HELP LOCKF John Williams, Feb 1989
LIB * LOCKF is a simple Pop-11 interface to the C library function
lockf, a tool for file locking. The locks created by lockf are advisory
(they do not affect file access permissions), and ephemeral (they only
exist for the duration of the process that creates the lock). See
MAN * LOCKF for full details.
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1 Procedures defined by LIB LOCKF
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syslockf(device, lock_op, nbytes) -> success_flag [procedure]
Applies the lock operation lock_op to the file described by
device (which must be writeable). nbytes specifies the number of
bytes after the current file pointer to lock; if 0, the entire
file is locked. The result success_flag is true if the lock
operation succeeds; and false if the lock operation fails
because the file is already locked by another process. An error
is signalled if lock_op fails for any other reason.
lock_op must be one of the following values:
Integer Macro Function
0 F_ULOCK Unlock a previously locked section
1 F_LOCK Lock a section
2 F_TLOCK Test and lock a section (non-blocking)
3 F_TEST Test section for other process' locks
Note that calls to syslockf with lock_op = F_LOCK are
uninterruptable. Use syslock if this is a problem.
syslock(device, wait) -> locked [procedure]
Attempts to lock the file described by device. If wait is true,
will wait if necessary till the file is free. Returns true if
the file was succesfully locked, and false otherwise.
sysunlock(device) -> unlocked [procedure]
Attempts to unlock the file described by device, returning true
if succesful, false otherwise.
--- C.unix/help/lockf
--- Copyright University of Sussex 1995. All rights reserved.