PHP 7.2 CURLFile Gives “Invalid Filename” Warning

Question

I am having an issue using the CURLFile object (curl_file_create). I have tried a number of approaches, but no matter what I try, I end up getting a PHP Warning in the log files and the file is omitted from my cURL call.

First, some information:

• PHP 7.2
• Files have been confirmed that they exist and are readable by PHP/Apache
• php-curl and related php libraries are up-to-date
• This is a snippet from within an object, thus the references to $this. All variables are loading correctly.
• This is a continuation of another question I started that, when narrowed, seems to be unrelated to the primary original topic (mailgun). It can be referenced at this URL if you like, but I intend to close that question shortly. Mailgun Attachments with PHP cURL - No SDK
• Note in the code block where I have commented out several other variants of trying to add the file -- all of them create the same warning/result

Code Block

$curl = curl_init();

$curlOpts = array(
    CURLOPT_POST => 1,
    CURLOPT_URL => $postUrl,
    CURLOPT_TIMEOUT => 20,
    CURLOPT_RETURNTRANSFER => 1,
    CURLOPT_HTTPAUTH => CURLAUTH_BASIC,
    CURLOPT_USERPWD => 'api:' . $this->apiKey
);

$postFields = array(
    'from' => $email->from,
    'to' => $email->to,
    'subject' => $email->subject
);

if (strlen($email->cc) > 0) {
    $postFields['cc'] = $email->cc;
}

if (strlen($email->bcc) > 0) {
    $postFields['bcc'] = $email->bcc;
}

if (strlen($email->html) > 0) {
    $postFields['html'] = $email->html;
} else {
    $postFields['text'] = $email->text;
}

if (count($email->attachments) > 0) {
    // Curl attachments for < PHP5.5 not supported
    if (function_exists('curl_file_create')) {
        $curlOpts[CURLOPT_SAFE_UPLOAD] = 1; // for < PHP 7
        //$curlOpts[CURLOPT_HTTPHEADER] = array('Content-Type: multipart/form-data');
        //$postFields['attachment'] = curl_file_create($email->attachments[0]);
        for ($i = 1; $i <= count($email->attachments); $i++) {
            $postFields['attachment[' . $i . ']'] = curl_file_create($email->attachments[$i - 1], 'text/csv', basename($email->attachments[$i - 1]));
            //$postFields['attachment[' . $i . ']'] = curl_file_create('/var/www/sites/domain/contact.csv', 'text/csv', 'contact.csv');
            //$postFields['attachment[' . $i . ']'] = curl_file_create('test.txt', 'text/plain', 'test.txt');
            //$postFields['attachment[' . $i . ']'] = curl_file_create(realpath('test.txt'), 'text/plain', 'test.txt');
            //$postFields['attachment[' . $i . ']'] = new \CURLFile($email->attachments[$i - 1]);
        }
    } else {
        \D3DevelForms\Models\Error::CreateAndSaveSystemError(
            $plugin, 
            \D3DevelForms\Common::ERROR_WARNING, 
            'PHP 5.5 or newer required for Mailgun Attachments', 
            \D3DevelForms\Models\Error::ERROR_CODE_API_MAILGUN_LOCAL_ERROR,
            'You are using an outdated version of PHP. Email attachments via Mailgun will be ignored.');
    }
}

$curlOpts[CURLOPT_POSTFIELDS] = $postFields;

$log->UpdateDebugLog('Mailgun API Options', $curlOpts);

curl_setopt_array($curl, $curlOpts);

$curl_response = curl_exec($curl);
$info = curl_getinfo($curl);

Curl Options ($curlOpts)

Array
(
    [47] => 1
    [10002] => https://api.mailgun.net/v3/devtester.devtest.com/messages
    [13] => 20
    [19913] => 1
    [107] => 1
    [10005] => api:APIKEY
    [-1] => 1
    [10015] => Array
        (
            [from] => Dev Tester <devtester@devtest.com>
            [to] => devemail@gmail.com
            [subject] => Form Summary
            [text] => My Text Content
            [attachment[1]] => CURLFile Object
                (
                    [name] => /var/www/path_to/my_file.csv
                    [mime] => text/csv
                    [postname] => my_file.csv
                )

        )

)

Curl Info Returned ($info)

Array
(
    [url] => https://api.mailgun.net/v3/devtester.devtest.com/messages
    [content_type] => application/json
    [http_code] => 200
    [header_size] => 388
    [request_size] => 312
    [filetime] => -1
    [ssl_verify_result] => 0
    [redirect_count] => 0
    [total_time] => 0.503718
    [namelookup_time] => 0.004273
    [connect_time] => 0.0932
    [pretransfer_time] => 0.279756
    [size_upload] => 1021
    [size_download] => 105
    [speed_download] => 208
    [speed_upload] => 2026
    [download_content_length] => 105
    [upload_content_length] => 1021
    [starttransfer_time] => 0.368725
    [redirect_time] => 0
    [redirect_url] => 
    [primary_ip] => Y.Y.Y.Y
    [certinfo] => Array
        (
        )

    [primary_port] => 443
    [local_ip] => X.X.X.X
    [local_port] => 38636
)

Update: When testing with cURL from command line, it does work as intended including when I run it as an the apache process.

sudo -u apache curl -s --user 'api:APIKEY' \
    https://api.mailgun.net/v3/devtester.devtest.com/messages \
    -F from='Dev Tester <devtest@devtester.devtest.com>' \
    -F to='devtester@gmail.com' \
    -F subject='Hello' \
    -F text='Testing some Mailgun awesomness!' \
    -F attachment=@/var/www/path_to/my_file.csv
{
    "id": "<AA.BB.CC@devtester.devtest.com>",
    "message": "Queued. Thank you."
}

I am getting a PHP warning in the Apache logs, that appears as follows:

"PHP Warning: curl_setopt_array(): Invalid filename for key attachment[1]"

This is tricky because I have confirmed the following:

• The file exists
• The file is readable by Apache
• The file path does not include any characters outside of letters, numbers, slashes and hyphens
• Because the file is generated within the same thread, I have tried referencing a static file, but the result is the same.

Answer 1

Eureka. The problem is using curl_setopt_array. I was able to correct the issue like so:

//$curlOpts[CURLOPT_POSTFIELDS] = $postFields;

$log->UpdateDebugLog('Mailgun API Options', $curlOpts);

curl_setopt_array($curl, $curlOpts);
curl_setopt($curl, CURLOPT_POSTFIELDS, $postFields);

I didn't come across any documentation on this limitation with curl_setopt_array, so I'm not sure if this was improper usage on my part or if this is an unknown bug.