dual-mode logger, console or syslog

Author: amigniter

CMakeLists.txt

@@ -14,7 +14,7 @@ set (CMAKE_CXX_STANDARD 11)
 set (CXX_STANDARD_REQUIRED ON)
 
 option(USE_TLS "Enable TLS/SSL support using OpenSSL" OFF)
-option(USE_DEBUG "Enable debug output" OFF)
+option(LIBWSC_USE_DEBUG "Enable debug (verbose) output" OFF)
 option(BUILD_SHARED_LIBS "Build shared libraries instead of static ones" OFF)
 
 set(LIBEVENT_COMPONENTS libevent pthreads)
@@ -27,8 +27,6 @@ endif()
 find_package(Libevent REQUIRED COMPONENTS ${LIBEVENT_COMPONENTS})
 find_package(ZLIB REQUIRED)
 
-# include_directories(${LIBEVENT_INCLUDE_DIRS})
-
 if (${CMAKE_SYSTEM_NAME} MATCHES "Linux")
   set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 endif()
@@ -39,7 +37,6 @@ endif()
 
 set (LIBWSC_SOURCES 
   libwsc/WebSocketClient.cpp 
-  libwsc/Logger.cpp 
   libwsc/Utf8Validator.cpp 
   libwsc/base64.cpp)
 set (LIBWSC_HEADERS 
@@ -68,8 +65,8 @@ target_link_libraries(libwsc
     ZLIB::ZLIB
 )
 
-if (USE_DEBUG)
-    target_compile_definitions(libwsc PRIVATE USE_DEBUG)
+if (LIBWSC_USE_DEBUG)
+    target_compile_definitions(libwsc PRIVATE LIBWSC_USE_DEBUG)
 endif()
 
 if (USE_TLS)

libwsc/Logger.cpp

@@ -1,5 +1,7 @@
 /*
  *  Logger.h
+ *  Dual-mode logger: console or syslog
+ * 
  *  Author: Milan M.
  *  Copyright (c) 2025 AMSOFTSWITCH LTD. All rights reserved.
  */
@@ -9,37 +11,99 @@
 
 #include <cstdio>
 #include <cstring>
+#include <syslog.h>
+#include <unistd.h>
+#include <sys/time.h>
+#include <ctime>
 
-void log_debug(const char* message);
-void log_error(const char* message);
+/**
+ * \brief Determines if logs should go to syslog (non-interactive) or console.
+ */
+inline bool logger_use_syslog() {
+    static bool initialized = false;
+    static bool use_syslog = false;
+    if (!initialized) {
+        initialized = true;
+        use_syslog = !isatty(STDOUT_FILENO);
+        if (use_syslog) openlog(nullptr, LOG_PID, LOG_DAEMON);
+    }
+    return use_syslog;
+}
+
+/**
+ * \brief Fill buf with current timestamp "YYYY-MM-DD HH:MM:SS.mmm".
+ */
+inline void current_timestamp(char* buf, size_t len) {
+    struct timeval tv;
+    gettimeofday(&tv, nullptr);
+    struct tm tm_info;
+    localtime_r(&tv.tv_sec, &tm_info);
+    int ms = tv.tv_usec / 1000;
+    strftime(buf, len, "%Y-%m-%d %H:%M:%S", &tm_info);
+    size_t sl = strlen(buf);
+    snprintf(buf + sl, len - sl, ".%03d", ms);
+}
+
+/**
+ * \brief Internal debug logger: writes to stdout or syslog.
+ */
+inline void log_debug_impl(const char* message) {
+#ifdef LIBWSC_USE_DEBUG
+    char ts[32]; current_timestamp(ts, sizeof(ts));
+    if (logger_use_syslog()) {
+        syslog(LOG_DEBUG, "%s", message);
+    } else {
+        fprintf(stdout, "[DEBUG %s] %s\n", ts, message);
+        fflush(stdout);
+    }
+#else
+    (void)message;
+#endif
+}
+
+/**
+ * \brief Internal error logger: writes to stderr or syslog.
+ */
+inline void log_error_impl(const char* message) {
+    char ts[32]; current_timestamp(ts, sizeof(ts));
+    if (logger_use_syslog()) {
+        syslog(LOG_ERR, "%s", message);
+    } else {
+        fprintf(stderr, "[ERROR %s] %s\n", ts, message);
+        fflush(stderr);
+    }
+}
 
-inline void log_debug_fmt(const char* message) {
-    log_debug(message);
+// Zero-arg overloads to avoid format-security warnings
+inline void log_debug_fmt_impl(const char* fmt) {
+    log_debug_impl(fmt);
 }
-inline void log_error_fmt(const char* message) {
-    log_error(message);
+inline void log_error_fmt_impl(const char* fmt) {
+    log_error_impl(fmt);
 }
 
+// Templated overloads for formatting
 template<typename... Args>
-inline void log_debug_fmt(const char* fmt, Args... args) {
+inline void log_debug_fmt_impl(const char* fmt, Args... args) {
     char buf[256];
     snprintf(buf, sizeof(buf), fmt, args...);
-    log_debug(buf);
+    log_debug_impl(buf);
 }
 
 template<typename... Args>
-inline void log_error_fmt(const char* fmt, Args... args) {
+inline void log_error_fmt_impl(const char* fmt, Args... args) {
     char buf[256];
     snprintf(buf, sizeof(buf), fmt, args...);
-    log_error(buf);
+    log_error_impl(buf);
 }
 
-#ifdef USE_DEBUG
-    #define LOG_DEBUG(...) log_debug_fmt(__VA_ARGS__)
+// Public macros
+#ifdef LIBWSC_USE_DEBUG
+    #define log_debug(...)   log_debug_fmt_impl(__VA_ARGS__)
 #else
-    #define LOG_DEBUG(...) ((void)0)
+    #define log_debug(...)   ((void)0)
 #endif
 
-#define LOG_ERROR(...) log_error_fmt(__VA_ARGS__)
+#define log_error(...)     log_error_fmt_impl(__VA_ARGS__)
 
 #endif // LOGGER_H