Integration between Wordpress and File Uploader (https://github.com/valums/file-uploader/tree/2.1.2).

gistfile1.txt

<?php

// inicializa Wordpress
require_once( dirname(__FILE__) . '/../../../wp-load.php' );

// list of valid extensions, ex. array("jpeg", "xml", "bmp")
$allowedExtensions = array("jpeg", "png", "jpg");
// max file size in bytes
$sizeLimit = 2 * 1024 * 1024;

require( get_theme_root() . '/' . get_template() . '/fileuploader/uploader.php' );

$uploader = new qqFileUploader($allowedExtensions, $sizeLimit);

// destination path - uploads/formrestrita/[slug of the user]
$wp_upload_dir = wp_upload_dir();
$targetPath = "{$wp_upload_dir['basedir']}/formrestrita/{$_REQUEST['user']}";

// create the path, if don't exist
if( ! is_dir( $targetPath ) ) {
  mkdir( $targetPath );
	chmod( $targetPath, 0777 );
}

$targetPath .= "/{$_REQUEST['name']}";
// create the field path, if don't exist
if( ! is_dir( $targetPath ) ) {
	mkdir( $targetPath );
	chmod( $targetPath, 0777 );
}

$fileName = slugify( $fileParts['filename'] );

// Call handleUpload() with the name of the folder, relative to PHP's getcwd()
$result = $uploader->handleUpload( $targetPath );

if( isset( $result['success'] ) && $result['success'] ) {
	// save the information in the database
	$user = get_user_by('login', $_REQUEST['user']);
	$files = get_user_meta( $user->ID, 'files_area_restrita', true );
	$files[$_REQUEST['name']][] = $result['file'];
	update_user_meta( $user->ID, 'files_area_restrita', $files );
	
	$result['file_url'] = "{$wp_upload_dir['baseurl']}/formrestrita/{$_REQUEST['user']}/{$_REQUEST['name']}/{$result['filename']}";
	$result['remove_url'] = get_bloginfo( 'siteurl' ) . "/area-restrita/remove-upload/{$user->user_login}/{$result['filename']}";
	$result['image'] = get_bloginfo( 'template_url' ) . "/images/cancel.png";
}


// to pass data through iframe you will need to encode all html tags
echo htmlspecialchars(json_encode($result), ENT_NOQUOTES);