Appliance: drop cables when taking down appliance

[dseguin]

Summary

None

Purpose of change

• Fixes Extension cord disappears when taking down appliance #59168

Describe the solution

When taking down an appliance, call vehicle::shed_loose_parts to handle dropping any power connections. Any items used to connect two or more appliances and/or vehicles will be dropped at the appliances position.

Describe alternatives you've considered

N/A

Testing

Taking down a standing lamp connected in various ways to other appliances and a vehicle:

2022-08-31.01-03-24.mp4

Additional context

While testing this originally, I ran into a bug where an appliance had a fake part while being taken down. So instead of calling map::destroy_vehicle, the parts list gets accessed after the real part is removed, causing this use-after-free output from ASAN:

(snip)

==48386==ERROR: AddressSanitizer: heap-use-after-free on address 0x61c00019ac20 at pc 0x55555eddea45 bp 0x7fffffff91d0 sp 0x7fffffff91c0
READ of size 8 at 0x61c00019ac20 thread T0
    #0 0x55555eddea44 in std::_Rb_tree<point, std::pair<point const, std::vector<int, std::allocator<int> > >, std::_Select1st<std::pair<point const, std::vector<int, std::allocator<int> > > >, std::less<point>, std::allocator<std::pair<point const, std::vector<int, std::allocator<int> > > > >::_M_begin() const /usr/include/c++/9/bits/stl_tree.h:756
    #1 0x55555edd4b93 in std::_Rb_tree<point, std::pair<point const, std::vector<int, std::allocator<int> > >, std::_Select1st<std::pair<point const, std::vector<int, std::allocator<int> > > >, std::less<point>, std::allocator<std::pair<point const, std::vector<int, std::allocator<int> > > > >::find(point const&) const /usr/include/c++/9/bits/stl_tree.h:2575
    #2 0x55555edc1862 in std::map<point, std::vector<int, std::allocator<int> >, std::less<point>, std::allocator<std::pair<point const, std::vector<int, std::allocator<int> > > > >::find(point const&) const /usr/include/c++/9/bits/stl_map.h:1194
    #3 0x55555ed25418 in vehicle::parts_at_relative(point const&, bool, bool) const src/vehicle.cpp:2418
    #4 0x55555ebfd3e9 in veh_interact::complete_vehicle(Character&) src/veh_interact.cpp:3514
    #5 0x5555595549fc in activity_handlers::vehicle_finish(player_activity*, Character*) src/activity_handlers.cpp:1863
    #6 0x5555595a33d9 in std::_Function_handler<void (player_activity*, Character*), void (*)(player_activity*, Character*)>::_M_invoke(std::_Any_data const&, player_activity*&&, Character*&&) /usr/include/c++/9/bits/std_function.h:300
    #7 0x5555596c65ff in std::function<void (player_activity*, Character*)>::operator()(player_activity*, Character*) const /usr/include/c++/9/bits/std_function.h:688
    #8 0x5555596c19b5 in activity_type::call_finish(player_activity*, Character*) const src/activity_type.cpp:118
    #9 0x55555de69d15 in player_activity::do_turn(Character&) src/player_activity.cpp:378
    #10 0x55555abfe103 in do_turn() src/do_turn.cpp:665
    #11 0x55555c3e20d4 in main src/main.cpp:789
    #12 0x7ffff6e7d082 in __libc_start_main ../csu/libc-start.c:308
    #13 0x5555592498bd in _start (/home/dtsadmin/Builds/Cataclysm-DDA/cataclysm-tiles+0x3cf58bd)

0x61c00019ac20 is located 928 bytes inside of 1792-byte region [0x61c00019a880,0x61c00019af80)
freed by thread T0 here:
    #0 0x7ffff768ec65 in operator delete(void*, unsigned long) ../../../../src/libsanitizer/asan/asan_new_delete.cc:177
    #1 0x55555acc7c40 in std::default_delete<vehicle>::operator()(vehicle*) const /usr/include/c++/9/bits/unique_ptr.h:81
    #2 0x55555acbc7ac in std::unique_ptr<vehicle, std::default_delete<vehicle> >::~unique_ptr() /usr/include/c++/9/bits/unique_ptr.h:292
    #3 0x55555c42f35a in map::destroy_vehicle(vehicle*) src/map.cpp:515
    #4 0x55555ed1b923 in vehicle::part_removal_cleanup() src/vehicle.cpp:1925
    #5 0x55555ebfd340 in veh_interact::complete_vehicle(Character&) src/veh_interact.cpp:3513
    #6 0x5555595549fc in activity_handlers::vehicle_finish(player_activity*, Character*) src/activity_handlers.cpp:1863
    #7 0x5555595a33d9 in std::_Function_handler<void (player_activity*, Character*), void (*)(player_activity*, Character*)>::_M_invoke(std::_Any_data const&, player_activity*&&, Character*&&) /usr/include/c++/9/bits/std_function.h:300
    #8 0x5555596c65ff in std::function<void (player_activity*, Character*)>::operator()(player_activity*, Character*) const /usr/include/c++/9/bits/std_function.h:688
    #9 0x5555596c19b5 in activity_type::call_finish(player_activity*, Character*) const src/activity_type.cpp:118
    #10 0x55555de69d15 in player_activity::do_turn(Character&) src/player_activity.cpp:378
    #11 0x55555abfe103 in do_turn() src/do_turn.cpp:665
    #12 0x55555c3e20d4 in main src/main.cpp:789
    #13 0x7ffff6e7d082 in __libc_start_main ../csu/libc-start.c:308

