[libc] Implemented wmemmove

libc/config/linux/x86_64/entrypoints.txt

@@ -364,6 +364,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.wchar.btowc
     libc.src.wchar.wcslen
     libc.src.wchar.wctob
+    libc.src.wchar.wmemmove
     libc.src.wchar.wmemset
     libc.src.wchar.wcschr
     libc.src.wchar.wcspbrk

libc/include/wchar.yaml

@@ -72,3 +72,11 @@ functions:
       - type: __restricted wchar_t *
       - type: const __ restricted wchar_t *
       - type: size_t
+  - name: wmemmove
+    standards:
+      - stdc
+    return_type: wchar_t *
+    arguments:
+      - type: wchar_t *
+      - type: const wchar_t *
+      - type: size_t

libc/src/wchar/CMakeLists.txt

@@ -104,3 +104,16 @@ add_entrypoint_object(
     libc.hdr.wchar_macros
     libc.src.__support.wctype_utils
 )
+
+add_entrypoint_object(
+  wmemmove
+  SRCS
+    wmemmove.cpp
+  HDRS
+    wmemmove.h
+  DEPENDS
+    libc.hdr.types.size_t
+    libc.hdr.wchar_macros
+    libc.src.__support.wctype_utils
+    libc.src.__support.macros.null_check
+)

libc/src/wchar/wmemmove.cpp

@@ -0,0 +1,28 @@
+//===-- Implementation of wmemmove ----------------------------------------===//
+//
+// 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/wmemmove.h"
+
+#include "hdr/types/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/null_check.h"
+#include "src/string/memory_utils/inline_memmove.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(wchar_t *, wmemmove,
+                   (wchar_t * dest, const wchar_t *src, size_t n)) {
+  LIBC_CRASH_ON_NULLPTR(dest);
+  LIBC_CRASH_ON_NULLPTR(src);
+
+  inline_memmove(dest, src, n * sizeof(wchar_t));
+  return dest;
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/wchar/wmemmove.h

@@ -0,0 +1,22 @@
+//===-- Implementation header for wmemmove --------------------------------===//
+//
+// 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_WMEMMOVE_H
+#define LLVM_LIBC_SRC_WCHAR_WMEMMOVE_H
+
+#include "hdr/types/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+wchar_t *wmemmove(wchar_t *dest, const wchar_t *src, size_t n);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_WCHAR_WMEMMOVE_H

libc/test/src/wchar/CMakeLists.txt

@@ -94,3 +94,13 @@ add_libc_test(
   DEPENDS
     libc.src.wchar.wmemcpy
 )
+
+add_libc_test(
+  wmemmove_test
+  SUITE
+    libc_wchar_unittests
+  SRCS
+    wmemmove_test.cpp
+  DEPENDS
+    libc.src.wchar.wmemmove
+)

