linux-ext4 - Re: algorithm for half-md4 used in htree directories

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Message-ID: <CAF1vpkiK6=gvqD27sLaDnB79ekjKzYjwEP5=u9+D_mQi_5oJwA@mail.gmail.com>
Date:   Mon, 18 Oct 2021 19:56:13 +0300
From:   Avi Deitcher <avi@...tcher.net>
To:     "Theodore Ts'o" <tytso@....edu>
Cc:     linux-ext4@...r.kernel.org
Subject: Re: algorithm for half-md4 used in htree directories

Yes, it definitely was my silly use of sizeof() instead of strlen().
Switch to strlen(), and my test program's output (using little-endian
for each u32) gives the exact same output.

Looks like I owe you that beer (and happy to share it with you) next
time we are in the same place!

On Fri, Oct 15, 2021 at 10:50 PM Theodore Ts'o <tytso@....edu> wrote:
>
> Oh, and taking a quick look at your program, here's at least one of
> the bugs:
>
> static void calculate(char *name) {
>                       ^^^^^^^^^^
> ...
>     __ext4fs_dirhash(name, sizeof(name), &hinfo);
>                            ^^^^^^^^^^^^
>
> With apologies to the movie "The Princess Bride"[1]:
>
>     You fell victim to one of the classic blunders!  The most famous
>     is to never get involved in a land war in Asia, but only slightly
>     less well-known is this: 'taking the size of a C pointer is
>     generally not what you had wanted to do'!  :-)
>
> [1] https://www.youtube.com/watch?v=R7TFPQqglb4
>
>                                - Ted



-- 
Avi Deitcher
avi@...tcher.net
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