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

[Rajveer Singh Bharadwaj via libc-commits]

https://github.com/Rajveer100 created https://github.com/llvm/llvm-project/pull/110676

Resolves #110548

Definition:

```c++
int ctime_s(char *buffer, size_t buffer_size, const time_t *t_ptr);

```

>From 269dd2c6f3da208c44966862458f9b82a72da996 Mon Sep 17 00:00:00 2001
From: Rajveer <rajveer.developer at icloud.com>
Date: Tue, 1 Oct 2024 19:09:11 +0530
Subject: [PATCH] [libc] Add `ctime_s`

Resolves #110548

Definition:

```c++
int ctime_s(char *buffer, size_t buffer_size, const time_t *t_ptr);

```
---
 libc/src/time/ctime_s.cpp | 39 +++++++++++++++++++++++++++++++++++++++
 libc/src/time/ctime_s.h   | 21 +++++++++++++++++++++
 2 files changed, 60 insertions(+)
 create mode 100644 libc/src/time/ctime_s.cpp
 create mode 100644 libc/src/time/ctime_s.h

diff --git a/libc/src/time/ctime_s.cpp b/libc/src/time/ctime_s.cpp
new file mode 100644
index 00000000000000..407e241ab9ef99
--- /dev/null
+++ b/libc/src/time/ctime_s.cpp
@@ -0,0 +1,39 @@
+//===-- Implementation of ctime_s function --------------------------------===//
+//
+// 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 "ctime_s.h"
+#include "src/__support/CPP/limits.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "time_utils.h"
+#include <cerrno>
+
+namespace LIBC_NAMESPACE_DECL {
+
+using LIBC_NAMESPACE::time_utils::TimeConstants;
+
+LLVM_LIBC_FUNCTION(int, ctime_s,
+                   (char *buffer, size_t buffer_size, const time_t *t_ptr)) {
+  if (t_ptr == nullptr || buffer == nullptr ||
+      *time > cpp::numeric_limits<int32_t>::max()) {
+    return EINVAL;
+  }
+
+  if (buffer_size < TimeConstants::ASCTIME_MAX_BYTES) {
+    return ERANGE;
+  }
+
+  if (time_utils::asctime(time_utils::localtime(t_ptr), buffer, buffer_size) ==
+      nullptr) {
+    return EINVAL;
+  }
+
+  return 0;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/time/ctime_s.h b/libc/src/time/ctime_s.h
new file mode 100644
index 00000000000000..023c4b5b3cbc7f
--- /dev/null
+++ b/libc/src/time/ctime_s.h
@@ -0,0 +1,21 @@
+//===-- Implementation header of ctime_s ------------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_TIME_CTIME_S_H
+#define LLVM_LIBC_SRC_TIME_CTIME_S_H
+
+#include "hdr/types/time_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+int ctime_s(char *buffer, size_t buffer_size, const time_t *t_ptr);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_TIME_CTIME_S_H