DIO_FCNTL(3) 1 DIO_FCNTL(3)
dio_fcntl - Performs a c library fcntl on fd
SYNOPSIS
mixed dio_fcntl (resource $fd, int $cmd, [mixed $args])
DESCRIPTION
The dio_fcntl(3) function performs the operation specified by $cmd on the file descriptor $fd. Some commands require additional arguments
$args to be supplied.
PARAMETERS
o $fd
- The file descriptor returned by dio_open(3).
o $cmd
- Can be one of the following operations:
o F_SETLK - Lock is set or cleared. If the lock is held by someone else dio_fcntl(3) returns -1.
o F_SETLKW - like F_SETLK, but in case the lock is held by someone else, dio_fcntl(3) waits until the lock is released.
o F_GETLK - dio_fcntl(3) returns an associative array (as described above) if someone else prevents lock. If there is no
obstruction key "type" will set to F_UNLCK.
o F_DUPFD - finds the lowest numbered available file descriptor greater than or equal to $args and returns them.
o 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.
o $args
-$args is an associative array, when $cmd is F_SETLK or F_SETLLW, with the following keys:
o start - offset where lock begins
o length - size of locked area. zero means to end of file
o whence - Where l_start is relative to: can be SEEK_SET, SEEK_END and SEEK_CUR
o type - type of lock: can be F_RDLCK (read lock), F_WRLCK (write lock) or F_UNLCK (unlock)
RETURN VALUES
Returns the result of the C call.
EXAMPLES
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);
?>
NOTES
Note
This function is not implemented on Windows platforms.
PHP Documentation Group DIO_FCNTL(3)
