[libc-commits] [libc] 22dd9a2 - [libc] wmemchr implementation (#142640)

via libc-commits libc-commits at lists.llvm.org
Tue Jun 3 17:05:17 PDT 2025


Author: sribee8
Date: 2025-06-03T17:05:14-07:00
New Revision: 22dd9a24830ef29c25a8634777772282a3f33598

URL: https://github.com/llvm/llvm-project/commit/22dd9a24830ef29c25a8634777772282a3f33598
DIFF: https://github.com/llvm/llvm-project/commit/22dd9a24830ef29c25a8634777772282a3f33598.diff

LOG: [libc] wmemchr implementation (#142640)

Implemented wmemchr and tests.
Fixes: #121183

---------

Co-authored-by: Sriya Pratipati <sriyap at google.com>

Added: 
    libc/src/wchar/wmemchr.cpp
    libc/src/wchar/wmemchr.h
    libc/test/src/wchar/wmemchr_test.cpp

Modified: 
    libc/config/linux/x86_64/entrypoints.txt
    libc/include/wchar.yaml
    libc/src/wchar/CMakeLists.txt
    libc/test/src/wchar/CMakeLists.txt

Removed: 
    


################################################################################
diff  --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index ed2994d1273c4..959bdbf08dbea 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -379,6 +379,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.wchar.wcsstr
     libc.src.wchar.wcsncat
     libc.src.wchar.wcscpy
+    libc.src.wchar.wmemchr
 
     # sys/uio.h entrypoints
     libc.src.sys.uio.writev

diff  --git a/libc/include/wchar.yaml b/libc/include/wchar.yaml
index 18b77a2711f7e..877be48b6a10f 100644
--- a/libc/include/wchar.yaml
+++ b/libc/include/wchar.yaml
@@ -86,6 +86,14 @@ functions:
       - type: const wchar_t *
       - type: const wchar_t *
       - type: size_t
+  - name: wmemchr
+    standards:
+      - stdc
+    return_type: const wchar_t *
+    arguments:
+      - type: const wchar_t *
+      - type: wchar_t
+      - type: size_t
   - name: wmempcpy
     standards:
       - gnu

diff  --git a/libc/src/wchar/CMakeLists.txt b/libc/src/wchar/CMakeLists.txt
index b131d2feeda06..759f708c2247a 100644
--- a/libc/src/wchar/CMakeLists.txt
+++ b/libc/src/wchar/CMakeLists.txt
@@ -185,6 +185,17 @@ add_entrypoint_object(
     libc.src.string.string_utils
 )
 
+add_entrypoint_object(
+  wmemchr
+  SRCS
+    wmemchr.cpp
+  HDRS
+    wmemchr.h
+  DEPENDS
+    libc.hdr.types.size_t
+    libc.hdr.wchar_macros
+)
+
 add_entrypoint_object(
   wmempcpy
   SRCS

diff  --git a/libc/src/wchar/wmemchr.cpp b/libc/src/wchar/wmemchr.cpp
new file mode 100644
index 0000000000000..8a1cd6ce43890
--- /dev/null
+++ b/libc/src/wchar/wmemchr.cpp
@@ -0,0 +1,27 @@
+//===-- Implementation of wmemchr -----------------------------------------===//
+//
+// 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/wmemchr.h"
+
+#include "hdr/types/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(const wchar_t *, wmemchr,
+                   (const wchar_t *s, wchar_t c, size_t n)) {
+  size_t i = 0;
+  for (; i < n; ++i)
+    if (s[i] == c)
+      return (s + i);
+  return nullptr;
+}
+
+} // namespace LIBC_NAMESPACE_DECL

diff  --git a/libc/src/wchar/wmemchr.h b/libc/src/wchar/wmemchr.h
new file mode 100644
index 0000000000000..55412907ddca6
--- /dev/null
+++ b/libc/src/wchar/wmemchr.h
@@ -0,0 +1,22 @@
+//===-- Implementation header for wmemchr ---------------------------------===//
+//
+// 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_WMEMCHR_H
+#define LLVM_LIBC_SRC_WCHAR_WMEMCHR_H
+
+#include "hdr/types/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+const wchar_t *wmemchr(const wchar_t *s, wchar_t c, size_t n);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_WCHAR_WMEMCHR_H

diff  --git a/libc/test/src/wchar/CMakeLists.txt b/libc/test/src/wchar/CMakeLists.txt
index 89c3048ae262b..6293e8e3d55cf 100644
--- a/libc/test/src/wchar/CMakeLists.txt
+++ b/libc/test/src/wchar/CMakeLists.txt
@@ -105,6 +105,16 @@ add_libc_test(
     libc.src.wchar.wcsspn
 )
 
