+ register struct fs *fs = ip->i_fs;
+ daddr_t lbn = lblkno(fs, offset);
+ int base = blkoff(fs, offset);
+ int bsize = blksize(fs, ip, lbn);
+ daddr_t bn = fsbtodb(fs, bmap(ip, lbn, B_WRITE, base, bsize));
+ register struct buf *bp;
+
+ if (u.u_error)
+ return (0);
+ bp = bread(ip->i_dev, bn, bsize);
+ if (bp->b_flags & B_ERROR) {
+ brelse(bp);
+ return (0);
+ }
+ if (res)
+ *res = bp->b_un.b_addr + base;
+ return (bp);
+}
+
+/*
+ * Check if a directory is empty or not.
+ * Inode supplied must be locked.
+ *
+ * Using a struct dirtemplate here is not precisely
+ * what we want, but better than using a struct direct.
+ *
+ * NB: does not handle corrupted directories.
+ */
+dirempty(ip)
+ register struct inode *ip;
+{
+ register off_t off;
+ struct dirtemplate dbuf;
+ register struct direct *dp = (struct direct *)&dbuf;
+ int error, count;
+#define MINDIRSIZ (sizeof (struct dirtemplate) / 2)
+
+ for (off = 0; off < ip->i_size; off += dp->d_reclen) {
+ error = rdwri(UIO_READ, ip, (caddr_t)dp, MINDIRSIZ,
+ off, 1, &count);
+ /*
+ * Since we read MINDIRSIZ, residual must
+ * be 0 unless we're at end of file.
+ */
+ if (error || count != 0)
+ return (0);
+ /* skip empty entries */
+ if (dp->d_ino == 0)
+ continue;
+ /* accept only "." and ".." */
+ if (dp->d_namlen > 2)
+ return (0);
+ if (dp->d_name[0] != '.')
+ return (0);
+ /*
+ * At this point d_namlen must be 1 or 2.
+ * 1 implies ".", 2 implies ".." if second
+ * char is also "."
+ */
+ if (dp->d_namlen == 1 || dp->d_name[1] == '.')
+ continue;
+ return (0);
+ }
+ return (1);
+}
+
+/*
+ * Check if source directory is in the path of the target directory.
+ * Target is supplied locked, source is unlocked.
+ * The target is always iput() before returning.
+ */
+checkpath(source, target)
+ struct inode *source, *target;
+{
+ struct dirtemplate dirbuf;
+ register struct inode *ip;
+ int error = 0;
+
+ ip = target;
+ if (ip->i_number == source->i_number) {
+ error = EEXIST;
+ goto out;
+ }
+ if (ip->i_number == ROOTINO)
+ goto out;
+
+ for (;;) {
+ if ((ip->i_mode&IFMT) != IFDIR) {
+ error = ENOTDIR;
+ break;
+ }
+ error = rdwri(UIO_READ, ip, (caddr_t)&dirbuf,
+ sizeof (struct dirtemplate), (off_t)0, 1, (int *)0);
+ if (error != 0)
+ break;
+ if (dirbuf.dotdot_namlen != 2 ||
+ bcmp(dirbuf.dotdot_name, "..", 3) != 0) {
+ error = ENOTDIR;
+ break;
+ }
+ if (dirbuf.dotdot_ino == source->i_number) {
+ error = EINVAL;
+ break;
+ }
+ if (dirbuf.dotdot_ino == ROOTINO)
+ break;
+ iput(ip);
+ ip = iget(ip->i_dev, ip->i_fs, dirbuf.dotdot_ino);
+ if (ip == NULL) {
+ error = u.u_error;
+ break;
+ }
+ }