Description:
------------
cURL multi enter into an infinite loop when CURLOPT_INFILESIZE doesn't match the size of sended data.

In the test script below I intentionally set the CURLOPT_INFILESIZE to the size of the sended data plus 1 byte.

In the documentation we can see that CURLOPT_READFUNCTION should return an empty string to signal an EOF.

So it's what I done in the following script.

So since CURLOPT_READFUNCTION returned the EOF signal which indicates that there's nothing to wait for, I expected cURL to bail out and throwing an error (or at least timeout), but the test script run into an infinite loop instead.


Test script:
---------------
$options = [
    CURLOPT_HTTP_VERSION   => CURL_HTTP_VERSION_1_1,
    CURLOPT_RETURNTRANSFER => false,
    CURLOPT_HEADER         => false,
    CURLOPT_CUSTOMREQUEST  => 'PUT',
    CURLOPT_UPLOAD         => true,
    CURLOPT_URL            => 'http://httpbin.org/put',
    CURLOPT_CONNECTTIMEOUT => 1,
    CURLOPT_HTTPHEADER     => [
        'Content-Type: text/plain; charset=UTF-8',
    ],
    CURLOPT_READFUNCTION   => function($handle, $fp, $length) {
        static $data = 'HelloWorld';
        $readed = $data;
        $data = '';
        echo "Length asked: '{$length}'\n";
        echo "Readed: '{$readed}'\n";
        return $readed;
    },
    CURLOPT_INFILESIZE     => strlen('HelloWorld') + 1 // The extra byte
];

$handle = curl_init();
curl_setopt_array($handle, $options);

$mh = curl_multi_init();
curl_multi_add_handle($mh, $handle);

$running = 0;
do {
    if (curl_multi_select($mh) === -1) {
        usleep(1000);
    }
    curl_multi_exec($mh, $running);
    echo "Number of running request(s): '{$running}'\n";
} while ($running > 0);


Expected result:
----------------
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
Length asked: '16384'
Readed: 'HelloWorld'
# of running request(s): '1'
Length asked: '16384'
Readed: ''
# of running request(s): '1'
# of running request(s): '0'

And a call to curl_strerror() should be able to display the error.

Actual result:
--------------
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
Length asked: '16384'
Readed: 'HelloWorld'
# of running request(s): '1'
Length asked: '16384'
Readed: ''
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
# of running request(s): '1'
... etc.