+add_libc_test(
+  wmemchr_test
+  SUITE
+    libc_wchar_unittests
+  SRCS
+    wmemchr_test.cpp
+  DEPENDS
+    libc.src.wchar.wmemchr
+)
+
 add_libc_test(
   wmemcmp_test
   SUITE

diff  --git a/libc/test/src/wchar/wmemchr_test.cpp b/libc/test/src/wchar/wmemchr_test.cpp
new file mode 100644
index 0000000000000..6b25bd83b16ee
--- /dev/null
+++ b/libc/test/src/wchar/wmemchr_test.cpp
@@ -0,0 +1,92 @@
+//===-- Unittests for wmemchr ---------------------------------------------===//
+//
+// 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/wmemchr.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcWMemChrTest, FindsCharacterAfterNullTerminator) {
+  // wmemchr should continue searching after a null terminator.
+  const size_t size = 5;
+  const wchar_t src[size] = {L'a', L'\0', L'b', L'c', L'\0'};
+  ASSERT_EQ(LIBC_NAMESPACE::wmemchr(src, L'b', size), (src + 2));
+}
+
+TEST(LlvmLibcWMemChrTest, FindsCharacterInNonNullTerminatedCollection) {
+  const size_t size = 3;
+  const wchar_t src[size] = {L'a', L'b', L'c'};
+  ASSERT_EQ(LIBC_NAMESPACE::wmemchr(src, L'b', size), (src + 1));
+}
+
+TEST(LlvmLibcWMemChrTest, FindsFirstCharacter) {
+  const size_t size = 6;
+  const wchar_t *src = L"abcde";
+  // Should return original array since 'a' is the first character.
+  ASSERT_EQ(LIBC_NAMESPACE::wmemchr(src, L'a', size), (src));
+}
+
+TEST(LlvmLibcWMemChrTest, FindsMiddleCharacter) {
+  const size_t size = 6;
+  const wchar_t *src = L"abcde";
+  // Should return characters after and including 'c'.
+  ASSERT_EQ(LIBC_NAMESPACE::wmemchr(src, L'c', size), (src + 2));
+}
+
+TEST(LlvmLibcWMemChrTest, FindsLastCharacterThatIsNotNullTerminator) {
+  const size_t size = 6;
+  const wchar_t *src = L"abcde";
+  // Should return 'e' and null terminator.
+  ASSERT_EQ(LIBC_NAMESPACE::wmemchr(src, L'e', size), (src + 4));
+}
+
+TEST(LlvmLibcWMemChrTest, FindsNullTerminator) {
+  const size_t size = 6;
+  const wchar_t *src = L"abcde";
+  // Should return null terminator.
+  ASSERT_EQ(LIBC_NAMESPACE::wmemchr(src, L'\0', size), (src + 5));
+}
+
+TEST(LlvmLibcWMemChrTest, CharacterNotWithinStringShouldReturnNullptr) {
+  const size_t size = 6;
+  const wchar_t *src = L"abcde";
+  // Should return nullptr.
+  ASSERT_EQ(LIBC_NAMESPACE::wmemchr(src, L'z', size), nullptr);
+}
+
+TEST(LlvmLibcWMemChrTest, CharacterNotWithinSizeShouldReturnNullptr) {
+  const size_t size = 3;
+  const wchar_t *src = L"abcde";
+  // Should return nullptr.
+  ASSERT_EQ(LIBC_NAMESPACE::wmemchr(src, L'd', size), nullptr);
+}
+
+TEST(LlvmLibcWMemChrTest, TheSourceShouldNotChange) {
+  const size_t size = 3;
+  const wchar_t *src = L"ab";
+  ASSERT_EQ(LIBC_NAMESPACE::wmemchr(src, L'a', size), src);
+  ASSERT_TRUE(src[0] == L'a');
+  ASSERT_TRUE(src[1] == L'b');
+  ASSERT_EQ(LIBC_NAMESPACE::wmemchr(src, L'c', size), nullptr);
+  ASSERT_TRUE(src[0] == L'a');
+  ASSERT_TRUE(src[1] == L'b');
+}
+
+TEST(LlvmLibcWMemChrTest, EmptyStringShouldOnlyMatchNullTerminator) {
+  const size_t size = 1;
+  const wchar_t *src = L"";
+  ASSERT_EQ(LIBC_NAMESPACE::wmemchr(src, L'\0', size), src);
+  ASSERT_EQ(LIBC_NAMESPACE::wmemchr(src, L'c', size), nullptr);
+  ASSERT_EQ(LIBC_NAMESPACE::wmemchr(src, L'1', size), nullptr);
+  ASSERT_EQ(LIBC_NAMESPACE::wmemchr(src, L'?', size), nullptr);
+}
+
+TEST(LlvmLibcWMemChrTest, SingleRepeatedCharacterShouldReturnFirst) {
+  const size_t size = 6;
+  const wchar_t *src = L"XXXXX";
+  ASSERT_EQ(LIBC_NAMESPACE::wmemchr(src, L'X', size), src);
+}


        


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