options: handle alias options differently

When setting an alias option, its value is not saved in the file-local
options case. The ensure_backup function in m_config.c exits if it
encounters an aliased option, because it should not be saved
additionally to the original option. However, the original option is
likely never saved in this case.

Change it so that ensure_backup always accesses the original option.
The original option is the one that first appears in the option list.

2 files changed, 9 insertions, 10 deletions

diff --git a/m_config.c b/m_config.c
index 11272766d2..c8cf250807 100644
--- a/m_config.c
+++ b/m_config.c
@@ -161,7 +161,7 @@ static int config_destroy(void *p)
 {
     struct m_config *config = p;
     for (struct m_config_option *copt = config->opts; copt; copt = copt->next) {
-        if (copt->flags & M_CFG_OPT_ALIAS)
+        if (copt->alias_owner)
             continue;
         if (copt->opt->type->flags & M_OPT_TYPE_DYNAMIC) {
             m_option_free(copt->opt, copt->data);
@@ -219,14 +219,14 @@ void m_config_free(struct m_config *config)
 
 static void ensure_backup(struct m_config *config, struct m_config_option *co)
 {
+    while (co->alias_owner)
+        co = co->alias_owner;
     if (!config->file_local_mode)
         return;
     if (co->opt->type->flags & M_OPT_TYPE_HAS_CHILD)
         return;
     if (co->opt->flags & M_OPT_GLOBAL)
         return;
-    if (co->flags & M_CFG_OPT_ALIAS)
-        return;
     if (co->global_backup)
         return;
     co->global_backup = talloc_zero_size(co, co->opt->type->size);
@@ -319,12 +319,12 @@ static void m_config_add_option(struct m_config *config,
             for (struct m_config_option *i = config->opts; i; i = i->next) {
                 if (co->data == i->data) {
                     // So we don't save the same vars more than 1 time
-                    co->flags |= M_CFG_OPT_ALIAS;
+                    co->alias_owner = i;
                     break;
                 }
             }
         }
-        if (co->flags & M_CFG_OPT_ALIAS) {
+        if (co->alias_owner) {
             assert(!arg->defval);
         } else {
             if (arg->defval) {
diff --git a/m_config.h b/m_config.h
index 80897ce0e4..6bb1f4ff35 100644
--- a/m_config.h
+++ b/m_config.h
@@ -43,10 +43,12 @@ struct m_config_option {
     void *data;
     // Raw value of the backup of the global value (or NULL).
     void *global_backup;
-    // See \ref ConfigOptionFlags.
-    unsigned int flags;
     // If this is a suboption, the option that contains this option.
     struct m_config_option *parent;
+    // If this option aliases another, more important option. The alias_owner
+    // option is the one that has the most correct option type for the data
+    // variable, and which is considered the original.
+    struct m_config_option *alias_owner;
 };
 
 // Profiles allow to predefine some sets of options that can then
@@ -91,9 +93,6 @@ typedef struct m_config {
     int (*includefunc)(struct m_config *conf, char *filename);
 } m_config_t;
 
-// Set if another option already uses the same variable.
-#define M_CFG_OPT_ALIAS  (1 << 1)
-
 // Create a new config object.
 struct m_config *
 m_config_new(void *optstruct,