1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2.. c:namespace:: DTV.dmx 3 4.. _dmx_fread: 5 6======================= 7Digital TV demux read() 8======================= 9 10Name 11---- 12 13Digital TV demux read() 14 15Synopsis 16-------- 17 18.. c:function:: size_t read(int fd, void *buf, size_t count) 19 20Arguments 21--------- 22 23``fd`` 24 File descriptor returned by a previous call to :c:func:`open()`. 25 26 ``buf`` 27 Buffer to be filled 28 29``count`` 30 Max number of bytes to read 31 32Description 33----------- 34 35This system call returns filtered data, which might be section or Packetized 36Elementary Stream (PES) data. The filtered data is transferred from 37the driver’s internal circular buffer to ``buf``. The maximum amount of data 38to be transferred is implied by count. 39 40.. note:: 41 42 if a section filter created with 43 :c:type:`DMX_CHECK_CRC <dmx_sct_filter_params>` flag set, 44 data that fails on CRC check will be silently ignored. 45 46Return Value 47------------ 48 49On success 0 is returned. 50 51On error -1 is returned, and the ``errno`` variable is set 52appropriately. 53 54.. tabularcolumns:: |p{2.5cm}|p{15.0cm}| 55 56.. flat-table:: 57 :header-rows: 0 58 :stub-columns: 0 59 :widths: 1 16 60 61 - - ``EWOULDBLOCK`` 62 - No data to return and ``O_NONBLOCK`` was specified. 63 64 - - ``EOVERFLOW`` 65 - The filtered data was not read from the buffer in due time, 66 resulting in non-read data being lost. The buffer is flushed. 67 68 - - ``ETIMEDOUT`` 69 - The section was not loaded within the stated timeout period. 70 See ioctl :ref:`DMX_SET_FILTER` for how to set a timeout. 71 72 - - ``EFAULT`` 73 - The driver failed to write to the callers buffer due to an 74 invalid \*buf pointer. 75 76The generic error codes are described at the 77:ref:`Generic Error Codes <gen-errors>` chapter. 78