fix(printf): fix negative argument precision

Fixes #25

2 files changed, 5 insertions, 1 deletions

diff --git a/printf.c b/printf.c
index 50af893..d71665f 100644
--- a/printf.c
+++ b/printf.c
@@ -464,7 +464,8 @@ static int _vsnprintf(out_fct_type out, char* buffer, const size_t maxlen, const
         precision = _atoi(&format);

       }

       else if (*format == '*') {

-        precision = (unsigned int)va_arg(va, int);

+        const int prec = (int)va_arg(va, int);

+        precision = prec > 0 ? (unsigned int)prec : 0U;

         format++;

       }

     }

diff --git a/test/test_suite.cpp b/test/test_suite.cpp
index 05b95f7..e693851 100644
--- a/test/test_suite.cpp
+++ b/test/test_suite.cpp
@@ -1226,6 +1226,9 @@ TEST_CASE("misc", "[]" ) {
   test::sprintf(buffer, "%.*f", 2, 0.33333333);

   REQUIRE(!strcmp(buffer, "0.33"));

 

+  test::sprintf(buffer, "%.*d", -1, 1);

+  REQUIRE(!strcmp(buffer, "1"));

+

   test::sprintf(buffer, "%.3s", "foobar");

   REQUIRE(!strcmp(buffer, "foo"));