incr_parse() Hangs on Certain Inputs

[DabeDotCom]

Notably, inputs that end in a number or [tfn]:

perl -MJSON::PP -e 'print JSON::PP->new->incr_parse(q|{"key": 1|)'

Whereas JSON::XS returns silently:

perl -MJSON::XS -e 'print JSON::XS->new->incr_parse(q|{"key": 1|)'

My fix is pretty trivial:

--- a/lib/JSON/PP.pm
+++ b/lib/JSON/PP.pm
@@ -1699,2 +1699,3 @@ INCR_PARSE:
         } elsif ( $mode == INCR_M_TFN ) {
+            last INCR_PARSE if $p >= $len && $self->{incr_nest};
             while ( $len > $p ) {
@@ -1710,2 +1711,3 @@ INCR_PARSE:
         } elsif ( $mode == INCR_M_NUM ) {
+            last INCR_PARSE if $p >= $len && $self->{incr_nest};
             while ( $len > $p ) {

But it's the tests that I spent the most time on (which is why I've left the PR unsquashed...)

Because the current behavior gets stuck in an infinite loop, I wanted to properly timeout, which meant reaching for Test::Fork:

use Test::Fork;
sub run_test {
    my ($num_tests, $input, $sub) = @_;
    my $pid = fork_ok($num_tests => sub {
        setpgrp 0, 0;
        $sub->($input);
    });

    local $SIG{ALRM} = sub { warn "\e[31mnot ok - '$input' hung; killing $pid...\e[m\n"; kill -9, $pid };
    alarm 10;
    waitpid $pid, 0;
    alarm 0;
}

If you have a better way, I'm all ears! :-D

[charsbar]

Thanks for the PR. Could you 1) fix the test and Makefile.PL not to depend on Test::Fork because JSON::PP is a core module and I don't want to add non-core dependency here, and could you also 2) remove JSON::XS from the loop because that should be for JSON.pm?

[DabeDotCom]

Thanks for the PR. Could you 1) fix the test and Makefile.PL not to depend on Test::Fork because JSON::PP is a core module and I don't want to add non-core dependency here, and could you also 2) remove JSON::XS from the loop because that should be for JSON.pm?

"Done."

PS: You're right of course... It's not actually a test of JSON::XS; I just wanted to prove (to myself, at least) that JSON::PP and JSON::XS were producing the same results — and yeah, I see how that's better suited to JSON. 👍

Cheers! :-D

[charsbar]

Sorry for the delay. Thank you!