test failure on HP-PARISC: Rack::Utils#test_0013_raise an exception if the params are too deep:

[DerDakon]

Test output:

Error:
Rack::Utils#test_0013_raise an exception if the params are too deep:
SystemStackError: stack level too deep
    /var/tmp/portage/dev-ruby/rack-2.1.1/work/ruby25/rack-2.1.1/lib/rack/query_parser.rb:199:in `each'
    /var/tmp/portage/dev-ruby/rack-2.1.1/work/ruby25/rack-2.1.1/lib/rack/query_parser.rb:199:in `to_h'
    /var/tmp/portage/dev-ruby/rack-2.1.1/work/ruby25/rack-2.1.1/lib/rack/query_parser.rb:205:in `block in to_h'
    /var/tmp/portage/dev-ruby/rack-2.1.1/work/ruby25/rack-2.1.1/lib/rack/query_parser.rb:199:in `each'
    /var/tmp/portage/dev-ruby/rack-2.1.1/work/ruby25/rack-2.1.1/lib/rack/query_parser.rb:199:in `to_h'
[…]
    /var/tmp/portage/dev-ruby/rack-2.1.1/work/ruby25/rack-2.1.1/lib/rack/query_parser.rb:205:in `block in to_h'
    /var/tmp/portage/dev-ruby/rack-2.1.1/work/ruby25/rack-2.1.1/lib/rack/query_parser.rb:199:in `each'
    /var/tmp/portage/dev-ruby/rack-2.1.1/work/ruby25/rack-2.1.1/lib/rack/query_parser.rb:199:in `to_h'
    /var/tmp/portage/dev-ruby/rack-2.1.1/work/ruby25/rack-2.1.1/lib/rack/query_parser.rb:76:in `parse_nested_query'
    /var/tmp/portage/dev-ruby/rack-2.1.1/work/ruby25/rack-2.1.1/lib/rack/utils.rb:103:in `parse_nested_query'
    /var/tmp/portage/dev-ruby/rack-2.1.1/work/ruby25/rack-2.1.1/test/spec_utils.rb:129:in `block (2 levels) in <top (required)>'


rails test var/tmp/portage/dev-ruby/rack-2.1.1/work/ruby25/rack-2.1.1/test/spec_utils.rb:122

Common pitfall: the stack on HPPA machines grows upwards. This one is Gentoo Linux

[leahneukirchen]

Apparently the stack on HPPA is not enough to do 100 recursion levels.

1. Perhaps something like 16 is a better default?
2. QueryParser#parse_nested_query should catch SystemStackError

[DerDakon]

The size is not unusual, I never had problems with it. Usually it's the direction that causes issues as getting the bottom of the stack is constant and always returns the first address of the stack, but not the current one.

[leahneukirchen]

Well, the stack order is a Ruby issue, not a Rack problem.
Which version of Ruby is that?

I don't see benefit in allowing 100 times nested query parameters.

Can you run ruby -e 'def r(n); p n; r(n+1); end; r 1' and show how big it gets?
Does it get more when you export RUBY_THREAD_VM_STACK_SIZE=1000000?

The output of ulimit -s would be interesting too.

[DerDakon]

Without: 11911
With: 22803
ulimit -s: 8192

[leahneukirchen]

Weird, here on x86_64 I get 10918 but it runs that test fine.

[mikegee]

@DerDakon did you elide many lines of duplicated output with […] in the original post here, or did ruby do that? If you did, how many lines where there? (around 100 or over 10,000)

[DerDakon]

The first 'each' is in line 41, the 'parse_nested_query' is in line 166 of the log.

[jeremyevans]

This should be easy to work around on HA-PARISC by setting:

Rack::Utils.default_query_parser = QueryParser.make_default(65536, 16)

While I agree that 16 levels "ought to be enough for anybody", I guess we should consider cases larger than that. Maybe 32 levels? I'll submit a PR for that.