Re: locking utmp

["Miquel van Smoorenburg" <miquels@cistron.nl>]

In article <[🔎] 20020319003413.2730F22BF@lyta.coker.com.au>,
Russell Coker  <russell@coker.com.au> wrote:
>fcntl64(4, F_SETLKW, {type=F_RDLCK, whence=SEEK_SET, start=0, len=0}) = 0
>
>I need to know why it wants to lock a range of length 0.  Is this a bug or is 
>there some good reason for it?

The standard linux fcntl() manpage doesn't explain it, but google'ing
on "l_len zero" brings up manpages from other Unices which do:

http://www.tac.eu.org/cgi-bin/man-cgi?fcntl+2

    "Locks may start and extend beyond the current end of a file, but may not
     start or extend before the beginning of the file.  A lock is set to ex-
     tend to the largest possible value of the file offset for that file if
     l_len is set to zero. If l_whence and l_start point to the beginning of
     the file, and l_len is zero, the entire file is locked."

Mike.