Wordpress Ajax setcookie WAMP/LAMP disparities - php

Question

In a wordpress themed-plugin for e-commerce I have two ajax/php scripts setting cookies (both in the same directory) The ajax calls are set from the same "cart.js" The first script sets/updates an anonymous cart cookie when a cart is either created or updated. The second checks if customer/user exists, or creates one anew and --in either case -- logs them in if not already, before the cart gets passed to PayPal. As such, upon returning from paypal the customer/user (now logged in) is presented with an overview / review of the status of their orders (new and old).
On my WAMP develpment stack, this works flawlessly, while on the hosted (linux) installation
the cart_cookie script works as expected, while the checkout/customer_cookie throws...
[14-May-2013 02:08:50]
PHP Warning: session_start()
[<a href='function.session-start'>function.session-start</a>]:
Cannot send session cache limiter - headers already sent
(output started at /home2/alternam/public_html/demo/wp-content/themes/AM_Wallaby_Kids/checkout.php:2)
in /home2/alternam/public_html/demo/wp-content/plugins/cat-man/catalog-manager.php on line 23
Subsequently, the user is NOT logged in, and the cart is not converted (updated with relevant customer data). Wish I saw a way to pare this down to a minimum, but as I have no earthly idea why the two scripts behave so differently across platforms I'll apologize in advance for the lengthy post and include them both in their entirety below, and ask if anyone can see some obvious reason for the disparity? Thanks for your patience.
P.S. Both WAMP and LAMP stacks running php 5.2
cart_add.php (works both WAMP && LAMP)
<?php
ob_start();
require_once(preg_replace("/wp-content.*/","wp-load.php",__FILE__));
ob_end_clean();
$ud_cart = $product_name = $product_url = $reset = "";
$_POST = filter_input_array(INPUT_POST, FILTER_SANITIZE_STRING);# Sanitize Post Input
foreach ($_POST as $key => $val)
{ if(!is_array($val)) $$key = html_entity_decode($val,ENT_QUOTES);
else $$key = $val;
}
if($ud_cart)
{ $reset =1;
$amt_cart[0] = $cart_id;
if(#$items) foreach($items as $key => $item )$amt_cart[] = $item;
$amt_cart = serialize($amt_cart);
}
if($reset)
{ // Initiated from the cart (tpl_cart.php on page load) to remove out-of-stock items
// from OLD CARTS -- where items have gone out-of-stock since cart created -- OR
// to simply update/remove cart items upon user request (user clicks Update|Remove)
if($amt_cart)
{ $amt_cart = stripslashes($amt_cart);
setcookie(AMART_CART, $amt_cart, time()+60*60*24*90, COOKIEPATH, COOKIE_DOMAIN);
}
exit;
}
// Create Cart, and add, update, or remove Cart-Items from within the catalog gallery && product detail pages
$add = array("product_id" => $product_id, "product_name" => $product_name, "product_type" => $product_type,"product_url" => $product_url,"qty" => $qty);
$update = "";
if( isset( $_COOKIE[AMART_CART] ) )
{ $amt_cart = stripslashes($_COOKIE[AMART_CART]);
$amt_cart = unserialize($amt_cart);
foreach($amt_cart as $key => $item)
{ if($key == 0 ) $amt_cart_id = $item;
else
{ foreach($item as $attr => $value)
{ if($product_id != $value) continue;
else
{ $update = 1;
if($qty == 0 )
{ unset($amt_cart[$key]);
break;
} else $amt_cart[$key]['qty'] = $qty;
}
}
}
}
if(!$update) $amt_cart[] = $add;
setcookie(AMART_CART, serialize($amt_cart), time()+60*60*24*90, COOKIEPATH, COOKIE_DOMAIN);
}
else
{ unset($_SESSION[STORE_ID]['dest_zip'], $_SESSION[STORE_ID]['dest_ctry']);
$amt_cart[0] = uniqid(AMART_CART);
$amt_cart[] = $add;
setcookie(AMART_CART, serialize($amt_cart), time()+60*60*24*90, COOKIEPATH, COOKIE_DOMAIN);
}
?>
checkout.php (works on WAMP, fails on LAMP)
<?php
// TPL CART POSTS VIA AJAX CALL IN cart.js
ob_start();
require_once(preg_replace("/wp-content.*/","wp-load.php",__FILE__));
ob_end_clean();
$_POST = filter_input_array(INPUT_POST, FILTER_SANITIZE_STRING);
global $current_user, $wpfx;
$buyer_address1 = $buyer_address2 = $buyer_city = $buyer_region = $buyer_postal_code = $buyer_country = $buyer_ctry_code ="";
foreach ($_POST as $key => $val) $$key = $val;
foreach($buyer as $key => $val) $$key = $val;
$user_is_admin = current_user_can('manage_options');
if(!is_user_logged_in() || $user_is_admin )
{ if($userID = email_exists($email))
{ $user_info = $user_info = get_userdata($userID);
$user_login = $user_info->user_login;
$display_name = $user_info->display_name;
$welcome = "Welcome Back $display_name!";
}
if(#$welcome)
{ if(!$user_is_admin )
{ if(!$user_cnfm) die($welcome);
$auth = get_object_vars(wp_authenticate($user_login, $user_pass));
if(array_key_exists('errors',$auth)) die("Password Error");
wp_set_auth_cookie( $userID, true);
wp_set_current_user($userID, $user_login);
}
update_user_meta( $userID, 'customer', 1);
}
else
{ $buyer_name = "$buyer_first $buyer_last";
$ship_to_name = "$first_name $last_name";
if($ship_to_self)
{ foreach ( $ctry_opts as $key=>$value ) if (strcasecmp($country, $value) == 0) $buyer_country = $key;
$buyer_address1 = $address1;
$buyer_address2 = $address2;
$buyer_city = $city;
$buyer_region = $state;
$buyer_postal_code = $zip;
$buyer_ctry_code =strtolower($country);
} else foreach ( $ctry_opts as $key=>$value ) if ($buyer_ctry_code == $value) $buyer_country = $key;
$userdata = $user_cookie = array(
'user_login' => $email,
'user_email'=> $email,
'user_pass'=>$user_pass,
'first_name'=>$buyer_first,
'last_name'=>$buyer_last,
'display_name' =>$buyer_name,
'address1' => $buyer_address1,//null if not ship to self
'address2' => $buyer_address2,//null if not ship to self
'city' => $buyer_city,//google guess if not ship to self
'region' => $buyer_region,//google guess if not ship to self
'postal_code' => $buyer_postal_code,//null if not ship to self
'country' => $buyer_country,//google guess if not ship to self
'ctry_code' => $buyer_ctry_code,//google guess if not ship to self
'customer' => '1'
);
$userID = wp_insert_user( $userdata );
if(!$user_is_admin)
{ wp_set_auth_cookie( $userID, true);
wp_set_current_user($userID, $email);
}
unset($user_cookie['user_login'],$user_cookie['user_pass'],$user_cookie['display_name']);
setcookie('AMART_CUSTOMER', serialize($user_cookie), time()+60*60*24*180, COOKIEPATH, COOKIE_DOMAIN);
}
}
if(is_user_logged_in())
{ if(!$user_is_admin) $userID = $current_user->ID;
$cart_id = $item_name;
$cart = $wpdb->get_row("SELECT * FROM {$wpfx}amt_carts WHERE cart_id = '$cart_id'", ARRAY_A);
if( $cart['host_checkout'] && isset($store_options->paypal_live) && $store_options->paypal_live !=='false')
$host_checkout = true;
$ship_to = serialize( array('first_name' => $first_name,'last_name' => $last_name,'address1' => $address1,'address2' => $address2,'city' => $city, 'state' => $state,'postal_code' => $zip,'country' =>$country));
$attributes = array('ship_to' => $ship_to, 'customer_id'=>$userID, 'checkout_date'=>$now);
$where = array('cart_id' => $cart_id);
$wpdb->update("{$wpfx}amt_carts", $attributes,$where);
}
?>

