php man page for eio_read

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.
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