title: Reading whole files in Lua
body: <p>I am trying to read a full mp3 file in order to read out the id3 tags. That's when I noticed that file:read("*a") apparently does not read the full file but rather a small part. So I tried to build some kind of workaround in order to get the content of the whole file:</p>
  
  <pre><code>function readAll(file)
      local f = io.open(file, "r")
      local content = ""
      local length = 0
  
      while f:read(0) ~= "" do
          local current = f:read("*all")
  
          print(#current, length)
          length = length + #current
  
          content = content .. current
      end
  
      return content
  end
  </code></pre>
  
  <p>for my testfile, this shows that 256 reading operations are performed, reading a total of ~113kB (the whole file is ~7MB). Though this should be enough to read most id3 tags, I wonder why Lua behaves in this way (especially because it does not when reading large textbased files such as *.obj or *.ase). Is there any explanation for this behaviour or maybe a solution to reliably read the whole file?</p>