Answer 1

This is, I believe, due to a difference in PHP configuration. I cannot tell you more without knowing the full list of POST variables, besides broad guidelines.
This is what I assume is causing the issue:
You're assigning $_POST[key] to $key. This is fine
You're then looping through $buyers. If $_POST["buyers"] was not set or not an array, this will throw a notice.
A notice is an echo. You are not in an output buffering context, which therefore causes the headers to also be sent. If the headers are sent and you later send a cookie or other header info, you get the warning you are getting.
One of your dev environments probably has error_reporting set to E_NONE. Check this in the PHP information. If set to E_NONE, your code will work. If not, you will get that message. Consider always checking for the existence and correct type of your functions. A good way to do so concisely is as follows:
foreach (((array)$buyers) as $v) {
if $buyers is undefined, you will get an empty array. If buyers had one element you will have an array with one element. Otherwise, you will get the array you had.

Answer 2

Okay...
As much as Sébastien's answer made good sense (and was even correct in some regard), and grateful as I am to him for pointing out that Notice level errors are essentially an echo causing headers to be sent, and for demonstrating a new way (to me) of ensuring an array exists in a foreach loop... the problem actually appears to stem from the differences between Linux and Windows newline characters, which I discovered when opening the hosted "cart_add.php" (from FileZilla ftp ) for editing in Notepad++. I was surprised to find extra newlines for every line of code. (Not the way the file was written). On a whim, I highlighted the first doubled newline, and replaced all with \n. Uploading the file (which had worked before on either stack) cart_add.php subsequently returned an error indicating something like no such function - phpob_start.
Aha!
On my windows box, coding in Notepad++ and comparing files in Beyond Compare, the hosted (Linux) files appear to be exact copies of the local source files, however file sizes tell a different story (local / windows files invariably larger) which I suspect is owed to the difference in newline characters (\n\r) in windows, and (\n) on linux.
Now, the problem I face is
Gaining an understanding of why replacing (in Notepad++) all doubled newlines with \n (Linux standard) cased the script to break.
Establishing a means of safeguarding against this issue in the future
but perhaps that is a matter for a separate post?