linux-kernel - Re: [PATCH v1 01/19] lib/string_helpers: Introduce kasprintf

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Date:   Sat, 06 Nov 2021 00:34:51 -0700
From:   Joe Perches <joe@...ches.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Jianqun Xu <jay.xu@...k-chips.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Sai Krishna Potthuri <lakshmi.sai.krishna.potthuri@...inx.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org
Cc:     Bamvor Jian Zhang <bamv2005@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Gregory Clement <gregory.clement@...tlin.com>,
        Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Patrice Chotard <patrice.chotard@...s.st.com>,
        Michal Simek <michal.simek@...inx.com>,
        Andy Shevchenko <andy@...nel.org>
Subject: Re: [PATCH v1 01/19] lib/string_helpers: Introduce
 kasprintf_strarray()

On Fri, 2021-11-05 at 14:42 +0200, Andy Shevchenko wrote:
> We have a few users already that basically want to have array of
> sequential strings to be allocated and filled.
> 
> Provide a helper for them (basically adjusted version from gpio-mockup.c).

I think this is overkill and unnecessary bloat for the number of
actual or possible in-tree uses.  The devm_ variant too.

And it'd be useful to have an 0/n patch cover letter describing
why the patchset is useful so I could reply to that instead of the
1/n.

> diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h
[]
> @@ -100,6 +100,7 @@ char *kstrdup_quotable(const char *src, gfp_t gfp);
>  char *kstrdup_quotable_cmdline(struct task_struct *task, gfp_t gfp);
>  char *kstrdup_quotable_file(struct file *file, gfp_t gfp);
>  
> +char **kasprintf_strarray(gfp_t gfp, const char *prefix, size_t n);
>  void kfree_strarray(char **array, size_t n);
>  
>  #endif
> diff --git a/lib/string_helpers.c b/lib/string_helpers.c
[]
> @@ -674,6 +674,39 @@ char *kstrdup_quotable_file(struct file *file, gfp_t gfp)
>  }
>  EXPORT_SYMBOL_GPL(kstrdup_quotable_file);
>  
> +/**
> + * kasprintf_strarray - allocate and fill array of sequential strings
> + * @gfp: flags for the slab allocator
> + * @prefix: prefix to be used
> + * @n: amount of lines to be allocated and filled
> + *
> + * Allocates and fills @n strings using pattern "%s-%zu", where prefix
> + * is provided by caller. The caller is responsible to free them with
> + * kfree_strarray() after use.
> + *
> + * Returns array of strings or NULL when memory can't be allocated.
> + */
> +char **kasprintf_strarray(gfp_t gfp, const char *prefix, size_t n)
> +{
> +	char **names;
> +	size_t i;
> +
> +	names = kcalloc(n + 1, sizeof(char *), gfp);
> +	if (!names)
> +		return NULL;
> +
> +	for (i = 0; i < n; i++) {
> +		names[i] = kasprintf(gfp, "%s-%zu", prefix, i);
> +		if (!names[i]) {
> +			kfree_strarray(names, i);
> +			return NULL;
> +		}
> +	}
> +
> +	return names;
> +}
> +EXPORT_SYMBOL_GPL(kasprintf_strarray);
> +
>  /**
>   * kfree_strarray - free a number of dynamically allocated strings contained
>   *                  in an array and the array itself