Re: [PATCH v3 1/5] seq_file: provide an analogue of print_hex_dump()

[Geert Uytterhoeven]

Hi Andy,

On Mon, Sep 1, 2014 at 10:36 AM, Andy Shevchenko
<andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
>> ... and extra copying for no good reason.  Why not check that we have
>> enough space in buffer and generate directly into it?  See what e.g.
>> seq_escape() is doing...
>
> What about this variant?

I think it needs a call to seq_set_overflow() in case the buffer is too small,
so the caller will retry with a bigger buffer.

>
> @@ -794,6 +795,47 @@ void seq_pad(struct seq_file *m, char c)
>  }
>  EXPORT_SYMBOL(seq_pad);
>
> +/* Analogue of print_hex_dump() */
> +void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type,
> +                 int rowsize, int groupsize, const void *buf, size_t len,
> +                 bool ascii)
> +{
> +       const u8 *ptr = buf;
> +       int i, linelen, remaining = len;
> +       int ret;
> +
> +       if (rowsize != 16 && rowsize != 32)
> +               rowsize = 16;
> +
> +       for (i = 0; i < len; i += rowsize) {
> +               linelen = min(remaining, rowsize);
> +               remaining -= rowsize;
> +
> +               ret = seq_printf(m, "%s", prefix_str);
> +               if (ret < 0)
> +                       break;
> +
> +               if (prefix_type == DUMP_PREFIX_ADDRESS)
> +                       ret = seq_printf(m, "%p: ", ptr + i);
> +               else if (prefix_type == DUMP_PREFIX_OFFSET)
> +                       ret = seq_printf(m, "%.8x: ", i);
> +               if (ret < 0)
> +                       break;
> +
> +               if (m->size < m->count + groupsize * 2 + 1)
> +                       break;
> +
> +               hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
> +                                  m->buf + m->count, m->size - m->count,
> +                                  ascii);
> +
> +               ret = seq_putc(m, '\n');
> +               if (ret < 0)
> +                       break;
> +       }
> +}
> +EXPORT_SYMBOL(seq_hex_dump);

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

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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