Provide a separate build argument to set plugin search path

[bbhtt]

At the moment both the install and search path are tied to the same build argument PLUGIN_DIRECTORY. It'd be useful to have a separate build argument for the search path for sandboxed applications.

Something like this potentially:

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 041f3b8e..ffd96174 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -67,6 +67,7 @@ LIST (APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake/modules")
 
 option(ENABLE_PLUGIN_LOADING "Support loading of plugins" ON)
 set(PLUGIN_DIRECTORY "${CMAKE_INSTALL_FULL_LIBDIR}/libheif" CACHE STRING "Plugin install directory")
+set(PLUGIN_SEARCH_DIRECTORY "${CMAKE_INSTALL_FULL_LIBDIR}/libheif" CACHE STRING "Plugin search directory")
 
 if (ENABLE_PLUGIN_LOADING)
     set(PLUGIN_LOADING_SUPPORTED_AND_ENABLED TRUE)
diff --git a/libheif/api/libheif/heif_version.h.in b/libheif/api/libheif/heif_version.h.in
index fae2cb81..ddc112d0 100644
--- a/libheif/api/libheif/heif_version.h.in
+++ b/libheif/api/libheif/heif_version.h.in
@@ -33,6 +33,6 @@
 /* Version string */
 #define LIBHEIF_VERSION "@PROJECT_VERSION_MAJOR@.@PROJECT_VERSION_MINOR@.@PROJECT_VERSION_PATCH@"
 
-#define LIBHEIF_PLUGIN_DIRECTORY "@PLUGIN_DIRECTORY@"
+#define LIBHEIF_PLUGIN_DIRECTORY "@PLUGIN_SEARCH_DIRECTORY@"
 
 #endif  // LIBHEIF_HEIF_VERSION_H

The use case is that when building Flatpak runtimes, libheif is built with the plugin path /usr/lib/x86_64-linux-gnu/extension/libheif as we want the plugins to be installed in /usr/lib/x86_64-linux-gnu/extension/libheif. It cannot be set to /app/... as that is a special prefix not used outside Flatpak.

Then the contents of /usr/lib/x86_64-linux-gnu/extension/ is copied into the Flatpak extension and mounted at /app/lib/extension/libheif.

But libheif.so now wants the plugins to be in /usr/lib/x86_64-linux-gnu/extension/libheif while they are actually mounted at /app/lib/extension/libheif.

[bbhtt]

Setting the environment variable LIBHEIF_PLUGIN_PATH=/app/lib/extension/libheif solves the issue but ideally it'd be embedded into libheif.so itself so that it works by default.

[bradh]

This feels like a breaking change for any existing packaging that sets PLUGIN_DIRECTORY .

[farindk]

Yes, we would have to set PLUGIN_SEARCH_DIRECTORY to an empty string by default, in which case cmake will use PLUGIN_DIRECTORY. Or maybe even better: instead of adding a PLUGIN_SEARCH_DIRECTORY, add a PLUGIN_INSTALL_DIRECTORY that is used for installation if not empty.

[farindk]

@bbhtt Does that patch work for you? (Set the install path explicitly with PLUGIN_INSTALL_DIRECTORY.)

[bbhtt]

Thank you! It seems to work, I set it like this:

-DPLUGIN_INSTALL_DIRECTORY="/usr/lib/%{gcc_triplet}/extension/libheif"
-DPLUGIN_DIRECTORY="/app/lib/extension/libheif"

Mine was a quick hack to get something working.

[farindk]

@bbhtt Thanks for reporting this and testing the fix.