[helpers] Added an ability to redirect all output to syslog in case of daemon mode;

examples/helpers.c

@@ -21,9 +21,9 @@
  *
  */
 
+#define _GNU_SOURCE
 #include <stdio.h>
 #include <dirent.h>
-#define __USE_GNU
 #include <stdlib.h>
 #include <stdarg.h>
 #include <sys/types.h>
@@ -38,6 +38,7 @@
 #include <errno.h>
 #include <string.h>
 #include <fcntl.h>
+#include <syslog.h>
 
 int openlistener_socket(int port)
 {
@@ -117,6 +118,27 @@ int normalize_path(char *path)
   return 0;
 }
 
+/* syslog stuff */
+
+static size_t writer(void *cookie, char const *data, size_t len)
+{
+  (void)cookie;
+  syslog(LOG_DEBUG, "%.*s", (int)len, data);
+  return len;
+}
+static int noop(void) { return 0; }
+
+static cookie_io_functions_t log_fns = {
+  (void*) noop, (void*) writer, (void*) noop, (void*) noop
+};
+
+void tosyslog(FILE **pfp)
+{
+  setvbuf(*pfp = fopencookie(NULL, "w", log_fns), NULL, _IOLBF, 0);
+}
+
+/* daemonization stuff */
+
 #define DM_MAX_CLOSE 8192
 
 int daemonize(void)
@@ -166,5 +188,9 @@ int daemonize(void)
     return EBADFD;
   }
 
+  /* redirect output to syslog as well */
+  tosyslog(&stdout);
+  tosyslog(&stderr);
+
   return 0;
 }