Get console user on macOS using SCDynamicStoreCopyConsoleUser

get_user.go

package main

import (
	"fmt"
	"os/user"
	"strconv"
)

//#cgo LDFLAGS: -framework SystemConfiguration
/*
#import <SystemConfiguration/SystemConfiguration.h>

struct user_info {
	uid_t uid;
	gid_t gid;
	int error_code;
	const char * error;
};

struct user_info get_console_user() {
	struct user_info info;
	CFStringRef ref = SCDynamicStoreCopyConsoleUser(NULL, &info.uid, &info.gid);

	if (ref == NULL) {
		int code = SCError();
		if (code != kSCStatusOK) {
			info.error_code = code;
			info.error = SCErrorString(code);
		}
	} else {
		CFRelease(ref);
	}

	return info;
}
*/
import "C"

func GetConsoleUserID() (uid, gid int, err error) {
	info := C.get_console_user()
	if errstr := C.GoString(info.error); len(errstr) > 0 {
		err = fmt.Errorf("%s (SCError: %d)", errstr, info.error_code)
	}
	return int(info.uid), int(info.gid), err
}

func main() {
	uid, gid, err := GetConsoleUserID()
	if err != nil {
		panic(fmt.Errorf("could get console user id: %w", err))
	}

	usr, err := user.LookupId(strconv.Itoa(uid))
	if err != nil {
		panic(fmt.Errorf("could not look up user: %w", err))
	}

	fmt.Println("User:", usr.Username)

	grp, err := user.LookupGroupId(strconv.Itoa(gid))
	if err != nil {
		panic(fmt.Errorf("could not look up group: %w", err))
	}

	fmt.Println("Group:", grp.Name)
}