Nmap Development: Re: [Lua snippit] print_hex

["Patrick Donnelly" <batrick.donnelly () gmail com>]

On Sat, Sep 6, 2008 at 9:51 AM, Ron <ron () skullsecurity net> wrote:
> You version seems to have an off-by-one error that cuts off the last hex
> byte. I added a +1/-1 to compensate.
Good catch!

> Maybe now this is perfect? :)
That looks fine. I put the "out" local out of the function definition
to prevent the string from repeatedly being remade (numbers are
constant folded but not strings). I did this mainly to expose people
on the list to some good practices (among other things I did), even
though it probably won't make a huge difference in a debugging
function. If you moved it inside because you didn't want to clutter
the surrounding function (the file) with variables, you can surround
the print_hex function with do ... end to force scoping. e.g.:

do
  local out = "..."
  function print_hex(str)
    ...
  end
end

> -- Print out a string in hex, for debugging.
> function print_hex(str)
>
>    local out = "%08x"..(" %02x"):rep(16).."   ";
>    local len, a = #str, 1;
>    repeat
>        if a + 16 > len then -- partial line?
>
>            io.write(
>
>           -- 00000000 AB CD EF GH JK
>           ("%08x"..(" %02x"):rep(len-a+1)..("   "):rep(17+a-len-1)):format(
>               a-1, str:byte(a, a+16)),
>
>           --                                          abcdefg\n
>           str:sub(a, a+16):gsub("%c", "."), "\n");
>
>        else -- full line
>
>            io.write(
>
>           -- 00000000 AB CD EF GH JK LM NO PQ
>           out:format(a-1, str:byte(a, a+16)),
>
>           --                                    abcdefgh\n
>           str:sub(a, a+16):gsub("%c", "."), "\n");
>
>        end
>
>        a = a + 16;
>
>    until a > len;
>
>    -- Print out the length
>    io.write(("         Length: %d [0x%x]\n"):format(len, len))
>
> end
Cheers,

-- 
-Patrick Donnelly

"One of the lessons of history is that nothing is often a good thing
to do and always a clever thing to say."

-Will Durant

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