Logging code crashes

[Jehan]

I was testing mpv from git for bug #908 and it would crash each time a call to mp_dbg() is made, in particular when calling atomic_load_explicit(&root->reload_counter, memory_order_relaxed) in common/msg.c

I don't think this is related to the commit for #908 since it happens even with enca (as in the example below), whether or not detection fails or succeeds. Hence I open a new bug report.

Anyway here a backtrace:
Program received signal SIGSEGV, Segmentation fault.
mp_msg_test (log=log@entry=0x7c01a0, lev=lev@entry=6) at ../common/msg.c:133
133 atomic_load_explicit(&root->reload_counter, memory_order_relaxed))
(gdb) bt
#0 mp_msg_test (log=log@entry=0x7c01a0, lev=lev@entry=6) at ../common/msg.c:133
#1 0x000000000042c01a in mp_msg_va (log=0x7c01a0, lev=6, format=0x4e0568 "Detection with %.*s failed: fallback to %s\n", va=0x7fffffffd5f8)

at ../common/msg.c:337

#2 0x000000000042c0d2 in mp_msg (log=log@entry=0x7c01a0, lev=lev@entry=6,

format=format@entry=0x4e0568 "Detection with %.*s failed: fallback to %s\n") at ../common/msg.c:606

#3 0x000000000044a08b in mp_charset_guess (talloc_ctx=talloc_ctx@entry=0x7bfa70, log=log@entry=0x7c01a0, buf=..., user_cp=,

user_cp@entry=0x773fc0 "auto", flags=flags@entry=2) at ../misc/charset_conv.c:247

#4 0x000000000044a586 in mp_charset_guess_and_conv_to_utf8 (log=log@entry=0x7bfa70, buf=..., user_cp=user_cp@entry=0x773fc0 "auto",

flags=flags@entry=2) at ../misc/charset_conv.c:269

#5 0x0000000000434d75 in d_check_file (demuxer=0x7bfd40, check=) at ../demux/demux_libass.c:64
#6 0x000000000042f8ed in open_given_type (check=DEMUX_CHECK_NORMAL, params=0x7fffffffd970, stream=0x7fffe184e050,

desc=0x4ccb60 <demuxer_desc_libass>, log=0x7bf470, global=0x76cf60) at ../demux/demux.c:993

#7 demux_open (stream=0x7fffe184e050, params=params@entry=0x7fffffffd970, global=global@entry=0x76cf60) at ../demux/demux.c:1058
#8 0x000000000042fc4b in demux_open_url (url=url@entry=0x78a410 "some-sub.srt", params=0x7fffffffd970, cancel=, global=0x76cf60)

at ../demux/demux.c:1087

#9 0x000000000046ab0c in mp_add_external_file (mpctx=mpctx@entry=0x76c170, filename=, filter=filter@entry=STREAM_SUB)

at ../player/loadfile.c:710

#10 0x000000000046c022 in open_subtitles_from_options (mpctx=0x76c170) at ../player/loadfile.c:753
#11 play_current_file (mpctx=0x76c170) at ../player/loadfile.c:1151
#12 mp_play_files (mpctx=mpctx@entry=0x76c170) at ../player/loadfile.c:1398
#13 0x000000000046d30c in mpv_main (argc=, argv=0x7fffffffdb68) at ../player/main.c:533
#14 0x00007ffff1f08700 in __libc_start_main () from /lib64/libc.so.6
#15 0x000000000040ee39 in _start ()