Switch wapp_cpath_join_path to use Str8

src/os/cpath/cpath.c

@@ -1,5 +1,6 @@
 #include "cpath.h"
 #include "aliases.h"
+#include "str8.h"
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -7,16 +8,48 @@
 
 void join_root_and_leaf(const char *root, const char *leaf, char *dst);
 
-void join_path(char *dst, u64 count, ...) {
-  va_list args;
-
-  va_start(args, count);
-
-  for (u64 i = 0; i < count; ++i) {
-    join_root_and_leaf(dst, va_arg(args, const char *), dst);
+u32 wapp_cpath_join_path(Str8 *dst, const Str8List *parts) {
+  if (!dst || !parts) {
+    return CPATH_JOIN_INVALID_ARGS;
   }
 
-  va_end(args);
+  if (parts->node_count == 0) {
+    return CPATH_JOIN_EMPTY_PARTS;
+  }
+
+  Str8 separator = wapp_str8_buf(4);
+  wapp_str8_push_back(&separator, PATH_SEP);
+
+  u64 required_capacity = parts->node_count * separator.size + parts->total_size;
+  if (dst->capacity < required_capacity) {
+    return CPATH_JOIN_INSUFFICIENT_DST_CAPACITY;
+  }
+
+  // Handle first node
+  const Str8Node *first_node = wapp_str8_list_get(parts, 0);
+  wapp_str8_copy_str8_capped(dst, first_node->string);
+
+  const Str8Node *node = first_node;
+  for (u64 i = 1; i < parts->node_count; ++i) {
+    node = node->next;
+    if (node->string->size == 0) {
+      continue;
+    }
+
+    if (dst->size > 0) {
+      char dst_last     = wapp_str8_get(dst, dst->size - 1);
+      char node_start   = wapp_str8_get(node->string, 0);
+      bool add_path_sep = dst_last != PATH_SEP && node_start != PATH_SEP;
+
+      if (add_path_sep) {
+        wapp_str8_concat_capped(dst, &separator);
+      }
+    }
+
+    wapp_str8_concat_capped(dst, node->string);
+  }
+
+  return CPATH_JOIN_SUCCESS;
 }
 
 void dirup(char *dst, u64 levels, const char *path) {