error message:: item 1 does not exist

[mritzmann]

Hi

Sometimes I get the following error message. But this does not happen with every snapshot, with some it works without problems.

$ RUST_BACKTRACE=full /root/.cargo/bin/btsdu -p /snapshot/20210107-0315-day /snapshot/20210108-0315-day
At subvol /snapshot/20210108-0315-day
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Custom { kind: InvalidData, error: "item 1 does not exist" }', src/libcore/result.rs:1188:5
stack backtrace:
   0:     0x555767c89bf3 - backtrace::backtrace::libunwind::trace::h8cc7bd6ef9eecc96
                               at /usr/src/rustc-1.41.1/vendor/backtrace/src/backtrace/libunwind.rs:88
   1:     0x555767c89bf3 - backtrace::backtrace::trace_unsynchronized::h6d4579bff574314f
                               at /usr/src/rustc-1.41.1/vendor/backtrace/src/backtrace/mod.rs:66
   2:     0x555767c89bf3 - std::sys_common::backtrace::_print_fmt::h90c5eb8ce5c21ab3
                               at src/libstd/sys_common/backtrace.rs:84
   3:     0x555767c89bf3 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hd925cae363a8eae6
                               at src/libstd/sys_common/backtrace.rs:61
   4:     0x555767ca0d9d - core::fmt::write::h7f27f0f32a72efde
                               at src/libcore/fmt/mod.rs:1025
   5:     0x555767c88f95 - std::io::Write::write_fmt::h248d5ddff30f2014
                               at src/libstd/io/mod.rs:1426
   6:     0x555767c8b721 - std::sys_common::backtrace::_print::h998846397d49de77
                               at src/libstd/sys_common/backtrace.rs:65
   7:     0x555767c8b721 - std::sys_common::backtrace::print::he55a1a23a73d03c9
                               at src/libstd/sys_common/backtrace.rs:50
   8:     0x555767c8b721 - std::panicking::default_hook::{{closure}}::h80dc9a42e1547e54
                               at src/libstd/panicking.rs:193
   9:     0x555767c8b433 - std::panicking::default_hook::h50769e30da5feef3
                               at src/libstd/panicking.rs:210
  10:     0x555767c8bd9e - std::panicking::rust_panic_with_hook::hd0b3a149883f4cfb
                               at src/libstd/panicking.rs:471
  11:     0x555767c8b94e - rust_begin_unwind
                               at src/libstd/panicking.rs:375
  12:     0x555767ca33ce - core::panicking::panic_fmt::h2c5b80195dbe1b07
                               at src/libcore/panicking.rs:84
  13:     0x555767ca0557 - core::result::unwrap_failed::ha1cca7cc6769da6a
                               at src/libcore/result.rs:1188
  14:     0x555767c1cba2 - btsdu::main::h41c178f4c827c1ef
  15:     0x555767c17d23 - std::rt::lang_start::{{closure}}::h9b5b1195b9277998
  16:     0x555767c8b7e3 - std::rt::lang_start_internal::{{closure}}::h76f680a226ff04a4
                               at src/libstd/rt.rs:52
  17:     0x555767c8b7e3 - std::panicking::try::do_call::h299dda570ebabcf7
                               at src/libstd/panicking.rs:292
  18:     0x555767c8e30a - __rust_maybe_catch_panic
                               at src/libpanic_unwind/lib.rs:78
  19:     0x555767c7fab1 - std::panicking::try::hfaf428da211c915f
                               at src/libstd/panicking.rs:270
  20:     0x555767c7fab1 - std::panic::catch_unwind::hf2e7b412691ed4fa
                               at src/libstd/panic.rs:394
  21:     0x555767c7fab1 - std::rt::lang_start_internal::h3cc876a8b3f40e9c
                               at src/libstd/rt.rs:51
  22:     0x555767c1d2b5 - main
  23:     0x7f57c0ad409b - __libc_start_main
  24:     0x555767c1619a - _start
  25:                0x0 - <unknown>

I can't do much with it. Thought I leave the message here, maybe someone can say something about it. :-)

Best, Markus

---

$ uname -r
4.19.0-13-amd64

$ cat /etc/os-release 
PRETTY_NAME="Debian GNU/Linux 10 (buster)"
NAME="Debian GNU/Linux"
VERSION_ID="10"
VERSION="10 (buster)"
VERSION_CODENAME=buster
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"

$ dpkg --list | grep cargo
ii  cargo                                0.43.1-3~deb10u1             amd64        Rust package manager

$ dpkg --list | grep rust 
ii  libstd-rust-1.41:amd64               1.41.1+dfsg1-1~deb10u1       amd64        Rust standard libraries
ii  libstd-rust-dev:amd64                1.41.1+dfsg1-1~deb10u1       amd64        Rust standard libraries - development files
ii  rust-gdb                             1.41.1+dfsg1-1~deb10u1       all          Rust debugger (gdb)
ii  rustc                                1.41.1+dfsg1-1~deb10u1       amd64        Rust systems programming language

[rkapl]

Could you try with the latest version? e113e9f347c7d84080f00188a8ac3dd15575e18e may fix that

[mritzmann]

Thanks, that fixes the problem for me!

• [x] Searched for two snapshots where the problem occurs
• [x] Repository cloned and built with cargo build
• [x] Tested: the problem does not occur anymore