explode('; ', $finfo->file($fullpath));

						$mime = $mime[0];

					} elseif(function_exists('mime_content_type')) { // PHP 5.2

						$mime = mime_content_type($fullpath);

					}

				}

				if(!is_null($mime)) // fallback if the mime type is still unknown

					$url = sprintf('data:%s;base64,%s', $mime, base64_encode(file_get_contents($fullpath)));

	 * @return bool

	 */

	protected function is_file_supported_for_sideloading( $file ) {

		if ( class_exists( 'finfo' ) ) { // php 5.3+

			$finfo = new finfo( FILEINFO_MIME );

			$mime = explode( '; ', $finfo->file( $file ) );

			$type = $mime[0];

		} elseif ( function_exists( 'mime_content_type' ) ) { // PHP 5.2

			$type = mime_content_type( $file );

		} else {

			return false;

		}

		/**

		 * Filter the list of supported mime types for media sideloading.