dio_fcntl

PHP 手册
后退		前进

说明

mixed dio_fcntl ( resource fd, int cmd [, mixed args] )

The dio_fcntl() function performs the operation specified by cmd on the file descriptor fd. Some commands require additional arguments args to be supplied.

注: 本函数未在 Windows 平台下实现。

参数

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 above) 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:

"start" - offset where lock begins
"length" - size of locked area. zero means to end of file
"wenth" - Where l_start is relative to: can be SEEK_SET, SEEK_END and SEEK_CUR
"type" - type of lock: can be F_RDLCK (read lock), F_WRLCK (write lock) or F_UNLCK (unlock)

返回值

Returns the result of the C call.

范例

例子 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 succesfully set/cleared" ; } dio_close ( $fd ); ?>