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

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Date:   Tue, 21 Aug 2018 20:44:05 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     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>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: Re: [RFC][PATCH] lib/string: introduce sysfs_strncpy() and
 sysfs_strlcpy()

On (08/21/18 18:50), Sergey Senozhatsky wrote:
> 
> > int strcpy_trim(char *dst, size_t dstsize, const char *src, size_t
> > srcsize) - copy (potentially not '\0'-terminated) src to dst, trimming
> > leading and trailing whitespace. dstsize must be positive, and dst is
> > guaranteed to be '\0'-terminated. Returns the length of the string now
> > in dst, or -EOVERFLOW if some none-whitespace character was chopped.
> >
> > would cover all use cases?
> 

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.

This one returns a number of non-NULL bytes, which were copied
to dst, or 0.

---

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;
}