dio_fcntl
(PHP 4 >= 4.2.0, PHP 5 <= 5.0.5)
dio_fcntl — Performs a c library fcntl on fd
Description
The dio_fcntl() function performs the
operation specified by cmd on the file
descriptor fd. Some commands require
additional arguments args to be supplied.
Parameters
-
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- likeF_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 toF_UNLCK. -
F_DUPFD- finds the lowest numbered available file descriptor greater than or equal toargsand returns them. -
F_SETFL- Sets the file descriptors flags to the value specified byargs, which can beO_APPEND,O_NONBLOCKorO_ASYNC. To useO_ASYNCyou will need to use the PCNTL extension.
-
-
args -
argsis an associative array, whencmdisF_SETLKorF_SETLLW, with the following keys:-
start - offset where lock begins
-
length - size of locked area. zero means to end of file
-
whence - Where l_start is relative to: can be
SEEK_SET,SEEK_ENDandSEEK_CUR -
type - type of lock: can be
F_RDLCK(read lock),F_WRLCK(write lock) orF_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.
Коментарии
Actually, there's a small typo in the above docs. The parameter for where l_start is relative to is actually "whence" and not "wenth" like stated.