ucm: allow to ignore errors for the value substitution

It may be useful to ignore the errors where the environment
or sysfs values are not defined for the specific hardware.

Enhance substitution for 'syntax 3' so $${} substitution
means ignore the errors (return an empty string).

Signed-off-by: Jaroslav Kysela <perex@perex.cz>

1 files changed, 62 insertions, 50 deletions

diff --git a/src/ucm/ucm_subs.c b/src/ucm/ucm_subs.c
index d501da34..b2a1845c 100644
--- a/src/ucm/ucm_subs.c
+++ b/src/ucm/ucm_subs.c
@@ -268,6 +268,7 @@ int uc_mgr_get_substituted_value(snd_use_case_mgr_t *uc_mgr,
 	size_t size, nsize, idsize, rvalsize, dpos = 0;
 	const char *tmp;
 	char *r, *nr, *rval, v2[32];
+	bool ignore_error, allow_empty;
 	int err;
 
 	if (value == NULL)
@@ -279,62 +280,73 @@ int uc_mgr_get_substituted_value(snd_use_case_mgr_t *uc_mgr,
 		return -ENOMEM;
 
 	while (*value) {
-		if (*value == '$' && *(value+1) == '{') {
-			bool allow_empty = false;
-
-			MATCH_VARIABLE(value, "${OpenName}", rval_open_name, false);
-			MATCH_VARIABLE(value, "${ConfTopDir}", rval_conf_topdir, false);
-			MATCH_VARIABLE(value, "${ConfDir}", rval_conf_dir, false);
-			MATCH_VARIABLE(value, "${ConfName}", rval_conf_name, false);
-			MATCH_VARIABLE(value, "${CardNumber}", rval_card_number, true);
-			MATCH_VARIABLE(value, "${CardId}", rval_card_id, false);
-			MATCH_VARIABLE(value, "${CardDriver}", rval_card_driver, false);
-			MATCH_VARIABLE(value, "${CardName}", rval_card_name, false);
-			MATCH_VARIABLE(value, "${CardLongName}", rval_card_longname, false);
-			MATCH_VARIABLE(value, "${CardComponents}", rval_card_components, true);
-			MATCH_VARIABLE2(value, "${env:", rval_env);
-			MATCH_VARIABLE2(value, "${sys:", rval_sysfs);
-			MATCH_VARIABLE2(value, "${var:", rval_var);
-			MATCH_VARIABLE2(value, "${CardIdByName:", rval_card_id_by_name);
-			err = -EINVAL;
-			tmp = strchr(value, '}');
-			if (tmp) {
-				strncpy(r, value, tmp + 1 - value);
-				r[tmp + 1 - value] = '\0';
-				uc_error("variable '%s' is not known!", r);
-			} else {
-				uc_error("variable reference '%s' is not complete", value);
+		if (*value != '$') {
+__std:
+			r[dpos++] = *value;
+			value++;
+			continue;
+		}
+		ignore_error = false;
+		if (value[1] == '$' && value[2] == '{' && uc_mgr->conf_format >= 3) {
+			value++;
+			ignore_error = true;
+		} else if (value[1] != '{') {
+			goto __std;
+		}
+		allow_empty = false;
+		MATCH_VARIABLE(value, "${OpenName}", rval_open_name, false);
+		MATCH_VARIABLE(value, "${ConfTopDir}", rval_conf_topdir, false);
+		MATCH_VARIABLE(value, "${ConfDir}", rval_conf_dir, false);
+		MATCH_VARIABLE(value, "${ConfName}", rval_conf_name, false);
+		MATCH_VARIABLE(value, "${CardNumber}", rval_card_number, true);
+		MATCH_VARIABLE(value, "${CardId}", rval_card_id, false);
+		MATCH_VARIABLE(value, "${CardDriver}", rval_card_driver, false);
+		MATCH_VARIABLE(value, "${CardName}", rval_card_name, false);
+		MATCH_VARIABLE(value, "${CardLongName}", rval_card_longname, false);
+		MATCH_VARIABLE(value, "${CardComponents}", rval_card_components, true);
+		MATCH_VARIABLE2(value, "${env:", rval_env);
+		MATCH_VARIABLE2(value, "${sys:", rval_sysfs);
+		MATCH_VARIABLE2(value, "${var:", rval_var);
+		MATCH_VARIABLE2(value, "${CardIdByName:", rval_card_id_by_name);
+		err = -EINVAL;
+		tmp = strchr(value, '}');
+		if (tmp) {
+			strncpy(r, value, tmp + 1 - value);
+			r[tmp + 1 - value] = '\0';
+			uc_error("variable '%s' is not known!", r);
+		} else {
+			uc_error("variable reference '%s' is not complete", value);
+		}
+		goto __error;
+__rval:
+		if (rval == NULL || (!allow_empty && rval[0] == '\0')) {
+			free(rval);
+			if (ignore_error) {
+				value += idsize;
+				continue;
 			}
+			strncpy(r, value, idsize);
+			r[idsize] = '\0';
+			uc_error("variable '%s' is not defined in this context!", r);
+			err = -EINVAL;
 			goto __error;
-__rval:
-			if (rval == NULL || (!allow_empty && rval[0] == '\0')) {
+		}
+		value += idsize;
+		rvalsize = strlen(rval);
+		nsize = size + rvalsize - idsize;
+		if (nsize > size) {
+			nr = realloc(r, nsize);
+			if (nr == NULL) {
 				free(rval);
-				strncpy(r, value, idsize);
-				r[idsize] = '\0';
-				uc_error("variable '%s' is not defined in this context!", r);
-				err = -EINVAL;
+				err = -ENOMEM;
 				goto __error;
 			}
-			value += idsize;
-			rvalsize = strlen(rval);
-			nsize = size + rvalsize - idsize;
-			if (nsize > size) {
-				nr = realloc(r, nsize);
-				if (nr == NULL) {
-					free(rval);
-					err = -ENOMEM;
-					goto __error;
-				}
-				size = nsize;
-				r = nr;
-			}
-			strcpy(r + dpos, rval);
-			dpos += rvalsize;
-			free(rval);
-		} else {
-			r[dpos++] = *value;
-			value++;
+			size = nsize;
+			r = nr;
 		}
+		strcpy(r + dpos, rval);
+		dpos += rvalsize;
+		free(rval);
 	}
 	r[dpos] = '\0';