linux-kernel - Re: [PATCH 1/3] hexdump: Implement macro for converting large buffers

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Message-ID: <20250114144831.GI5497@kernel.org>
Date: Tue, 14 Jan 2025 14:48:31 +0000
From: Simon Horman <horms@...nel.org>
To: Nick Child <nnac123@...ux.ibm.com>
Cc: linux-kernel@...r.kernel.org, nick.child@....com,
	netdev@...r.kernel.org
Subject: Re: [PATCH 1/3] hexdump: Implement macro for converting large buffers

On Mon, Jan 13, 2025 at 04:17:19PM -0600, Nick Child wrote:
> Define for_each_line_in_hex_dump which loops over a buffer and calls
> hex_dump_to_buffer for each segment in the buffer. This allows the
> caller to decide what to do with the resulting string and is not
> limited by a specific printing format like print_hex_dump.
> 
> Signed-off-by: Nick Child <nnac123@...ux.ibm.com>
> ---
>  include/linux/printk.h | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/include/linux/printk.h b/include/linux/printk.h
> index 4217a9f412b2..d55968f7ac10 100644
> --- a/include/linux/printk.h
> +++ b/include/linux/printk.h
> @@ -755,6 +755,27 @@ enum {
>  extern int hex_dump_to_buffer(const void *buf, size_t len, int rowsize,
>  			      int groupsize, char *linebuf, size_t linebuflen,
>  			      bool ascii);
> +/**
> + * for_each_line_in_hex_dump - iterate over buffer, converting into hex ASCII
> + * @i - offset in @buff

nit: scripts/kernel-doc would like this to be "@i: ..." 

> + * @rowsize: number of bytes to print per line; must be 16 or 32
> + * @linebuf: where to put the converted data
> + * @linebuflen: total size of @linebuf, including space for terminating NUL
> + *		IOW >= (@rowsize * 2) + ((@rowsize - 1 / @groupsize)) + 1
> + * @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1)
> + * @buf: data blob to dump
> + * @len: number of bytes in the @buf
> + */
> + #define for_each_line_in_hex_dump(i, rowsize, linebuf, linebuflen, groupsize, \
> +				   buf, len) \
> +	for ((i) = 0;							\
> +	     (i) < (len) &&						\
> +	     hex_dump_to_buffer((unsigned char *)(buf) + (i),		\
> +				min((len) - (i), rowsize),		\
> +				(rowsize), (groupsize), (linebuf),	\
> +				(linebuflen), false);			\
> +	     (i) += (rowsize) == 16 || (rowsize) == 32 ? (rowsize) : 16	\
> +	    )
>  #ifdef CONFIG_PRINTK
>  extern void print_hex_dump(const char *level, const char *prefix_str,
>  			   int prefix_type, int rowsize, int groupsize,
> -- 
> 2.47.1
> 
>