doslock

Purpose

     Locks or unlocks a region in a DOS file.

Library

     DOS Services Library (libdos.a)

Syntax

     #include <dos.h>

     int doslock (dosfile, offset, length, code)
     DOSFILE dosfile;
     int offset, length, code;

Description

     The doslock  subroutine provides  a simple  mechanism for
     disallowing read/write  access by other processes  to the
     file whose handle is  specified by the dosfile parameter.
     If code is  L_LOCK, and no part of the  region is already
     locked by another process, then the region is locked.  If
     code is L_UNLOCK,  and the exact region  has already been
     locked  by  the  current  process,  then  the  region  is
     unlocked.

Return Value

     If  the  doslock  subroutine  fails, a  value  of  -1  is
     returned and doserrno is set  to indicate the error.  For
     L_LOCK,  the error  means  that the  lock failed,  either
     because  the region  was already  locked, or  because the
     lock list  is full.  For  L_UNLOCK, the error  means that
     the region was not locked.

Related Information

     In  this book:   "DOS services  library," "dosread,"  and
     "doswrite."