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Prepare for using the V4L2CameraFile as a container for file-specific
information in the V4L2 compatibility layer by making it a required
argument for all V4L2CameraProxy calls that are directed from
V4L2CompatManager, which are intercepted via LD_PRELOAD. Change
V4L2CameraFile accordingly.
Also change V4L2CompatManager accordingly. Instead of keeping a map of
file descriptors to V4L2CameraProxy instances, we keep a map of
V4L2CameraFile instances to V4L2CameraProxy instances. When the
proxy methods are called, feed the file as a parameter.
The dup function is also modified, in that it is removed from
V4L2CameraProxy, and is handled completely in V4L2CompatManager, as a
map from file descriptors to V4L2CameraFile instances.
Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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With relation to opening files, the kernel has three objects related to
files:
- inodes, that represent files on disk
- file objects, that are allocated at open() time and store all data
related to the open file
- file descriptors, that are integers that map to a file
In the V4L2 compatibility layer, V4L2CameraProxy, which wraps a single
libcamera camera via V4L2Camera, is more or less equivalent to the
inode. We also already have file descriptors (that are really eventfds)
that mirror the file descriptors. Here we create a V4L2CameraFile to
model the file objects, to contain information related to the open file,
namely if the file has been opened as non-blocking, and the V4L2
priority (to support VIDIOC_G/S_PRIORITY later on). This new class
allows us to more cleanly support multiple open later on, since we can
move out of V4L2CameraProxy the handling of mapping the fd to the open
file information.
Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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