[mixed$data = NULL]
eio_open opens file specified by path in access mode mode with
Path of the file to be opened.
In some SAPIs(e.g. PHP-FPM) it could fail, if you don't specify full path.
One of EIO_O_* constants, or their combinations. EIO_O_* constants have the same meaning, as their corresponding O_* counterparts defined in fnctl.h C header file. Default is EIO_O_RDWR.
One of EIO_S_I* constants, or their combination (via bitwise OR operator). The constants have the same meaning as their S_I* counterparts defined in sys/stat.h C header file. Required, if a file is created. Otherwise ignored.
The request priority: EIO_PRI_DEFAULT, EIO_PRI_MIN, EIO_PRI_MAX, or null. If null passed, pri internally is set to EIO_PRI_DEFAULT.
callback function is called when the request is done. It should match the following prototype:
void callback(mixed $data, int $result[, resource $req]);
is custom data passed to the request.
request-specific result value; basically, the value returned by corresponding system call.
is optional request resource which can be used with functions like eio_get_last_error
Arbitrary variable passed to callback.
eio_open returns file descriptor in result argument of callback on success; otherwise, result is equal to -1.