<ab.json jtc -w'<address>l[:]<Lbl>k<>k' -u"$map" -u'>Lbl<t' / -w'<address>l' fails with SEGV

[D4N]

The following example from User Guide.md:

bash $ map='{"postal code":"zip","street address":"street"}'
bash $ <ab.json jtc -w'<address>l[:]<Lbl>k<>k' -u"$map" -u'>Lbl<t' / -w'<address>l'

results in a crash:

AddressSanitizer:DEADLYSIGNAL
=================================================================
==240254==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000008 (pc 0x7f2f272dc3ee bp 0x7ffd929298d0 sp 0x7ffd92928e18 T0)
==240254==The signal is caused by a READ memory access.
==240254==Hint: address points to the zero page.
    #0 0x7f2f272dc3ee in std::_Rb_tree_decrement(std::_Rb_tree_node_base*) (/lib64/libstdc++.so.6+0xc33ee)
    #1 0x5d8c65 in std::_Rb_tree_iterator<std::pair<unsigned long const, Json> >::operator--() /usr/bin/../lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10/bits/stl_tree.h:302:12
    #2 0x5d8c65 in std::reverse_iterator<std::_Rb_tree_iterator<std::pair<unsigned long const, Json> > >::operator->() const /usr/bin/../lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10/bits/stl_iterator.h:228:2
    #3 0x5d8c65 in Jtc::advance_to_next_src(Json::iterator&, long) /home/dan/projects/github.com/ldn-softdev/jtc/jtc.cpp:1761:41
    #4 0x5d9f14 in Jtc::advance_to_next_src(Json::iterator&, long) /home/dan/projects/github.com/ldn-softdev/jtc/jtc.cpp
    #5 0x5cc962 in Jtc::collect_itr_bindings(Json::iterator&, Jtc::Grouping) /home/dan/projects/github.com/ldn-softdev/jtc/jtc.cpp:1704:8
    #6 0x5ee68b in Jtc::process_offsets_(std::deque<std::deque<Json::iterator, std::allocator<Json::iterator> >, std::allocator<std::deque<Json::iterator, std::allocator<Json::iterator> > > >&, std::vector<std::vector<long, std::allocator<long> >, std::allocator<std::vector<long, std::allocator<long> > > >&, unsigned long, std::vector<unsigned long, std::allocator<unsigned long> >&) /home/dan/projects/github.com/ldn-softdev/jtc/jtc.cpp:2770:2
    #7 0x5ec516 in Jtc::process_walk_iterators_(std::deque<std::deque<Json::iterator, std::allocator<Json::iterator> >, std::allocator<std::deque<Json::iterator, std::allocator<Json::iterator> > > >&) /home/dan/projects/github.com/ldn-softdev/jtc/jtc.cpp:2694:2
    #8 0x5cb111 in Jtc::walk_interleaved_(void (Jtc::*)(Json::iterator&, Jtc::Grouping)) /home/dan/projects/github.com/ldn-softdev/jtc/jtc.cpp:2678:3
    #9 0x5c5c86 in Jtc::upsert_json(char) /home/dan/projects/github.com/ldn-softdev/jtc/jtc.cpp:1666:2
    #10 0x5bc2e6 in Jtc::demux_opt() /home/dan/projects/github.com/ldn-softdev/jtc/jtc.cpp:1530:37
    #11 0x5b9cfb in run_single_optset(CommonResource&, Streamstr::const_iterator&, Json&, Json&) /home/dan/projects/github.com/ldn-softdev/jtc/jtc.cpp:914:29
    #12 0x5b6c47 in run_decomposed_optsets(CommonResource&, Streamstr::const_iterator&) /home/dan/projects/github.com/ldn-softdev/jtc/jtc.cpp:888:3
    #13 0x5b00cb in main /home/dan/projects/github.com/ldn-softdev/jtc/jtc.cpp:814:6
    #14 0x7f2f26f01041 in __libc_start_main (/lib64/libc.so.6+0x27041)
    #15 0x47850d in _start (/home/dan/projects/github.com/ldn-softdev/jtc/jtc+0x47850d)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV (/lib64/libstdc++.so.6+0xc33ee) in std::_Rb_tree_decrement(std::_Rb_tree_node_base*)
==240254==ABORTING

[ldn-softdev]

I'll take a look. It seems another Linux-specific failure (under MacOS the sanitizer does not catch this, nor jtc crashes). Thanks for catching.

[ldn-softdev]

This one is indeed a bug, which should even occur on the MacOS, but for some reasons the MacOS is tolerant to this issue (hence it sneaks past the unit test):

when resolving a value via the reverse iterator, an empty std::map (in this case jtmp_.rbegin()->VALUE) it should produce a seg fault (which is observed on LInux, but it's not observed on the MacOS).

the fix will be pushed soon together with the other reported issue.