[libc] Add ctime_s

Resolves #110548

Definition:

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

```

Author: Rajveer100

libc/config/baremetal/arm/entrypoints.txt

@@ -205,6 +205,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.time.asctime_r
     libc.src.time.ctime
     libc.src.time.ctime_r
+    libc.src.time.ctime_s
     libc.src.time.difftime
     libc.src.time.gmtime
     libc.src.time.gmtime_r

libc/config/baremetal/riscv/entrypoints.txt

@@ -201,6 +201,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.time.asctime_r
     libc.src.time.ctime
     libc.src.time.ctime_r
+    libc.src.time.ctime_s
     libc.src.time.difftime
     libc.src.time.gmtime
     libc.src.time.gmtime_r

libc/config/linux/aarch64/entrypoints.txt

@@ -969,6 +969,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.time.asctime_r
     libc.src.time.ctime
     libc.src.time.ctime_r
+    libc.src.time.ctime_s
     libc.src.time.clock
     libc.src.time.clock_gettime
     libc.src.time.difftime

libc/config/linux/riscv/entrypoints.txt

@@ -901,6 +901,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.time.asctime_r
     libc.src.time.ctime
     libc.src.time.ctime_r
+    libc.src.time.ctime_s
     libc.src.time.clock
     libc.src.time.clock_gettime
     libc.src.time.difftime

libc/config/linux/x86_64/entrypoints.txt

@@ -1026,6 +1026,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.time.asctime_r
     libc.src.time.ctime
     libc.src.time.ctime_r
+    libc.src.time.ctime_s
     libc.src.time.clock
     libc.src.time.clock_gettime
     libc.src.time.difftime

libc/docs/date_and_time.rst

@@ -59,6 +59,8 @@ Implementation Status
 +---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+
 | ctime_r             | |check| | |check| |         |     |check|     |         |         |         |         |         |         |         |         |
 +---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+
+| ctime_s             | |check| | |check| |         |     |check|     |         |         |         |         |         |         |         |         |
++---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+
 | clock               | |check| | |check| |         |     |check|     |         |         |         |         |         |         |         |         |
 +---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+
 | clock_getcpuclockid |         |         |         |                 |         |         |         |         |         |         |         |         |

libc/hdr/types/rsize_t.h

@@ -0,0 +1,23 @@
+//===-- Proxy for rsize_t -------------------------------------------------===//
+//
+// 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_HDR_TYPES_RSIZE_T_H
+#define LLVM_LIBC_HDR_TYPES_RSIZE_T_H
+
+#ifdef LIBC_FULL_BUILD
+
+#include "include/llvm-libc-types/rsize_t.h"
+
+#else
+
+#define __need_rsize_t
+#include <stddef.h>
+#undef __need_rsize_t
+
+#endif // LIBC_FULL_BUILD
+
+#endif // LLVM_LIBC_HDR_TYPES_RSIZE_T_H

libc/include/llvm-libc-types/rsize_t.h

@@ -0,0 +1,16 @@
+//===-- Definition of rsize_t type ----------------------------------------===//
+//
+// 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_TYPES_RSIZE_T_H
+#define LLVM_LIBC_TYPES_RSIZE_T_H
+
+#include "size_t.h"
+
+typedef size_t rsize_t;
+
+#endif // LLVM_LIBC_TYPES_RSIZE_T_H

libc/newhdrgen/yaml/time.yaml

@@ -37,6 +37,14 @@ functions:
     arguments:
       - type: const time_t *
       - type: char *
+  - name: ctime_s
+    standard:
+      - stdc
+    return_type: int
+    arguments:
+      - type: char *
+      - type: size_t
+      - type: const time_t *
   - name: clock
     standard:
       - stdc

libc/spec/stdc.td

@@ -1630,6 +1630,15 @@ def StdC : StandardSpec<"stdc"> {
                   ArgSpec<CharPtr>,
               ]
           >,
+          FunctionSpec<
+              "ctime_s",
+              RetValSpec<IntType>,
+              [
+                  ArgSpec<CharPtr>,
+                  ArgSpec<SizeTType>,
+                  ArgSpec<ConstTimeTTypePtr>,
+              ]
+          >,
           FunctionSpec<
               "clock",
               RetValSpec<ClockT>,