fix the empty config error

@@ -1182,6 +1182,13 @@ int SrsConfig::parse_buffer(_srs_internal::SrsConfigBuffer* buffer)
     if ((ret = root->parse(buffer)) != ERROR_SUCCESS) {
         return ret;
     }
+
+    // check empty
+    if (root->directives.size() == 0) {
+        ret = ERROR_SYSTEM_CONFIG_INVALID;
+        srs_error("conf is empty, ret=%d", ret);
+        return ret;
+    }
     
     // check root directives.
     for (int i = 0; i < (int)root->directives.size(); i++) {
@@ -1200,7 +1207,7 @@ int SrsConfig::parse_buffer(_srs_internal::SrsConfigBuffer* buffer)
     }
     
     // check rtmp port specified by directive listen.
-    if (_srs_config->get_listen().size() <= 0) {
+    if (get_listen().size() <= 0) {
         ret = ERROR_SYSTEM_CONFIG_INVALID;
         srs_error("directive \"listen\" is empty, ret=%d", ret);
         return ret;

@@ -53,6 +53,20 @@ int MockSrsConfigBuffer::fullfill(const char* /*filename*/)
     return ERROR_SUCCESS;
 }
 
+MockSrsConfig::MockSrsConfig()
+{
+}
+
+MockSrsConfig::~MockSrsConfig()
+{
+}
+
+int MockSrsConfig::parse(string buf)
+{
+    MockSrsConfigBuffer buffer(buf);
+    return parse_buffer(&buffer);
+}
+
 VOID TEST(ConfigTest, CheckMacros)
 {
 #ifndef SRS_CONSTS_LOCALHOST
@@ -777,3 +791,9 @@ VOID TEST(ConfigDirectiveTest, ParseLineNormal)
     EXPECT_EQ(0, (int)dir2.directives.size());
     EXPECT_EQ(3, (int)dir2.conf_line);
 }
+
+VOID TEST(ConfigMainTest, ParseEmpty)
+{
+    MockSrsConfig conf;
+    EXPECT_TRUE(ERROR_SUCCESS != conf.parse(""));
+}

@@ -42,4 +42,13 @@ public:
     virtual int fullfill(const char* filename);
 };
 
+class MockSrsConfig : public SrsConfig
+{
+public:
+    MockSrsConfig();
+    virtual ~MockSrsConfig();
+public:
+    virtual int parse(std::string buf);
+};
+
 #endif