stty: add combination settings

[willshuttleworth]

fixes for #3860. i added the function combo_to_flags() which takes a combination name as a string and decomposes the combination into the individual settings. this function returns a vec of all the flags that correspond to the combination, which are then appended to the valid_args vec that is used during arg parsing. one of the combinations is not fully complete yet, as it requires functionality in #3859, which i will tackle next.

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/misc/tee (passes in this run but fails in the 'main' branch)
Skipping an intermittent issue tests/timeout/timeout (passes in this run but fails in the 'main' branch)

[tertsdiepraam]

These are never supposed to fail right? Maybe we should unwrap them? It's better to know early if it doesn't work. I forget how this worked, but maybe we can use the ArgOptions directly?

[tertsdiepraam]

This could also be done in a more functional style with less repetition:

let flags = ["xcase", ...];
let flags = flags
    .iter()
    .map(|f| {
        ArgOptions::Flags(string_to_flag(f).unwrap())
    })
    .collect();

(or don't unwrap and use filter_map)

This also makes it easier to see what these combo flags map to.

[willshuttleworth]

I definitely agree that the current way I did this is repetitive. I like the functional approach, I'll change it towards that. Unwrapping should be fine, assuming that every flag in every combination is available on all necessary platforms. Maybe some flags in combinations aren't available on something like macOS? I'll need to investigate further.

[willshuttleworth]

So there are flags that exist in combinations and aren't present on macOS. olcuc for example. I'm thinking its better to not unwrap and use filter_map because the alternative is having cfg platform directives in both flags.rs and stty.rs for the same flags.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/timeout/timeout (fails in this run but passes in the 'main' branch)

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/timeout/timeout (fails in this run but passes in the 'main' branch)

[willshuttleworth]

@tertsdiepraam @cakebaker anything else you'd like me to change?

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/timeout/timeout (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/tail/inotify-dir-recreate (passes in this run but fails in the 'main' branch)

[cakebaker]

Shouldn't there be the same flags as for lcase/LCASE? From the help:

[-]lcase      same as xcase iuclc olcuc

[willshuttleworth]

with GNU stty, '-lcase'/'-LCASE' yields '-xcase -iuclc -olcuc'

[cakebaker]

cs8 is not negated according to the help:

litout        same as -parenb -istrip -opost cs8

Suggested change

	flags = vec!["-parenb", "-istrip", "-opost", "-cs8"];
	flags = vec!["-parenb", "-istrip", "-opost", "cs8"];

[cakebaker]

I think it's nl0, not n10:

Suggested change

	"-onocr", "-onlret", "n10", "cr0", "tab0", "bs0", "vt0", "ff0", "isig", "-tostop",
	"-onocr", "-onlret", "nl0", "cr0", "tab0", "bs0", "vt0", "ff0", "isig", "-tostop",

[cakebaker]

I think it's -flusho instead of -flush0:

Suggested change

	"-ofdel", "-echoprt", "echoctl", "echoke", "-extproc", "-flush0",
	"-ofdel", "-echoprt", "echoctl", "echoke", "-extproc", "-flusho",

[willshuttleworth]

good catch, thanks!

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/misc/stdbuf (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/misc/tee (passes in this run but fails in the 'main' branch)

[cakebaker]

Thanks!