[libc-commits] [libc] [libc] wcsncat implementation (PR #142431)
via libc-commits
libc-commits at lists.llvm.org
Mon Jun 2 09:51:46 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libc
Author: None (sribee8)
<details>
<summary>Changes</summary>
Implemented wcsncat and tests.
---
Full diff: https://github.com/llvm/llvm-project/pull/142431.diff
7 Files Affected:
- (modified) libc/config/linux/x86_64/entrypoints.txt (+1)
- (modified) libc/include/wchar.yaml (+8)
- (modified) libc/src/wchar/CMakeLists.txt (+12)
- (added) libc/src/wchar/wcsncat.cpp (+32)
- (added) libc/src/wchar/wcsncat.h (+23)
- (modified) libc/test/src/wchar/CMakeLists.txt (+10)
- (added) libc/test/src/wchar/wcsncat_test.cpp (+82)
``````````diff
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 545b9227349fe..6c3c5f7fc0de0 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -370,6 +370,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.wchar.wcsspn
libc.src.wchar.wmemcmp
libc.src.wchar.wmemcpy
+ libc.src.wchar.wcsncat
# sys/uio.h entrypoints
libc.src.sys.uio.writev
diff --git a/libc/include/wchar.yaml b/libc/include/wchar.yaml
index bfd9a10342019..5528d6a65553c 100644
--- a/libc/include/wchar.yaml
+++ b/libc/include/wchar.yaml
@@ -72,3 +72,11 @@ functions:
- type: __restrict wchar_t *
- type: const __restrict wchar_t *
- type: size_t
+ - name: wcsncat
+ standards:
+ - stdc
+ return_type: wchar_t *
+ arguments:
+ - type: __restrict wchar_t *
+ - type: const __restrict wchar_t *
+ - type: size_t
diff --git a/libc/src/wchar/CMakeLists.txt b/libc/src/wchar/CMakeLists.txt
index 9db121762348b..dba5f8ee525f2 100644
--- a/libc/src/wchar/CMakeLists.txt
+++ b/libc/src/wchar/CMakeLists.txt
@@ -104,3 +104,15 @@ add_entrypoint_object(
libc.hdr.wchar_macros
libc.src.__support.wctype_utils
)
+
+add_entrypoint_object(
+ wcsncat
+ SRCS
+ wcsncat.cpp
+ HDRS
+ wcsncat.h
+ DEPENDS
+ libc.hdr.types.size_t
+ libc.hdr.wchar_macros
+ libc.src.string.string_utils
+)
diff --git a/libc/src/wchar/wcsncat.cpp b/libc/src/wchar/wcsncat.cpp
new file mode 100644
index 0000000000000..c8be2903a1158
--- /dev/null
+++ b/libc/src/wchar/wcsncat.cpp
@@ -0,0 +1,32 @@
+//===-- Implementation of wcsncat -----------------------------------------===//
+//
+// 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/wcsncat.h"
+
+#include "hdr/types/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/string/string_utils.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(wchar_t *, wcsncat,
+ (wchar_t *__restrict s1, const wchar_t *__restrict s2,
+ size_t n)) {
+ size_t size = internal::string_length(s1);
+ size_t i = 0;
+ for (; s2[i] && i < n; ++i) {
+ s1[size + i] = s2[i];
+ }
+ // Appending null character to the end of the result.
