fix src/tracer.hxx stack-buffer-overflow when using vsnprintf's retur…

…n value (#502) (#503)

* fix src/tracer.hxx stack-buffer-overflow when using vsnprintf's return value (#502)

* 1. add logger_test to code coverage test 2. logger_test set printTestMessage to true   (#502)

---------

Co-authored-by: byronhe <[email protected]>

CMakeLists.txt

@@ -321,6 +321,7 @@ if (CODE_COVERAGE GREATER 0)
         timer_test
         strfmt_test
         stat_mgr_test
+        logger_test
     )
 
     # lcov

src/tracer.hxx

@@ -25,36 +25,38 @@ limitations under the License.
 #include <stdarg.h>
 
 #ifdef _WIN32
-static inline std::string msg_if_given
-                          ( _Printf_format_string_ const char* format,
-                            ... ) {
+static inline std::string msg_if_given(_Printf_format_string_ const char* format, ...) {
 #else
 static inline std::string msg_if_given(const char* format, ...)
     __attribute__((format(printf, 1, 2)));
 
-
-static inline std::string msg_if_given
-                          ( const char* format,
-                            ... ) {
+static inline std::string msg_if_given(const char* format, ...) {
 #endif
     if (format[0] == 0x0) {
         return "";
-    } else {
-        _fix_format(format);
-        size_t len = 0;
-        char msg[2048];
+    }
+    _fix_format(format);
+    std::string msg(2048, '\0');
+    for (int i = 0; i < 2; ++i) {
         va_list args;
         va_start(args, format);
-        len = vsnprintf(msg, 2048, format, args);
+        const int len = vsnprintf(&msg[0], msg.size(), format, args);
         va_end(args);
-
-        // Get rid of newline at the end.
-        if (msg[len-1] == '\n') {
-            len--;
-            msg[len] = 0x0;
+        if (len < 0) {
+            return std::string("invalid format ") + format;
         }
-        return std::string(msg, len);
+        if (static_cast<size_t>(len) < msg.size()) {
+            msg.resize(len);
+            break;
+        }
+        msg.resize(len + 1);
+    }
+
+    // Get rid of newline at the end.
+    if ((not msg.empty()) && (msg.back() == '\n')) {
+        msg.pop_back();
     }
+    return msg;
 }
 
 #define L_TRACE (6)

tests/CMakeLists.txt

@@ -81,3 +81,10 @@ add_dependencies(stat_mgr_test
 target_link_libraries(stat_mgr_test
                       ${BUILD_DIR}/${LIBRARY_OUTPUT_NAME})
 
+add_executable(logger_test
+               unit/logger_test.cxx)
+add_dependencies(logger_test
+                 static_lib)
+target_link_libraries(logger_test
+                      ${BUILD_DIR}/${LIBRARY_OUTPUT_NAME})
+

tests/unit/logger_test.cxx

@@ -0,0 +1,111 @@
+/************************************************************************
+Modifications Copyright 2017-2019 eBay Inc.
+Author/Developer(s): Jung-Sang Ahn
+
+Original Copyright:
+See URL: https://github.com/datatechnology/cornerstone
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    https://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+**************************************************************************/
+
+#include "libnuraft/logger.hxx"
+#include "tracer.hxx"
+
+#include "test_common.h"
+#include <cstddef>
+#include <iostream>
+#include <sstream>
+#include <string>
+
+using namespace nuraft;
+
+namespace logger_test {
+
+class ToStringStreamLogger : public nuraft::logger {
+public:
+    ToStringStreamLogger() = default;
+
+    ~ToStringStreamLogger() = default;
+
+    void put_details(int level,
+                     const char* source_file,
+                     const char* func_name,
+                     size_t line_number,
+                     const std::string& msg) override {
+
+        static const char* const lv_names[7] = {
+            "====", "FATL", "ERRO", "WARN", "INFO", "DEBG", "TRAC"};
+
+        ss << lv_names[level] << " [" << source_file << ":" << line_number << ", "
+           << func_name << "]" << msg << "\n";
+    }
+
+    std::string to_str() const { return ss.str(); }
+
+    std::stringstream ss;
+};
+
+int logger_basic_test() {
+
+    ToStringStreamLogger logger;
+    nuraft::logger* l_ = &logger;
+    p_db("hello %s", "world");
+
+    std::cout << logger.to_str();
+    return 0;
+}
+
+int logger_long_line_test() {
+
+    for (int i = 1800; i < 4096; ++i) {
+        const std::string str(i, 'a');
+
+        ToStringStreamLogger logger;
+        nuraft::logger* l_ = &logger;
+        p_db("long string: %s", str.c_str());
+
+        const std::string log_str = logger.to_str();
+        CHK_GT(log_str.size(), str.size());
+        // std::cout << log_str;
+    }
+
+    for (int i = 1; i < 1024; i *= 2) {
+        const std::string str(1024UL * i, 'a');
+
+        ToStringStreamLogger logger;
+        nuraft::logger* l_ = &logger;
+        p_db("long string: %s", str.c_str());
+
+        const std::string log_str = logger.to_str();
+        CHK_GT(log_str.size(), str.size());
+        // std::cout << log_str;
+    }
+
+    return 0;
+}
+
+} // namespace logger_test
+using namespace logger_test;
+
+int main(int argc, char** argv) {
+    TestSuite ts(argc, argv);
+
+    ts.options.printTestMessage = true;
+
+    ts.doTest("logger basic test", logger_basic_test);
+
+    ts.doTest("logger long line test", logger_long_line_test);
+
+    return 0;
+}
+