EIO_READ(3) 1 EIO_READ(3)
eio_read - Read from a file descriptor at given offset.
SYNOPSIS
resource eio_read (mixed $fd, int $length, int $offset, int $pri, callable $callback, [mixed $data = NULL])
DESCRIPTION
eio_read(3) reads up to $length bytes from $fd file descriptor at $offset. The read bytes are stored in $result argument of $callback.
PARAMETERS
o $fd
- Stream, Socket resource, or numeric file descriptor
o $length
- Maximum number of bytes to read.
o $offset
- Offset within the file.
o $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.
o $callback
-$callback function is called when the request is done. It should match the following prototype:
void callback(mixed $data, int $result[, resource $req]);
o $data
-is custom data passed to the request.
o $result
-request-specific result value; basically, the value returned by corresponding system call.
o $req
-is optional request resource which can be used with functions like eio_get_last_error(3)
o $data
- Arbitrary variable passed to $callback.
RETURN VALUES
eio_read(3) stores read bytes in $result argument of $callback function.
EXAMPLES
Example #1
eio_read(3) 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.
PHP Documentation Group EIO_READ(3)