--:Minify:--
-- Usage:
--   umount <mountpoint>        unmount; auto-detach loop device if one is found
--   umount -l <id>             detach loop device without unmounting (force)
--   umount --no-detach <mpt>   unmount but leave loop device attached
--   umount --help

local name = syscall.getTask(syscall.getpid()).name
local args, opts = {}, { l=false, ["no-detach"]=false, help=false }

for _, v in ipairs({...}) do
    if v:sub(1,2) == "--" then
        local o = v:sub(3)
        if opts[o] ~= nil then opts[o] = true
        else print(name..": unrecognised option '"..v.."'")
             print("try '"..name.." --help' for more information.")
             syscall.exit(1); return end
    elseif v:sub(1,1) == "-" then
        for i = 2, #v do
            local c = v:sub(i,i)
            if opts[c] ~= nil then opts[c] = true
            else print(name..": invalid option '-"..c.."'")
                 print("try '"..name.." --help' for more information.")
                 syscall.exit(1); return end
        end
    else
        table.insert(args, v)
    end
end

if opts.help then
    print("Usage: "..name.." <mountpoint>")
    print("       "..name.." --no-detach <mountpoint>")
    print("       "..name.." -l <loopid>")
    print("")
    print("Unmount a filesystem mounted at <mountpoint>.")
    print("")
    print("  <mountpoint>          unmount and auto-detach any loop device")
    print("  --no-detach           unmount but keep the loop device attached")
    print("  -l <loopid>           forcibly detach a loop device (no unmount)")
    print("")
    print("Requires root.")
    return
end

if opts.l then
    if #args < 1 then
        print(name..": -l requires a loop device id")
        print("try '"..name.." --help' for more information.")
        syscall.exit(1); return
    end
    local id = args[1]
    local ok, err = pcall(syscall.lodetach, id)
    if not ok then
        local msg = tostring(err)
        if msg:find("EPERM")  then msg = "Permission denied"
        elseif msg:find("ENXIO")  then msg = "no such loop device '"..id.."'"
        elseif msg:find("EBUSY")  then msg = "'"..id.."' is still mounted - unmount first or omit -l"
        end
        print(name..": "..msg); syscall.exit(1); return
    end
    syscall.devctl(1, "sfgc", 10)
    print(name..": detached "..id)
    syscall.devctl(1, "sfgc", 1)
    return
end

if #args < 1 then
    print(name..": missing mount point operand")
    print("try '"..name.." --help' for more information.")
    syscall.exit(1); return
end

local mpt = args[1]
if mpt:sub(1,1) ~= "/" then mpt = syscall.getcwd().."/"..mpt end

local loopIdToDetach = nil
if not opts["no-detach"] then
    local lok, devs = pcall(syscall.lolist)
    if lok then
        loopIdToDetach = {}
        for id in pairs(devs) do
            loopIdToDetach[#loopIdToDetach + 1] = id
        end
    end
end

local ok, err = pcall(syscall.umount, mpt)
if not ok then
    local msg = tostring(err)
    if msg:find("EPERM")  then msg = "Permission denied"
    elseif msg:find("EINVAL") then msg = "'"..args[1].."' is not a mount point"
    elseif msg:find("EBUSY")  then msg = "'"..args[1].."' is busy - close open files first"
    end
    print(name..": "..msg); syscall.exit(1); return
end

syscall.devctl(1, "sfgc", 10)
print(name..": unmounted "..mpt)
syscall.devctl(1, "sfgc", 1)

if loopIdToDetach then
    for _, id in ipairs(loopIdToDetach) do
        local dok = pcall(syscall.lodetach, id)
        if dok then
            syscall.devctl(1, "sfgc", 14)
            print(name..": auto-detached "..id)
            syscall.devctl(1, "sfgc", 1)
        end
    end
end