[libcamera-devel] [PATCH v1 01/10] libcamera: pipeline: Add a platform configuration file helper

[David Plowman]

Hi Naush

Thanks for this patch!

On Fri, 14 Oct 2022 at 14:18, Naushir Patuck via libcamera-devel
<libcamera-devel at lists.libcamera.org> wrote:
>
> Add a new helper function PipelineHandler::configurationFile() that returns
> the full path of a named configuration file. This configuration file may be read
> by pipeline handlers for platform specific configuration parameters on
> initialisation.
>
> The mechanism for searching for the configuration file is similar to the IPA
> configuration file:
>
> - In the source tree if libcamera is not installed
> - Otherwise in standard system locations (etc and share directories).
>
> When stored in the source tree, configuration files shall be located in a 'data'
> subdirectory of their respective pipeline handler directory.
>
> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> ---
>  include/libcamera/internal/pipeline_handler.h |  2 +
>  src/libcamera/pipeline_handler.cpp            | 57 +++++++++++++++++++
>  2 files changed, 59 insertions(+)
>
> diff --git a/include/libcamera/internal/pipeline_handler.h b/include/libcamera/internal/pipeline_handler.h
> index b6139a88d421..6648975f15de 100644
> --- a/include/libcamera/internal/pipeline_handler.h
> +++ b/include/libcamera/internal/pipeline_handler.h
> @@ -74,6 +74,8 @@ protected:
>         virtual int queueRequestDevice(Camera *camera, Request *request) = 0;
>         virtual void stopDevice(Camera *camera) = 0;
>
> +       std::string configurationFile(const std::string &name) const;
> +
>         CameraManager *manager_;
>
>  private:
> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> index 588a3db30e82..998dcece05f2 100644
> --- a/src/libcamera/pipeline_handler.cpp
> +++ b/src/libcamera/pipeline_handler.cpp
> @@ -8,6 +8,7 @@
>  #include "libcamera/internal/pipeline_handler.h"
>
>  #include <chrono>
> +#include <sys/stat.h>
>  #include <sys/sysmacros.h>
>
>  #include <libcamera/base/log.h>
> @@ -625,6 +626,62 @@ void PipelineHandler::disconnect()
>         }
>  }
>
> +/**
> + * \brief Retrieve the absolute path to a platform configuration file
> + * \param[in] name The configuration file name
> + *
> + * This function locates a named platform configuration file and returns
> + * its absolute path to the pipeline handler. It searches the following
> + * directories, in order:
> + *
> + * - If libcamera is not installed, the src/libcamera/pipeline/ directory within
> + *   the source tree ; otherwise
> + * - The system data (share/libcamera/pipeline/) directory.
> + *
> + * The system directories are not searched if libcamera is not installed.
> + *
> + * \return The full path to the pipeline handler configuration file, or an empty
> + * string if no configuration file can be found
> + */
> +std::string PipelineHandler::configurationFile(const std::string &name) const
> +{
> +       struct stat statbuf;
> +       int ret;
> +
> +       std::string root = utils::libcameraSourcePath();
> +       if (!root.empty()) {
> +               /*
> +                * When libcamera is used before it is installed, load
> +                * configuration files from the source directory. The
> +                * configuration files are then located in the 'data'
> +                * subdirectory of the corresponding IPA module.
> +                */
> +               std::string confDir = root + "src/libcamera/pipeline/data";
> +
> +               LOG(Pipeline, Info)
> +                       << "libcamera is not installed. Loading platform configuration file from '"
> +                       << confDir << "'";
> +
> +               std::string confPath = confDir + "/" + name;
> +               ret = stat(confPath.c_str(), &statbuf);
> +               if (ret == 0 && (statbuf.st_mode & S_IFMT) == S_IFREG)

I guess I was just wondering slightly whether this is worth checking
given that we fail with a helpful message anyway if we can't open the
file, but it's fine like this too, so probably just ignore me!

Reviewed-by: David Plowman <david.plowman at raspberrypi.com>

Thanks!
David

> +                       return confPath;
> +
> +       } else {
> +               /* Else look in the system locations. */
> +               std::string confPath = std::string(LIBCAMERA_DATA_DIR) + "/pipeline/" + name;
> +               ret = stat(confPath.c_str(), &statbuf);
> +               if (ret == 0 && (statbuf.st_mode & S_IFMT) == S_IFREG)
> +                       return confPath;
> +       }
> +
> +       LOG(Pipeline, Error)
> +               << "Configuration file '" << name
> +               << "' not found for pipeline handler '" << PipelineHandler::name() << "'";
> +
> +       return std::string();
> +}
> +
>  /**
>   * \var PipelineHandler::manager_
>   * \brief The Camera manager associated with the pipeline handler
> --
> 2.25.1
>