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protect WrapCGI against SIGCHLD handlers #596

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Merged
miyagawa merged 1 commit into from
Jul 24, 2017
Merged

protect WrapCGI against SIGCHLD handlers #596

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11 changes: 8 additions & 3 deletions lib/Plack/App/WrapCGI.pm
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ sub prepare_app {
pipe( my $stdoutr, my $stdoutw );
pipe( my $stdinr, my $stdinw );

local $SIG{CHLD} = 'DEFAULT';

my $pid = fork();
Carp::croak("fork failed: $!") unless defined $pid;
Expand Down Expand Up @@ -64,13 +65,17 @@ sub prepare_app {
# close STDIN so child will stop waiting
close $stdinw;

my $res = '';
while (waitpid($pid, WNOHANG) <= 0) {
my $res = ''; my $waited_pid;
while (($waited_pid = waitpid($pid, WNOHANG)) == 0) {
$res .= slurp_fh($stdoutr);
}
$res .= slurp_fh($stdoutr);

if (POSIX::WIFEXITED($?)) {
# -1 means that the child went away, and something else
# (probably some global SIGCHLD handler) took care of it;
# yes, we just reset $SIG{CHLD} above, but you can never
# be too sure
if (POSIX::WIFEXITED($?) || $waited_pid == -1) {
return CGI::Parse::PSGI::parse_cgi_output(\$res);
} else {
Carp::croak("Error at run_on_shell CGI: $!");
Expand Down
26 changes: 26 additions & 0 deletions t/Plack-Middleware/wrapcgi_exec.t
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Expand Up @@ -136,5 +136,31 @@ print \$q->header(-type => "text/plain"), \$result;
undef $tmp;
};

# test that SIGCHLD handlers don't interfere
{
my $tmp = File::Temp->new(CLEANUP => 1);
print $tmp <<"...";
#!$^X
use CGI;
my \$q = CGI->new;
print \$q->header, "Hello";
...
close $tmp;

chmod(oct("0700"), $tmp->filename) or die "Cannot chmod";

local $SIG{CHLD} = 'IGNORE';
my $app_exec = Plack::App::WrapCGI->new(script => "$tmp", execute => 1)->to_app;
test_psgi app => $app_exec, client => sub {
my $cb = shift;

my $res = $cb->(GET "http://localhost/");
is $res->code, 200;
is $res->content, "Hello";
};

undef $tmp;
};

done_testing;