Add syslog output + message logging

Makefile.am

@@ -150,6 +150,8 @@ mavlink_routerd_SOURCES = \
 	src/mavlink-router/main.cpp \
 	src/mavlink-router/mainloop.cpp \
 	src/mavlink-router/mainloop.h \
+	src/mavlink-router/message_log.cpp \
+	src/mavlink-router/message_log.h \
 	src/mavlink-router/pollable.h \
 	src/mavlink-router/pollable.cpp \
 	src/mavlink-router/timeout.h \
@@ -220,6 +222,8 @@ mainloop_test_SOURCES = \
 	src/mavlink-router/logendpoint.h \
 	src/mavlink-router/mainloop_test.cpp \
 	src/mavlink-router/mainloop.cpp \
+	src/mavlink-router/message_log.cpp \
+	src/mavlink-router/message_log.h \
 	src/mavlink-router/pollable.cpp \
 	src/mavlink-router/pollable.h \
 	src/mavlink-router/timeout.cpp \

examples/config.sample

@@ -48,8 +48,8 @@
 #       Default: 0 (disabled)
 #
 #   DebugLogLevel
-#       One of <error>, <warning>, <info> or <debug>. Which debug log
-#       level is being used by mavlink-router, with <debug> being the
+#       One of <error>, <warning>, <info>, <debug> or <trace>. Which debug log
+#       level is being used by mavlink-router, with <trace> being the
 #       most verbose.
 #       Default:<info>
 #

mavlink-router.service.in

@@ -3,7 +3,7 @@ Description=MAVLink Router
 
 [Service]
 Type=simple
-ExecStart=@bindir@/mavlink-routerd
+ExecStart=@bindir@/mavlink-routerd --syslog
 Restart=always
 Nice=-20
 WatchdogSec=5s

src/common/log.cpp

@@ -22,6 +22,7 @@
 #include <unistd.h>
 #include <stdio.h>
 #include <string.h>
+#include <syslog.h>
 #include <sys/uio.h>
 
 #define COLOR_RED          "\033[31m"
@@ -34,6 +35,7 @@
 Log::Level Log::_max_level = Level::INFO;
 int Log::_target_fd = -1;
 bool Log::_show_colors;
+Log::Backend Log::_backend = Log::Backend::STDERR;
 
 const char *Log::_get_color(Level level)
 {
@@ -51,28 +53,46 @@ const char *Log::_get_color(Level level)
         return COLOR_WHITE;
     case Level::DEBUG:
         return COLOR_LIGHTBLUE;
+    case Level::TRACE:
+        break;
     }
 
     return nullptr;
 }
 
-int Log::open()
+int Log::open(Backend backend)
 {
     assert_or_return(_target_fd < 0, -1);
 
-    /* for now, only logging is supported only to stderr */
-    _target_fd =  STDERR_FILENO;
+    _backend = backend;
 
-    if (isatty(_target_fd))
-        _show_colors = true;
+    switch (backend) {
+    case Backend::STDERR:
+        _target_fd =  STDERR_FILENO;
+
+        if (isatty(_target_fd))
+            _show_colors = true;
+
+        break;
+    case Backend::SYSLOG:
+        openlog(nullptr, LOG_CONS, LOG_USER);
+        break;
+    }
 
     return 0;
 }
 
 int Log::close()
 {
-    /* see _target_fd on open() */
-    fflush(stderr);
+    switch (_backend) {
+    case Backend::STDERR:
+        /* see _target_fd on open() */
+        fflush(stderr);
+        break;
+    case Backend::SYSLOG:
+        closelog();
+        break;
+    }
 
     return 0;
 }
@@ -82,17 +102,14 @@ void Log::set_max_level(Level level)
     _max_level = level;
 }
 
-void Log::logv(Level level, const char *format, va_list ap)
+void Log::logv_to_fd(int fd, Log::Level level, const char *format, va_list ap)
 {
     struct iovec iovec[6] = { };
     const char *color;
     int n = 0;
     char buffer[LINE_MAX];
     int save_errno;
 
-    if (_max_level < level)
-        return;
-
     /* so %m works as expected */
     save_errno = errno;
 
@@ -115,7 +132,25 @@ void Log::logv(Level level, const char *format, va_list ap)
 
     IOVEC_SET_STRING(iovec[n++], "\n");
 
-    (void)writev(_target_fd, iovec, n);
+    (void)writev(fd, iovec, n);
+}
+
+void Log::logv(Level level, const char *format, va_list ap)
+{
+    if (_max_level < level)
+        return;
+
+    switch (_backend) {
+    case Backend::STDERR:
+        logv_to_fd(_target_fd, level, format, ap);
+        break;
+    case Backend::SYSLOG:
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wformat-nonliteral"
+        vsyslog(syslog_log_level(level), format, ap);
+#pragma GCC diagnostic pop
+        break;
+    }
 }
 
 void Log::log(Level level, const char *format, ...)
@@ -126,3 +161,16 @@ void Log::log(Level level, const char *format, ...)
     logv(level, format, ap);
     va_end(ap);
 }
+
+int Log::syslog_log_level(Log::Level level)
+{
+    switch (level) {
+    case Level::ERROR: return LOG_ERR;
+    case Level::WARNING: return LOG_WARNING;
+    case Level::NOTICE: return LOG_NOTICE;
+    case Level::INFO: return LOG_INFO;
+    case Level::DEBUG: return LOG_DEBUG;
+    case Level::TRACE: return LOG_DEBUG;
+    }
+    return LOG_DEBUG;
+}

src/common/log.h

@@ -31,9 +31,15 @@ class Log {
         NOTICE,
         INFO,
         DEBUG,
+        TRACE,
     };
 
-    static int open();
+    enum class Backend {
+        STDERR,
+        SYSLOG,
+    };
+
+    static int open(Backend backend);
     static int close();
 
     static Level get_max_level() _pure_ { return _max_level; }
@@ -43,13 +49,18 @@ class Log {
     static void log(Level level, const char *format, ...) _printf_format_(2, 3);
 
 protected:
+    static void logv_to_fd(int fd, Level level, const char *format, va_list ap);
     static const char *_get_color(Level level);
 
+    static int syslog_log_level(Level level);
+
     static int _target_fd;
     static Level _max_level;
     static bool _show_colors;
+    static Backend _backend;
 };
 
+#define log_trace(...) Log::log(Log::Level::TRACE, __VA_ARGS__)
 #define log_debug(...) Log::log(Log::Level::DEBUG, __VA_ARGS__)
 #define log_info(...) Log::log(Log::Level::INFO, __VA_ARGS__)
 #define log_notice(...) Log::log(Log::Level::NOTICE, __VA_ARGS__)