.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
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.. c:namespace:: DTV.dmx
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.. _dmx_fread:
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=======================
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Digital TV demux read()
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=======================
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Name
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----
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Digital TV demux read()
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Synopsis
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--------
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.. c:function:: size_t read(int fd, void *buf, size_t count)
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Arguments
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---------
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``fd``
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File descriptor returned by a previous call to :c:func:`open()`.
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``buf``
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Buffer to be filled
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``count``
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Max number of bytes to read
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Description
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-----------
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This system call returns filtered data, which might be section or Packetized
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Elementary Stream (PES) data. The filtered data is transferred from
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the driver’s internal circular buffer to ``buf``. The maximum amount of data
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to be transferred is implied by count.
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.. note::
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if a section filter created with
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:c:type:`DMX_CHECK_CRC <dmx_sct_filter_params>` flag set,
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data that fails on CRC check will be silently ignored.
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Return Value
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------------
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On success 0 is returned.
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On error -1 is returned, and the ``errno`` variable is set
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appropriately.
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.. tabularcolumns:: |p{2.5cm}|p{15.0cm}|
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.. flat-table::
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 16
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- - ``EWOULDBLOCK``
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- No data to return and ``O_NONBLOCK`` was specified.
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- - ``EOVERFLOW``
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- The filtered data was not read from the buffer in due time,
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resulting in non-read data being lost. The buffer is flushed.
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- - ``ETIMEDOUT``
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- The section was not loaded within the stated timeout period.
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See ioctl :ref:`DMX_SET_FILTER` for how to set a timeout.
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- - ``EFAULT``
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- The driver failed to write to the callers buffer due to an
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invalid \*buf pointer.
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The generic error codes are described at the
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:ref:`Generic Error Codes <gen-errors>` chapter.
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