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

*** 25,36 ****
--- 25,47 ----
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   */
+ /*
+  * Copyright (c) 2013, Joyent, Inc. All Rights Reserved.
+  */
  
  
+ #ifndef EXTERN_H
+ #define EXTERN_H
+ 
+ #include <sys/types.h>
+ #include <sys/stat.h>
+ #include <port.h>
+ 
+ 
  #define WR(p, size) do { \
          if (write(STDOUT_FILENO, p, size) != (ssize_t)size) \
                  oerr(); \
          } while (0)
  
*** 46,55 ****
--- 57,67 ----
  
  struct file_info {
          FILE *fp;
          char *file_name;
          struct stat st;
+         file_obj_t fobj;
  };
  
  typedef struct file_info file_info_t;
  
  enum STYLE { NOTSET = 0, FBYTES, FLINES, RBYTES, RLINES, REVERSE };
*** 65,69 ****
--- 77,83 ----
  void oerr(void);
  int mapprint(struct mapinfo *, off_t, off_t);
  int maparound(struct mapinfo *, off_t);
  
  extern int Fflag, fflag, qflag, rflag, rval, no_files;
+ 
+ #endif  /* EXTERN_H */