PHP cURL - how to upload contents of a variable as a file via HTTP request?

Question

There are lots of answers to "upload file with php curl", and they all require that a physical file exists on the machine. It's uploaded by referencing the @ symbol before the filename in the POST fields.

However, I have the file data already in a PHP variable: $data. How can I upload this directly without needing to first write it to a file?

I tried this:

$ch = curl_init();
curl_setopt_array($ch, [
    CURLOPT_URL => SERVER_URL . '/test.php?abc=def&ghi=jkl',
    CURLOPT_RETURNTRANSFER => 1,
    CURLOPT_TIMEOUT => 120,
    CURLOPT_POST => 1,
    CURLOPT_CUSTOMREQUEST => "POST",
    CURLOPT_POSTFIELDS => ['file' => $data],
    CURLOPT_HTTPHEADER => ["Content-type: multipart/form-data"],
    CURLOPT_HEADER => true,
    CURLOPT_INFILESIZE => strlen($data)
]);

$response = curl_exec($ch);

But my server gives an error that POST Content-Length exceeds the server limit of 8388608 bytes. However, in my php.ini file on the server, I have upload_max_filesize = 500M. So it looks like this POST is not being treated as a multipart file upload, but instead is trying to jam all the file data into the POST request.

Community · Accepted Answer · 2020-06-20 09:12:55Z

1

You could first write your string to a file in the /tmp folder. I'm not certain, but I think you might be required to do this if you want to post a file. The documentation says :

7.0.0 Support for disabling the CURLOPT_SAFE_UPLOAD option has been removed. All curl file uploads must use CURLFile.

EDIT: Please check the docs on post_max_size:

post_max_size integer

Sets max size of post data allowed. This setting also affects file upload. To upload large files, this value must be larger than upload_max_filesize. Generally speaking, memory_limit should be larger than post_max_size...

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Jan 23, 2019 at 22:49

S. Imp

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2 Comments

Ryan Griggs Over a year ago

I know I can write the data to a file... I was trying to avoid that extra step. If it's not possible, I will do it. I just felt like I was missing something obvious. Thanks

S. Imp Over a year ago

@RyanGriggs try adjusting your post_max_size value to something large enough to accommodate the file (or attempt a smaller test file) and see if it works. It just might -- although that "all curl file uploads must use CURLFile" warning for php 7.0.0 seems pretty ominous for forward-compatibility. You could also consider altering your script that handles the upload to accept the information as a string. You would probably want to base64 encode it to make sure it survives transit from curl to server.

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