Seek to a position

说明

eio_seek(
    mixed $fd,
    int $offset,
    int $whence,
    int $pri = EIO_PRI_DEFAULT,
    callable $callback = NULL,
    mixed $data = NULL
): resource

eio_seek() repositions the offset of the open file associated with stream, Socket instance, or file descriptor specified by fd to the argument offset according to the directive whence.

参数

fd

Stream, Socket instance, or numeric file descriptor.

offset

Starting point from which data is to be read.

whence

whence values are:

EIO_SEEK_SET - Set position equal to offset bytes.
EIO_SEEK_CUR - Set position to current location plus offset.
EIO_SEEK_END - Set position to end-of-file plus offset.

pri

请求的优先级：EIO_PRI_DEFAULT，EIO_PRI_MIN，EIO_PRI_MAX 或 null。如果是 null，pri 将设为 EIO_PRI_DEFAULT。

callback

callback 函数在请求完成时被调用。其应匹配一下原型：

void callback(mixed $data, int $result[, resource $req]);

data: 传递给请求的用户数据。
result: 针对请求的结果的值。通常是相应的系统调用返回的值。
req: 可选的请求资源，可被 eio_get_last_error() 之类的函数使用。

data

Arbitrary variable passed to callback.

返回值

eio_seek() returns request resource on success, 或者在失败时返回 false.