The dio_fcntl function performs the operation specified by cmd on the file descriptor fd. Some commands require additional arguments args to be supplied.
The file descriptor returned by dio_open.
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 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
whence - 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)
Returns the result of the C call.
This function is not implemented on Windows platforms.