replace strings.SplitN with strings.Cut

[amghazanfari]

there are some cases in the code that this pattern used "strings.SplitN(expression, pattern, 2)"

as we see in #4403 strings.Cut has better performance than strings.SplitN.

i changed some of these cases (for rest of them i wasn't sure that it break the functionality or not)

[thaJeztah]

It's common in go to use short variable names when the distance between defining and using them is short; also to avoid type suffixes (like String here`)

In situations like this, ok is also a common name (instead of the doesHaveGid); while doesHaveGid is somewhat more descriptive, it's likely clear from the code what it's handling; using ok can reduce cognitive overload, as a reader can recognize the pattern without understanding if doesHaveGid has additional purpose or (due to the longer name) possibly used further away from its declaration.

e.g., this could look like;

uid, gid, ok := strings.Cut(user, ":")
if ok {
	v, err := strconv.Atoi(gid)
	if err != nil {
		return nil, fmt.Errorf("bad gid: %w", err)
	}
	p.User.GID = uint32(v)
}
v, err := strconv.Atoi(uid)
if err != nil {
    return nil, fmt.Errorf("bad uid: %w", err)
}
p.User.UID = uint32(v)

Somewhat orthogonal to this PR (as it's existing code), but wondering if the strconv.Atoi(gid) would be better replaced with strconv.ParseUint(gid, 10, 32), given that we're ultimately casting to a uint32; i.e. strconv.Atoi("4294967296") will result in gid (uint32) 0.

[amghazanfari]

thanks for your comment. I change the variable names.

[thaJeztah]

thanks!

code changes LGTM, but could you squash the commits?

[amghazanfari]

thanks!

code changes LGTM, but could you squash the commits?

done

[thaJeztah]

oh! If you still have time; I notice your DCO sign-off is using your GitHub handle, not your actual name; https://github.com/opencontainers/runc/blob/main/CONTRIBUTING.md#sign-your-work

using your real name (sorry, no pseudonyms or anonymous contributions.)

To be on the safe side (the DCO bot is sometimes picky), you may want to update your Git config (user.name) as well accordingly.

[amghazanfari]

oh! If you still have time; I notice your DCO sign-off is using your GitHub handle, not your actual name; https://github.com/opencontainers/runc/blob/main/CONTRIBUTING.md#sign-your-work

using your real name (sorry, no pseudonyms or anonymous contributions.)

To be on the safe side (the DCO bot is sometimes picky), you may want to update your Git config (user.name) as well accordingly.

thanks for saying. I changed my user.name as well as my sign