On Mon, 4 Sep 2017 17:00:15 +0200
Phil Sutter <p...@nwl.cc> wrote:
> On Mon, Sep 04, 2017 at 02:49:20PM +0000, David Laight wrote:
> > From: Phil Sutter
> > > Sent: 01 September 2017 17:53
> > > By making use of strncpy(), both implementations are really simple so
> > > there is no need to add libbsd as additional dependency.
> > >
> > ...
> > > +
> > > +size_t strlcpy(char *dst, const char *src, size_t size)
> > > +{
> > > + if (size) {
> > > + strncpy(dst, src, size - 1);
> > > + dst[size - 1] = '\0';
> > > + }
> > > + return strlen(src);
> > > +}
> >
> > Except that isn't really strlcpy().
> > Better would be:
> > len = strlen(src) + 1;
> > if (len <= size)
> > memcpy(dst, src, len);
> > else if (size) {
> > dst[size - 1] = 0;
> > memcpy(dst, src, size - 1);
> > }
> > return len - 1;
>
> Please elaborate: Why isn't my version "really" strlcpy()? Why is your
> proposed version better?
>
> Thanks, Phil
Linux kernel:
size_t strlcpy(char *dest, const char *src, size_t size)
{
size_t ret = strlen(src);
if (size) {
size_t len = (ret >= size) ? size - 1 : ret;
memcpy(dest, src, len);
dest[len] = '\0';
}
return ret;
}
FreeBSD:
size_t
strlcpy(char * __restrict dst, const char * __restrict src, size_t dsize)
{
const char *osrc = src;
size_t nleft = dsize;
/* Copy as many bytes as will fit. */
if (nleft != 0) {
while (--nleft != 0) {
if ((*dst++ = *src++) == '\0')
break;
}
}
/* Not enough room in dst, add NUL and traverse rest of src. */
if (nleft == 0) {
if (dsize != 0)
*dst = '\0'; /* NUL-terminate dst */
while (*src++)
;
}
return(src - osrc - 1); /* count does not include NUL */
}
They all give the same results for some basic tests.
Test FreeBSD Linux Iproute2
"",0: 0 "JUNK" 0 "JUNK" 0 "JUNK"
"",1: 0 "" 0 "" 0 ""
"",8: 0 "" 0 "" 0 ""
"foo",0: 3 "JUNK" 3 "JUNK" 3 "JUNK"
"foo",3: 3 "fo" 3 "fo" 3 "fo"
"foo",4: 3 "foo" 3 "foo" 3 "foo"
"foo",8: 3 "foo" 3 "foo" 3 "foo"
"longstring",0: 10 "JUNK" 10 "JUNK" 10 "JUNK"
"longstring",8: 10 "longstr" 10 "longstr" 10 "longstr"
