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lib/CGI/Parse/PSGI/Streaming.pm  view on Meta::CPAN

package CGI::Parse::PSGI::Streaming;
use strict;
use warnings;
our $VERSION = '1.0.1'; # VERSION
use HTTP::Response;
use CGI::Parse::PSGI::Streaming::Handle;
use SelectSaver;

# ABSTRACT: creates a filehandle that parses CGI output and writes to a PSGI responder


sub parse_cgi_output_streaming_fh {
    my ($responder) = @_;

    # ugly-ish way to get a ref to a new filehandle
    my $output = \do {local *HANDLE};

    # state for the callback closure
    my $headers; # string, accumulated headers
    my $response; # HTTP::Response object with parsed headers
    my $writer; # the writer object returned by the responder

    ## no critic(ProhibitTies)
    tie *{$output},'CGI::Parse::PSGI::Streaming::Handle', sub {
        # this callback is invoked with whatever bytes were printed to
        # the filehandle; it will be called with no argument (or an
        # undef) when the filehandle is closed
        my ($data) = @_;

        # reset the default filehandle to the real STDOUT, just in
        # case: it's nice to make sure all the callbacks are invoked
        # with the state they expect
        my $saver = SelectSaver->new("::STDOUT");

        # if we're still parsing the headers
        if (!$response) {
            if (defined $data) {
                $headers .= $data;
            }
            else { # closed file before the end of headers
                $headers = "HTTP/1.1 500 Internal Server Error\x0d\x0a";
            }

            # still more headers to come, return to the CGI
            return unless $headers =~ /\x0d?\x0a\x0d?\x0a/;

            # since we may have received the last bytes of the headers
            # together with the first bytes of the body, we want to
            # make sure that $headers contains only the headers, and
            # $data contains only the body (or '')
            ($headers,$data) =
                ($headers =~ m{\A(.+?)\x0d?\x0a\x0d?\x0a(.*)\z}sm);

            # HTTP::Response wants things formatted like... an HTTP
            # response. CGI output is slightly different. Let's cheat.
            unless ( $headers =~ /^HTTP/ ) {
                $headers = "HTTP/1.1 200 OK\x0d\x0a" . $headers;
            }

            $response = HTTP::Response->parse($headers);

            # RFC 3875 6.2.3
            if ($response->header('Location') && !$response->header('Status')) {
                $response->header('Status', 302);
            }
        }

        # this is not a "elsif"! we may have the start of the body
        # with the same 'print' as the end of the headers, and we want
        # to stream out that body already
        if ($response) { # we have parsed the headers
            if ( $response->code == 500 && !defined($data) ) {
                # filehandle closed after a raw 500, synthesise a body
                $responder->([
                    500,
                    [ 'Content-Type' => 'text/html' ],
                    [ $response->error_as_HTML ]
                ]);
                return;
            }
            # we haven't sent the headers to the PSGI backend yet
            if (!$writer) {
                my $status = $response->header('Status') || 200;
                $status =~ s/\s+.*$//; # remove ' OK' in '200 OK'
                # PSGI doesn't allow having Status header in the response
                $response->remove_header('Status');

                # we send the status and headers, we get a writer
                # object back
                $writer = $responder->([
                    $status,