[libc-commits] [libc] [libc] Add `ctime_s` (PR #110676)

[Nick Desaulniers via libc-commits]

================
@@ -0,0 +1,76 @@
+//===-- Unittests for ctime_s ---------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "hdr/errno_macros.h"
+#include "src/errno/libc_errno.h"
+#include "src/time/ctime_s.h"
+#include "src/time/time_utils.h"
+#include "test/UnitTest/Test.h"
+#include "test/src/time/TmHelper.h"
+
+using LIBC_NAMESPACE::time_utils::TimeConstants;
+
+TEST(LlvmLibcCtimeS, Nullptr) {
+  int result;
+  result = LIBC_NAMESPACE::ctime_s(nullptr, 0, nullptr);
+  ASSERT_EQ(EINVAL, result);
+
+  char buffer[TimeConstants::ASCTIME_BUFFER_SIZE];
+  result = LIBC_NAMESPACE::ctime_s(buffer, sizeof(buffer), nullptr);
+  ASSERT_EQ(EINVAL, result);
+  ASSERT_EQ('\0', buffer[0]);
+
+  time_t t;
+  result = LIBC_NAMESPACE::ctime_s(nullptr, 0, &t);
+  ASSERT_EQ(EINVAL, result);
+}
+
+TEST(LlvmLibcCtimeS, InvalidBufferSize) {
+  char buffer[TimeConstants::ASCTIME_BUFFER_SIZE];
+  time_t t;
+  int result;
+
+  t = 0;
+  result = LIBC_NAMESPACE::ctime_s(buffer, 0, &t);
+  ASSERT_EQ(ERANGE, result);
+
+  result = LIBC_NAMESPACE::ctime_s(buffer, RSIZE_MAX + 1, &t);
+  ASSERT_EQ(ERANGE, result);
+}
+
+TEST(LlvmLibcCtimeS, ValidUnixTimestamp0) {
+  char buffer[TimeConstants::ASCTIME_BUFFER_SIZE];
+  time_t t;
+  int result;
+  // 1970-01-01 00:00:00. Test with a valid buffer size.
+  t = 0;
+  result = LIBC_NAMESPACE::ctime_s(buffer, sizeof(buffer), &t);
+  ASSERT_STREQ("Thu Jan  1 00:00:00 1970\n", buffer);
+  ASSERT_EQ(0, result);
+}
+
+TEST(LlvmLibcCtimeS, ValidUnixTimestamp32Int) {
+  char buffer[TimeConstants::ASCTIME_BUFFER_SIZE];
+  time_t t;
+  int result;
+  // 2038-01-19 03:14:07. Test with a valid buffer size.
+  t = 2147483647;
+  result = LIBC_NAMESPACE::ctime_s(buffer, sizeof(buffer), &t);
----------------
nickdesaulniers wrote:

```suggestion
  // 2038-01-19 03:14:07. Test with a valid buffer size.
  time_t t = 2147483647;
  int result = LIBC_NAMESPACE::ctime_s(buffer, sizeof(buffer), &t);
```

https://github.com/llvm/llvm-project/pull/110676