+ s1[size + i] = L'\0';
+ return s1;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/wchar/wcsncat.h b/libc/src/wchar/wcsncat.h
new file mode 100644
index 0000000000000..978645e90c6ba
--- /dev/null
+++ b/libc/src/wchar/wcsncat.h
@@ -0,0 +1,23 @@
+//===-- Implementation header for wcsncat ---------------------------------===//
+//
+// 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_WCSNCAT_H
+#define LLVM_LIBC_SRC_WCHAR_WCSNCAT_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 *wcsncat(wchar_t *__restrict s1, const wchar_t *__restrict s2,
+ size_t n);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_WCHAR_WCSNCAT_H
diff --git a/libc/test/src/wchar/CMakeLists.txt b/libc/test/src/wchar/CMakeLists.txt
index 9bc230e0bddf3..8e5a389257842 100644
--- a/libc/test/src/wchar/CMakeLists.txt
+++ b/libc/test/src/wchar/CMakeLists.txt
@@ -94,3 +94,13 @@ add_libc_test(
DEPENDS
libc.src.wchar.wmemcpy
)
+
+add_libc_test(
+ wcsncat_test
+ SUITE
+ libc_wchar_unittests
+ SRCS
+ wcsncat_test.cpp
+ DEPENDS
+ libc.src.wchar.wcsncat
+)
diff --git a/libc/test/src/wchar/wcsncat_test.cpp b/libc/test/src/wchar/wcsncat_test.cpp
new file mode 100644
index 0000000000000..47359f88cec9e
--- /dev/null
+++ b/libc/test/src/wchar/wcsncat_test.cpp
@@ -0,0 +1,82 @@
+//===-- Unittests for wcscat ---------------------------------------------===//
+//
+// 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/wcsncat.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcWCSNCatTest, EmptyDest) {
+ wchar_t dest[4] = {L'\0'};
+ const wchar_t *src = L"abc";
+
+ // Start by copying nothing
+ LIBC_NAMESPACE::wcsncat(dest, src, 0);
+ ASSERT_TRUE(dest[0] == L'\0');
+
+ // Copying part of it.
+ LIBC_NAMESPACE::wcsncat(dest, src, 1);
+ ASSERT_TRUE(dest[0] == L'a');
+ ASSERT_TRUE(dest[1] == L'\0');
+
+ // Resetting for the last test.
+ dest[0] = '\0';
+
+ // Copying all of it.
+ LIBC_NAMESPACE::wcsncat(dest, src, 3);
+ ASSERT_TRUE(dest[0] == L'a');
+ ASSERT_TRUE(dest[1] == L'b');
+ ASSERT_TRUE(dest[2] == L'c');
+ ASSERT_TRUE(dest[3] == L'\0');
+}
+
+TEST(LlvmLibcWCSNCatTest, NonEmptyDest) {
+ wchar_t dest[7] = {L'x', L'y', L'z', L'\0'};
+ const wchar_t *src = L"abc";
+
+ // Adding on only part of the string
+ LIBC_NAMESPACE::wcsncat(dest, src, 1);
+ ASSERT_TRUE(dest[0] == L'x');
+ ASSERT_TRUE(dest[1] == L'y');
+ ASSERT_TRUE(dest[2] == L'z');
+ ASSERT_TRUE(dest[3] == L'a');
+ ASSERT_TRUE(dest[4] == L'\0');
+
+ // Copying more without resetting
+ LIBC_NAMESPACE::wcsncat(dest, src, 2);
+ ASSERT_TRUE(dest[0] == L'x');
+ ASSERT_TRUE(dest[1] == L'y');
+ ASSERT_TRUE(dest[2] == L'z');
+ ASSERT_TRUE(dest[3] == L'a');
+ ASSERT_TRUE(dest[4] == L'a');
+ ASSERT_TRUE(dest[5] == L'b');
+ ASSERT_TRUE(dest[6] == L'\0');
+
+ // Setting end marker to make sure it overwrites properly.
+ dest[3] = L'\0';
+
+ // Copying all of it.
+ LIBC_NAMESPACE::wcsncat(dest, src, 3);
+ ASSERT_TRUE(dest[0] == L'x');
+ ASSERT_TRUE(dest[1] == L'y');
+ ASSERT_TRUE(dest[2] == L'z');
+ ASSERT_TRUE(dest[3] == L'a');
+ ASSERT_TRUE(dest[4] == L'b');
+ ASSERT_TRUE(dest[5] == L'c');
+ ASSERT_TRUE(dest[6] == L'\0');
+
+ // Check that copying still works when count > src length.
+ dest[0] = L'\0';
+ // And that it doesn't write beyond what is necessary.
+ dest[4] = L'Z';
+ LIBC_NAMESPACE::wcsncat(dest, src, 4);
+ ASSERT_TRUE(dest[0] == L'a');
+ ASSERT_TRUE(dest[1] == L'b');
+ ASSERT_TRUE(dest[2] == L'c');
+ ASSERT_TRUE(dest[3] == L'\0');
+ ASSERT_TRUE(dest[4] == L'Z');
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/142431
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