fix(printf): pass dummy buffer for printf to _vsnprintf instead of NULL

Fixes #15

1 files changed, 2 insertions, 1 deletions

diff --git a/printf.c b/printf.c
index 56f60d6..f1a51e2 100644
--- a/printf.c
+++ b/printf.c
@@ -647,7 +647,8 @@ int printf(const char* format, ...)
 {

   va_list va;

   va_start(va, format);

-  const int ret = _vsnprintf(_out_char, NULL, (size_t)-1, format, va);

+  char buffer[1];

+  const int ret = _vsnprintf(_out_char, buffer, (size_t)-1, format, va);

   va_end(va);

   return ret;

 }