implemented mbsrtowcs

Author: Sriya Pratipati

libc/src/wchar/mbsrtowcs.cpp

@@ -0,0 +1,47 @@
+//===-- Implementation of mbsrtowcs ---------------------------------------===//
+//
+// 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/mbsrtowcs.h"
+
+#include "hdr/types/size_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/wchar/mbstate.h"
+#include "src/__support/wchar/string_converter.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(size_t, mbsrtowcs,
+                   (wchar_t *__restrict dst, const char **__restrict src,
+                    size_t len, mbstate_t *__restrict ps)) {
+  static internal::mbstate internal_mbstate;
+  internal::StringConverter<char8_t> str_conv(
+      reinterpret_cast<const char8_t *>(src),
+      ps == nullptr ? &internal_mbstate
+                    : reinterpret_cast<internal::mbstate *>(ps),
+      len);
+
+  int dst_idx = 0;
+  ErrorOr<char32_t> converted = str_conv.popUTF32();
+  while (converted.has_value()) {
+    dst[dst_idx] = converted.value();
+    dst_idx++;
+    converted = str_conv.popUTF32();
+  }
+
+  src += str_conv.getSourceIndex();
+  if (converted.error() == -1) // if we hit conversion limit
+    return dst_idx;
+
+  libc_errno = converted.error();
+  return -1;
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/wchar/mbsrtowcs.h

@@ -0,0 +1,24 @@
+//===-- Implementation header for mbsrtowcs -------------------------------===//
+//
+// 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_MBSRTOWCS_H
+#define LLVM_LIBC_SRC_WCHAR_MBSRTOWCS_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 mbsrtowcs(wchar_t *__restrict dst, const char **__restrict src,
+                 size_t len, mbstate_t *__restrict ps);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_WCHAR_MBSRTOWCS_H

libc/src/wchar/mbstowcs.cpp

@@ -18,7 +18,7 @@
 
 namespace LIBC_NAMESPACE_DECL {
 
-LLVM_LIBC_FUNCTION(int, mbstowcs,
+LLVM_LIBC_FUNCTION(size_t, mbstowcs,
                    (wchar_t *__restrict pwcs, const char *__restrict s,
                     size_t n)) {
   static internal::mbstate internal_mbstate;

libc/src/wchar/mbstowcs.h

@@ -15,7 +15,7 @@
 
 namespace LIBC_NAMESPACE_DECL {
 
-int mbstowcs(wchar_t *__restrict pwcs, const char *__restrict s, size_t n);
+size_t mbstowcs(wchar_t *__restrict pwcs, const char *__restrict s, size_t n);
 
 } // namespace LIBC_NAMESPACE_DECL