Function cache_symlink_resolve

freebsd/kern/vfs_cache.c:4858–4915

* Resolve a symlink. Called by filesystem-specific routines. * * Code flow is: * ... -> cache_fplookup_symlink -> VOP_FPLOOKUP_SYMLINK -> cache_symlink_resolve */

 * ... -> cache_fplookup_symlink -> VOP_FPLOOKUP_SYMLINK -> cache_symlink_resolve
 */
int
cache_symlink_resolve(struct cache_fpl *fpl, const char *string, size_t len)
{
	struct nameidata *ndp;
	struct componentname *cnp;
	size_t adjust;

	ndp = fpl->ndp;
	cnp = fpl->cnp;

	if (__predict_false(len == 0)) {
		return (ENOENT);
	}

	if (__predict_false(len > MAXPATHLEN - 2)) {
		if (cache_fpl_istrailingslash(fpl)) {
			return (EAGAIN);
		}
	}

	ndp->ni_pathlen = fpl->nulchar - cnp->cn_nameptr - cnp->cn_namelen + 1;
#ifdef INVARIANTS
	if (ndp->ni_pathlen != fpl->debug.ni_pathlen) {
		panic("%s: mismatch (%zu != %zu) nulchar %p nameptr %p [%s] ; full string [%s]\n",
		    __func__, ndp->ni_pathlen, fpl->debug.ni_pathlen, fpl->nulchar,
		    cnp->cn_nameptr, cnp->cn_nameptr, cnp->cn_pnbuf);
	}
#endif

	if (__predict_false(len + ndp->ni_pathlen > MAXPATHLEN)) {
		return (ENAMETOOLONG);
	}

	if (__predict_false(ndp->ni_loopcnt++ >= MAXSYMLINKS)) {
		return (ELOOP);
	}

	adjust = len;
	if (ndp->ni_pathlen > 1) {
		bcopy(ndp->ni_next, cnp->cn_pnbuf + len, ndp->ni_pathlen);
	} else {
		if (cache_fpl_istrailingslash(fpl)) {
			adjust = len + 1;
			cnp->cn_pnbuf[len] = '/';
			cnp->cn_pnbuf[len + 1] = '\0';
		} else {
			cnp->cn_pnbuf[len] = '\0';
		}
	}
	bcopy(string, cnp->cn_pnbuf, len);

	ndp->ni_pathlen += adjust;
	cache_fpl_pathlen_add(fpl, adjust);
	cnp->cn_nameptr = cnp->cn_pnbuf;
	fpl->nulchar = &cnp->cn_nameptr[ndp->ni_pathlen - 1];
	fpl->tvp = NULL;
	return (0);
}