env: Complete generic support for writable list

This completes what 890feec started by selecting ENV_APPEND and loading the default env before any other sources. This ensures that load operations pick up all non-writable vars from the default env and only permitted parts from other locations according to the regular priorities. With this change, boards only need to define the list of writable variables but no longer have to provide a custom env_get_location implementation. CC: Joe Hershberger <[email protected]> CC: Marek Vasut <[email protected]> CC: Stefan Herbrechtsmeier <[email protected]> Signed-off-by: Jan Kiszka <[email protected]> Reviewed-by: Marek Vasut <[email protected]>
matwey · Feb 10, 2023 · 5ab8105 · 5ab8105
1 parent 0106504
commit 5ab8105
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diff --git a/env/Kconfig b/env/Kconfig
@@ -733,6 +733,7 @@ config ENV_APPEND
 
 config ENV_WRITEABLE_LIST
 	bool "Permit write access only to listed variables"
+	select ENV_APPEND
 	help
 	  If defined, only environment variables which explicitly set the 'w'
 	  writeable flag can be written and modified at runtime. No variables

diff --git a/env/env.c b/env/env.c
@@ -192,6 +192,14 @@ int env_load(void)
 	int best_prio = -1;
 	int prio;
 
+	if (CONFIG_IS_ENABLED(ENV_WRITEABLE_LIST)) {
+		/*
+		 * When using a list of writeable variables, the baseline comes
+		 * from the built-in default env. So load this first.
+		 */
+		env_set_default(NULL, 0);
+	}
+
 	for (prio = 0; (drv = env_driver_lookup(ENVOP_LOAD, prio)); prio++) {
 		int ret;