+ /*
+ * 2) If target doesn't exist, link the target
+ * to the source and unlink the source.
+ * Otherwise, rewrite the target directory
+ * entry to reference the source inode and
+ * expunge the original entry's existence.
+ */
+ if (xp == NULL) {
+ if (dp->i_dev != ip->i_dev)
+ panic("rename: EXDEV");
+ /*
+ * Account for ".." in new directory.
+ * When source and destination have the same
+ * parent we don't fool with the link count.
+ */
+ if (doingdirectory && newparent) {
+ if ((unsigned short)dp->i_nlink >= LINK_MAX) {
+ error = EMLINK;
+ goto bad;
+ }
+ dp->i_nlink++;
+ dp->i_flag |= ICHG;
+ if (error = VOP_UPDATE(ITOV(dp), &time, &time, 1))
+ goto bad;
+ }
+ if (error = ufs_direnter(ip, tndp)) {
+ if (doingdirectory && newparent) {
+ dp->i_nlink--;
+ dp->i_flag |= ICHG;
+ (void)VOP_UPDATE(ITOV(dp), &time, &time, 1);
+ }
+ goto bad;
+ }
+ ufs_iput(dp);
+ } else {
+ if (xp->i_dev != dp->i_dev || xp->i_dev != ip->i_dev)
+ panic("rename: EXDEV");
+ /*
+ * Short circuit rename(foo, foo).
+ */
+ if (xp->i_number == ip->i_number)
+ panic("rename: same file");
+ /*
+ * If the parent directory is "sticky", then the user must
+ * own the parent directory, or the destination of the rename,
+ * otherwise the destination may not be changed (except by
+ * root). This implements append-only directories.
+ */
+ if ((dp->i_mode & ISVTX) && tndp->ni_cred->cr_uid != 0 &&
+ tndp->ni_cred->cr_uid != dp->i_uid &&
+ xp->i_uid != tndp->ni_cred->cr_uid) {
+ error = EPERM;
+ goto bad;
+ }
+ /*
+ * Target must be empty if a directory and have no links
+ * to it. Also, ensure source and target are compatible
+ * (both directories, or both not directories).
+ */
+ if ((xp->i_mode&IFMT) == IFDIR) {
+ if (!ufs_dirempty(xp, dp->i_number, tndp->ni_cred) ||
+ xp->i_nlink > 2) {
+ error = ENOTEMPTY;
+ goto bad;
+ }
+ if (!doingdirectory) {
+ error = ENOTDIR;
+ goto bad;
+ }
+ cache_purge(ITOV(dp));
+ } else if (doingdirectory) {
+ error = EISDIR;
+ goto bad;
+ }
+ if (error = ufs_dirrewrite(dp, ip, tndp))
+ goto bad;
+ /*
+ * If the target directory is in the same
+ * directory as the source directory,
+ * decrement the link count on the parent
+ * of the target directory.
+ */
+ if (doingdirectory && !newparent) {
+ dp->i_nlink--;
+ dp->i_flag |= ICHG;
+ }
+ ufs_iput(dp);
+ /*
+ * Adjust the link count of the target to
+ * reflect the dirrewrite above. If this is
+ * a directory it is empty and there are
+ * no links to it, so we can squash the inode and
+ * any space associated with it. We disallowed
+ * renaming over top of a directory with links to
+ * it above, as the remaining link would point to
+ * a directory without "." or ".." entries.
+ */
+ xp->i_nlink--;
+ if (doingdirectory) {
+ if (--xp->i_nlink != 0)
+ panic("rename: linked directory");
+ error = VOP_TRUNCATE(ITOV(xp), (u_long)0, IO_SYNC);
+ }
+ xp->i_flag |= ICHG;
+ ufs_iput(xp);
+ xp = NULL;