img_size.lua

#!/usr/bin/env lua

-- This program aims to compress too big image when they are uploded
-- A directory and every subdirectories are watched via lua inotify binding :
-- http://github.com/hoelzro/linotify/
--
--
--
--
-- Requirements :
--
-- * lua
-- * linotify : http://github.com/hoelzro/linotify/
-- * lfs : http://www.keplerproject.org/luafilesystem/manual.html
-- * ruby
-- * smusher : gem install smusher

require "lfs"

-- variables
local inotify = require 'inotify'
local handle = inotify.init()
-- watched root dir
local root = "."
-- who will received the emails if it is too big
local emails = {"[email protected]"}
-- global vars
dirs = {}
-- max size is 200Ko
-- 1Ko = 1024 bytes
max_size_in_bytes = 1024 * 200

-- a function that return a tree of dirs
function dirtree(dir)
  assert(dir and dir ~= "", "directory parameter is missing or empty")
  if string.sub(dir, -1) == "/" then
    dir=string.sub(dir, 1, -2)
  end

  local function yieldtree(dir)
    for entry in lfs.dir(dir) do
      if entry ~= "." and entry ~= ".." then
        entry=dir.."/"..entry
        local attr=lfs.attributes(entry)
        if attr.mode == "directory" then
          coroutine.yield(entry,attr)
          yieldtree(entry)
        end
      end
    end
  end

  return coroutine.wrap(function() yieldtree(dir) end)
end

function is_image(p)
  return p and (
    ((string.len(p) > 4) and (string.lower(string.sub(p, -4)) == ".jpg")) or
    ((string.len(p) > 5) and (string.lower(string.sub(p, -5)) == ".jpeg")) or
    ((string.len(p) > 4) and (string.lower(string.sub(p, -4)) == ".png")) or
    ((string.len(p) > 4) and (string.lower(string.sub(p, -4)) == ".gif")))
end

function is_oversized(p)
  return lfs.attributes(p).size > max_size_in_bytes
end

function watch_dir(p)
  dirs[handle:addwatch(p, inotify.IN_CREATE)] = p
end

-- watching root
watch_dir(root)
-- watching every subdirectory
for filename in dirtree(".") do
  watch_dir(filename)
end

-- infinite loop
while true do
  local events = handle:read()
  for _, ev in ipairs(events) do
    local path = dirs[ev.wd].."/"..ev.name
    -- if it's a dir we stating to watch it
    if lfs.attributes(path).mode == "directory" then
      -- we need first to have full path
      dirs[handle:addwatch(path, inotify.IN_CREATE)] = path
    elseif is_image(path) then
      os.execute("smusher "..path.." -c")
    end
    if is_oversized(path) and (is_png(path) or is_jpeg(path)) then
      os.execute("echo '"..path.." is too big' | mail -s 'too big image has been just uploaded' "..table.concat(emails," "))
    end
  end
end