til_settings: add an optional til_settings_t.prefix

Preparatory commit for bridging the gap separating a baked
til_setup_t from a runtime-populated descendant til_settings_t
like modules::rtv produces for its channels via
til_module_setup_randomize().

For these currently orphaned til_settings_t instances we don't
readily have access to the logical ancestor til_settings_t that
was used to produce the module_context's bound til_setup_t.  But
we don't really need the ancestor til_settings_t, all we _really_
want is the ancestral path to prefix the orphan til_settings_t
instances.

So this commit introduces supplying a prefix which gets prepended
to paths printed via the settings instance.  A later commit will
make use of this in modules::rtv when producing the settings
instance passed to til_module_setup_randomize()

1 files changed, 15 insertions, 1 deletions

diff --git a/src/til_settings.c b/src/til_settings.c
index b6f277c..9fe57e6 100644
--- a/src/til_settings.c
+++ b/src/til_settings.c
@@ -32,6 +32,7 @@ char * strndup(const char *s, size_t n)
 /* Split form of key=value[,key=value...] settings string */
 typedef struct til_settings_t {
 	const til_settings_t	*parent;
+	const char		*prefix;
 	const char		*label;
 	unsigned		num;
 	til_setting_t		**entries;
@@ -77,7 +78,7 @@ static til_setting_t * add_setting(til_settings_t *settings, const char *key, co
 
 
 /* split settings_string into a data structure */
-til_settings_t * til_settings_new(const til_settings_t *parent, const char *label, const char *settings_string)
+til_settings_t * til_settings_new(const char *prefix, const til_settings_t *parent, const char *label, const char *settings_string)
 {
 	til_settings_fsm_state_t	state = TIL_SETTINGS_FSM_STATE_COMMA;
 	const char			*p;
@@ -92,6 +93,12 @@ til_settings_t * til_settings_new(const til_settings_t *parent, const char *labe
 	if (!settings)
 		goto _err;
 
+	if (prefix) {
+		settings->prefix = strdup(prefix);
+		if (!settings->prefix)
+			goto _err;
+	}
+
 	settings->parent = parent;
 	settings->label = strdup(label);
 	if (!settings->label)
@@ -199,6 +206,7 @@ til_settings_t * til_settings_free(til_settings_t *settings)
 
 		free((void *)settings->entries);
 		free((void *)settings->label);
+		free((void *)settings->prefix);
 		free(settings);
 	}
 
@@ -636,6 +644,12 @@ int til_settings_print_path(const til_settings_t *settings, FILE *out)
 	for (i = 0; i < n_parents; i++) {
 		int	r;
 
+		if (parents[i]->prefix) {
+			r = fprintf(out, "%s", parents[i]->prefix);
+			if (r < 0)
+				return r;
+		}
+
 		r = fprintf(out, "/%s", parents[i]->label);
 		if (r < 0)
 			return r;