3484 enhance and document tail follow support
Reviewed by: Joshua M. Clulow <jmc@joyent.com>

*** 22,31 ****
--- 22,35 ----
  /*
   * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
+ /*
+  * Copyright (c) 2013, Joyent, Inc. All rights reserved.
+  */
+ 
  #ifndef _SYS_PORT_IMPL_H
  #define _SYS_PORT_IMPL_H
  
  
  #ifdef  __cplusplus
*** 309,318 ****
--- 313,323 ----
  #define FOP_FILE_SETSECATTR     0x00020000
  #define FOP_FILE_SETATTR_ATIME  0x00040000
  #define FOP_FILE_SETATTR_MTIME  0x00080000
  #define FOP_FILE_SETATTR_CTIME  0x00100000
  #define FOP_FILE_LINK_SRC       0x00200000
+ #define FOP_FILE_TRUNC          0x00400000
  
  /*
   * File modification event.
   */
  #define FOP_MODIFIED_MASK       (FOP_FILE_WRITE|FOP_FILE_CREATE \
*** 337,350 ****
                                  |FOP_FILE_SYMLINK|FOP_FILE_SETATTR_CTIME \
                                  |FOP_FILE_LINK_SRC|FOP_FILE_SETSECATTR)
  
  
  /*
   * valid watchable events
   */
  #define FILE_EVENTS_MASK        (FILE_ACCESS|FILE_MODIFIED|FILE_ATTRIB \
!                                 |FILE_NOFOLLOW)
  /* --- End file events --- */
  
  /*
   * port_kstat_t contains the event port kernel values which are
   * exported to kstat.
--- 342,360 ----
                                  |FOP_FILE_SYMLINK|FOP_FILE_SETATTR_CTIME \
                                  |FOP_FILE_LINK_SRC|FOP_FILE_SETSECATTR)
  
  
  /*
+  * File trunc event
+  */
+ #define FOP_TRUNC_MASK          (FOP_FILE_TRUNC|FOP_FILE_CREATE)
+ 
+ /*
   * valid watchable events
   */
  #define FILE_EVENTS_MASK        (FILE_ACCESS|FILE_MODIFIED|FILE_ATTRIB \
!                                 |FILE_NOFOLLOW|FILE_TRUNC)
  /* --- End file events --- */
  
  /*
   * port_kstat_t contains the event port kernel values which are
   * exported to kstat.