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

Fixes #15

2 files changed, 23 insertions, 7 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;

 }

diff --git a/test/test_suite.cpp b/test/test_suite.cpp
index a5c087c..9a02b1e 100644
--- a/test/test_suite.cpp
+++ b/test/test_suite.cpp
@@ -40,23 +40,38 @@ namespace test {
 

 

 // dummy putchar

-void test::_putchar(char)

-{ }

+static char   printf_buffer[100];

+static size_t printf_idx = 0U;

+void test::_putchar(char character)

+{

+  printf_buffer[printf_idx++] = character;

+}

 

 

 

 TEST_CASE("printf", "[]" ) {

-  char buffer[100] ;

+  char buffer[100];

 

+  printf_idx = 0U;

+  memset(printf_buffer, 0xCC, 100U);

   REQUIRE(test::printf("% d", 4232) == 5);

+  REQUIRE(!strcmp(printf_buffer, " 4232"));

+}

+

+

+TEST_CASE("snprintf", "[]" ) {

+  char buffer[100];

 

   test::snprintf(buffer, 100U, "%d", -1000);

   REQUIRE(!strcmp(buffer, "-1000"));

+

+  test::snprintf(buffer, 3U, "%d", -1000);

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

 }

 

 

 TEST_CASE("space flag", "[]" ) {

-  char buffer[100] ;

+  char buffer[100];

 

   test::sprintf(buffer, "% d", 42);

   REQUIRE(!strcmp(buffer, " 42"));

@@ -130,7 +145,7 @@ TEST_CASE("space flag", "[]" ) {
 

 

 TEST_CASE("+ flag", "[]" ) {

-  char buffer[100] ;

+  char buffer[100];

 

   test::sprintf(buffer, "%+d", 42);

   REQUIRE(!strcmp(buffer, "+42"));

@@ -195,7 +210,7 @@ TEST_CASE("+ flag", "[]" ) {
 

 

 TEST_CASE("0 flag", "[]" ) {

-  char buffer[100] ;

+  char buffer[100];

 

   test::sprintf(buffer, "%0d", 42);

   REQUIRE(!strcmp(buffer, "42"));