[libc-commits] [libc] [libc] Implemented wcsrchr (PR #142436)
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libc-commits at lists.llvm.org
Mon Jun 2 10:24:28 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libc
Author: Uzair Nawaz (uzairnawaz)
<details>
<summary>Changes</summary>
Implemented wcsrchr and added tests
---
Full diff: https://github.com/llvm/llvm-project/pull/142436.diff
7 Files Affected:
- (modified) libc/config/linux/x86_64/entrypoints.txt (+1)
- (modified) libc/include/wchar.yaml (+7)
- (modified) libc/src/wchar/CMakeLists.txt (+11)
- (added) libc/src/wchar/wcsrchr.cpp (+31)
- (added) libc/src/wchar/wcsrchr.h (+21)
- (modified) libc/test/src/wchar/CMakeLists.txt (+10)
- (added) libc/test/src/wchar/wcsrchr_test.cpp (+68)
``````````diff
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 545b9227349fe..e6cbfe0257a3e 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -367,6 +367,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.wchar.wmemset
libc.src.wchar.wcschr
libc.src.wchar.wcspbrk
+ libc.src.wchar.wcsrchr
libc.src.wchar.wcsspn
libc.src.wchar.wmemcmp
libc.src.wchar.wmemcpy
diff --git a/libc/include/wchar.yaml b/libc/include/wchar.yaml
index bfd9a10342019..39732feb62fcd 100644
--- a/libc/include/wchar.yaml
+++ b/libc/include/wchar.yaml
@@ -49,6 +49,13 @@ functions:
arguments:
- type: const wchar_t *
- type: const wchar_t *
+ - name: wcsrchr
+ standards:
+ - stdc
+ return_type: const wchar_t *
+ arguments:
+ - type: const wchar_t *
+ - type: wchar_t
- name: wcsspn
standards:
- stdc
diff --git a/libc/src/wchar/CMakeLists.txt b/libc/src/wchar/CMakeLists.txt
index 9db121762348b..dd597550e06d8 100644
--- a/libc/src/wchar/CMakeLists.txt
+++ b/libc/src/wchar/CMakeLists.txt
@@ -68,6 +68,17 @@ add_entrypoint_object(
libc.src.__support.wctype_utils
)
+add_entrypoint_object(
+ wcsrchr
+ SRCS
+ wcsrchr.cpp
+ HDRS
+ wcsrchr.h
+ DEPENDS
+ libc.hdr.wchar_macros
+ libc.src.__support.wctype_utils
+)
+
add_entrypoint_object(
wcsspn
SRCS
diff --git a/libc/src/wchar/wcsrchr.cpp b/libc/src/wchar/wcsrchr.cpp
new file mode 100644
index 0000000000000..bb4e373bb1ce1
--- /dev/null
+++ b/libc/src/wchar/wcsrchr.cpp
@@ -0,0 +1,31 @@
+//===-- Implementation of wcsrchr -----------------------------------------===//
+//
+// 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/wcsrchr.h"
+
+#include "hdr/types/wchar_t.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(const wchar_t *, wcsrchr, (const wchar_t *s, wchar_t c)) {
+ LIBC_CRASH_ON_NULLPTR(s);
+
+ const wchar_t *last_occurrence = nullptr;
+ while (true) {
+ if (*s == c)
+ last_occurrence = s;
+ if (*s == L'\0')
+ return last_occurrence;
+ ++s;
+ }
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/wchar/wcsrchr.h b/libc/src/wchar/wcsrchr.h
new file mode 100644
index 0000000000000..5e9d8c3c2db92
--- /dev/null
+++ b/libc/src/wchar/wcsrchr.h
@@ -0,0 +1,21 @@
+//===-- Implementation header for wcsrchr ---------------------------------===//
+//
+// 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_WCSRCHR_H
+#define LLVM_LIBC_SRC_WCHAR_WCSRCHR_H
+
+#include "hdr/types/wchar_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+const wchar_t *wcsrchr(const wchar_t *s, wchar_t c);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_WCHAR_WCSRCHR_H
diff --git a/libc/test/src/wchar/CMakeLists.txt b/libc/test/src/wchar/CMakeLists.txt
index 9bc230e0bddf3..6a212a620f853 100644
--- a/libc/test/src/wchar/CMakeLists.txt
+++ b/libc/test/src/wchar/CMakeLists.txt
@@ -65,6 +65,16 @@ add_libc_test(
libc.src.wchar.wcspbrk
)
+add_libc_test(
+ wcsrchr_test
+ SUITE
+ libc_wchar_unittests
+ SRCS
+ wcsrchr_test.cpp
+ DEPENDS
+ libc.src.wchar.wcsrchr
+)
+
add_libc_test(
wcsspn_test
SUITE
diff --git a/libc/test/src/wchar/wcsrchr_test.cpp b/libc/test/src/wchar/wcsrchr_test.cpp
new file mode 100644
index 0000000000000..707dfb6756ee9
--- /dev/null
+++ b/libc/test/src/wchar/wcsrchr_test.cpp
@@ -0,0 +1,68 @@
+//===-- Unittests for wcsrchr ---------------------------------------------===//
+//
+// 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/wcsrchr.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcWCSRChrTest, FindsFirstCharacter) {
+ // Should return pointer to original string since 'a' is the first character.
