Add the utility function vn_commname() to retrieve the command name

from the vfs namecache, when available.

Reviewed by:	rwatson, rdivacky
Tested by:	pho

2 files changed, 20 insertions, 0 deletions

diff --git a/sys/kern/vfs_cache.c b/sys/kern/vfs_cache.c
index 6e49a1b..3d254f3 100644
--- a/sys/kern/vfs_cache.c
+++ b/sys/kern/vfs_cache.c
@@ -838,3 +838,22 @@ vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
 	*retbuf = bp;
 	return (0);
 }
+
+int
+vn_commname(struct vnode *vp, char *buf, u_int buflen)
+{
+	struct namecache *ncp;
+	int l;
+
+	CACHE_LOCK();
+	ncp = TAILQ_FIRST(&vp->v_cache_dst);
+	if (!ncp) {
+		CACHE_UNLOCK();
+		return (ENOENT);
+	}
+	l = min(ncp->nc_nlen, buflen - 1);
+	memcpy(buf, ncp->nc_name, l);
+	CACHE_UNLOCK();
+	buf[l] = '\0';
+	return (0);
+}
diff --git a/sys/sys/vnode.h b/sys/sys/vnode.h
index feeac69..b82ab13 100644
--- a/sys/sys/vnode.h
+++ b/sys/sys/vnode.h
@@ -579,6 +579,7 @@ int	speedup_syncer(void);
 	vn_fullpath(FIRST_THREAD_IN_PROC(p), (p)->p_textvp, rb, rfb)
 int	vn_fullpath(struct thread *td, struct vnode *vn,
 	    char **retbuf, char **freebuf);
+int	vn_commname(struct vnode *vn, char *buf, u_int buflen);
 int	vaccess(enum vtype type, mode_t file_mode, uid_t file_uid,
 	    gid_t file_gid, mode_t acc_mode, struct ucred *cred,
 	    int *privused);