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(PHP 4 >= 4.2.0, PHP 5 < 5.1.0)
dio_fcntl — Performs a c library fcntl on fd
The dio_fcntl() function performs the
operation specified by cmd
on the file
descriptor fd
. Some commands require
additional arguments args
to be supplied.
fd
The file descriptor returned by dio_open().
cmd
Can be one of the following operations:
F_SETLK
- Lock is set or cleared. If the lock
is held by someone else dio_fcntl() returns
-1.
F_SETLKW
- like F_SETLK
,
but in case the lock is held by someone else,
dio_fcntl() waits until the lock is released.
F_GETLK
- dio_fcntl()
returns an associative array (as described below) if someone else
prevents lock. If there is no obstruction key "type" will set
to F_UNLCK
.
F_DUPFD
- finds the lowest numbered available
file descriptor greater than or equal to args
and returns them.
F_SETFL
- Sets the file descriptors flags to
the value specified by args
, which can be
O_APPEND
, O_NONBLOCK
or
O_ASYNC
. To use O_ASYNC
you will need to use the PCNTL
extension.
args
args
is an associative array, when
cmd
is F_SETLK
or
F_SETLLW
, with the following keys:
Returns the result of the C call.
Example #1 Setting and clearing a lock
<?php
$fd = dio_open('/dev/ttyS0', O_RDWR);
if (dio_fcntl($fd, F_SETLK, Array("type"=>F_WRLCK)) == -1) {
// the file descriptor appears locked
echo "The lock can not be cleared. It is held by someone else.";
} else {
echo "Lock successfully set/cleared";
}
dio_close($fd);
?>
Note: This function is not implemented on Windows platforms.