linux-kernel - Re: [RFC][PATCH] lib/string: introduce sysfs_strncpy() and sysfs

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Date:   Tue, 21 Aug 2018 15:00:58 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Arnd Bergmann <arnd@...db.de>, Martin Wilck <mwilck@...e.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [RFC][PATCH] lib/string: introduce sysfs_strncpy() and
 sysfs_strlcpy()

On Tue, 2018-08-21 at 20:44 +0900, Sergey Senozhatsky wrote:

> Something like below? Not tested, since we are still in "is this
> what we want" phase.

> Returning the length of dst/-EOVERFLOW is a bit inconvenient, because
> "the length" forces us to have size_t return, which is unsigned.

We have for ages ssize_t to workaround that.

> size_t strcpy_trim(char *dst, size_t dstsz, const char *src, size_t
> srcsz)
> {
> 	const char *end;
> 	size_t ret = 0;
> 	size_t len = 0;
> 
> 	if (!dstsz || !srcsz)
> 		goto out;
> 
> 	end = src + srcsz - 1;
> 	while (end >= src && isspace(*end))
> 		end--;
> 	end++;
> 	while (src < end && isspace(*src))
> 		src++;
> 	len = (src >= end) ? 0 : end - src;
> 	if (!len)
> 		goto out;
> 
> 	ret = len;
> 	if (len >= dstsz)
> 		len = dstsz - 1;
> 	memcpy(dst, src, len);
> out:
> 	dst[len] = '\0';
> 	return ret == len ? ret : -EOVERFLOW;
> }

Wouldn't be better to split out something like

strnstrip() out of strim(), with simultaneous changes to strim(),
strstrip(), and use it here?


-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy