[libc-commits] [libc] [libc] wcsncat implementation (PR #142431)
via libc-commits
libc-commits at lists.llvm.org
Mon Jun 2 13:07:59 PDT 2025
https://github.com/sribee8 updated https://github.com/llvm/llvm-project/pull/142431
>From 1aba677553e162637e9c9c1b717c30367d76d3e5 Mon Sep 17 00:00:00 2001
From: Sriya Pratipati <sriyap at google.com>
Date: Mon, 2 Jun 2025 16:49:04 +0000
Subject: [PATCH 1/3] [libc] wcsncat implementation
Implemented wcsncat and tests.
---
libc/config/linux/x86_64/entrypoints.txt | 1 +
libc/include/wchar.yaml | 8 +++
libc/src/wchar/CMakeLists.txt | 12 ++++
libc/src/wchar/wcsncat.cpp | 32 +++++++++
libc/src/wchar/wcsncat.h | 22 +++++++
libc/test/src/wchar/CMakeLists.txt | 10 +++
libc/test/src/wchar/wcsncat_test.cpp | 82 ++++++++++++++++++++++++
7 files changed, 167 insertions(+)
create mode 100644 libc/src/wchar/wcsncat.cpp
create mode 100644 libc/src/wchar/wcsncat.h
create mode 100644 libc/test/src/wchar/wcsncat_test.cpp
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..d7b03e9d43616
--- /dev/null
+++ b/libc/src/wchar/wcsncat.h
@@ -0,0 +1,22 @@
+//===-- 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');
+}
>From f8f8f1ef07c5a5280843a2c9a88b4a1af12c7b6d Mon Sep 17 00:00:00 2001
From: Sriya Pratipati <sriyap at google.com>
Date: Mon, 2 Jun 2025 16:50:25 +0000
Subject: [PATCH 2/3] [libc] wcsncat implementation
Implemented wcsncat and tests.
---
libc/src/wchar/wcsncat.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/libc/src/wchar/wcsncat.h b/libc/src/wchar/wcsncat.h
index d7b03e9d43616..978645e90c6ba 100644
--- a/libc/src/wchar/wcsncat.h
+++ b/libc/src/wchar/wcsncat.h
@@ -15,7 +15,8 @@
namespace LIBC_NAMESPACE_DECL {
-wchar_t *wcsncat(wchar_t *__restrict s1, const wchar_t *__restrict s2, size_t n);
+wchar_t *wcsncat(wchar_t *__restrict s1, const wchar_t *__restrict s2,
+ size_t n);
} // namespace LIBC_NAMESPACE_DECL
>From 21d368d6a78fabdf8ad4c8ece6f2c3e8c0a38d16 Mon Sep 17 00:00:00 2001
From: Sriya Pratipati <sriyap at google.com>
Date: Mon, 2 Jun 2025 20:07:48 +0000
Subject: [PATCH 3/3] Removed unnecessary braces
---
libc/src/wchar/wcsncat.cpp | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/libc/src/wchar/wcsncat.cpp b/libc/src/wchar/wcsncat.cpp
index c8be2903a1158..62595b4b5418c 100644
--- a/libc/src/wchar/wcsncat.cpp
+++ b/libc/src/wchar/wcsncat.cpp
@@ -21,9 +21,8 @@ LLVM_LIBC_FUNCTION(wchar_t *, wcsncat,
size_t n)) {
size_t size = internal::string_length(s1);
size_t i = 0;
- for (; s2[i] && i < n; ++i) {
+ 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;
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