NekoCWD/libcamera
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treewide: Query list of cameras just once

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This is more efficient since only a single vector will be constructed,
and furthermore, it prevents the TOCTOU issue that might arise when
the list of cameras changes between the two queries.

Signed-off-by: Barnabás Pőcze <pobrn@protonmail.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
This commit is contained in:
Barnabás Pőcze 2024-04-29 14:24:09 +00:00 • committed by Kieran Bingham
parent aee16c0691
commit e77a275110
3 changed files with 18 additions and 10 deletions
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12
Documentation/guides/application-developer.rst
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@ -116,19 +116,21 @@ available.
.. code:: cpp
if (cm->cameras().empty()) {
auto cameras = cm->cameras();
if (cameras.empty()) {
std::cout << "No cameras were identified on the system."
<< std::endl;
cm->stop();
return EXIT_FAILURE;
}
std::string cameraId = cm->cameras()[0]->id();
camera = cm->get(cameraId);
std::string cameraId = cameras[0]->id();
auto camera = cm->get(cameraId);
/*
* Note that is equivalent to:
* camera = cm->cameras()[0];
* Note that `camera` may not compare equal to `cameras[0]`.
* In fact, it might simply be a `nullptr`, as the particular
* device might have disappeared (and reappeared) in the meantime.
*/
Once a camera has been selected an application needs to acquire an exclusive