1 files changed, 26 insertions, 0 deletions
diff --git a/libc/test/src/stdio/fprintf_test.cpp b/libc/test/src/stdio/fprintf_test.cpp
index 6799323..b035b6d 100644
--- a/libc/test/src/stdio/fprintf_test.cpp
+++ b/libc/test/src/stdio/fprintf_test.cpp
@@ -15,6 +15,10 @@
 
 #include "src/stdio/fprintf.h"
 
+#include "src/__support/CPP/limits.h"
+#include "src/__support/macros/properties/architectures.h"
+#include "test/UnitTest/ErrnoCheckingTest.h"
+#include "test/UnitTest/ErrnoSetterMatcher.h"
 #include "test/UnitTest/Test.h"
 
 namespace printf_test {
@@ -31,6 +35,8 @@ using ::fread;
 #endif // LIBC_COPT_STDIO_USE_SYSTEM_FILE
 } // namespace printf_test
 
+using LlvmLibcFPrintfTest = LIBC_NAMESPACE::testing::ErrnoCheckingTest;
+
 TEST(LlvmLibcFPrintfTest, WriteToFile) {
   const char *FILENAME = APPEND_LIBC_TEST("fprintf_output.test");
   auto FILE_PATH = libc_make_test_file_path(FILENAME);
@@ -78,6 +84,26 @@ TEST(LlvmLibcFPrintfTest, WriteToFile) {
   written =
       LIBC_NAMESPACE::fprintf(file, "Writing to a read only file should fail.");
   EXPECT_LT(written, 0);
+  ASSERT_ERRNO_FAILURE();
+
+  ASSERT_EQ(printf_test::fclose(file), 0);
+}
+
+#if !defined(LIBC_COPT_PRINTF_NO_NULLPTR_CHECKS) &&                            \
+    !defined(LIBC_COPT_PRINTF_DISABLE_WRITE_INT) &&                            \
+    !defined(LIBC_TARGET_ARCH_IS_GPU)
+TEST(LlvmLibcFPrintfTest, NullPtrCheck) {
+  const char *FILENAME = APPEND_LIBC_TEST("fprintf_nullptr.test");
+  auto FILE_PATH = libc_make_test_file_path(FILENAME);
+
+  ::FILE *file = printf_test::fopen(FILE_PATH, "w");
+  ASSERT_FALSE(file == nullptr);
+
+  int ret =
+      LIBC_NAMESPACE::fprintf(file, "hello %n", static_cast<int *>(nullptr));
+  EXPECT_LT(ret, 0);
+  ASSERT_ERRNO_FAILURE();
 
   ASSERT_EQ(printf_test::fclose(file), 0);
 }
+#endif // LIBC_COPT_PRINTF_NO_NULLPTR_CHECKS