previously allocated by thread T0 here:
    #0 0x7ffff768d587 in operator new(unsigned long) ../../../../src/libsanitizer/asan/asan_new_delete.cc:104
    #1 0x55555e4d5ce7 in std::_MakeUniq<vehicle>::__single_object std::make_unique<vehicle>() /usr/include/c++/9/bits/unique_ptr.h:857
    #2 0x55555e49e3a9 in submap::load(JsonIn&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int) src/savegame_json.cpp:5033
    #3 0x55555c67c994 in mapbuffer::deserialize(JsonIn&) src/mapbuffer.cpp:306
    #4 0x55555c67bb4c in operator() src/mapbuffer.cpp:276
    #5 0x55555c67d4b9 in _M_invoke /usr/include/c++/9/bits/std_function.h:300
    #6 0x555559eb0ac8 in std::function<void (JsonIn&)>::operator()(JsonIn&) const /usr/include/c++/9/bits/std_function.h:688
    #7 0x555559ea8473 in operator() src/cata_utility.cpp:436
    #8 0x555559eac44e in _M_invoke /usr/include/c++/9/bits/std_function.h:300
    #9 0x555559eb0a48 in std::function<void (std::istream&)>::operator()(std::istream&) const /usr/include/c++/9/bits/std_function.h:688
    #10 0x555559ea7628 in read_from_file(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::function<void (std::istream&)> const&) src/cata_utility.cpp:392
    #11 0x555559ea8341 in read_from_file_optional(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::function<void (std::istream&)> const&) src/cata_utility.cpp:428
    #12 0x555559ea85f5 in read_from_file_optional_json(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::function<void (JsonIn&)> const&) src/cata_utility.cpp:434
    #13 0x55555c67c0c9 in mapbuffer::unserialize_submaps(coords::coord_point<tripoint, (coords::origin)1, (coords::scale)1> const&) src/mapbuffer.cpp:275
    #14 0x55555c67968a in mapbuffer::lookup_submap(coords::coord_point<tripoint, (coords::origin)1, (coords::scale)1> const&) src/mapbuffer.cpp:112
    #15 0x55555c4a59e2 in map::loadn(tripoint const&, bool, bool) src/map.cpp:7555
    #16 0x55555c4a704e in map::loadn(point const&, bool, bool) src/map.cpp:7651
    #17 0x55555c4a0952 in map::load(coords::coord_point<tripoint, (coords::origin)1, (coords::scale)1> const&, bool, bool) src/map.cpp:7230
    #18 0x55555b12bf5b in game::load_map(coords::coord_point<tripoint, (coords::origin)1, (coords::scale)1> const&, bool) src/game.cpp:799
    #19 0x55555e38d6ee in game::unserialize(std::istream&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) src/savegame.cpp:236
    #20 0x55555b15cdf1 in operator() src/game.cpp:2757
    #21 0x55555b25f361 in _M_invoke /usr/include/c++/9/bits/std_function.h:300
    #22 0x555559eb0a48 in std::function<void (std::istream&)>::operator()(std::istream&) const /usr/include/c++/9/bits/std_function.h:688
    #23 0x555559ea7628 in read_from_file(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::function<void (std::istream&)> const&) src/cata_utility.cpp:392
    #24 0x55555b15db5e in game::load(save_t const&) src/game.cpp:2755
    #25 0x55555c40b387 in main_menu::load_character_tab(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) src/main_menu.cpp:1015
    #26 0x55555c405f78 in main_menu::opening_screen() src/main_menu.cpp:819
    #27 0x55555c3e2017 in main src/main.cpp:783
    #28 0x7ffff6e7d082 in __libc_start_main ../csu/libc-start.c:308

SUMMARY: AddressSanitizer: heap-use-after-free /usr/include/c++/9/bits/stl_tree.h:756 in std::_Rb_tree<point, std::pair<point const, std::vector<int, std::allocator<int> > >, std::_Select1st<std::pair<point const, std::vector<int, std::allocator<int> > > >, std::less<point>, std::allocator<std::pair<point const, std::vector<int, std::allocator<int> > > > >::_M_begin() const
Shadow bytes around the buggy address:
  0x0c388002b530: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c388002b540: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c388002b550: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c388002b560: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c388002b570: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
=>0x0c388002b580: fd fd fd fd[fd]fd fd fd fd fd fd fd fd fd fd fd
  0x0c388002b590: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c388002b5a0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c388002b5b0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c388002b5c0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c388002b5d0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
  Shadow gap:              cc
==48386==ABORTING

The fix I used was to skip fake parts when checking the remaining part count (2604d39)