use vprintf() when available

config.h.contiki

@@ -50,6 +50,7 @@
 #ifdef CONTIKI_TARGET_MINIMAL_NET
 #undef HAVE_ASSERT_H
 #define assert(x)
+#define HAVE_VPRINTF
 #endif /* CONTIKI_TARGET_MINIMAL_NET */
 
 #if defined(TMOTE_SKY)

config.h.in

@@ -79,6 +79,9 @@
 /* Define to 1 if you have the <unistd.h> header file. */
 #undef HAVE_UNISTD_H
 
+/* Define to 1 if you have the `vprintf' function. */
+#undef HAVE_VPRINTF
+
 /* Define to the address where bug reports for this package should be sent. */
 #undef PACKAGE_BUGREPORT
 

configure.in

@@ -74,7 +74,7 @@ dnl AC_TYPE_UINT64_T
 
 # Checks for library functions.
 AC_FUNC_MALLOC
-AC_CHECK_FUNCS([memset select socket strdup strerror])
+AC_CHECK_FUNCS([memset select socket strdup strerror vprintf])
 
 AC_CONFIG_HEADERS([config.h])
 

debug.c

@@ -224,7 +224,9 @@ dsrv_log(log_t level, char *format, ...) {
     printf("%s ", loglevels[level]);
 
   va_start(ap, format);
+#ifdef HAVE_VPRINTF
   vprintf(format, ap);
+#endif
   va_end(ap);
   fflush(stdout);
 }
@@ -244,7 +246,11 @@ dsrv_log(log_t level, char *format, ...) {
     PRINTF("%s ", loglevels[level]);
 
   va_start(ap, format);
+#ifdef HAVE_VPRINTF
+  vprintf(format, ap);
+#else /* HAVE_VPRINTF */
   PRINTF(format, ap);
+#endif /* HAVE_VPRINTF */
   va_end(ap);
 }
 #endif /* WITH_CONTIKI */