env: Refactor apply into change_ok

Move the read of the old value to inside the check function.  In some
cases it can be avoided all together and at the least the code is only
called from one place.

Also name the function and the callback to more clearly describe what
it does.

Pass the ENTRY instead of just the name for direct access to the whole
data structure.

Pass an enum to the callback that specifies the operation being approved.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>

common/cmd_nvedit.c

@@ -208,10 +208,20 @@ static int do_env_grep(cmd_tbl_t *cmdtp, int flag,
  * overwriting of write-once variables.
  */
 
-int env_check_apply(const char *name, const char *oldval,
+int env_change_ok(const ENTRY *item, const char *newval, enum env_op op,
-			const char *newval, int flag)
+	int flag)
 {
 	int   console = -1;
+	const char *name;
+#if !defined(CONFIG_ENV_OVERWRITE) && defined(CONFIG_OVERWRITE_ETHADDR_ONCE) \
+&& defined(CONFIG_ETHADDR)
+	const char *oldval = NULL;
+
+	if (op != env_op_create)
+		oldval = item->data;
+#endif
+
+	name = item->key;
 
 	/* Default value for NULL to protect string-manipulating functions */
 	newval = newval ? : "";
@@ -242,12 +252,12 @@ int env_check_apply(const char *name, const char *oldval,
 #endif /* CONFIG_CONSOLE_MUX */
 	}
 
+#ifndef CONFIG_ENV_OVERWRITE
 	/*
 	 * Some variables like "ethaddr" and "serial#" can be set only once and
 	 * cannot be deleted, unless CONFIG_ENV_OVERWRITE is defined.
 	 */
-#ifndef CONFIG_ENV_OVERWRITE
+	if (op != env_op_create &&		/* variable exists */
-	if (oldval != NULL &&			/* variable exists */
 		(flag & H_FORCE) == 0) {	/* and we are not forced */
 		if (strcmp(name, "serial#") == 0 ||
 		    (strcmp(name, "ethaddr") == 0
@@ -265,7 +275,7 @@ int env_check_apply(const char *name, const char *oldval,
 	 * (which will erase all variables prior to calling this),
 	 * we want the baudrate to actually change - for real.
 	 */
-	if (oldval != NULL ||			/* variable exists */
+	if (op != env_op_create ||		/* variable exists */
 		(flag & H_NOCLEAR) == 0) {	/* or env is clear */
 		/*
 		 * Switch to new baudrate if new baudrate is supported
@@ -339,20 +349,6 @@ static int _do_env_set(int flag, int argc, char * const argv[])
 	}
 
 	env_id++;
-	/*
-	 * search if variable with this name already exists
-	 */
-	e.key = name;
-	e.data = NULL;
-	hsearch_r(e, FIND, &ep, &env_htab, 0);
-
-	/*
-	 * Perform requested checks.
-	 */
-	if (env_check_apply(name, ep ? ep->data : NULL, value, 0)) {
-		debug("check function did not approve, refusing\n");
-		return 1;
-	}
 
 	/* Delete only ? */
 	if (argc < 3 || argv[2] == NULL) {

common/env_common.c

@@ -40,7 +40,7 @@ DECLARE_GLOBAL_DATA_PTR;
 #include <env_default.h>
 
 struct hsearch_data env_htab = {
-	.apply = env_check_apply,
+	.change_ok = env_change_ok,
 };
 
 static uchar __env_get_char_spec(int index)
@@ -162,6 +162,7 @@ void env_relocate(void)
 {
 #if defined(CONFIG_NEEDS_MANUAL_RELOC)
 	env_reloc();
+	env_htab.change_ok += gd->reloc_off;
 #endif
 	if (gd->env_valid == 0) {
 #if defined(CONFIG_ENV_IS_NOWHERE) || defined(CONFIG_SPL_BUILD)

include/environment.h

@@ -188,13 +188,12 @@ int set_default_vars(int nvars, char * const vars[]);
 int env_import(const char *buf, int check);
 
 /*
- * Check if variable "name" can be changed from oldval to newval,
+ * Check if variable "item" can be changed to newval
- * and if so, apply the changes (e.g. baudrate).
  * When (flag & H_FORCE) is set, it does not print out any error
  * message and forces overwriting of write-once variables.
  */
-int env_check_apply(const char *name, const char *oldval,
+int env_change_ok(const ENTRY *item, const char *newval, enum env_op op,
-			const char *newval, int flag);
+	int flag);
 
 #endif /* DO_DEPS_ONLY */
 

include/search.h

@@ -32,6 +32,12 @@
 
 #define __set_errno(val) do { errno = val; } while (0)
 
