[libc] Implemented wcsdup libc function (#150453)

Implemented wcsdup by templating internal strdup function

Author: uzairnawaz

libc/config/linux/x86_64/entrypoints.txt

@@ -377,6 +377,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.wchar.wcsrchr
     libc.src.wchar.wcsspn
     libc.src.wchar.wcscspn
+    libc.src.wchar.wcsdup
     libc.src.wchar.wmemcmp
     libc.src.wchar.wmempcpy
     libc.src.wchar.wmemcpy

libc/include/wchar.yaml

@@ -226,6 +226,12 @@ functions:
     arguments:
       - type: wchar_t *__restrict
       - type: const wchar_t *__restrict
+  - name: wcsdup
+    standards:
+      - stdc
+    return_type: wchar_t *
+    arguments:
+      - type: const wchar_t *
   - name: wcslcpy
     standards:
       - stdc

libc/src/string/allocating_string_utils.h

@@ -20,15 +20,15 @@
 namespace LIBC_NAMESPACE_DECL {
 namespace internal {
 
-LIBC_INLINE cpp::optional<char *> strdup(const char *src) {
+template <typename T> LIBC_INLINE cpp::optional<T *> strdup(const T *src) {
   if (src == nullptr)
     return cpp::nullopt;
   size_t len = string_length(src) + 1;
   AllocChecker ac;
-  char *newstr = new (ac) char[len];
+  T *newstr = new (ac) T[len];
   if (!ac)
     return cpp::nullopt;
-  inline_memcpy(newstr, src, len);
+  inline_memcpy(newstr, src, len * sizeof(T));
   return newstr;
 }
 

libc/src/wchar/CMakeLists.txt

@@ -255,6 +255,19 @@ add_entrypoint_object(
     libc.hdr.wchar_macros
 )
 
+add_entrypoint_object(
+  wcsdup
+  SRCS
+    wcsdup.cpp
+  HDRS
+    wcsdup.h
+  DEPENDS
+    libc.hdr.types.wchar_t
+    libc.src.__support.libc_errno
+    libc.src.__support.macros.config
+    libc.src.string.allocating_string_utils
+)
+
 add_entrypoint_object(
   wcspbrk
   SRCS

libc/src/wchar/wcsdup.cpp

@@ -0,0 +1,27 @@
+//===-- Implementation of wcsdup -----------------------------------------===//
+//
+// 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/wcsdup.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/string/allocating_string_utils.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(wchar_t *, wcsdup, (const wchar_t *wcs)) {
+  auto dup = internal::strdup(wcs);
+  if (dup)
+    return *dup;
+  if (wcs != nullptr)
+    libc_errno = ENOMEM;
+  return nullptr;
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/wchar/wcsdup.h

@@ -0,0 +1,21 @@
+//===-- Implementation header for wcsdup ----------------------------------===//
+//
+// 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_WCSDUP_H
+#define LLVM_LIBC_SRC_WCHAR_WCSDUP_H
+
+#include "hdr/types/wchar_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+wchar_t *wcsdup(const wchar_t *wcs);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_WCHAR_WCSDUP_H

libc/test/src/wchar/CMakeLists.txt

@@ -24,6 +24,17 @@ add_libc_test(
     libc.src.wchar.wcsnlen
 )
 
+add_libc_test(
+  wcsdup_test
+  SUITE
+    libc_wchar_unittests
+  SRCS
+    wcsdup_test.cpp
+  DEPENDS
+    libc.hdr.types.wchar_t
+    libc.src.wchar.wcsdup
+)
+
 add_libc_test(
   btowc_test
   SUITE

libc/test/src/wchar/wcsdup_test.cpp

@@ -0,0 +1,48 @@
+//===-- Unittests for wcsdup ----------------------------------------------===//
+//
+// 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 "hdr/types/wchar_t.h"
+#include "src/wchar/wcsdup.h"
+#include "test/UnitTest/ErrnoCheckingTest.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcWcsDupTest = LIBC_NAMESPACE::testing::ErrnoCheckingTest;
+
+TEST_F(LlvmLibcWcsDupTest, EmptyString) {
+  const wchar_t *empty = L"";
+
+  wchar_t *result = LIBC_NAMESPACE::wcsdup(empty);
+  ASSERT_ERRNO_SUCCESS();
+
+  ASSERT_NE(result, static_cast<wchar_t *>(nullptr));
+  ASSERT_NE(empty, const_cast<const wchar_t *>(result));
+  ASSERT_TRUE(empty[0] == result[0]);
+  ::free(result);
+}
+
+TEST_F(LlvmLibcWcsDupTest, AnyString) {
+  const wchar_t *abc = L"abc";
+
+  wchar_t *result = LIBC_NAMESPACE::wcsdup(abc);
+  ASSERT_ERRNO_SUCCESS();
+
+  ASSERT_NE(result, static_cast<wchar_t *>(nullptr));
+  ASSERT_NE(abc, const_cast<const wchar_t *>(result));
+  ASSERT_TRUE(abc[0] == result[0]);
+  ASSERT_TRUE(abc[1] == result[1]);
+  ASSERT_TRUE(abc[2] == result[2]);
+  ASSERT_TRUE(abc[3] == result[3]);
+  ::free(result);
+}
+
+TEST_F(LlvmLibcWcsDupTest, NullPtr) {
+  wchar_t *result = LIBC_NAMESPACE::wcsdup(nullptr);
+  ASSERT_ERRNO_SUCCESS();
+
+  ASSERT_EQ(result, static_cast<wchar_t *>(nullptr));
+}