[libcamera-devel] [PATCH v1.1 02/11] libcamera: utils: Add a function to retrieve the libcamera source tree

[Laurent Pinchart]

Hi Kieran,

On Mon, Apr 27, 2020 at 01:26:10PM +0100, Kieran Bingham wrote:
> On 27/04/2020 13:18, Laurent Pinchart wrote:
> > Similarly to libcameraBuildPath(), there's a need to locate resources
> > within the source tree when running libcamera without installing it.
> > Support this use case with a new utils::libcameraSourcePath() function.
> > 
> > The implementation uses a symlink from the build root to the source root
> > in order to avoid hardcoding the path to the source root in the
> > libcamera.so binary.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> 
> Nice, I like this much more ;-)

So do I :-)

> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> 
> > ---
> > Changes since v1:
> > 
> > - Use a symlink to the source tree to avoid hardcoding the path in the
> >   libcamera.so binary
> > ---
> >  meson.build                   |  6 +++++
> >  src/libcamera/include/utils.h |  1 +
> >  src/libcamera/utils.cpp       | 49 ++++++++++++++++++++++++++++++++---
> >  3 files changed, 53 insertions(+), 3 deletions(-)
> > 
> > diff --git a/meson.build b/meson.build
> > index c6e6a934e54e..ec5bc970f5b6 100644
> > --- a/meson.build
> > +++ b/meson.build
> > @@ -93,6 +93,12 @@ if get_option('test')
> >      subdir('test')
> >  endif
> >  
> > +# Create a symlink from the build root to the source root. This is used when
> > +# running libcamera from the build directory to locate resources in the source
> > +# directory (such as IPA configuration files).
> > +run_command('ln', '-fs', meson.source_root(),
> > +            join_paths(meson.build_root(), 'source'))
> > +
> 
> Is this run on every build? or just the first?
> 
> It's a fairly 'cheap' command so it likely doesn't matter if it's run
> everytime...

It's run every time meson is run, but not every time ninja is run.

> >  configure_file(output : 'config.h', configuration : config_h)
> >  
> >  pkg_mod = import('pkgconfig')
> > diff --git a/src/libcamera/include/utils.h b/src/libcamera/include/utils.h
> > index 242eeded9d50..3334ff16613d 100644
> > --- a/src/libcamera/include/utils.h
> > +++ b/src/libcamera/include/utils.h
> > @@ -188,6 +188,7 @@ private:
> >  details::StringSplitter split(const std::string &str, const std::string &delim);
> >  
> >  std::string libcameraBuildPath();
> > +std::string libcameraSourcePath();
> >  
> >  } /* namespace utils */
> >  
> > diff --git a/src/libcamera/utils.cpp b/src/libcamera/utils.cpp
> > index 97f9b632e45b..a96ca7f40cbd 100644
> > --- a/src/libcamera/utils.cpp
> > +++ b/src/libcamera/utils.cpp
> > @@ -10,10 +10,13 @@
> >  #include <dlfcn.h>
> >  #include <elf.h>
> >  #include <iomanip>
> > +#include <limits.h>
> >  #include <link.h>
> >  #include <sstream>
> >  #include <stdlib.h>
> >  #include <string.h>
> > +#include <sys/stat.h>
> > +#include <sys/types.h>
> >  #include <unistd.h>
> >  
> >  /**
> > @@ -360,9 +363,10 @@ bool isLibcameraInstalled()
> >   *
> >   * During development, it is useful to run libcamera binaries directly from the
> >   * build directory without installing them. This function helps components that
> > - * need to locate resources, such as IPA modules or IPA proxy workers, by
> > - * providing them with the path to the root of the build directory. Callers can
> > - * then use it to complement or override searches in system-wide directories.
> > + * need to locate resources in the build tree, such as IPA modules or IPA proxy
> > + * workers, by providing them with the path to the root of the build directory.
> > + * Callers can then use it to complement or override searches in system-wide
> > + * directories.
> >   *
> >   * If libcamera has been installed, the build directory path is not available
> >   * and this function returns an empty string.
> > @@ -385,6 +389,45 @@ std::string libcameraBuildPath()
> >  	return dirname(info.dli_fname) + "/../../";
> >  }
> >  
> > +/**
> > + * \brief Retrieve the path to the source directory
> > + *
> > + * During development, it is useful to run libcamera binaries directly from the
> > + * build directory without installing them. This function helps components that
> > + * need to locate resources in the source tree, such as IPA configuration
> > + * files, by providing them with the path to the root of the source directory.
> > + * Callers can then use it to complement or override searches in system-wide
> > + * directories.
> > + *
> > + * If libcamera has been installed, the source directory path is not available
> > + * and this function returns an empty string.
> > + *
> > + * \return The path to the source directory if running from a build directory,
> > + * or an empty string otherwise
> > + */
> > +std::string libcameraSourcePath()
> > +{
> > +	std::string path = libcameraBuildPath();
> > +	if (path.empty())
> > +		return std::string();
> > +
> > +	path += "source";
> > +
> > +	char *real = realpath(path.c_str(), nullptr);
> > +	if (!real)
> > +		return std::string();
> > +
> > +	path = real;
> > +	free(real);
> > +
> > +	struct stat statbuf;
> > +	int ret = stat(path.c_str(), &statbuf);
> > +	if (ret < 0 || (statbuf.st_mode & S_IFMT) != S_IFDIR)
> > +		return std::string();
> > +
> > +	return path + "/";
> > +}
> > +
> >  } /* namespace utils */
> >  
> >  } /* namespace libcamera */

-- 
Regards,

Laurent Pinchart