Php/docs/function.eio-read

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• Eio Functions
• Read from a file descriptor at given offset

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, 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 writingeio_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