(PECL eio >= 0.0.1dev)
eio_sendfile — Transfer data between file descriptors
$out_fd
, mixed $in_fd
, int $offset
, int $length
[, int $pri
[, callable $callback
[, string $data
]]] ) : resourceeio_sendfile() copies data between one file descriptor and another. See SENDFILE(2) man page for details.
out_fdOutput stream, Socket resource, or file descriptor. Should be opened for writing.
in_fdInput stream, Socket resource, or file descriptor. Should be opened for reading.
offsetOffset within the source file.
lengthNumber of bytes to copy.
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.
eio_sendfile() returns request resource on success or FALSE on error.