config: Access OPT_MUST_SAVE in the real option, not alias.

So, if elinks.conf contains a "set" command for an alias and ELinks
updates that, it now knows it doesn't have to append another "set"
command for the underlying option.

src/config/conf.c

@@ -292,7 +292,9 @@ parse_set(struct option *opt_tree, struct conf_parsing_state *state,
 			}
 		} else {
 			/* rewriting a configuration file */
-			if (opt->flags & OPT_DELETED) {
+			struct option *flagsite = indirect_option(opt);
+
+			if (flagsite->flags & OPT_DELETED) {
 				/* Replace the "set" command with an
 				 * "unset" command.  */
 				add_to_string(mirror, "unset ");
@@ -308,7 +310,7 @@ parse_set(struct option *opt_tree, struct conf_parsing_state *state,
 			}
 			/* Remember that the option need not be
 			 * written to the end of the file.  */
-			opt->flags &= ~OPT_MUST_SAVE;
+			flagsite->flags &= ~OPT_MUST_SAVE;
 		}
 		mem_free(val);
 	}
@@ -360,7 +362,9 @@ parse_unset(struct option *opt_tree, struct conf_parsing_state *state,
 			else mark_option_as_deleted(opt);
 		} else {
 			/* rewriting a configuration file */
-			if (opt->flags & OPT_DELETED) {
+			struct option *flagsite = indirect_option(opt);
+
+			if (flagsite->flags & OPT_DELETED) {
 				/* The "unset" command is already in the file,
 				 * and unlike with "set", there is no value
 				 * to be updated.  */
@@ -376,7 +380,7 @@ parse_unset(struct option *opt_tree, struct conf_parsing_state *state,
 			}
 			/* Remember that the option need not be
 			 * written to the end of the file.  */
-			opt->flags &= ~OPT_MUST_SAVE;
+			flagsite->flags &= ~OPT_MUST_SAVE;
 		}
 	}
 

src/config/options.c

@@ -164,7 +164,7 @@ static int no_autocreate = 0;
  * work this way because the alias may have the ::OPT_ALIAS_NEGATE flag.
  * Instead, if the caller tries to read or set the value of the alias,
  * the functions associated with ::OPT_ALIAS will forward the operation
- * to the underlying option.  */
+ * to the underlying option.  However, see indirect_option().  */
 struct option *
 get_opt_rec(struct option *tree, const unsigned char *name_)
 {
@@ -248,6 +248,27 @@ get_opt_rec_real(struct option *tree, const unsigned char *name)
 	return opt;
 }
 
+/** If @a opt is an alias, return the option to which it refers.
+ *
+ * @warning Because the alias may have the ::OPT_ALIAS_NEGATE flag,
+ * the caller must not access the value of the returned option as if
+ * it were also the value of the alias.  However, it is safe to access
+ * flags such as ::OPT_MUST_SAVE and ::OPT_DELETED.  */
+struct option *
+indirect_option(struct option *alias)
+{
+	struct option *real;
+
+	if (alias->type != OPT_ALIAS) return alias; /* not an error */
+
+	real = get_opt_rec(config_options, alias->value.string);
+	assertm(real != NULL, "%s aliased to unknown option %s!",
+		alias->name, alias->value.string);
+	if_assert_failed return alias;
+
+	return real;
+}
+
 /* Fetch pointer to value of certain option. It is guaranteed to never return
  * NULL. Note that you are supposed to use wrapper get_opt(). */
 union option_value *

src/config/options.h

@@ -223,6 +223,7 @@ extern void checkout_option_values(struct option_resolver *resolvers,
 
 extern struct option *get_opt_rec(struct option *, const unsigned char *);
 extern struct option *get_opt_rec_real(struct option *, const unsigned char *);
+struct option *indirect_option(struct option *);
 #ifdef CONFIG_DEBUG
 extern union option_value *get_opt_(unsigned char *, int, enum option_type, struct option *, unsigned char *);
 #define get_opt(tree, name, type) get_opt_(__FILE__, __LINE__, type, tree, name)