list: fix first()/last() invalid input ret code

list_first()/last() were returning an invalid CDADA_SUCCESS (false)
when input was invalid.

Reported-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: msune

CHANGELOG.md

@@ -20,6 +20,7 @@ Legend:
 - [B] bbitmap: make `cdada_bbitmap_dump()` set `size_used` in buffered paths too
 - [B] bbitmap: fix corrupted BSD license header in `bbitmap.h`
 - [B] str: fix uint32_t underflow in `cdada_str_rtraverse()` on empty strings
+- [B] list: fix `cdada_list_first()`/`cdada_list_last()` returning `CDADA_SUCCESS` on invalid input
 - [O] tests: add coverage for `cdada_strerr()` valid, boundary and high invalid values
 - [O] tests: add `oom_create_test` coverage for create paths (`list`, `map`, `queue`, `set`, `stack`, `str`, `bbitmap`)
 - [O] tests: add coverage for `cdada_str_replace_all()` empty-match invalid input and self-overlap replacement

src/list.cc

@@ -403,7 +403,7 @@ static int __cdada_list_first_last(const cdada_list_t* list, bool first,
 	__cdada_list_int_t* m = (__cdada_list_int_t*)list;
 
 	if(unlikely(!m || m->magic_num != CDADA_MAGIC || !key))
-		return false;
+		return CDADA_E_INVALID;
 
 	try{
 		int c = m->ops? 0 : m->val_len;
@@ -452,7 +452,7 @@ static int __cdada_list_first_last(const cdada_list_t* list, bool first,
 	}catch(...){}
 
 	CDADA_ASSERT(0);
-	return false;
+	return CDADA_E_UNKNOWN;
 }
 
 int cdada_list_first(const cdada_list_t* list, void* key){

test/list_test.c

@@ -1232,6 +1232,14 @@ int test_basics(){
 	rv = cdada_list_remove(list, NULL);
 	TEST_ASSERT(rv == CDADA_E_INVALID);
 
+	rv = cdada_list_first(NULL, ptr_not_null);
+	TEST_ASSERT(rv == CDADA_E_INVALID);
+	rv = cdada_list_first(list, NULL);
+	TEST_ASSERT(rv == CDADA_E_INVALID);
+	rv = cdada_list_last(NULL, ptr_not_null);
+	TEST_ASSERT(rv == CDADA_E_INVALID);
+	rv = cdada_list_last(list, NULL);
+	TEST_ASSERT(rv == CDADA_E_INVALID);
 
 	//Now destroy
 	rv = cdada_list_destroy(list);