began implementing public function

Author: uzairnawaz

libc/src/__support/wchar/wcsrtombs.cpp

@@ -25,7 +25,7 @@ ErrorOr<size_t> wcsrtombs(char *__restrict dst, const wchar_t **__restrict src,
                           size_t len, mbstate *__restrict ps) {
   static_assert(sizeof(wchar_t) == 4);
 
-  if (dst == nullptr)
+  if (src == nullptr || dst == nullptr)
     return Error(-1);
 
   size_t bytes_written = 0;

libc/src/__support/wchar/wcsrtombs.h

@@ -19,7 +19,7 @@ namespace LIBC_NAMESPACE_DECL {
 namespace internal {
 
 ErrorOr<size_t> wcsrtombs(char *__restrict dst, const wchar_t **__restrict src,
-                          size_t len, mbstate_t *__restrict ps);
+                          size_t len, mbstate *__restrict ps);
 
 } // namespace internal
 } // namespace LIBC_NAMESPACE_DECL

libc/src/wchar/wcsrtombs.cpp

@@ -1,38 +1,38 @@
-//===-- Implementation of wcrtomb -----------------------------------------===//
+//===-- Implementation of wcsrtombs ---------------------------------------===//
 //
 // 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 "src/wchar/wcrtomb.h"
+#include "src/wchar/wcsrtombs.h"
 
 #include "hdr/types/mbstate_t.h"
 #include "hdr/types/wchar_t.h"
 #include "src/__support/common.h"
 #include "src/__support/libc_errno.h"
 #include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
 #include "src/__support/wchar/mbstate.h"
-#include "src/__support/wchar/wcrtomb.h"
+#include "src/__support/wchar/wcsrtombs.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
-LLVM_LIBC_FUNCTION(size_t, wcrtomb,
-                   (char *__restrict s, wchar_t wc, mbstate_t *__restrict ps)) {
+LLVM_LIBC_FUNCTION(size_t, wcsrtombs,
+                   (char *__restrict dst, const wchar_t **__restrict src,
+                    size_t len, mbstate_t *__restrict ps)) {
   static internal::mbstate internal_mbstate;
 
-  // when s is nullptr, this is equivalent to wcrtomb(buf, L'\0', ps)
-  char buf[sizeof(wchar_t) / sizeof(char)];
-  if (s == nullptr) {
-    s = buf;
-    wc = L'\0';
-  }
+  LIBC_CRASH_ON_NULLPTR(src);
+  char buf[len];
+  if (dst == nullptr)
+    dst = buf;
 
-  auto result = internal::wcrtomb(
-      s, wc,
+  auto result = internal::wcsrtombs(
+      dst, src, len,
       ps == nullptr ? &internal_mbstate
-                    : reinterpret_cast<internal::mbstate *>(ps), 4);
+                    : reinterpret_cast<internal::mbstate *>(ps));
 
   if (!result.has_value()) {
     libc_errno = EILSEQ;

libc/src/wchar/wcsrtombs.h

@@ -0,0 +1,24 @@
+//===-- Implementation header for wcsrtombs ---------------------*- 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_WCHAR_WCSRTOMBS_H
+#define LLVM_LIBC_SRC_WCHAR_WCSRTOMBS_H
+
+#include "hdr/types/mbstate_t.h"
+#include "hdr/types/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+size_t wcsrtombs(char *__restrict dst, const wchar_t **__restrict src,
+                 size_t len, mbstate_t *__restrict ps);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_WCHAR_WCSRTOMBS_H