Re: Enhance ptyfs to handle multiple instances.

[Ilya Zykov <netbsd%izyk.ru@localhost>]

Hello!

For not accumulate many changes and keep patch clear. 
I am sending some error fix and modifications for future work and discussion 
too. 
Please, if possible, include it in current tree.

Little explanations:
1. We shouldn't mount more than one ptyfs.(dependency from unmount order). 
   Panic, if unmount first mount without the rest.
2. Some changes for correct working inside chroot:
   If mount point is outside chroot we can't any more get pts pathname.
   Correct getting pathname if mount point inside chroot.

fs/ptyfs/ptyfs_vfsops.c |   21 ++++++++++++++-------
kern/tty_ptm.c          |    9 ++++++++-
2 files changed, 22 insertions(+), 8 deletions(-)

Ilya.

Index: nbcur/src/sys/fs/ptyfs/ptyfs_vfsops.c
diff -u nbcur/src/sys/fs/ptyfs/ptyfs_vfsops.c:1.1.1.1 
nbcur/src/sys/fs/ptyfs/ptyfs_vfsops.c:1.7
--- nbcur/src/sys/fs/ptyfs/ptyfs_vfsops.c:1.1.1.1       Tue Mar  4 22:16:03 2014
+++ nbcur/src/sys/fs/ptyfs/ptyfs_vfsops.c       Wed Mar 19 15:41:47 2014
@@ -109,14 +109,16 @@
        buf = malloc(MAXBUF, M_TEMP, M_WAITOK);
        bp = buf + MAXBUF;
        *--bp = '\0';
-       error = getcwd_common(cwdi->cwdi_rdir, rootvnode, &bp,
+       error = getcwd_common(mp->mnt_vnodecovered, cwdi->cwdi_rdir, &bp,
            buf, MAXBUF / 2, 0, l);
-       if (error)      /* XXX */
+       if (error) {    /* Mount point is out of rdir */
+               rv = NULL;
                goto out;
+       }
 
        len = strlen(bp);
        if (len < sizeof(mp->mnt_stat.f_mntonname))     /* XXX */
-               rv += len;
+               rv += strlen(rv) - len;
 out:
        free(buf, M_TEMP);
        return rv;
@@ -128,6 +130,7 @@
 {
        struct mount *mp = pt->arg;
        size_t len;
+       const char *np;
 
        switch (ms) {
        case 'p':
@@ -135,9 +138,13 @@
                len = snprintf(tbuf, bufsiz, "/dev/null");
                break;
        case 't':
-               len = snprintf(tbuf, bufsiz, "%s/%llu", ptyfs__getpath(l, mp),
-                   (unsigned long long)minor(dev));
-               break;
+               np = ptyfs__getpath(l, mp);
+               if ( np ) {
+                       len = snprintf(tbuf, bufsiz, "%s/%llu", np,
+                               (unsigned long long)minor(dev));
+                       break;
+               }
+               return EOPNOTSUPP;
        default:
                return EINVAL;
        }
@@ -241,7 +248,7 @@
                return 0;
        }
 
-#if 0
+#if 1
        /* Don't allow more than one mount */
        if (ptyfs_count)
                return EBUSY;
Index: nbcur/src/sys/kern/tty_ptm.c
diff -u nbcur/src/sys/kern/tty_ptm.c:1.1.1.2 nbcur/src/sys/kern/tty_ptm.c:1.2
--- nbcur/src/sys/kern/tty_ptm.c:1.1.1.2        Mon Mar 17 15:46:10 2014
+++ nbcur/src/sys/kern/tty_ptm.c        Wed Mar 19 12:59:47 2014
@@ -381,7 +381,9 @@
                        goto bad;
 
                /* now, put the indices and names into struct ptmget */
-               return pty_fill_ptmget(l, newdev, cfd, sfd, data);
+               if ((error = pty_fill_ptmget(l, newdev, cfd, sfd, data)) != 0 )
+                       break;  /* goto bad2 */
+               return 0;
        default:
 #ifdef COMPAT_60
                error = compat_60_ptmioctl(dev, cmd, data, flag, l);
@@ -391,6 +393,11 @@
                DPRINTF(("ptmioctl EINVAL\n"));
                return EINVAL;
        }
+/* bad2: close sfd too */
+       fp = fd_getfile(sfd);
+       if (fp != NULL) {
+               fd_close(sfd);
+       }
  bad:
        fp = fd_getfile(cfd);
        if (fp != NULL) {