env: make himport_r() selective on variables

Add 2 new arguments to himport_r():

 o "nvars", "vars": number and list of variables to take into account
   (0 means ALL)

NOTE: This patch does not change the current behaviour.

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

common/cmd_nvedit.c

@@ -914,7 +914,8 @@ static int do_env_import(cmd_tbl_t *cmdtp, int flag,
 		addr = (char *)ep->data;
 	}
 
-	if (himport_r(&env_htab, addr, size, sep, del ? 0 : H_NOCLEAR) == 0) {
+	if (himport_r(&env_htab, addr, size, sep, del ? 0 : H_NOCLEAR,
+			0, NULL) == 0) {
 		error("Environment import failed: errno = %d\n", errno);
 		return 1;
 	}

common/env_common.c

@@ -196,7 +196,8 @@ void set_default_env(const char *s)
 	}
 
 	if (himport_r(&env_htab, (char *)default_environment,
-			sizeof(default_environment), '\0', 0) == 0)
+			sizeof(default_environment), '\0', 0,
+			0, NULL) == 0)
 		error("Environment import failed: errno = %d\n", errno);
 
 	gd->flags |= GD_FLG_ENV_READY;
@@ -221,7 +222,8 @@ int env_import(const char *buf, int check)
 		}
 	}
 
-	if (himport_r(&env_htab, (char *)ep->data, ENV_SIZE, '\0', 0)) {
+	if (himport_r(&env_htab, (char *)ep->data, ENV_SIZE, '\0', 0,
+			0, NULL)) {
 		gd->flags |= GD_FLG_ENV_READY;
 		return 1;
 	}

include/search.h

@@ -94,9 +94,13 @@ extern ssize_t hexport_r(struct hsearch_data *__htab,
 		     const char __sep, char **__resp, size_t __size,
 		     int argc, char * const argv[]);
 
+/*
+ * nvars: length of vars array
+ * vars: array of strings (variable names) to import (nvars == 0 means all)
+ */
 extern int himport_r(struct hsearch_data *__htab,
 		     const char *__env, size_t __size, const char __sep,
-		     int __flag);
+		     int __flag, int nvars, char * const vars[]);
 
 /* Flags for himport_r() */
 #define	H_NOCLEAR	(1 << 0) /* do not clear hash table before importing */

lib/hashtable.c

@@ -603,6 +603,24 @@ 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[])
+{
+	int i = 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;
+	}
+	debug("Skipping non-listed variable %s\n", name);
+
+	return 0;
+}
+
 /*
  * Import linearized data into hash table.
  *
@@ -639,7 +657,8 @@ ssize_t hexport_r(struct hsearch_data *htab, const char sep,
  */
 
 int himport_r(struct hsearch_data *htab,
-	      const char *env, size_t size, const char sep, int flag)
+		const char *env, size_t size, const char sep, int flag,
+		int nvars, char * const vars[])
 {
 	char *data, *sp, *dp, *name, *value;
 
@@ -726,6 +745,8 @@ int himport_r(struct hsearch_data *htab,
 			*dp++ = '\0';	/* terminate name */
 
 			debug("DELETE CANDIDATE: \"%s\"\n", name);
+			if (!is_var_in_set(name, nvars, vars))
+				continue;
 
 			if (hdelete_r(name, htab) == 0)
 				debug("DELETE ERROR ##############################\n");
@@ -743,6 +764,10 @@ int himport_r(struct hsearch_data *htab,
 		*sp++ = '\0';	/* terminate value */
 		++dp;
 
+		/* Skip variables which are not supposed to be processed */
+		if (!is_var_in_set(name, nvars, vars))
+			continue;
+
 		/* enter into hash table */
 		e.key = name;
 		e.data = value;