Switch wapp_cpath_join_path to use Str8

src/os/cpath/cpath.h

@@ -3,6 +3,7 @@
 
 #include "aliases.h"
 #include "platform.h"
+#include "str8.h"
 
 #ifdef __cplusplus
 BEGIN_C_LINKAGE
@@ -16,13 +17,17 @@ BEGIN_C_LINKAGE
 #error "Unrecognised platform"
 #endif
 
-#define NUMPARTS(...) (sizeof((const char *[]){"", __VA_ARGS__}) / sizeof(const char *) - 1)
-
-#define wapp_cpath_join_path(DST, ...) join_path(DST, NUMPARTS(__VA_ARGS__), __VA_ARGS__)
 #define wapp_cpath_dirname(DST, PATH) dirup(DST, 1, PATH)
 #define wapp_cpath_dirup(DST, COUNT, PATH) dirup(DST, COUNT, PATH)
 
-void join_path(char *dst, u64 count, ...);
+enum {
+  CPATH_JOIN_SUCCESS = 0,
+  CPATH_JOIN_INVALID_ARGS,
+  CPATH_JOIN_EMPTY_PARTS,
+  CPATH_JOIN_INSUFFICIENT_DST_CAPACITY,
+};
+
+u32  wapp_cpath_join_path(Str8 *dst, const Str8List *parts);
 void dirup(char *dst, u64 levels, const char *path);
 
 #ifdef __cplusplus