pSOSystem System Calls - Read

lock_f pHILE+ System Calls
lock_f Locks or unlocks part or all of an open file.
#include
unsigned long lock_f(
unsigned long fid, /* file identifier */
unsigned long startpos, /* starting lock position */
unsigned long bcount /* number of bytes to lock */
)
Volume Types
Description
Arguments
Return Value
pHILE+ formatted volumes.
lock_f() locks or unlocks part or all of an open file. Following a lock_f() system
call, only the task that set the lock can access the locked bytes and only through the
connection (the file identifier) used to set the lock.
A lock_f() call replaces any previous locks it set through the same connection
with the new lock. Thus, only one lock per connection can be set. lock_f() with
bcount = 0 is used to remove a lock.
A file can have as many locks as it has connections if the locks do not overlap. If a
task attempts to lock a region already locked through a different connection, an
error is returned, even if the two connections are from the same task.
fid Specifies the file identifier of the file to lock.
startpos Specifies the starting byte of the locked region.
bcount Specifies the length of the locked region in bytes.
This system call returns 0 on success or an error code on failure.
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