llmnrd: add command line option to log to syslog instead of stdio

When llmnrd daemonizes stdout and stderr are redirected to /dev/null
and all logs are lost. This adds a cli option -s / --syslog to send
the logs to syslog instead.

Signed-off-by: Diego Santa Cruz <Diego.SantaCruz@spinetix.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/log.c b/log.c
new file mode 100644
index 0000000..603db7f
--- /dev/null
+++ b/log.c
@@ -0,0 +1,39 @@
+#include <stdarg.h>
+#include <stdbool.h>
+
+#include "log.h"
+
+static bool use_syslog;
+
+void log_lvl(int lvl, const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+
+	if (!use_syslog) {
+		FILE *out = stderr;
+		switch (lvl) {
+		case LOG_ERR:
+			fputs("Error: ", stderr);
+			break;
+		case LOG_WARNING:
+			fputs("Warning: ", stderr);
+			break;
+		case LOG_INFO:
+		case LOG_DEBUG:
+			out = stdout;
+			break;
+		}
+		vfprintf(out, fmt, ap);
+	} else {
+		vsyslog(lvl, fmt, ap);
+	}
+
+	va_end(ap);
+}
+
+void log_to_syslog(void)
+{
+	use_syslog = true;
+}