Various problems in different id handling in `id` command

[sylvestre]

Component

id

Description

Various problems in different id handling in id command

Test / Reproduction Steps

1. id pretty print crash on malformed group id
   Issue:
   uutils id command crashes when given a malformed group id for pretty printing.
   Test:

sudo setpriv --regid 1337 --clear-groups target/release/id -p
login    root
uid    root

thread 'main' panicked at src/uu/id/src/id.rs:503:49:
called `Result::unwrap()` on an `Err` value: Custom { kind: NotFound, error: "No such id: 1337" }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

2. inconsistency in uutil's id & C version
   Issue:
   uutils id command shows incorrect group information when the effective group ID is changed.
   Test:
   add two users first

useradd -u 2000 u2000 -M
useradd -u 3000 u3000 -M

then

sudo setpriv --reuid 3000 --egid 2000 --clear-groups target/release/id
uid=3000(u3000) gid=0(root) egid=2000(u2000) groups=0(root)
sudo setpriv --reuid 3000 --egid 2000 --clear-groups id
uid=3000(u3000) gid=0(root) egid=2000(u2000) groups=2000(u2000)

3. Incorrect User ID Handling in uutils id Command
   Issue:
   The uutils id command incorrectly displays user information when the effective group ID is changed, leading to inconsistencies with the expected output (pretty print & compact print).
   Test:
   add two users first

useradd -u 2000 u2000 -M
useradd -u 3000 u3000 -M

then

sudo setpriv --euid 3000 --egid 2000 --clear-groups target/release/id
uid=0(root) gid=0(root) euid=3000(u3000) egid=2000(u2000) groups=0(root)
sudo setpriv --euid 3000 --egid 2000 --clear-groups target/release/id -p
login    root
uid    root
euid    root
groups    u2000

[denendaden]

I can work on this, thought the first issue appears to have already been fixed.

[denendaden]

Issue 2 seems to be caused by the following line (src/uucore/src/lib/features/entries.rs, line 121):

let egid = arg_id.unwrap_or_else(crate::features::process::getegid);

which is being called on this line (src/uu/id/src/id.rs, line 311):

let groups = entries::get_groups_gnu(Some(gid)).unwrap();

and gid is being defined in here (line 257):

let (uid, gid) = possible_pw.as_ref().map_or(
    {
        let use_effective = !state.rflag && (state.uflag || state.gflag || state.gsflag);
        if use_effective {
            (geteuid(), getegid())
        } else {
            (getuid(), getgid())
        }
    },
    |p| (p.uid, p.gid),
);

so that the gid is being used in the list of groups instead of the egid. Replacing Some(gid) with None in line 311 therefore causes the egid to be included in groups and not the gid when they differ, which appears to bring the behavior in line with GNU id. Let me know if there's anything I'm missing with this.