+ const wchar_t *src = L"abcde";
+ ASSERT_EQ(LIBC_NAMESPACE::wcsrchr(src, L'a'), src);
+}
+
+TEST(LlvmLibcWCSRChrTest, FindsMiddleCharacter) {
+ // Should return pointer to 'c'.
+ const wchar_t *src = L"abcde";
+ ASSERT_EQ(LIBC_NAMESPACE::wcsrchr(src, L'c'), (src + 2));
+}
+
+TEST(LlvmLibcWCSRChrTest, FindsLastCharacterThatIsNotNullTerminator) {
+ // Should return pointer to 'e'.
+ const wchar_t *src = L"abcde";
+ ASSERT_EQ(LIBC_NAMESPACE::wcsrchr(src, L'e'), (src + 4));
+}
+
+TEST(LlvmLibcWCSRChrTest, FindsNullTerminator) {
+ // Should return pointer to null terminator.
+ const wchar_t *src = L"abcde";
+ ASSERT_EQ(LIBC_NAMESPACE::wcsrchr(src, L'\0'), (src + 5));
+}
+
+TEST(LlvmLibcWCSRChrTest, CharacterNotWithinStringShouldReturnNullptr) {
+ // Since 'z' is not within the string, should return nullptr.
+ const wchar_t *src = L"abcde";
+ ASSERT_EQ(LIBC_NAMESPACE::wcsrchr(src, L'z'), nullptr);
+}
+
+TEST(LlvmLibcWCSRChrTest, ShouldFindLastOfDuplicates) {
+ // Should return pointer to the last '1'.
+ const wchar_t *src = L"abc1def1ghi";
+ ASSERT_EQ((int)(LIBC_NAMESPACE::wcsrchr(src, L'1') - src), 7);
+
+ // Should return pointer to the last 'X'
+ const wchar_t *dups = L"XXXXX";
+ ASSERT_EQ(LIBC_NAMESPACE::wcsrchr(dups, L'X'), dups + 4);
+}
+
+TEST(LlvmLibcWCSRChrTest, EmptyStringShouldOnlyMatchNullTerminator) {
+ // Null terminator should match
+ const wchar_t *src = L"";
+ ASSERT_EQ(src, LIBC_NAMESPACE::wcsrchr(src, L'\0'));
+ // All other characters should not match
+ ASSERT_EQ(LIBC_NAMESPACE::wcsrchr(src, L'Z'), nullptr);
+ ASSERT_EQ(LIBC_NAMESPACE::wcsrchr(src, L'3'), nullptr);
+ ASSERT_EQ(LIBC_NAMESPACE::wcsrchr(src, L'*'), nullptr);
+}
+
+#if defined(LIBC_ADD_NULL_CHECKS) && !defined(LIBC_HAS_SANITIZER)
+TEST(LlvmLibcWCSRChrTest, NullptrCrash) {
+ // Passing in a nullptr should crash the program.
+ EXPECT_DEATH([] { LIBC_NAMESPACE::wcsrchr(nullptr, L'a'); }, WITH_SIGNAL(-1));
+}
+#endif // LIBC_HAS_ADDRESS_SANITIZER
``````````
</details>
https://github.com/llvm/llvm-project/pull/142436
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