fix(lru/server/router): 合并后评审的三项修复

include/uvhttp_server.h

@@ -262,6 +262,13 @@ uvhttp_error_t uvhttp_server_stop(uvhttp_server_t* server);
  * @note Added in v2.10. The five-step sequence remains available for callers
  *       that need to keep the router handle - prefer this for everything else.
  *
+ * @note This entry builds a bare server: no `uvhttp_context_t` and no
+ *       `uvhttp_config_t` are attached. Every config-backed setting on the
+ *       result therefore falls back to its compile-time constant (backlog,
+ *       tcp_keepalive_timeout). If you need those tunable, use the five-step
+ *       sequence with a context instead - wiring a config into this path is
+ *       tracked separately.
+ *
  * @example
  *   uvhttp_server_t* server = NULL;
  *   uvhttp_route_t routes[] = {
@@ -331,6 +338,12 @@ uvhttp_error_t uvhttp_server_set_handler(uvhttp_server_t* server,
  *       uvhttp_server_free. A NULL router is only a no-op when the server
  *       holds none already; once a router has been taken, NULL is rejected
  *       like any other pointer.
+ *
+ * @note The guard above is per-server, so it does NOT stop the same router
+ *       from being handed to two different servers. Do that and both
+ *       uvhttp_server_free calls release it: the second one is a double free
+ *       (ASan reports it at free time, far from the assignment). One router
+ *       belongs to exactly one server.
  */
 uvhttp_error_t uvhttp_server_take_router(uvhttp_server_t* server,
                                          uvhttp_router_t* router);
@@ -348,6 +361,10 @@ uvhttp_error_t uvhttp_server_take_router(uvhttp_server_t* server,
  *       as uvhttp_server_take_router. No detach operation exists: a NULL
  *       context is only a no-op when the server holds none already, and is
  *       rejected once one has been taken.
+ *
+ * @note Like take_router, the guard is per-server: handing the same context
+ *       to two servers makes both destroy it - a double free at free time.
+ *       One context belongs to exactly one server.
  */
 uvhttp_error_t uvhttp_server_take_context(uvhttp_server_t* server,
                                           struct uvhttp_context* context);

src/uvhttp_lru_cache.c

@@ -677,12 +677,26 @@ void uvhttp_lru_cache_reset_stats(cache_manager_t* cache) {
 
 /**
  * set maximum file size for cache
+ *
+ * The write point is the ONLY guard for this field: uvhttp_lru_cache_create
+ * takes no max_file_size argument (it hardcodes a 1GB default), and put()
+ * applies it as a hard cutoff (content_length > max_file_size, see the
+ * "check if file size exceeds limit" branch). A zero written here therefore
+ * bricks the cache - every later put returns UVHTTP_ERROR_INVALID_PARAM with
+ * only a WARN as explanation - so it is rejected like the two setters above
+ * instead of being written silently.
  */
 void uvhttp_lru_cache_set_max_file_size(cache_manager_t* cache,
                                         size_t max_file_size) {
     if (!cache)
         return;
 
+    if (max_file_size == 0) {
+        UVHTTP_LOG_WARN(
+            "Ignoring max_file_size=0 (put() would reject every entry)");
+        return;
+    }
+
     cache->max_file_size = max_file_size;
 }
 

src/uvhttp_router.c

@@ -352,8 +352,15 @@ static uvhttp_error_t migrate_to_trie(uvhttp_router_t* router) {
                  * already had; only the route that triggered migration fails.
                  *
                  * The trie nodes built so far stay in the pool unreferenced
-                 * (use_trie is 0, so no lookup reaches them) and are reused by
-                 * the next attempt, which walks the array again from the root.
+                 * (use_trie is 0, so no lookup reaches them); they are neither
+                 * freed nor reachable, so the pool grows monotonically until a
+                 * migration succeeds or the router is freed. A retry re-walks
+                 * the array from the root and find_or_create_child matches by
+                 * segment name, so it reuses the nodes already there (traced
+                 * by reading, not by a test - the failure here is the 12-child
+                 * cap, which no route removal can relieve, so the
+                 * "fail then succeed" transition has no test).
+                 *
                  * Freeing or detaching old_routes here would destroy every
                  * previously registered route. */
                 return UVHTTP_ERROR_OUT_OF_MEMORY;

test/unit/test_lru_cache_capacity.cpp

@@ -196,4 +196,50 @@ TEST_F(LruCacheCapacity, SetMaxEntriesAcceptsPositiveValue) {
     EXPECT_EQ(cache_->max_entries, 3);
 }
 
+/* ========== set_max_file_size：写点不变量 ========== */
+
+/*
+ * put() 在「check if file size exceeds limit」分支用
+ *     if (content_length > cache->max_file_size) → INVALID_PARAM
+ * 对内容长度做硬截断。而 create() 根本不接收 max_file_size（默认 1GB 写死在
+ * lru_cache.c:82），所以 setter 是这个字段唯一的守卫。
+ *
+ * 评审探针实证：set_max_file_size(cache, 0) 之后，每次 put 都以 -1 失败 ——
+ * 缓存被砖化，调用方只看到一串 "File size exceeds limit" 的 WARN。
+ * 本次补上与另两个 setter 同范式的下限校验。
+ */
+
+TEST_F(LruCacheCapacity, SetMaxFileSizeRejectsZero) {
+    Create(kBudget);
+
+    uvhttp_lru_cache_set_max_file_size(cache_, 0);
+
+    EXPECT_EQ(cache_->max_file_size, 1024u * 1024 * 1024)
+        << "create 把默认值写死为 1GB；setter 不得把 0 写进去";
+}
+
+/* 核心回归：0 不得砖化缓存。砖化的表现是 put 永久 INVALID_PARAM。 */
+TEST_F(LruCacheCapacity, ZeroMaxFileSizeDoesNotBrickTheCache) {
+    Create(kBudget);
+
+    uvhttp_lru_cache_set_max_file_size(cache_, 0);
+
+    EXPECT_EQ(Put("/after.bin", 64, 's'), UVHTTP_OK)
+        << "写入 0 之后 put 必须仍能成功（评审探针在此处实测返回 -1）";
+    EXPECT_EQ(cache_->entry_count, 1);
+}
+
+/* 合法值仍然立即生效：小于新上限的进得去，大于的被拒 */
+TEST_F(LruCacheCapacity, SetMaxFileSizeAcceptsPositiveValue) {
+    Create(kBudget);
+
+    uvhttp_lru_cache_set_max_file_size(cache_, 1024);
+    EXPECT_EQ(cache_->max_file_size, 1024u);
+
+    EXPECT_EQ(Put("/small.bin", 512, 's'), UVHTTP_OK)
+        << "小于新上限的内容应能放入";
+    EXPECT_EQ(Put("/big.bin", 4096, 'b'), UVHTTP_ERROR_INVALID_PARAM)
+        << "大于新上限的内容应被拒（文件大小判定先于内存预算判定）";
+}
+
 #endif /* UVHTTP_FEATURE_STATIC_FILES */