eio_read
(PECL eio >= 0.0.1dev)
eio_read — Read from a file descriptor at given offset.
Description
resource eio_read ( mixed $fd , int $length , int $offset , int $pri , callable $callback [, mixed $data = NULL ] ) 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, or NULL. If NULL passed, pri internally is set to EIO_PRI_DEFAULT.
callback
callback function 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
- eio_write
- eio_close
- eio_event_loop
← eio_poll
eio_readahead →
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