linux-kernel - Re: [PATCH v4 1/2] lib/string_helpers: Introduce parse_int_array

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Date:   Fri, 2 Sep 2022 14:23:10 +0200
From:   Amadeusz Sławiński 
        <amadeuszx.slawinski@...ux.intel.com>
To:     Cezary Rojewski <cezary.rojewski@...el.com>,
        alsa-devel@...a-project.org, broonie@...nel.org
Cc:     tiwai@...e.com, perex@...ex.cz,
        pierre-louis.bossart@...ux.intel.com, hdegoede@...hat.com,
        lgirdwood@...il.com, kai.vehmanen@...ux.intel.com,
        peter.ujfalusi@...ux.intel.com, ranjani.sridharan@...ux.intel.com,
        yung-chuan.liao@...ux.intel.com, willy@...radead.org,
        linux-kernel@...r.kernel.org, andy@...nel.org,
        intel-poland@...ists.intel.com, andy.shevchenko@...il.com
Subject: Re: [PATCH v4 1/2] lib/string_helpers: Introduce
 parse_int_array_user()

On 9/2/2022 2:29 PM, Cezary Rojewski wrote:
> Add new helper function to allow for splitting specified user string
> into a sequence of integers. Internally it makes use of get_options() so
> the returned sequence contains the integers extracted plus an additional
> element that begins the sequence and specifies the integers count.
> 
> Suggested-by: Andy Shevchenko <andy.shevchenko@...il.com>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
> Signed-off-by: Cezary Rojewski <cezary.rojewski@...el.com>
> ---
>   include/linux/string_helpers.h |  2 ++
>   lib/string_helpers.c           | 45 ++++++++++++++++++++++++++++++++++
>   2 files changed, 47 insertions(+)
> 
> diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h
> index 4d72258d42fd..dc2e726fd820 100644
> --- a/include/linux/string_helpers.h
> +++ b/include/linux/string_helpers.h
> @@ -21,6 +21,8 @@ enum string_size_units {
>   void string_get_size(u64 size, u64 blk_size, enum string_size_units units,
>   		     char *buf, int len);
>   
> +int parse_int_array_user(const char __user *from, size_t count, int **array);
> +
>   #define UNESCAPE_SPACE		BIT(0)
>   #define UNESCAPE_OCTAL		BIT(1)
>   #define UNESCAPE_HEX		BIT(2)
> diff --git a/lib/string_helpers.c b/lib/string_helpers.c
> index 5ed3beb066e6..d0c8f6ecf84c 100644
> --- a/lib/string_helpers.c
> +++ b/lib/string_helpers.c
> @@ -131,6 +131,51 @@ void string_get_size(u64 size, u64 blk_size, const enum string_size_units units,
>   }
>   EXPORT_SYMBOL(string_get_size);
>   
> +/**
> + * parse_int_array_user - Split string into a sequence of integers
> + * @from:	The user space buffer to read from
> + * @ppos:	The current position in the buffer

There is no such parameter?

> + * @count:	The maximum number of bytes to read
> + * @tkns:	Returned pointer to sequence of integers

s/tkns/array/ ?

> + *
> + * On success @tkns is allocated and initialized with a sequence of

ditto

> + * integers extracted from the @from plus an additional element that
> + * begins the sequence and specifies the integers count.
> + *
> + * Caller takes responsibility for freeing @tkns when it is no longer

ditto

> + * needed.
> + */
> +int parse_int_array_user(const char __user *from, size_t count, int **array)
> +{
> +	int *ints, nints;
> +	char *buf;
> +	int ret = 0;
> +
> +	buf = memdup_user_nul(from, count);
> +	if (IS_ERR(buf))
> +		return PTR_ERR(buf);
> +
> +	get_options(buf, 0, &nints);
> +	if (!nints) {
> +		ret = -ENOENT;
> +		goto free_buf;
> +	}
> +
> +	ints = kcalloc(nints + 1, sizeof(*ints), GFP_KERNEL);
> +	if (!ints) {
> +		ret = -ENOMEM;
> +		goto free_buf;
> +	}
> +
> +	get_options(buf, nints + 1, ints);
> +	*array = ints;
> +
> +free_buf:
> +	kfree(buf);
> +	return ret;
> +}
> +EXPORT_SYMBOL(parse_int_array_user);
> +
>   static bool unescape_space(char **src, char **dst)
>   {
>   	char *p = *dst, *q = *src;