eio_read
(PECL eio >= 0.0.1dev)
eio_read — Read from a file descriptor at given offset
Description
eio_read ( mixed $fd , int $length , int $offset , int $pri , callable $callback [, mixed $data = NULL ] ) : resource
eio_read() reads up to length bytes from fd file descriptor at offset. The read bytes are stored in result argument of callback.
Parameters
-
fd -
Stream, Socket resource, or numeric file descriptor
-
length -
Maximum number of bytes to read.
-
offset -
Offset within the file.
-
pri -
The request priority:
EIO_PRI_DEFAULT,EIO_PRI_MIN,EIO_PRI_MAX, ornull. Ifnullpassed,priinternally is set toEIO_PRI_DEFAULT. -
callback -
callbackfunction is called when the request is done. It should match the following prototype:void callback(mixed $data, int $result[, resource $req]);
-
data -
is custom data passed to the request.
-
result -
request-specific result value; basically, the value returned by corresponding system call.
-
req -
is optional request resource which can be used with functions like eio_get_last_error()
-
-
data -
Arbitrary variable passed to
callback.
Return Values
eio_read() stores read bytes in result argument of callback function.
Examples
Example #1 eio_read() example
<?php
// Open a temporary file and write some bytes there
$temp_filename = "eio-temp-file.tmp";
$fp = fopen($temp_filename, "w");
fwrite($fp, "1234567890");
fclose($fp);
/* Is called when eio_read() is done */
function my_read_cb($data, $result) {
global $temp_filename;
// Output read bytes
var_dump($result);
// Close file
eio_close($data);
eio_event_loop();
// Remove temporary file
@unlink($temp_filename);
}
/* Is called when eio_open() is done */
function my_file_opened_callback($data, $result) {
// $result should contain the file descriptor
if ($result > 0) {
// Read 5 bytes starting from third
eio_read($result, 5, 2, EIO_PRI_DEFAULT, "my_read_cb", $result);
eio_event_loop();
} else {
// eio_open() failed
unlink($data);
}
}
// Open the file for reading and writing
eio_open($temp_filename, EIO_O_RDWR, NULL,
EIO_PRI_DEFAULT, "my_file_opened_callback", $temp_filename);
eio_event_loop();
?> The above example will output something similar to:
string(5) "34567"
See Also
- eio_open() - Opens a file
- eio_write() - Write to file
- eio_close() - Close file
- eio_event_loop() - Polls libeio until all requests proceeded
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Licensed under the Creative Commons Attribution License v3.0 or later.
https://www.php.net/manual/en/function.eio-read.php