The Absence of an ‘S’ Can Create a Big Mess

Lea Cohen — Mon, 25 May 2020 13:10:04 +0000

After deploying one of our sites to production, one of my colleagues wrote to me on Slack:

Look at the image at the bottom of the front page. In Test, the image is a rectangle, and in production, it’s square. How can that be? The Production code and images are an exact duplicate of the Test site’s code and images.

The left side shows the rectangle image on the test site; the right side is the square image on Production. Credit to Rachel Bratt-Tannenbaum for artistically designing the screenshots

Weird. This is a standard WordPress site built with Elementor and using one of the Pojo themes. What on earth could have caused this difference in sizes and proportions?

First Step — Dev Tools

I started by checking the Dev Tools and found that not only were the sizes different, but the image source was different: the image in the test site came from the year and month folder in the uploads folder, and the image on production came from the thumbs folder in the uploads folder.

The left side shows the image source on the test site is in the thumbs folder; the right side is the image source on Production, in the year/month folder. Credit to Rachel Bratt-Tannenbaum for artistically designing the screenshots

The colleague who brought this problem to my attention gave me a lead: the CSS class given to the image was small-thumbnail. A quick search led her to the recent_post.php file in the theme’s content folder, and that’s where I started my journey in search of the culprit.

Down the Rabbit Hole

The code that retrieves the image url in content/recent_post.php was easy to locate:

$image_url = Pojo_Thumbnails::get_post_thumbnail_url( array( 'width' => '360', 'height' => '360', 'crop' => true, 'placeholder' => true ) ) )

This was my starting point, and from there, I started following the clues. The first clue led me to the get_post_thumbnail_url function, which resides in the \core\helpers\class-pojo-thumbnails.php theme file:

The function get_post_thumbnail_url calls a few WordPress functions. Those aren’t suspects because I know them, and none of them retrieves a url with the thumbs folder in it. The only Pojo theme-specific function that’s called is get_attachment_image_src, and that’s where I continued my search.

The get_attachment_image_src, like its predecessor get_post_thumbnail_url, mainly calls WP functions. Here, the only theme-specific function that’s called is get_thumb.

The get_thumb function calls the Class’s init() function which, in turn, includes the BFI_Thumb.php file which reside in the Pojo theme’s /core/helpers/bfi_thumb folder. Then the get_thumb function calls the bfi_thumb function:

Here, the function doesn’t directly call another function but uses the call_user_func PHP function to call the next function dynamically. call_user_func's first parameter is a callback function. In our case, this parameter is an array, in which the first item is a class name, and the second item is the function within that class. While the second item was explicitly defined — the ‘thumb’ function — the class was determined using the BFI_Class_Factory::getNewestVersion function, which retrieved the newest version of BFI_Thumb. I’ll spare you the intricacies of the Newest Version calculation and tell you that in our installation, the class name is BFI_Thumb_1_2.

Thankfully, the BFI_Thumb_1_2 class resides in the same file, so all that was needed was that I hop over to its thumb function.

Nearing the End

The thumb function, in contrast to its predecessors, isn’t a short little 10–20 lines function. This one is a lengthy, detailed ~170 line function, with many conditions and exit-points. On the other hand, it’s very well commented.

Luckily, the line in which the divergence of the Test site from production occurred, was pretty early on:

As I debugged the code (shamefully, I used the echo function to do the debugging), I got to the point of divergence:
The code in Production entered this condition, and the Test code — didn’t:

strpos( $url, $upload_url ) !== false

The condition is: Does the image url contain the upload url? In other words — is the image inside this site’s uploads folder?
Now, I knew that the images on both sites ARE in the upload folder. So why isn’t the condition being met on Test???

I checked the values of $url and $upload_url:

$url = https://test-server/site-name/wp-content/uploads/2019/06/בריא1.jpg

$upload_url = http://test-server/site-name/wp-content/uploads

Do you see the difference in the url?

The $url’s protocol is HTTPS, and the $upload_url's protocol is HTTP!

Somewhere, somehow, even though the site uses the https protocol, the upload folder’s definition omitted the s. That’s the reason that the code didn’t enter the condition!

Now all that was left was for me to find where the $upload_url is defined. The code states that it’s defined in the $upload_info[‘baseurl’] parameter, but where is that parameter set? Hmmm… baseurl. Sounds familiar. Don’t I know that from somewhere? Isn’t that defined in the wp-admin of the site — in Settings -> General?

It is! I fixed the two URLs that set the site address, adding an s after the HTTP— and voila! The image on the Test site miraculously became identical to the one on the Production site.

Why were they a different size and proportion?

Although I didn’t go on to read the rest of the code, I assume that when the image IS in the uploads dir, the code creates a copy and puts it in the thumbs folder and returns that address, and when the image isn’t there — the image’s original address is returned.

What Have We Learned?