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.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
.. c:namespace:: V4L
.. _VIDIOC_REMOVE_BUFS:
************************
ioctl VIDIOC_REMOVE_BUFS
************************
Name
====
VIDIOC_REMOVE_BUFS - Removes buffers from a queue
Synopsis
========
.. c:macro:: VIDIOC_REMOVE_BUFS
``int ioctl(int fd, VIDIOC_REMOVE_BUFS, struct v4l2_remove_buffers *argp)``
Arguments
=========
``fd``
File descriptor returned by :c:func:`open()`.
``argp``
Pointer to struct :c:type:`v4l2_remove_buffers`.
Description
===========
Applications can optionally call the :ref:`VIDIOC_REMOVE_BUFS` ioctl to
remove buffers from a queue.
:ref:`VIDIOC_CREATE_BUFS` ioctl support is mandatory to enable :ref:`VIDIOC_REMOVE_BUFS`.
This ioctl is available if the ``V4L2_BUF_CAP_SUPPORTS_REMOVE_BUFS`` capability
is set on the queue when :c:func:`VIDIOC_REQBUFS` or :c:func:`VIDIOC_CREATE_BUFS`
are invoked.
.. c:type:: v4l2_remove_buffers
.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
.. flat-table:: struct v4l2_remove_buffers
:header-rows: 0
:stub-columns: 0
:widths: 1 1 2
* - __u32
- ``index``
- The starting buffer index to remove. This field is ignored if count == 0.
* - __u32
- ``count``
- The number of buffers to be removed with indices 'index' until 'index + count - 1'.
All buffers in this range must be valid and in DEQUEUED state.
:ref:`VIDIOC_REMOVE_BUFS` will always check the validity of ``type`, if it is
invalid it returns ``EINVAL`` error code.
If count is set to 0 :ref:`VIDIOC_REMOVE_BUFS` will do nothing and return 0.
* - __u32
- ``type``
- Type of the stream or buffers, this is the same as the struct
:c:type:`v4l2_format` ``type`` field. See
:c:type:`v4l2_buf_type` for valid values.
* - __u32
- ``reserved``\ [13]
- A place holder for future extensions. Drivers and applications
must set the array to zero.
Return Value
============
On success 0 is returned, on error -1 and the ``errno`` variable is set
appropriately. The generic error codes are described at the
:ref:`Generic Error Codes <gen-errors>` chapter. If an error occurs, no
buffers will be freed and one of the error codes below will be returned:
EBUSY
File I/O is in progress.
One or more of the buffers in the range ``index`` to ``index + count - 1`` are not
in DEQUEUED state.
EINVAL
One or more of the buffers in the range ``index`` to ``index + count - 1`` do not
exist in the queue.
The buffer type (``type`` field) is not valid.
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