[v18,11/12] config: Make configuration file locations configurable
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Message ID 20250912142915.53949-13-mzamazal@redhat.com
State New
Headers show
Series
  • Add global configuration file
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Commit Message

Milan Zamazal Sept. 12, 2025, 2:29 p.m. UTC 
To support easy switching of configurations, let's introduce
LIBCAMERA_CONFIG_DIR and LIBCAMERA_CONFIG_NAME environment variables.

LIBCAMERA_CONFIG_DIR environment variable specifies a directory or a
list of directories separated by colons where to look for the libcamera
configuration file before trying the standard locations.  This override
can be useful in a meson devenv.

LIBCAMERA_CONFIG_NAME
- specifies the path of the configuration file to load if it is an
  absolute path (useful to quickly try some configuration); or
- prevents any configuration file from loading if it is defined and
  empty (useful to disable all configuration files); or
- specifies the path of the configuration file to load, relative to
  the configuration directories (useful to quickly select between
  different configurations).

If a configuration file specified by those environment variables doesn't
exist, no configuration file is loaded.

Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
---
 Documentation/runtime_configuration.rst | 13 +++++++
 src/libcamera/global_configuration.cpp  | 50 +++++++++++++++++--------
 2 files changed, 47 insertions(+), 16 deletions(-)

Patch
diff mbox series 

diff --git a/Documentation/runtime_configuration.rst b/Documentation/runtime_configuration.rst
index 702139544..5307f3645 100644
--- a/Documentation/runtime_configuration.rst
+++ b/Documentation/runtime_configuration.rst
@@ -19,6 +19,19 @@  order:
 - LIBCAMERA_SYSCONF_DIR/configuration.yaml
 - LIBCAMERA_DATA_DIR/libcamera/configuration.yaml
 
+If LIBCAMERA_CONFIG_DIR environment variable is non-empty then it
+specifies additional directories where to look for the configuration
+file, before looking at the standard locations. It can be a single
+directory or multiple directories separated by colons.
+
+The default name of the configuration file, configuration.yaml, can be
+overridden in LIBCAMERA_CONFIG_NAME environment variable. The variable
+can specify just an alternative configuration file name to be looked up
+in the locations above, or a whole absolute path. If an absolute path is
+specified then it is the only location that is used; if the given file
+doesn't exist then no configuration file is read. If the variable is
+defined but empty, no configuration is loaded.
+
 The first configuration file found wins, configuration files in other
 locations are ignored.
 
diff --git a/src/libcamera/global_configuration.cpp b/src/libcamera/global_configuration.cpp
index 592edcf30..8c2670e03 100644
--- a/src/libcamera/global_configuration.cpp
+++ b/src/libcamera/global_configuration.cpp
@@ -23,13 +23,6 @@ 
 
 namespace libcamera {
 
-namespace {
-const std::vector<std::filesystem::path> globalConfigurationFiles = {
-	std::filesystem::path(LIBCAMERA_SYSCONF_DIR) / "configuration.yaml",
-	std::filesystem::path(LIBCAMERA_DATA_DIR) / "configuration.yaml",
-};
-}
-
 LOG_DEFINE_CATEGORY(Configuration)
 
 /**
@@ -80,6 +73,33 @@  bool GlobalConfiguration::loadFile(const std::filesystem::path &fileName)
 
 void GlobalConfiguration::load()
 {
+	const char *libcameraConfigName =
+		utils::secure_getenv("LIBCAMERA_CONFIG_NAME");
+	if (libcameraConfigName && libcameraConfigName[0] == '\0')
+		return;
+	if (!libcameraConfigName)
+		libcameraConfigName = "";
+
+	std::filesystem::path configName(libcameraConfigName);
+
+	if (configName.is_absolute()) {
+		loadFile(configName);
+		return;
+	}
+
+	if (configName.empty())
+		configName = std::filesystem::path("configuration.yaml");
+
+	std::vector<std::filesystem::path> configurationDirectories;
+
+	const char *configDir = utils::secure_getenv("LIBCAMERA_CONFIG_DIR");
+	if (configDir) {
+		for (auto const &path : utils::split(configDir, ":")) {
+			if (!path.empty())
+				configurationDirectories.push_back(path);
+		}
+	}
+
 	std::filesystem::path userConfigurationDirectory;
 	const char *xdgConfigHome = utils::secure_getenv("XDG_CONFIG_HOME");
 	if (xdgConfigHome) {
@@ -90,18 +110,16 @@  void GlobalConfiguration::load()
 			userConfigurationDirectory =
 				std::filesystem::path(home) / ".config";
 	}
+	if (!userConfigurationDirectory.empty())
+		configurationDirectories.push_back(
+			userConfigurationDirectory / "libcamera");
 
-	if (!userConfigurationDirectory.empty()) {
-		std::filesystem::path user_configuration_file =
-			userConfigurationDirectory / "libcamera" / "configuration.yaml";
-		if (loadFile(user_configuration_file))
-			return;
-	}
+	configurationDirectories.push_back(LIBCAMERA_SYSCONF_DIR);
+	configurationDirectories.push_back(LIBCAMERA_DATA_DIR);
 
-	for (const auto &path : globalConfigurationFiles) {
-		if (loadFile(path))
+	for (const auto &path : configurationDirectories)
+		if (loadFile(path / configName))
 			return;
-	}
 }
 
 /**