Lua: “zrget” module

test-zrget.lua

zrget = require 'zrget'
zrget.download(
  'https://raw.githubusercontent.com/zr-tex8r/scllmk/master/doc/logo.png',
  'logo.png',
  function (d) return d:sub(1, 4) == '\137PNG' end)
-- EOF

zrget.lua

-- zrget.lua
local info = 'zrget v0.3.0 2020/08/26'
local zrget
-- NOTE: This file can be used as a Lua module, but to copy & paste
-- the section below is also okay.
----------------------------------------
zrget = (function(M)
  -- parameters
  M.max_trial = M.max_trial  or 3
  M.interval  = M.interval   or 1 -- second
  M.log       = M.log        or true

  -- helpers
  local lfs = require 'lfs'
  local socket = require 'socket'
  local tempb = '__zrget'
  local win = (lfs.attributes('C:\\NUL', 'mode') ~= nil)
  local function upath(pth)
    return (win) and pth:gsub('\\', '/') or pth
  end
  local function npath(pth)
    return (win) and pth:gsub('/', '\\') or pth
  end
  local function log_print(s)
    io.stderr:write("zrget: ", s, "\n")
  end
  local function log(fmt, ...)
    if not M.log then return end
    local l = (type(M.log) == 'function') and M.log or log_print
    l(tostring(fmt):format(...))
  end
  local function file_ok(pth)
    return ((lfs.attributes(pth, 'size') or 0) > 0)
  end
  local function execute(clfmt, ...)
    local cl = clfmt:format(...)
    if M.verbose then log("RUN: %s", cl) end
    local ok = os.execute(cl)
    return (ok == true) or (ok == 0)
  end
  local function exefile(pth)
    pth = npath(pth..(win and '.exe' or ''))
    return (file_ok(pth) or nil) and pth
  end
  local function validate(vprc, pth)
    if not file_ok(pth) then return false end
    local h = io.open(pth, 'rb')
    local d = h and h:read('*a')
    if h then h:close() end
    local r = d and (not vprc or vprc(d))
    if not r then log("Validation failure") end
    return r and d
  end

  -- TeXLive stuffs
  local kpse
  pcall(function()
    kpse = require 'kpse'
    kpse.set_program_name('luatex')
  end)
  local tlpkg = kpse and kpse.var_value('SELFAUTOPARENT')
  tlpkg = tlpkg and tlpkg..'/tlpkg'
  local tlwget = tlpkg and exefile(tlpkg..'/installer/wget/wget')
  local tlperl = tlpkg and exefile(tlpkg..'/tlperl/bin/perl')

  -- methods
  local fcout, fcerr, ftdst =
      tempb..'-1.out', tempb..'-2.out', tempb..'-0.bin'
  local method_list = {
    {
      name = 'wget';
      checker = 'wget --version'; check_tag = 'Wget';
      loader = function(src)
        return execute('wget -q --no-check-certificate "%s" -O %s 2>%s',
            src, ftdst, fcerr)
      end
    },
    {
      name = 'curl';
      checker = 'curl --version'; check_tag = 'curl';
      loader = function(src)
        return execute('curl -k -s "%s" -o %s 2>%s',
            src, ftdst, fcerr)
      end
    },
    {
      name = 'tl-wget';
      checker = tlwget and tlwget..' --version'; check_tag = 'Wget';
      loader = function(src)
        return execute('%s -q --no-check-certificate "%s" -O %s 2>%s',
            tlwget, src, ftdst, fcerr)
      end
    },
    {
      name = 'powershell';
      checker = 'powershell -Help'; check_tag = 'PowerShell';
      loader = function(src)
        return execute('powershell -Command Invoke-WebRequest '..
            '"%s" -OutFile %s 2>%s',
            src, ftdst, fcerr)
      end
    },
    {
      name = 'tl-perl';
      checker = tlperl and tlperl..' --version'; check_tag = '?Perl';
      loader = function(src)
        return false -- TODO: make it
      end
    },
  }

  -- main procedure
  function M.download(url, dst, vprc)
    url = tostring(url):gsub('[\1-\31 \"\'<>\\`{|}]',
      function(s) return ('%%%02X'):format(string.byte(s)) end)
    if dst then
      if file_ok(dst) then
        log("File '%s' already exists", dst)
        return false
      end
      os.remove(dst)
    end
    --
    local data
    for tc = 1, M.max_trial do
      for _, mth in ipairs(method_list) do
        repeat
          if not mth.checker or mth.pass then break end
          log("Try method '%s'...(%s)", mth.name, tc)
          -- check
          execute('%s 1>%s 2>%s', mth.checker, fcout, fcerr)
          local hso = io.open(fcout, 'rb')
          local p = (hso and hso:read('*a') or ''):find(mth.check_tag, 1, true)
          hso:close()
          if not p then
            log("Method '%s' is not available", mth.name)
            mth.pass = true
            break
          end
          -- download
          log("Try downloading...")
          os.remove(ftdst)
          if mth.loader(url) then
            data = validate(vprc, ftdst)
            if data then break end
          end
          socket.sleep(M.interval)
          os.remove(ftdst)
        until true
        if data then break end
      end
      if data then break end
    end
    --
    local what = (dst) and ("File '%s'"):format(dst) or "Data"
    if data then
      if dst then os.rename(ftdst, dst) end
      log("%s is successfully downloaded", what)
    else
      log("%s cannot be downloaded", what)
    end
    --
    for _, f in ipairs {ftdst, fcerr, fcout} do
      os.remove(f)
    end
    return data
  end

  return M
end)({})
----------------------------------------

return zrget
-- EOF