env: add check/apply logic to himport_r()

Change hashtable so that a callback function will decide whether a
variable can be overwritten, and possibly apply the changes.

So add a new field to struct hsearch_data:

 o "apply" callback function to check whether a variable can be
    overwritten, and possibly immediately apply the changes;
    when NULL, no check is performed.

And a new argument to himport_r():
 o "do_apply": whether to call the apply callback function

NOTE: This patch does not change the current behavior.

Signed-off-by: Gerlando Falauto <gerlando.falauto@keymile.com>
Reviewed-by: Marek Vasut <marex@denx.de>

2 files changed, 7 insertions, 4 deletions

diff --git a/common/cmd_nvedit.c b/common/cmd_nvedit.c
index c601b3ac27..ddf3b8dfe4 100644
--- a/common/cmd_nvedit.c
+++ b/common/cmd_nvedit.c
@@ -202,6 +202,7 @@ static int do_env_grep(cmd_tbl_t *cmdtp, int flag,
  * environment variable, then (if successful) apply the changes to internals so
  * to make them effective.  Code for this function was taken out of
  * _do_env_set(), which now calls it instead.
+ * Also called as a callback function by himport_r().
  * Returns 0 in case of success, 1 in case of failure.
  * When (flag & H_FORCE) is set, do not print out any error message and force
  * overwriting of write-once variables.
@@ -915,7 +916,7 @@ static int do_env_import(cmd_tbl_t *cmdtp, int flag,
 	}
 
 	if (himport_r(&env_htab, addr, size, sep, del ? 0 : H_NOCLEAR,
-			0, NULL) == 0) {
+			0, NULL, 0 /* do_apply */) == 0) {
 		error("Environment import failed: errno = %d\n", errno);
 		return 1;
 	}
diff --git a/common/env_common.c b/common/env_common.c
index c5cefd8a50..b9865bf630 100644
--- a/common/env_common.c
+++ b/common/env_common.c
@@ -136,7 +136,9 @@ const uchar default_environment[] = {
 	"\0"
 };
 
-struct hsearch_data env_htab;
+struct hsearch_data env_htab = {
+	.apply = env_check_apply,
+};
 
 static uchar __env_get_char_spec(int index)
 {
@@ -197,7 +199,7 @@ void set_default_env(const char *s)
 
 	if (himport_r(&env_htab, (char *)default_environment,
 			sizeof(default_environment), '\0', 0,
-			0, NULL) == 0)
+			0, NULL, 0 /* do_apply */) == 0)
 		error("Environment import failed: errno = %d\n", errno);
 
 	gd->flags |= GD_FLG_ENV_READY;
@@ -223,7 +225,7 @@ int env_import(const char *buf, int check)
 	}
 
 	if (himport_r(&env_htab, (char *)ep->data, ENV_SIZE, '\0', 0,
-			0, NULL)) {
+			0, NULL, 0 /* do_apply */)) {
 		gd->flags |= GD_FLG_ENV_READY;
 		return 1;
 	}