+enum env_op {
+	env_op_create,
+	env_op_delete,
+	env_op_overwrite,
+};
+
 /* Action which shall be performed in the call the hsearch.  */
 typedef enum {
 	FIND,
@@ -59,14 +65,13 @@ struct hsearch_data {
 	unsigned int filled;
 /*
  * Callback function which will check whether the given change for variable
- * "name" from "oldval" to "newval" may be applied or not, and possibly apply
+ * "item" to "newval" may be applied or not, and possibly apply such change.
- * such change.
  * When (flag & H_FORCE) is set, it shall not print out any error message and
  * shall force overwriting of write-once variables.
 .* Must return 0 for approval, 1 for denial.
  */
-	int (*apply)(const char *name, const char *oldval,
+	int (*change_ok)(const ENTRY *__item, const char *newval, enum env_op,
-			const char *newval, int flag);
+		int flag);
 };
 
 /* Create a new hashing table which will at most contain NEL elements.  */

lib/hashtable.c

@@ -66,12 +66,16 @@
  * Instead the interface of all functions is extended to take an argument
  * which describes the current status.
  */
+
 typedef struct _ENTRY {
 	int used;
 	ENTRY entry;
 } _ENTRY;
 
 
+static void _hdelete(const char *key, struct hsearch_data *htab, ENTRY *ep,
+	int idx);
+
 /*
  * hcreate()
  */
@@ -259,6 +263,17 @@ static inline int _compare_and_overwrite_entry(ENTRY item, ACTION action,
 	    && strcmp(item.key, htab->table[idx].entry.key) == 0) {
 		/* Overwrite existing value? */
 		if ((action == ENTER) && (item.data != NULL)) {
+			/* check for permission */
+			if (htab->change_ok != NULL && htab->change_ok(
+			    &htab->table[idx].entry, item.data,
+			    env_op_overwrite, flag)) {
+				debug("change_ok() rejected setting variable "
+					"%s, skipping it!\n", item.key);
+				__set_errno(EPERM);
+				*retval = NULL;
+				return 0;
+			}
+
 			free(htab->table[idx].entry.data);
 			htab->table[idx].entry.data = strdup(item.data);
 			if (!htab->table[idx].entry.data) {
@@ -383,6 +398,17 @@ int hsearch_r(ENTRY item, ACTION action, ENTRY ** retval,
 
 		++htab->filled;
 
+		/* check for permission */
+		if (htab->change_ok != NULL && htab->change_ok(
+		    &htab->table[idx].entry, item.data, env_op_create, flag)) {
+			debug("change_ok() rejected setting variable "
+				"%s, skipping it!\n", item.key);
+			_hdelete(item.key, htab, &htab->table[idx].entry, idx);
+			__set_errno(EPERM);
+			*retval = NULL;
+			return 0;
+		}
+
 		/* return new entry */
 		*retval = &htab->table[idx].entry;
 		return 1;
@@ -404,6 +430,18 @@ int hsearch_r(ENTRY item, ACTION action, ENTRY ** retval,
  * do that.
  */
 
+static void _hdelete(const char *key, struct hsearch_data *htab, ENTRY *ep,
+	int idx)
+{
+	/* free used ENTRY */
+	debug("hdelete: DELETING key \"%s\"\n", key);
+	free((void *)ep->key);
+	free(ep->data);
+	htab->table[idx].used = -1;
+
+	--htab->filled;
+}
+
 int hdelete_r(const char *key, struct hsearch_data *htab, int flag)
 {
 	ENTRY e, *ep;
@@ -420,19 +458,15 @@ int hdelete_r(const char *key, struct hsearch_data *htab, int flag)
 	}
 
 	/* Check for permission */
-	if (htab->apply != NULL &&
+	if (htab->change_ok != NULL &&
-	    htab->apply(ep->key, ep->data, NULL, flag)) {
+	    htab->change_ok(ep, NULL, env_op_delete, flag)) {
+		debug("change_ok() rejected deleting variable "
+			"%s, skipping it!\n", key);
 		__set_errno(EPERM);
 		return 0;
 	}
 
-	/* free used ENTRY */
+	_hdelete(key, htab, ep, idx);
-	debug("hdelete: DELETING key \"%s\"\n", key);
-	free((void *)ep->key);
-	free(ep->data);
-	htab->table[idx].used = -1;
-
-	--htab->filled;
 
 	return 1;
 }
@@ -800,24 +834,6 @@ int himport_r(struct hsearch_data *htab,
 		e.key = name;
 		e.data = value;
 
-		/* if there is an apply function, check what it has to say */
-		if (htab->apply != NULL) {
-			debug("searching before calling cb function"
-				" for  %s\n", name);
-			/*
-			 * Search for variable in existing env, so to pass
-			 * its previous value to the apply callback
-			 */
-			hsearch_r(e, FIND, &rv, htab, 0);
-			debug("previous value was %s\n", rv ? rv->data : "");
-			if (htab->apply(name, rv ? rv->data : NULL,
-				value, flag)) {
-				debug("callback function refused to set"
-					" variable %s, skipping it!\n", name);
-				continue;
-			}
-		}
-
 		hsearch_r(e, ENTER, &rv, htab, flag);
 		if (rv == NULL) {
 			printf("himport_r: can't insert \"%s=%s\" into hash table\n",