Failing to attach to nix build

[eonpatapon]

I'm using cntr from nixpkgs 19.09 (on NixOS), doesn't matter of which package build I'm trying to debug, it just fails ans locks completely the terminal

sudo RUST_BACKTRACE=full cntr attach -t command cntr-/nix/store/ih6pz06jrn806lx1315gc1djklxh6zfc-terraform-provider-keycloak-1.13.2
[sudo] password for eon: 
WARNING: the per-user profile dir /nix/var/nix/profiles/per-user/root should belong to user id 1000
thread '<unnamed>' panicked at 'BUG! got unknown d_entry type received from d_type', src/fs.rs:602:14
stack backtrace:
0:     0x55c51067844c - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hd5cf01a6458823ce
1:     0x55c51065f72d - core::fmt::write::h239984b34be80164
2:     0x55c510677151 - std::io::Write::write_fmt::h71b3597bde52e201
3:     0x55c51067a490 - std::panicking::default_hook::{{closure}}::h22b55119be64c15e
4:     0x55c510679f65 - std::panicking::rust_panic_with_hook::hc671c362d83d7750
5:     0x55c510658684 - std::panicking::begin_panic::hbfd0096d822b4d01
6:     0x55c51060d92a - cntr::fs::CntrFs::generic_readdir::h62575c5ba9c58ab2
7:     0x55c51061733f - fuse::request::Request::dispatch::h596ab4aba69542f6
8:     0x55c510651452 - std::sys_common::backtrace::__rust_begin_short_backtrace::h800c518d8b197517
9:     0x55c51063e146 - core::ops::function::FnOnce::call_once{{vtable.shim}}::h2f3283e15ccecb31
10:     0x55c510676c5f - <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once::h36570ddedd92a948
11:     0x55c510677dac - std::sys::unix::thread::Thread::new::thread_start::hac7b969fab3af94c
12:     0x7f46fce81ef7 - start_thread
13:     0x7f46fcba122f - __GI___clone
14:                0x0 - <unknown>

[Mic92]

If this error is reproducible than I could send you a version of cntr that actually prints the unsupported d_entry type.

[eonpatapon]

Sure, anything I can do to debug this

[Mic92]

Ok. Could build and run cntr from that commit: 4396e55

[eonpatapon]

sudo RUST_BACKTRACE=full cntr attach -t command cntr-/nix/store/xzdj2aah47qjkdysjv7ld9k1ls7yqw62-git-hub-1.0.3
WARNING: the per-user profile dir /nix/var/nix/profiles/per-user/root should belong to user id 1000
thread '<unnamed>' panicked at 'BUG! got unknown d_entry type received from d_type: 0', src/fs.rs:602:14
stack backtrace:
0:     0x5605054e352c - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hd5cf01a6458823ce
1:     0x5605054ca77d - core::fmt::write::h239984b34be80164
2:     0x5605054e2231 - std::io::Write::write_fmt::h71b3597bde52e201
3:     0x5605054e5570 - std::panicking::default_hook::{{closure}}::h22b55119be64c15e
4:     0x5605054e5045 - std::panicking::rust_panic_with_hook::hc671c362d83d7750
5:     0x5605054e4c0f - std::panicking::continue_panic_fmt::h65e4009de34f6bc6
6:     0x5605054e4bb9 - std::panicking::begin_panic_fmt::h3ee1dd8002c2d90b
7:     0x560505478978 - cntr::fs::CntrFs::generic_readdir::h62575c5ba9c58ab2
8:     0x56050548238f - fuse::request::Request::dispatch::h596ab4aba69542f6
9:     0x5605054bc4b2 - std::sys_common::backtrace::__rust_begin_short_backtrace::h800c518d8b197517
10:     0x5605054a91a6 - core::ops::function::FnOnce::call_once{{vtable.shim}}::h2f3283e15ccecb31
11:     0x5605054e1d3f - <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once::h36570ddedd92a948
12:     0x5605054e2e8c - std::sys::unix::thread::Thread::new::thread_start::hac7b969fab3af94c
13:     0x7fef56c42ef7 - start_thread
14:     0x7fef5696222f - __GI___clone
15:                0x0 - <unknown>

[Mic92]

That's interesting 0 means DT_UNKNOWN and there is no use equivalent: https://github.com/zargony/fuse-rs/blob/bf6d1cf03f3277e35b580f3c7b9999255d72ecf3/src/lib.rs#L34
I could map this onto a regular file... It would be interesting what inode has an unknown type.

[Mic92]

Maybe it could be just extended here: https://github.com/zargony/fuse-rs/blob/09fc9579d39c0edb846e8b7c5045d1ef6dc903da/src/reply.rs#L69

[Mic92]

It was actually documented here: zargony/fuse-rs#115