[PATCH v2 3/7] lib/hexdump.c: Optionally suppress lines of repeated bytes

Geert Uytterhoeven geert at linux-m68k.org
Mon May 13 07:01:14 UTC 2019

Hi Alastair,

Thanks for your patch!

On Wed, May 8, 2019 at 9:04 AM Alastair D'Silva <alastair at au1.ibm.com> wrote:
> From: Alastair D'Silva <alastair at d-silva.org>
> Some buffers may only be partially filled with useful data, while the rest
> is padded (typically with 0x00 or 0xff).
> This patch introduces a flag to allow the supression of lines of repeated
> bytes,

Given print_hex_dump() operates on entities of groupsize (1, 2, 4, or 8)
bytes, wouldn't it make more sense to consider repeated groups instead
of repeated bytes?

> which are replaced with '** Skipped %u bytes of value 0x%x **'

Using a custom message instead of just "*", like "hexdump" uses, will
require preprocessing the output when recovering the original binary
data by feeding it to e.g. "xxd".
This may sound worse than it is, though, as I never got "xxd" to work
without preprocessing anyway ;-)

    $ cat $(type -p unhexdump)
    sed 's/^[0-9a-f]*//' $1 | xxd -r -p | dd conv=swab



Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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