refactor: update FileCache to change nread type from ssize_t to int in Open method

Author: Yundi339

cmake/vars.cmake

@@ -103,7 +103,6 @@ set(HTTP_SERVER_HEADERS
     http/server/HttpContext.h
     http/server/HttpResponseWriter.h
     http/server/WebSocketServer.h
-    http/server/FileCache.h
 )
 
 set(MQTT_HEADERS

http/server/FileCache.cpp

@@ -120,7 +120,7 @@ file_cache_ptr FileCache::Open(const char* filepath, OpenParam* param) {
                     char* dst = fc->filebuf.base;
                     size_t remaining = fc->filebuf.len;
                     while (remaining > 0) {
-                        ssize_t nread = read(fd, dst, remaining);
+                        int nread = read(fd, dst, remaining);
                         if (nread < 0) {
                             if (errno == EINTR) continue;
                             hloge("Failed to read file: %s", filepath);