libc/test/src/wchar/wmemmove_test.cpp

@@ -0,0 +1,111 @@
+//===-- Unittests for wmemmove --------------------------------------------===//
+//
+// 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/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/wchar/wmemmove.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcWMemmoveTest, MoveZeroByte) {
+  wchar_t buffer[] = {L'a', L'b', L'y', L'z'};
+
+  wchar_t *ret = LIBC_NAMESPACE::wmemmove(buffer, buffer + 2, 0);
+  EXPECT_EQ(ret, buffer);
+
+  const wchar_t expected[] = {L'a', L'b', L'y', L'z'};
+  EXPECT_TRUE(buffer[0] == expected[0]);
+  EXPECT_TRUE(buffer[1] == expected[1]);
+  EXPECT_TRUE(buffer[2] == expected[2]);
+  EXPECT_TRUE(buffer[3] == expected[3]);
+}
+
+TEST(LlvmLibcWMemmoveTest, DstAndSrcPointToSameAddress) {
+  wchar_t buffer[] = {L'a', L'b'};
+
+  wchar_t *ret = LIBC_NAMESPACE::wmemmove(buffer, buffer, 1);
+  EXPECT_EQ(ret, buffer);
+
+  const wchar_t expected[] = {L'a', L'b'};
+  EXPECT_TRUE(buffer[0] == expected[0]);
+  EXPECT_TRUE(buffer[1] == expected[1]);
+}
+
+TEST(LlvmLibcWMemmoveTest, DstStartsBeforeSrc) {
+  // Set boundary at beginning and end for not overstepping when
+  // copy forward or backward.
+  wchar_t buffer[] = {L'z', L'a', L'b', L'c', L'z'};
+
+  wchar_t *dst = buffer + 1;
+  wchar_t *ret = LIBC_NAMESPACE::wmemmove(dst, buffer + 2, 2);
+  EXPECT_EQ(ret, dst);
+
+  const wchar_t expected[] = {L'z', L'b', L'c', L'c', L'z'};
+  EXPECT_TRUE(buffer[0] == expected[0]);
+  EXPECT_TRUE(buffer[1] == expected[1]);
+  EXPECT_TRUE(buffer[2] == expected[2]);
+  EXPECT_TRUE(buffer[3] == expected[3]);
+  EXPECT_TRUE(buffer[4] == expected[4]);
+}
+
+TEST(LlvmLibcWMemmoveTest, DstStartsAfterSrc) {
+  wchar_t buffer[] = {L'z', L'a', L'b', L'c', L'z'};
+
+  wchar_t *dst = buffer + 2;
+  wchar_t *ret = LIBC_NAMESPACE::wmemmove(dst, buffer + 1, 2);
+  EXPECT_EQ(ret, dst);
+
+  const wchar_t expected[] = {L'z', L'a', L'a', L'b', L'z'};
+  EXPECT_TRUE(buffer[0] == expected[0]);
+  EXPECT_TRUE(buffer[1] == expected[1]);
+  EXPECT_TRUE(buffer[2] == expected[2]);
+  EXPECT_TRUE(buffer[3] == expected[3]);
+  EXPECT_TRUE(buffer[4] == expected[4]);
+}
+
+// e.g. `Dst` follow `src`.
+// str: [abcdefghij]
+//      [__src_____]
+//      [_____Dst__]
+TEST(LlvmLibcWMemmoveTest, SrcFollowDst) {
+  wchar_t buffer[] = {L'z', L'a', L'b', L'z'};
+
+  wchar_t *dst = buffer + 1;
+  wchar_t *ret = LIBC_NAMESPACE::wmemmove(dst, buffer + 2, 1);
+  EXPECT_EQ(ret, dst);
+
+  const char expected[] = {L'z', L'b', L'b', L'z'};
+  EXPECT_TRUE(buffer[0] == expected[0]);
+  EXPECT_TRUE(buffer[1] == expected[1]);
+  EXPECT_TRUE(buffer[2] == expected[2]);
+  EXPECT_TRUE(buffer[3] == expected[3]);
+}
+
+TEST(LlvmLibcWMemmoveTest, DstFollowSrc) {
+  wchar_t buffer[] = {L'z', L'a', L'b', L'z'};
+
+  wchar_t *dst = buffer + 2;
+  wchar_t *ret = LIBC_NAMESPACE::wmemmove(dst, buffer + 1, 1);
+  EXPECT_EQ(ret, dst);
+
+  const char expected[] = {L'z', L'a', L'a', L'z'};
+  EXPECT_TRUE(buffer[0] == expected[0]);
+  EXPECT_TRUE(buffer[1] == expected[1]);
+  EXPECT_TRUE(buffer[2] == expected[2]);
+  EXPECT_TRUE(buffer[3] == expected[3]);
+}
+
+#if defined(LIBC_ADD_NULL_CHECKS) && !defined(LIBC_HAS_SANITIZER)
+TEST(LlvmLibcWMemmoveTest, NullptrCrash) {
+  wchar_t buffer[] = {L'a', L'b'};
+  // Passing in a nullptr should crash the program.
+  EXPECT_DEATH([&buffer] { LIBC_NAMESPACE::wmemmove(buffer, nullptr, 2); },
+               WITH_SIGNAL(-1));
+  EXPECT_DEATH([&buffer] { LIBC_NAMESPACE::wmemmove(nullptr, buffer, 2); },
+               WITH_SIGNAL(-1));
+}
+#endif // LIBC_HAS_ADDRESS_SANITIZER