--:Minify:--
local targetUser = ({ ... })[1] or "root"
local currentUid = syscall.getuid()
local targetUid  = syscall.getuidbyname(targetUser)

if not targetUid then
    print("su: user '" .. targetUser .. "' does not exist")
    syscall.exit(1)
    return
end

if currentUid ~= 0 then
    printInline("Password: ")
    local pw = ""
    while true do
        local ch = syscall.read(0)
        if not ch or ch == "" then
        elseif ch == "\n" then
            syscall.write(1, "\n")
            break
        elseif ch == "\b" then
            if #pw > 0 then pw = pw:sub(1, -2); syscall.write(1, "\b \b") end
        else
            pw = pw .. ch; syscall.write(1, "*")
        end
    end

    local ok, err = syscall.elevate(targetUser, pw)
    if not ok then
        sleep(1)
        print("su: Authentication failure")
        syscall.exit(1)
        return
    end
end

syscall.setuid(targetUid)

local pwent   = syscall.getpasswd(targetUid)
local shell   = (pwent and pwent.shell)   or "/bin/hysh"
local homedir = (pwent and pwent.homedir) or "/"

local ok_cd, err_cd = pcall(syscall.chdir, homedir)
if not ok_cd then
    homedir = "/"
    syscall.chdir(homedir)
end
syscall.setEnviron("HOME",  homedir)
syscall.setEnviron("USER",  targetUser)
syscall.setEnviron("SHELL", shell)

local ok, err = pcall(syscall.exec, shell)
if not ok then
    print("su: cannot exec shell '" .. shell .. "': " .. tostring(err))
    syscall.exit(1)
end