[alsa-devel] [PATCH] ucm: Return NULL from get_list0() and get_list20() in case of empty lists.

[Tanu Kaskinen]

alloc_str_list() sets the result to NULL too, so this patch
makes the behavior more consistent. This also fixes a crash
in PulseAudio, because PulseAudio assumes that
snd_use_case_get_list() always initializes the result, and
since snd_use_case_get_list() uses get_list20(), this
assumption didn't hold.
---
 src/ucm/main.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/ucm/main.c b/src/ucm/main.c
index 79901f8..4b37776 100644
--- a/src/ucm/main.c
+++ b/src/ucm/main.c
@@ -367,8 +367,10 @@ static int get_list0(struct list_head *list,
 	char *ptr, *str1;
 
 	cnt = alloc_str_list(list, 1, &res);
-	if (cnt <= 0)
+	if (cnt <= 0) {
+		*result = NULL;
 	        return cnt;
+	}
 	*result = (const char **)res;
 	list_for_each(pos, list) {
 		ptr = list_entry_offset(pos, char, offset);
@@ -414,8 +416,10 @@ static int get_list20(struct list_head *list,
 	char *ptr, *str1, *str2;
 
 	cnt = alloc_str_list(list, 2, &res);
-	if (cnt <= 0)
+	if (cnt <= 0) {
+		*result = NULL;
 	        return cnt;
+	}
         *result = (const char **)res;
 	list_for_each(pos, list) {
 		ptr = list_entry_offset(pos, char, offset);
-- 
1.7.9.5