cURL CURLOPT_WRITEFUNCTION and tmpfile()

Question

This code works:

// Create temp file to write to
$fp_tmp = tmpfile();

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $name);
curl_setopt($ch, CURLOPT_FILE, $fp_tmp);
curl_setopt($ch, CURLOPT_VERBOSE, 1);
curl_setopt($ch, CURLOPT_AUTOREFERER, false);
curl_setopt($ch, CURLOPT_REFERER, 'https://dl.dropboxusercontent.com');
curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
curl_setopt($ch, CURLOPT_HEADER, 0);

$result = curl_exec($ch);
curl_close($ch);

// Write the files
$fp = fopen($orderfile->getFileLocation(), 'w');
stream_copy_to_stream($fp_tmp, $fp);

This code does not:

// Create temp file to write to
$fp_tmp = tmpfile();

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $name);
curl_setopt($ch, CURLOPT_VERBOSE, 1);
curl_setopt($ch, CURLOPT_AUTOREFERER, false);
curl_setopt($ch, CURLOPT_REFERER, 'https://dl.dropboxusercontent.com');
curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_WRITEFUNCTION, function($ch, $str) use (&$fp_tmp) {
    $length = fwrite($fp_tmp, $str);
    return $length;
});

$result = curl_exec($ch);
curl_close($ch);

// Write the files
$fp = fopen($orderfile->getFileLocation(), 'w');
stream_copy_to_stream($fp_tmp, $fp);

I am assuming that I cannot pass a stream via the 'use' to a function this way as it fails to copy the data. I guess my question is, how can I write the content of $str to $fp_tmp using CURLOPT_WRITEFUNCTION?

Answer 1

I'm a dummy, I forgot to reset the pointer using fseek().

// Create temp file to write to
$fp_tmp = tmpfile();

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $name);
curl_setopt($ch, CURLOPT_VERBOSE, 1);
curl_setopt($ch, CURLOPT_AUTOREFERER, false);
curl_setopt($ch, CURLOPT_REFERER, 'https://dl.dropboxusercontent.com');
curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_WRITEFUNCTION, function($ch, $str) use (&$fp_tmp) {
    $length = fwrite($fp_tmp, $str);
    return $length;
});

$result = curl_exec($ch);
curl_close($ch);

// Write the files
$fp = fopen($orderfile->getFileLocation(), 'w');
fseek($fp_tmp, 0);
stream_copy_to_stream($fp_tmp, $fp);