Forking causes an error with PKCS#11 crypto module #550

Hi,

I'm not sure if there is anything Psysh can really do about this but I figured I would report the issue in case anyone else runs into it.

If you use Curl in a Psysh shell twice in a row with SSL you will encounter an error like this:

 cURL error 35: A PKCS #11 module returned CKR_DEVICE_ERROR, indicating that a problem has occurred with the token or slot. (see http://curl.haxx.se/libcurl/c/libcurl-errors.html)'

This appears to be caused (at least in my case) by the NSS libraries. The docs state:

It is an error to try to use a PKCS#11 crypto module in a process before it has been initialized in that process, even if the module was initialized in the parent process. Beginning in NSS 3.12.3, Softoken will detect this error.

I found two workarounds.

1.) Set usePcntl to false in the psysh config file as explained in #511.
2.) set the NSS environment variable NSS_STRICT_NOFORK to DISABLED as explained in the docs linked above, i.e. NSS_STRICT_NOFORK=DISABLED psysh

Reproduction steps:

1.) compile curl with NSS instead of openssl or libressl. It should say something like curl 7.29.0 (x86_64-redhat-linux-gnu) libcurl/7.29.0 NSS/3.28.4...
2.) compile php and the curl extension
3.) Install psysh and open a shell
4.) execute the following:

>>> $ch = curl_init()
=> curl resource #930
>>> curl_setopt($ch, CURLOPT_URL, "https://www.example.com/");
=> true
>>> curl_exec($ch)
<!doctype html>...
=> true
>>> curl_exec($ch)
=> false
>>> curl_error($ch)
=> "A PKCS #11 module returned CKR_DEVICE_ERROR, indicating that a problem has occurred with the token or slot."