[libcamera-devel] [PATCH 4/5] libcamera: ipa_manager: Search the runpath for IPA libraries

[Kieran Bingham]

Expose the IPA build path through the libcamera library runpath entry in
the elf string table. Utilise this path to search for compiled IPA
libraries when loading the IPAManager.

The build time path is removed during the library install phase.

Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
---
 src/libcamera/ipa_manager.cpp | 9 +++++++++
 src/libcamera/meson.build     | 1 +
 src/meson.build               | 7 +++++++
 3 files changed, 17 insertions(+)

diff --git a/src/libcamera/ipa_manager.cpp b/src/libcamera/ipa_manager.cpp
index 24fe709108fe..3dfe84fcf95e 100644
--- a/src/libcamera/ipa_manager.cpp
+++ b/src/libcamera/ipa_manager.cpp
@@ -102,6 +102,15 @@ IPAManager::IPAManager()
 	if (ret > 0)
 		ipaCount += ret;
 
+	/*
+	 * Utilise the Elf runpath to supply the IPA build directory, allowing
+	 * us to load IPA's before they are installed for testing and
+	 * development.
+	 */
+	const char *runpath = utils::get_runpath();
+	if (runpath)
+		ipaCount += addPath(runpath, true);
+
 	const char *modulePaths = utils::secure_getenv("LIBCAMERA_IPA_MODULE_PATH");
 	if (!modulePaths) {
 		if (!ipaCount)
diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
index 68d89559b290..87c5bbbb17a4 100644
--- a/src/libcamera/meson.build
+++ b/src/libcamera/meson.build
@@ -107,6 +107,7 @@ libcamera = shared_library('camera',
                            install : true,
                            link_with : libcamera_link_with,
                            include_directories : includes,
+                           build_rpath : ipa_build_path,
                            dependencies : libcamera_deps)
 
 libcamera_dep = declare_dependency(sources : [libcamera_api, libcamera_ipa_api, libcamera_h],
diff --git a/src/meson.build b/src/meson.build
index 5adcd61fd913..42e1eb984ccd 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -2,6 +2,13 @@ if get_option('android')
     subdir('android')
 endif
 
+# Provide libcamera with a reference to the current build for IPA
+# loading. This allows IPAs to be successfully loaded when tests and
+# applications are run from the build tree, but is stripped during the
+# install phase, ensuring we maintain reproducible builds.
+
+ipa_build_path = join_paths(meson.current_build_dir(), 'ipa')
+
 subdir('libcamera')
 subdir('ipa')
 subdir('cam')
-- 
2.20.1