[U-Boot] [PATCH v4 7/7] env: delete selected vars not present in imported env

[Gerlando Falauto]

When variables explicitly specified on the command line are not present
in the imported env, delete them from the running env.
If the variable is also missing from the running env, issue a warning.

Signed-off-by: Gerlando Falauto <gerlando.falauto at keymile.com>
---
 lib/hashtable.c |   48 +++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 41 insertions(+), 7 deletions(-)

diff --git a/lib/hashtable.c b/lib/hashtable.c
index f3f47de..b3d0b64 100644
--- a/lib/hashtable.c
+++ b/lib/hashtable.c
@@ -607,22 +607,32 @@ ssize_t hexport_r(struct hsearch_data *htab, const char sep,
  * himport()
  */
 
-/* Check whether variable name is amongst vars[] */
-static int is_var_in_set(const char *name, int nvars, char * const vars[])
+/*
+ * Check whether variable 'name' is amongst vars[],
+ * and remove all instances by setting the pointer to NULL
+ */
+static int is_var_in_set(const char *name, int nvars, char * vars[])
 {
 	int i = 0;
+	int res = 0;
 
 	/* No variables specified means process all of them */
 	if (nvars == 0)
 		return 1;
 
 	for (i = 0; i < nvars; i++) {
-		if (!strcmp(name, vars[i]))
-			return 1;
+		if (vars[i] == NULL)
+			continue;
+		/* If we found it, delete all of them */
+		if (!strcmp(name, vars[i])) {
+			vars[i] = NULL;
+			res = 1;
+		}
 	}
-	debug("Skipping non-listed variable %s\n", name);
+	if (!res)
+		debug("Skipping non-listed variable %s\n", name);
 
-	return 0;
+	return res;
 }
 
 /*
@@ -662,9 +672,11 @@ static int is_var_in_set(const char *name, int nvars, char * const vars[])
 
 int himport_r(struct hsearch_data *htab,
 		const char *env, size_t size, const char sep, int flag,
-		int nvars, char * const vars[], int do_apply)
+		int nvars, char * const __vars[], int do_apply)
 {
 	char *data, *sp, *dp, *name, *value;
+	char *vars[nvars];
+	int i;
 
 	/* Test for correct arguments.  */
 	if (htab == NULL) {
@@ -681,6 +693,10 @@ int himport_r(struct hsearch_data *htab,
 	memcpy(data, env, size);
 	dp = data;
 
+	/* make a local copy of the list of variables */
+	if (nvars)
+		memcpy(vars, __vars, sizeof(__vars[0]) * nvars);
+
 	if ((flag & H_NOCLEAR) == 0) {
 		/* Destroy old hash table if one exists */
 		debug("Destroy Hash Table: %p table = %p\n", htab,
@@ -809,6 +825,24 @@ int himport_r(struct hsearch_data *htab,
 	debug("INSERT: free(data = %p)\n", data);
 	free(data);
 
+	/* process variables which were not considered */
+	for (i = 0; i < nvars; i++) {
+		if (vars[i] == NULL)
+			continue;
+		/*
+		 * All variables which were not deleted from the variable list
+		 * were not present in the imported env
+		 * This could mean two things:
+		 * a) if the variable was present in current env, we delete it
+		 * b) if the variable was not present in current env, we notify
+		 *    it might be a typo
+		 */
+		if (hdelete_r(vars[i], htab, do_apply) == 0)
+			printf("WARNING: '%s' neither in running nor in imported env!\n", vars[i]);
+		else
+			printf("WARNING: '%s' not in imported env, deleting it!\n", vars[i]);
+	}
+
 	debug("INSERT: done\n");
 	return 1;		/* everything OK */
 }
-- 
1.7.10.4