Re: [RFC][PATCH] lib/string: introduce sysfs_strncpy() and sysfs_strlcpy()

[Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>]

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;
}