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To: freebsd-bugs@FreeBSD.ORG
Cc: tetsuya@secom-sis.co.jp, huntting@glarp.com
Subject: flock() EOPNOTSUPP for special files
Date: Mon, 17 Aug 1998 18:24:09 -0600
From: Brad Huntting <huntting@glarp.com>
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Dear FreeBSD folk:

I was having a problem using flock() on a tty device.  In the
process of investigating the problem I found that advisory locking
is not supported on special files at all.

This is contrary to nearly every other implementation of flock()
I can find (flock(open(/dev/tty)) works find on linux, hpux10,
bsdos3, sunos5, openbsd).

The patch below will allow flock() to work on any special device.
Note that this does not change the behavior of fcntl() since it
check f_type before calling VOP_ADVLOCK.  Other open trouble tickets
which are probably caused by this bug (or feature) include "kern/4243"
and "ports/3205".


thanx much,
brad


*** kern/kern_descrip.c.orig	Sat Dec 21 12:04:24 1996
--- kern/kern_descrip.c	Mon Aug 17 17:16:10 1998
***************
*** 927,934 ****
  	if ((unsigned)uap->fd >= fdp->fd_nfiles ||
  	    (fp = fdp->fd_ofiles[uap->fd]) == NULL)
  		return (EBADF);
- 	if (fp->f_type != DTYPE_VNODE)
- 		return (EOPNOTSUPP);
  	vp = (struct vnode *)fp->f_data;
  	lf.l_whence = SEEK_SET;
  	lf.l_start = 0;
--- 927,932 ----
*** miscfs/specfs/spec_vnops.c.orig	Sun Oct  6 15:19:33 1996
--- miscfs/specfs/spec_vnops.c	Mon Aug 17 18:08:52 1998
***************
*** 62,67 ****
--- 62,72 ----
  
  #include <miscfs/specfs/specdev.h>
  
+ #include <ufs/ufs/quota.h>
+ #include <ufs/ufs/inode.h>
+ #include <ufs/ufs/ufsmount.h>
+ #include <ufs/ufs/ufs_extern.h>
+ 
  static int	spec_ebadf __P((void));
  static int	spec_getattr __P((struct  vop_getattr_args *));
  
***************
*** 712,718 ****
  	} */ *ap;
  {
  
! 	return (EOPNOTSUPP);
  }
  
  /*
--- 717,723 ----
  	} */ *ap;
  {
  
! 	return ufs_advlock(ap);
  }
  
  /*

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