Re: Difference between a+b and bit32.band(a+b)

[waspoza <waspoza@...>]

On Fri, Sep 9, 2011 at 6:55 PM, waspoza <waspoza@gmail.com> wrote:
> Yes, this code is probably with errors. It does correct checksums for
> text files, but incorrect for binary files:

> ~/lua$ lua sha256.lua test.jpg -
> 969906c25ee94d6c14aca4edb9b48a1fb350331bd244781d5046699e02d2654c
>
> ~/lua$ sha256sum test.jpg
> fba5916247f503d4792f36af35f1356337e97073ba08b373059e33ab795b035e  test.jpg

Ok, I found the bug. Instead:

-- read a file and prints its hash, if given a file name

if arg[1] then
  local x = sha2.new256()
  for b in io.lines(arg[1], 2^12) do
    x:add(b)
  end
  print(x:close())
end

should be something like this:

if arg[1] then
  file = io.open (arg[1] , 'rb')
  local x = sha2.new256()
  while true do
    b = file:read(2^12)
    if not b then break end
    x:add(b)
  end
  file:close()
  print(x:close())
end

Its uglier, but gives correct checksums.
Looks like io.lines can't read binary files. :(