.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later .. c:namespace:: DTV.dmx

.. _dmx_fread:

======================= Digital TV demux read()

Name

Digital TV demux read()

Synopsis

.. c:function:: size_t read(int fd, void *buf, size_t count)

Arguments

fd File descriptor returned by a previous call to :c:func:open().

buf Buffer to be filled

count Max number of bytes to read

Description

This system call returns filtered data, which might be section or Packetized Elementary Stream (PES) data. The filtered data is transferred from the driver's internal circular buffer to buf. The maximum amount of data to be transferred is implied by count.

.. note::

if a section filter created with :c:type:DMX_CHECK_CRC <dmx_sct_filter_params> flag set, data that fails on CRC check will be silently ignored.

Return Value

On success 0 is returned.

On error -1 is returned, and the errno variable is set appropriately.

.. tabularcolumns:: |p{2.5cm}|p{15.0cm}|

.. flat-table:: :header-rows: 0 :stub-columns: 0 :widths: 1 16

-  -  ``EWOULDBLOCK``
   -  No data to return and ``O_NONBLOCK`` was specified.

-  -  ``EOVERFLOW``
   -  The filtered data was not read from the buffer in due time,
  resulting in non-read data being lost. The buffer is flushed.

-  -  ``ETIMEDOUT``
   -  The section was not loaded within the stated timeout period.
      See ioctl :ref:`DMX_SET_FILTER` for how to set a timeout.

-  -  ``EFAULT``
   -  The driver failed to write to the callers buffer due to an
      invalid \*buf pointer.

The generic error codes are described at the :ref:Generic Error Codes <gen-errors> chapter.