implemented mbsnrtowcs and tests

Author: Sriya Pratipati

libc/config/linux/x86_64/entrypoints.txt

@@ -1263,6 +1263,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.wchar.mbtowc
     libc.src.wchar.mbstowcs
     libc.src.wchar.mbsrtowcs
+    libc.src.wchar.mbsnrtowcs
     libc.src.wchar.wcrtomb
     libc.src.wchar.wctomb
   )

libc/include/wchar.yaml

@@ -70,6 +70,16 @@ functions:
       - type: const char **__restrict
       - type: size_t
       - type: mbstate_t *__restrict
+  - name: mbsnrtowcs
+    standards:
+      - stdc
+    return_type: size_t
+    arguments:
+      - type: wchar_t *__restrict
+      - type: const char **__restrict
+      - type: size_t
+      - type: size_t
+      - type: mbstate_t *__restrict
   - name: wmemset
     standards:
       - stdc

libc/src/__support/wchar/mbsnrtowcs.cpp

@@ -38,16 +38,18 @@ ErrorOr<size_t> mbsnrtowcs(wchar_t *__restrict dst, const char **__restrict src,
       dst[dst_idx] = converted.value();
     // null terminator should not be counted in return value
     if (converted.value() == L'\0') {
-      src = nullptr;
+      if (dst != nullptr)
+        *src = nullptr;
       return dst_idx;
     }
     dst_idx++;
     converted = str_conv.popUTF32();
   }
 
-  *src += str_conv.getSourceIndex();
-  if (converted.error() == -1) // if we hit conversion limit
+  if (converted.error() == -1) { // if we hit conversion limit
+    *src += str_conv.getSourceIndex();
     return dst_idx;
+  }
 
   return Error(converted.error());
 }

libc/src/wchar/CMakeLists.txt

@@ -187,7 +187,25 @@ add_entrypoint_object(
     libc.src.__support.common
     libc.src.__support.macros.config
     libc.src.__support.libc_errno
-    libc.src.__support.wchar.string_converter
+    libc.src.__support.wchar.mbstate
+    libc.src.__support.wchar.mbsnrtowcs
+    libc.src.__support.wchar.mbstate
+)
+
+add_entrypoint_object(
+  mbsnrtowcs
+  SRCS
+    mbsnrtowcs.cpp
+  HDRS
+    mbsnrtowcs.h
+  DEPENDS
+    libc.hdr.types.size_t
+    libc.hdr.types.wchar_t
+    libc.src.__support.common
+    libc.src.__support.macros.config
+    libc.src.__support.libc_errno
+    libc.src.__support.wchar.mbstate
+    libc.src.__support.wchar.mbsnrtowcs
     libc.src.__support.wchar.mbstate
 )
 

libc/src/wchar/mbsnrtowcs.cpp

@@ -0,0 +1,39 @@
+//===-- Implementation of mbsnrtowcs --------------------------------------===//
+//
+// 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/mbsnrtowcs.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/mbsnrtowcs.h"
+#include "src/__support/wchar/mbstate.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(size_t, mbsnrtowcs,
+                   (wchar_t *__restrict dst, const char **__restrict src,
+                    size_t nmc, size_t len, mbstate_t *__restrict ps)) {
+  static internal::mbstate internal_mbstate;
+  // If destination is null, ignore len
+  len = dst == nullptr ? SIZE_MAX : len;
+  auto ret = internal::mbsnrtowcs(
+      dst, src, nmc, len,
+      ps == nullptr ? &internal_mbstate
+                    : reinterpret_cast<internal::mbstate *>(ps));
+  if (!ret.has_value()) {
+    // Encoding failure
+    libc_errno = ret.error();
+    return -1;
+  }
+  return ret.value();
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/wchar/mbsnrtowcs.h

@@ -0,0 +1,24 @@
+//===-- Implementation header for mbsnrtowcs ------------------------------===//
+//
+// 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_MBSNRTOWCS_H
+#define LLVM_LIBC_SRC_WCHAR_MBSNRTOWCS_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 mbsnrtowcs(wchar_t *__restrict dst, const char **__restrict src,
+                 size_t nmc, size_t len, mbstate_t *__restrict ps);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_WCHAR_MBSNRTOWCS_H

libc/src/wchar/mbsrtowcs.cpp

@@ -13,40 +13,27 @@
 #include "src/__support/common.h"
 #include "src/__support/libc_errno.h"
 #include "src/__support/macros/config.h"
+#include "src/__support/wchar/mbsnrtowcs.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),
+  // If destination is null, ignore len
+  len = dst == nullptr ? SIZE_MAX : len;
+  auto ret = internal::mbsnrtowcs(
+      dst, src, SIZE_MAX, len,
       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();
-    // null terminator should not be counted in return value
-    if (converted.value() == L'\0') {
-      src = nullptr;
-      return dst_idx;
-    }
-    dst_idx++;
-    converted = str_conv.popUTF32();
+                    : reinterpret_cast<internal::mbstate *>(ps));
+  if (!ret.has_value()) {
+    // Encoding failure
+    libc_errno = ret.error();
+    return -1;
   }
-
-  *src += str_conv.getSourceIndex();
-  if (converted.error() == -1) // if we hit conversion limit
-    return dst_idx;
-
-  libc_errno = converted.error();
-  return -1;
+  return ret.value();
 }
 
 } // namespace LIBC_NAMESPACE_DECL

libc/src/wchar/mbstowcs.cpp

@@ -21,6 +21,7 @@ namespace LIBC_NAMESPACE_DECL {
 LLVM_LIBC_FUNCTION(size_t, mbstowcs,
                    (wchar_t *__restrict pwcs, const char *__restrict s,
                     size_t n)) {
+  // If destination is null, ignore n
   n = pwcs == nullptr ? SIZE_MAX : n;
   static internal::mbstate internal_mbstate;
   const char *temp = s;

libc/test/src/wchar/CMakeLists.txt

@@ -93,6 +93,22 @@ add_libc_test(
     libc.test.UnitTest.ErrnoCheckingTest
 )
 
+add_libc_test(
+  mbsnrtowcs_test
+  SUITE
+    libc_wchar_unittests
+  SRCS
+    mbsnrtowcs_test.cpp
+  DEPENDS
+    libc.src.__support.libc_errno
+    libc.src.__support.wchar.mbstate
+    libc.src.string.memset
+    libc.src.wchar.mbsnrtowcs
+    libc.hdr.types.mbstate_t
+    libc.hdr.types.wchar_t
+    libc.test.UnitTest.ErrnoCheckingTest
+)
+
 add_libc_test(
   wctob_test
   SUITE