Re: BUG: refs.c:1933: reference backend is unknown

From: René Scharfe <l.s.r@web.de>
Date: Sep 21, 2024, 21:22 UTC
Message-ID: <9bf5c254-4d87-4f6f-b278-d9df4d7897b5@web.de>
In-Reply-To: <9fdb9561bb0ad85e55ca3253cc4db9b098641e30@rjp.ie>

Am 21.09.24 um 20:06 schrieb Ronan Pigott:

Show 31 quoted lines

>
> The abort is reproducible exactly as written for me, but upon further
> examination it may depend on my config. Here is a minimal reproducer:
>
>   $ GIT_CONFIG_NOSYSTEM=1 GIT_CONFIG_GLOBAL=/dev/null git --git-dir=notexist -c 'includeif.onbranch:test/**.path=/dev/null' archive
>
>> bt
> #0  __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at pthread_kill.c:44
> #1  0x00007ffff7d78463 in __pthread_kill_internal (threadid=<optimized out>, signo=6) at pthread_kill.c:78
> #2  0x00007ffff7d1f120 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
> #3  0x00007ffff7d064c3 in __GI_abort () at abort.c:79
> #4  0x000055555585385a in BUG_vfl (file=<optimized out>, line=<optimized out>, fmt=0x555555905baf "reference backend is unknown", params=0x7fffffffd120) at /usr/src/debug/git/git-2.46.1/usage.c:317
> #5  BUG_fl (file=<optimized out>, line=<optimized out>, fmt=0x555555905baf "reference backend is unknown") at /usr/src/debug/git/git-2.46.1/usage.c:334
> #6  0x00005555557ca9d2 in ref_store_init (repo=<optimized out>, format=<optimized out>, gitdir=<optimized out>, flags=<optimized out>) at /usr/src/debug/git/git-2.46.1/refs.c:1933
> #7  ref_store_init (repo=0x5555559759a0 <the_repo.lto_priv>, format=<optimized out>, gitdir=<optimized out>, flags=15) at /usr/src/debug/git/git-2.46.1/refs.c:1923
> #8  get_main_ref_store (r=0x5555559759a0 <the_repo.lto_priv>) at /usr/src/debug/git/git-2.46.1/refs.c:1953
> #9  0x00005555556dcdf6 in include_by_branch (cond=0x55555599f503 "test/**.path", cond_len=7) at /usr/src/debug/git/git-2.46.1/config.c:309
> #10 include_condition_is_true (kvi=<optimized out>, inc=0x7fffffffd460, cond=0x55555599f503 "test/**.path", cond_len=7) at /usr/src/debug/git/git-2.46.1/config.c:409
> #11 git_config_include (var=var@entry=0x55555599f4f0 "includeif.onbranch:test/**.path", value=value@entry=0x55555599fa62 "/dev/null", ctx=ctx@entry=0x7fffffffd368, data=data@entry=0x7fffffffd460) at /usr/src/debug/git/git-2.46.1/config.c:439
> #12 0x00005555556d8753 in config_parse_pair (key=<optimized out>, value=0x55555599fa62 "/dev/null", kvi=kvi@entry=0x7fffffffd4a0, fn=fn@entry=0x5555556dcad0 <git_config_include>, data=data@entry=0x7fffffffd460) at /usr/src/debug/git/git-2.46.1/config.c:617
> #13 0x00005555556dc437 in parse_config_env_list (env=0x55555599fa40 "includeif.onbranch:test/**.path", kvi=0x7fffffffd4a0, fn=0x5555556dcad0 <git_config_include>, data=0x7fffffffd460) at /usr/src/debug/git/git-2.46.1/config.c:700
> #14 git_config_from_parameters (fn=0x5555556dcad0 <git_config_include>, data=0x7fffffffd460) at /usr/src/debug/git/git-2.46.1/config.c:773
> #15 do_git_config_sequence (opts=0x7fffffffd4b0, repo=0x0, fn=0x5555556dcad0 <git_config_include>, data=0x7fffffffd460) at /usr/src/debug/git/git-2.46.1/config.c:2131
> #16 config_with_options (fn=0x5555556dcad0 <git_config_include>, fn@entry=0x555555790940 <pager_command_config>, data=0x7fffffffd460, data@entry=0x7fffffffd7a0, config_source=config_source@entry=0x0, repo=repo@entry=0x0, opts=opts@entry=0x7fffffffd660) at /usr/src/debug/git/git-2.46.1/config.c:2174
> #17 0x00005555556dd110 in read_early_config (cb=0x555555790940 <pager_command_config>, data=0x7fffffffd7a0) at /usr/src/debug/git/git-2.46.1/config.c:2229
> #18 0x000055555555ea58 in check_pager_config (cmd=<optimized out>) at /usr/src/debug/git/git-2.46.1/pager.c:261
> #19 run_builtin (p=0x555555966a00 <commands.lto_priv+96>, argc=1, argv=0x7fffffffdd78) at /usr/src/debug/git/git-2.46.1/git.c:461
> #20 handle_builtin (argc=1, argv=0x7fffffffdd78) at /usr/src/debug/git/git-2.46.1/git.c:732
> #21 0x000055555555eaf9 in run_argv (argcp=0x7fffffffdb0c, argv=0x7fffffffdb30) at /usr/src/debug/git/git-2.46.1/git.c:796
> #22 0x00005555555597eb in cmd_main (argc=<optimized out>, argv=<optimized out>) at /usr/src/debug/git/git-2.46.1/git.c:931
> #23 main (argc=<optimized out>, argv=<optimized out>) at /usr/src/debug/git/git-2.46.1/common-main.c:64

Thanks, that helps. The BUG occurs during setup, before any command-specific code is executed. Affects other commands with the option RUN_SETUP_GENTLY as well, e.g. git grep.

Bisects to 173761e21b (setup: start tracking ref storage format, 2023-12-29, copying Patrick.

I wonder if the BUG at refs.c:1933 should just be turned into a die(). Or should ref_store_init() return NULL (or some other value indicating an error) and all callers need to be changed to deal with that?

Simply checking whether --git-dir points to an actual repo earlier is tempting, but would leave the case of it disappearing after the check unhandled.

René