"Tail of a it, being ridden"

[RojjaCebolla]

I was trying to find the "covetous chameleon in sokoban" bug, but instead I found a different bug:

I think the mount was a long worm tail.

[RojjaCebolla]

Crashed on killing the long worm tail segment.

  Generating more information you may report:
[00] /home/spl/install/games/lib/splicehackdir/splicehack(+0xe93a7) [0x5618dd81e3a7]
[01] /home/spl/install/games/lib/splicehackdir/splicehack(+0xe9b57) [0x5618dd81eb57]
[02] /home/spl/install/games/lib/splicehackdir/splicehack(+0xe9bc1) [0x5618dd81ebc1]
[03] /lib/x86_64-linux-gnu/libc.so.6(+0x41040) [0x7fc5d13db040]
[04] /home/spl/install/games/lib/splicehackdir/splicehack(x_monnam+0x7f) [0x5618dd7ebdbb]
[05] /home/spl/install/games/lib/splicehackdir/splicehack(mon_nam+0x3b) [0x5618dd7ecbde]
[06] /home/spl/install/games/lib/splicehackdir/splicehack(artifact_hit+0x1f4) [0x5618dd7a6ab0]
[07] /home/spl/install/games/lib/splicehackdir/splicehack(+0x24d527) [0x5618dd982527]
[08] /home/spl/install/games/lib/splicehackdir/splicehack(hmon+0x34) [0x5618dd985e42]
[09] /home/spl/install/games/lib/splicehackdir/splicehack(+0x260331) [0x5618dd995331]
[10] /home/spl/install/games/lib/splicehackdir/splicehack(+0x26191e) [0x5618dd99691e]
[11] /home/spl/install/games/lib/splicehackdir/splicehack(do_attack+0x25b3) [0x5618dd99af3d]
[12] /home/spl/install/games/lib/splicehackdir/splicehack(+0x108109) [0x5618dd83d109]
[13] /home/spl/install/games/lib/splicehackdir/splicehack(domove+0x30) [0x5618dd83fb85]
[14] /home/spl/install/games/lib/splicehackdir/splicehack(rhack+0x869) [0x5618dd7c3985]
[15] /home/spl/install/games/lib/splicehackdir/splicehack(moveloop+0x1356) [0x5618dd7942cd]
[16] /home/spl/install/games/lib/splicehackdir/splicehack(main+0x89e) [0x5618dd9c8c74]
[17] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xd5) [0x7fc5d13c2565]
[18] /home/spl/install/games/lib/splicehackdir/splicehack(_start+0x2e) [0x5618dd792cbe]
Aborted (core dumped)

I'm still on the hunt for the covetous bug. tactics() isn't in this dump so this probly is just longworm + riding + chameleon. (plus maybe vampshifting?)

[NullCGT]

This is (likely) not related to long worms. "Tail of a %s" tends to show up when an invalid pointer to a monster is hanging around, such as when a monster can no longer find the monster it is riding. Interacting with the tail in any way has the potential to cause a crash. It's something that I encountered a lot when writing the code, but I thought I had eliminated it completely.

Tagging this with the high priority label.

[RojjaCebolla]

Here's the stack trace from the server, with the double panic:

       Message: Process 12924 (splicehack) of user 5 dumped core.

                Stack trace of thread 12924:
                #0  0x00007f0a20078e97 n/a (/lib/x86_64-linux-gnu/libc.so.6)
                #1  0x0000560dea7cddc1 panic (splicehack-20210927-103246)
                #2  0x0000560dea881ed9 monsndx (splicehack-20210927-103246)
                #3  0x0000560dea9389d3 savemonchn (splicehack-20210927-103246)
                #4  0x0000560dea937a7f savelev (splicehack-20210927-103246)
                #5  0x0000560dea936d60 dosave0 (splicehack-20210927-103246)
                #6  0x0000560dea7cdf04 panic (splicehack-20210927-103246)
                #7  0x0000560dea881ed9 monsndx (splicehack-20210927-103246)
                #8  0x0000560dea87fff1 set_mon_data (splicehack-20210927-103246)
                #9  0x0000560dea97e4a9 enexto_core (splicehack-20210927-103246)
                #10 0x0000560dea97e2a3 enexto (splicehack-20210927-103246)
                #11 0x0000560dea878a3a mnexto (splicehack-20210927-103246)
                #12 0x0000560dea9ef1b3 tactics (splicehack-20210927-103246)
                #13 0x0000560dea886ff1 dochug (splicehack-20210927-103246)
                #14 0x0000560dea884b35 dochugw (splicehack-20210927-103246)
                #15 0x0000560dea86bd99 movemon (splicehack-20210927-103246)
                #16 0x0000560dea710b70 moveloop (splicehack-20210927-103246)
                #17 0x0000560deaa10820 main (splicehack-20210927-103246)
                #18 0x00007f0a2005bb97 n/a (/lib/x86_64-linux-gnu/libc.so.6)

[gebulmer]

Evilhack (which uses the splicehack riding code) appears to have fixed this

It's probably worth checking for other riding-related fixes in evilhack and taking them, but this is at least one related one:
k21971/EvilHack@0f9d029