[Bug 2132941] Re: Rust unwrap with UTF-8 symbols in environment variables

[Christoph Müllner]

** Package changed: coreutils (Ubuntu) => rust-coreutils (Ubuntu)

** Summary changed:

- Rust unwrap with UTF-8 symbols in environment variables
+ env: Rust unwrap with UTF-8 symbols in environment variables

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Title:
  env: Rust unwrap with UTF-8 symbols in environment variables

Status in rust-coreutils package in Ubuntu:
  New

Bug description:
  In Ubuntu 25.10, if an environment variable or its value contains a UTF-8 character, coreutils will unwrap in Rust's library/std/src/env.rs.
  Expected behavior is either to handle the UTF-8 character like any other character or to print an error message.

  Simple reproducer (tested with Bash):
    STR=$(echo -e "foo\xA0")
    # Generate environment variable 'foo' with UTF-8 value
    foo=$STR env | grep foo
    # Generate environment variable with UTF-8 name
    declare "$STR=bar" ; env | grep $STR

  The second command triggers this unwrap message in Ubuntu 25.10, but works fine on Fedora 43:
    thread 'main' panicked at library/std/src/env.rs:163:83:
    called `Result::unwrap()` on an `Err` value: "foo\xA0"
    note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

  The third command fails with "declare: `foo�=bar': not a valid identifier" (same on Ubuntu 25.10 and Fedora 43).
  Using `printf -v` shows the same error message.
  This behavior might be fine, but it can be bypassed by e.g. Perl:
    #!/usr/bin/perl
    $str = "foo\x{A0}";
    $ENV{$str} = 'bar';
    use open IN => ":raw";
    my @env = `env`;
    chomp (my @env = grep { s/^$str=// } @env);
    die("@env not equal to 'bar'") if "@env" ne "bar"

  This Perl script executes fine on Fedora 43, but triggers the following error in Ubuntu 25.10:
    thread 'main' panicked at library/std/src/env.rs:163:57:
    called `Result::unwrap()` on an `Err` value: "foo\xA0"
    note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

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