Make it possible to route messages to syslog

1 files changed, 39 insertions, 12 deletions

diff --git a/src/common.c b/src/common.c
index 8f7ffd1..800aea5 100644
--- a/src/common.c
+++ b/src/common.c
@@ -42,6 +42,7 @@
 #include <strings.h>
 #include <regex.h>
 #include <libgen.h>
+#include <syslog.h>
 
 #include <sys/socket.h>
 #include <sys/types.h>
@@ -86,28 +87,54 @@ extern char **environ;
 #define BLOCK_START  do {
 #define BLOCK_END    } while (0)
 
-// --- Utilities ---------------------------------------------------------------
+// --- Logging -----------------------------------------------------------------
 
 static void
-print_message (FILE *stream, const char *type, const char *fmt, ...)
-	ATTRIBUTE_PRINTF (3, 4);
+log_message_syslog (int prio, const char *quote, const char *fmt, va_list ap)
+{
+	va_list va;
+	va_copy (va, ap);
+	int size = vsnprintf (NULL, 0, fmt, va);
+	va_end (va);
+	if (size < 0)
+		return;
+
+	char buf[size + 1];
+	if (vsnprintf (buf, sizeof buf, fmt, ap) >= 0)
+		syslog (prio, "%s%s", quote, buf);
+}
 
 static void
-print_message (FILE *stream, const char *type, const char *fmt, ...)
+log_message_stdio (int prio, const char *quote, const char *fmt, va_list ap)
 {
-	va_list ap;
+	(void) prio;
+	FILE *stream = stderr;
 
-	va_start (ap, fmt);
-	fprintf (stream, "%s ", type);
+	fputs (quote, stream);
 	vfprintf (stream, fmt, ap);
 	fputs ("\n", stream);
+}
+
+static void (*g_log_message_real) (int, const char *, const char *, va_list)
+	= log_message_stdio;
+
+static void
+log_message (int priority, const char *quote, const char *fmt, ...)
+	ATTRIBUTE_PRINTF (3, 4);
+
+static void
+log_message (int priority, const char *quote, const char *fmt, ...)
+{
+	va_list ap;
+	va_start (ap, fmt);
+	g_log_message_real (priority, quote, fmt, ap);
 	va_end (ap);
 }
 
-#define print_fatal(...)    print_message (stderr, "fatal:",   __VA_ARGS__)
-#define print_error(...)    print_message (stderr, "error:",   __VA_ARGS__)
-#define print_warning(...)  print_message (stderr, "warning:", __VA_ARGS__)
-#define print_status(...)   print_message (stdout, "--",       __VA_ARGS__)
+#define print_fatal(...)    log_message (LOG_ERR,     "fatal: ",   __VA_ARGS__)
+#define print_error(...)    log_message (LOG_ERR,     "error: ",   __VA_ARGS__)
+#define print_warning(...)  log_message (LOG_WARNING, "warning: ", __VA_ARGS__)
+#define print_status(...)   log_message (LOG_INFO,    "-- ",       __VA_ARGS__)
 
 // --- Debugging and assertions ------------------------------------------------
 
@@ -122,7 +149,7 @@ static bool g_soft_asserts_are_deadly;  ///< soft_assert() aborts as well
 #define print_debug(...)                                                       \
 	BLOCK_START                                                                \
 		if (g_debug_mode)                                                      \
-			print_message (stderr, "debug:", __VA_ARGS__);                     \
+			log_message (LOG_DEBUG, "debug: ", __VA_ARGS__);                   \
 	BLOCK_END
 
 static void