Record Terminal

record.lua

local bit = require('bit')
local ffi = require('ffi')
local S = require('syscall')

ffi.cdef[[
  int execl(const char *path, const char *arg0, ...);
  int login_tty(int fd);
]]

local STDIN_FILENO = 0
local STDOUT_FILENO = 1
local done = false

local fd = S.open("out.log", "WRONLY,CREAT", "RWU")
local mpty = S.posix_openpt("rdwr,noctty")
mpty:grantpt()
mpty:unlockpt()
local pts_name = mpty:ptsname()
local spty = S.open(pts_name, "rdwr,noctty")
local termios = spty:tcgetattr()
termios:makeraw()
termios.c_lflag = bit.band(termios.lflag, bit.bnot(S.c.LFLAG["ICANON,ISIG,IEXTEN"]))
S.signal('chld', function() done = true end)

local function write_output(mpty, spty)
  ffi.C.close(STDIN_FILENO)
  local size = 8096
  local buffer = S.types.t.buffer(size)
  while true do
    local rv = S.read(mpty:getfd(), buffer, size)
    if rv > 0 then
      S.write(STDOUT_FILENO, buffer, rv)
      S.write(fd, buffer, rv)
    else
      break
    end
  end
  mpty:close()
  S.close(fd)
end

local function start_shell(mpty, spty)
  mpty:close()
  ffi.C.login_tty(spty:getfd())
  ffi.C.execl('/bin/sh', '-i')
  assert(false, 'could not spawn shell')
end

local child = S.fork()
if child < 0 then
  assert(false) -- fork failed
elseif child == 0 then
  -- child
  local subchild = S.fork()
  if subchild < 0 then
    assert(false) -- fork failed
  elseif subchild == 0 then
    write_output(mpty, spty)
  else
    start_shell(mpty, spty)
  end
else
  local size = 8096
  local buffer = S.types.t.buffer(size)
  while not done do
    local rv = S.read(STDIN_FILENO, buffer, size)
    if rv > 0 then
      S.write(mpty:getfd(), buffer, rv)
    else
      break
    end
  end
end