[src/trunk]: src/sys/fs/sysvbfs Fix bug in readdir loop condition.

[pooka <pooka%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/78ce40bc31e1
branches:  trunk
changeset: 341606:78ce40bc31e1
user:      pooka <pooka%NetBSD.org@localhost>
date:      Fri Nov 13 13:36:54 2015 +0000

description:
Fix bug in readdir loop condition.

Reading all dirents using a small buffer and multiple calls now works.

Bug found by "Shamar" on #rumpkernel

diffstat:

 sys/fs/sysvbfs/sysvbfs_vnops.c |  17 ++++++++++-------
 1 files changed, 10 insertions(+), 7 deletions(-)

diffs (50 lines):

diff -r b92996208503 -r 78ce40bc31e1 sys/fs/sysvbfs/sysvbfs_vnops.c
--- a/sys/fs/sysvbfs/sysvbfs_vnops.c    Fri Nov 13 11:43:26 2015 +0000
+++ b/sys/fs/sysvbfs/sysvbfs_vnops.c    Fri Nov 13 13:36:54 2015 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sysvbfs_vnops.c,v 1.58 2015/04/04 13:28:36 riastradh Exp $     */
+/*     $NetBSD: sysvbfs_vnops.c,v 1.59 2015/11/13 13:36:54 pooka Exp $ */
 
 /*-
  * Copyright (c) 2004 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sysvbfs_vnops.c,v 1.58 2015/04/04 13:28:36 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sysvbfs_vnops.c,v 1.59 2015/11/13 13:36:54 pooka Exp $");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -642,15 +642,18 @@
        if ((i + n) > bfs->n_dirent)
                n = bfs->n_dirent - i;
 
-       for (file = &bfs->dirent[i]; i < n; file++) {
-               if (file->inode == 0)
-                       continue;
+       DPRINTF("%s 1: %d %d %d\n", __func__, i, n, bfs->n_dirent);
+       for (file = &bfs->dirent[i]; n > 0; file++, i++) {
                if (i == bfs->max_dirent) {
                        DPRINTF("%s: file system inconsistent.\n",
                            __func__);
                        break;
                }
-               i++;
+               if (file->inode == 0)
+                       continue;
+
+               /* ok, we have a live one here */
+               n--;
                memset(dp, 0, sizeof(struct dirent));
                dp->d_fileno = file->inode;
                dp->d_type = file->inode == BFS_ROOT_INODE ? DT_DIR : DT_REG;
@@ -663,7 +666,7 @@
                        return error;
                }
        }
-       DPRINTF("%s: %d %d %d\n", __func__, i, n, bfs->n_dirent);
+       DPRINTF("%s 2: %d %d %d\n", __func__, i, n, bfs->n_dirent);
        *ap->a_eofflag = (i == bfs->n_dirent);
 
        free(dp, M_BFS);