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.. 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}|
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- - ``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.
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