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Laurent Pinchart 206fada99d libcamera: file_descriptor: Implement move semantics for constructor
The FileDescriptor class, when constructed from a numerical file
descriptor, duplicates the file descriptor and takes ownership of the
copy. The caller has to close the original file descriptor manually if
needed. This is inefficient as the dup() and close() calls could be
avoided, but can also lead to resource leakage, as recently shown by
commit 353fc4c223 ("libcamera: v4l2_videodevice: Fix dangling file
descriptor").

In an attempt to solve this problem, implement move semantics for the
FileDescriptor constructor. The constructor taking a numerical file
descriptor is split in two variants:

- A "fd copy" constructor that takes a const lvalue reference to a
  numerical file descriptor and duplicates it (corresponding to the
  current behaviour).
- A "fd move" constructor that takes a rvalue reference to a numerical
  file descriptor and takes ownership of it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
2020-05-19 18:07:49 +03:00
Documentation meson: Rename variables storing headers lists 2020-05-18 12:56:20 +03:00
include libcamera: file_descriptor: Implement move semantics for constructor 2020-05-19 18:07:49 +03:00
LICENSES licenses: License all meson files under CC0-1.0 2020-05-13 16:46:24 +03:00
package/gentoo/media-libs/libcamera licenses: Add SPDX headers to Gentoo ebuild 2020-04-15 19:51:56 +03:00
src libcamera: file_descriptor: Implement move semantics for constructor 2020-05-19 18:07:49 +03:00
test libcamera: Move IPA headers from include/ipa/ to include/libcamera/ipa/ 2020-05-16 03:38:47 +03:00
utils utils: raspberrypi: ctt: Fix pycodestyle E302 2020-05-13 17:00:25 +03:00
.clang-format licenses: Replace deprecated GPL-2.0 with GPL-2.0-only 2020-04-15 19:51:56 +03:00
.gitignore libcamera: Add Python cache and compiled files to .gitignore 2020-05-01 17:51:59 +03:00
meson.build licenses: License all meson files under CC0-1.0 2020-05-13 16:46:24 +03:00
meson_options.txt licenses: License all meson files under CC0-1.0 2020-05-13 16:46:24 +03:00
README.rst libcamera: Make IPA module signing mandatory for the meantime 2020-04-16 17:37:41 +03:00

.. SPDX-License-Identifier: CC-BY-SA-4.0

.. section-begin-libcamera

===========
 libcamera
===========

**A complex camera support library for Linux, Android, and ChromeOS**

Cameras are complex devices that need heavy hardware image processing
operations. Control of the processing is based on advanced algorithms that must
run on a programmable processor. This has traditionally been implemented in a
dedicated MCU in the camera, but in embedded devices algorithms have been moved
to the main CPU to save cost. Blurring the boundary between camera devices and
Linux often left the user with no other option than a vendor-specific
closed-source solution.

To address this problem the Linux media community has very recently started
collaboration with the industry to develop a camera stack that will be
open-source-friendly while still protecting vendor core IP. libcamera was born
out of that collaboration and will offer modern camera support to Linux-based
systems, including traditional Linux distributions, ChromeOS and Android.

.. section-end-libcamera
.. section-begin-getting-started

Getting Started
---------------

To fetch the sources, build and install:

::

  git clone git://linuxtv.org/libcamera.git
  cd libcamera
  meson build
  ninja -C build install

Dependencies
~~~~~~~~~~~~

The following Debian/Ubuntu packages are required for building libcamera.
Other distributions may have differing package names:

A C++ toolchain: [required]
	Either {g++, clang}

for libcamera: [required]
        meson (>= 0.47) ninja-build python3-yaml

        If your distribution doesn't provide a recent enough version of meson,
        you can install or upgrade it using pip3.

        .. code::

            pip3 install --user meson
            pip3 install --user --upgrade meson

for device hotplug enumeration: [optional]
	pkg-config libudev-dev

for documentation: [optional]
	python3-sphinx doxygen

for gstreamer: [optional]
	libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev

for IPA module signing: [required]
        libgnutls28-dev openssl

for qcam: [optional]
	qtbase5-dev libqt5core5a libqt5gui5 libqt5widgets5

Using GStreamer plugin
~~~~~~~~~~~~~~~~~~~~~~

To use GStreamer plugin from source tree, set the following environment so that
GStreamer can find it.

  export GST_PLUGIN_PATH=$(pwd)/build/src/gstreamer

The debugging tool `gst-launch-1.0` can be used to construct and pipeline and test
it. The following pipeline will stream from the camera named "Camera 1" onto the
default video display element on your system.

.. code::

  gst-launch-1.0 libcamerasrc camera-name="Camera 1" ! videoconvert ! autovideosink

.. section-end-getting-started