[libc-commits] [libc] 2ff2a07 - [libc] wcsncpy implementation (#142237)
via libc-commits
libc-commits at lists.llvm.org
Tue Jun 3 16:37:17 PDT 2025
Author: sribee8
Date: 2025-06-03T16:37:14-07:00
New Revision: 2ff2a076cc089f0c977ce7aea231ee5541879f8a
URL: https://github.com/llvm/llvm-project/commit/2ff2a076cc089f0c977ce7aea231ee5541879f8a
DIFF: https://github.com/llvm/llvm-project/commit/2ff2a076cc089f0c977ce7aea231ee5541879f8a.diff
LOG: [libc] wcsncpy implementation (#142237)
Implemented wcsncpy and tests for the function.
---------
Co-authored-by: Sriya Pratipati <sriyap at google.com>
Added:
libc/src/wchar/wcsncpy.cpp
libc/src/wchar/wcsncpy.h
libc/test/src/wchar/wcsncpy_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 f87e212eecbab..ed2994d1273c4 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -374,6 +374,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.wchar.wmemcmp
libc.src.wchar.wmempcpy
libc.src.wchar.wmemcpy
+ libc.src.wchar.wcsncpy
libc.src.wchar.wcscat
libc.src.wchar.wcsstr
libc.src.wchar.wcsncat
diff --git a/libc/include/wchar.yaml b/libc/include/wchar.yaml
index 087ace711f9a9..18b77a2711f7e 100644
--- a/libc/include/wchar.yaml
+++ b/libc/include/wchar.yaml
@@ -95,6 +95,14 @@ functions:
- type: const wchar_t *
- type: size_t
- name: wmemcpy
+ standards:
+ - stdc
+ return_type: wchar_t *
+ arguments:
+ - type: __restrict wchar_t *
+ - type: const __restrict wchar_t *
+ - type: size_t
+ - name: wcsncpy
standards:
- stdc
return_type: wchar_t *
diff --git a/libc/src/wchar/CMakeLists.txt b/libc/src/wchar/CMakeLists.txt
index 95246ad777697..b131d2feeda06 100644
--- a/libc/src/wchar/CMakeLists.txt
+++ b/libc/src/wchar/CMakeLists.txt
@@ -137,6 +137,18 @@ add_entrypoint_object(
libc.src.__support.wctype_utils
)
+add_entrypoint_object(
+ wcsncpy
+ SRCS
+ wcsncpy.cpp
+ HDRS
+ wcsncpy.h
+ DEPENDS
+ libc.hdr.types.size_t
+ libc.hdr.wchar_macros
+ libc.src.string.string_utils
+)
+
add_entrypoint_object(
wcscat
SRCS
diff --git a/libc/src/wchar/wcsncpy.cpp b/libc/src/wchar/wcsncpy.cpp
new file mode 100644
index 0000000000000..e7ae9a4a0da79
--- /dev/null
+++ b/libc/src/wchar/wcsncpy.cpp
@@ -0,0 +1,33 @@
+//===-- Implementation of wcsncpy -----------------------------------------===//
+//
+// 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/wcsncpy.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/memory_utils/inline_memcpy.h"
+#include "src/string/string_utils.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(wchar_t *, wcsncpy,
+ (wchar_t *__restrict s1, const wchar_t *__restrict s2,
+ size_t n)) {
+ size_t i = 0;
+ // Copy up until \0 is found.
+ for (; i < n && s2[i] != L'\0'; ++i)
+ s1[i] = s2[i];
+ // When s2 is shorter than n, append \0.
+ for (; i < n; ++i)
+ s1[i] = L'\0';
+ return s1;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/wchar/wcsncpy.h b/libc/src/wchar/wcsncpy.h
new file mode 100644
index 0000000000000..06c23f24bcde7
--- /dev/null
+++ b/libc/src/wchar/wcsncpy.h
@@ -0,0 +1,23 @@
+//===-- Implementation header for wcsncpy ---------------------------------===//
+//
+// 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_WCSNCPY_H
+#define LLVM_LIBC_SRC_WCHAR_WCSNCPY_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 *wcsncpy(wchar_t *__restrict s1, const wchar_t *__restrict s2,
+ size_t n);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_WCHAR_WCSNCPY_H
diff --git a/libc/test/src/wchar/CMakeLists.txt b/libc/test/src/wchar/CMakeLists.txt
index 859d33a22617f..89c3048ae262b 100644
--- a/libc/test/src/wchar/CMakeLists.txt
+++ b/libc/test/src/wchar/CMakeLists.txt
@@ -135,6 +135,16 @@ add_libc_test(
libc.src.wchar.wmemcpy
)
+add_libc_test(
+ wcsncpy_test
+ SUITE
+ libc_wchar_unittests
+ SRCS
+ wcsncpy_test.cpp
+ DEPENDS
+ libc.src.wchar.wcsncpy
+)
+
add_libc_test(
wcscat_test
SUITE
diff --git a/libc/test/src/wchar/wcsncpy_test.cpp b/libc/test/src/wchar/wcsncpy_test.cpp
new file mode 100644
index 0000000000000..9b5ffbe20b4a1
--- /dev/null
+++ b/libc/test/src/wchar/wcsncpy_test.cpp
@@ -0,0 +1,66 @@
+//===-- Unittests for wcsncpy ---------------------------------------------===//
+//
+// 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/wcsncpy.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcWCSNCpyTest, CopyZero) {
+ // Dest should remain unchanged.
+ wchar_t dest[3] = {L'a', L'b', L'\0'};
+ const wchar_t *src = L"x";
+ LIBC_NAMESPACE::wcsncpy(dest, src, 0);
+ ASSERT_TRUE(dest[0] == L'a');
+ ASSERT_TRUE(dest[1] == L'b');
+ ASSERT_TRUE(dest[2] == L'\0');
+}
+
+TEST(LlvmLibcWCSNCpyTest, CopyFullIntoEmpty) {
+ // Dest should be the exact same as src.
+ wchar_t dest[15];
+ const wchar_t *src = L"aaaaabbbbccccc";
+ LIBC_NAMESPACE::wcsncpy(dest, src, 15);
+ for (int i = 0; i < 15; i++)
+ ASSERT_TRUE(dest[i] == src[i]);
+}
+
+TEST(LlvmLibcWCSNCpyTest, CopyPartial) {
+ // First two characters of dest should be the first two characters of src.
+ wchar_t dest[] = {L'a', L'b', L'c', L'd', L'\0'};
+ const wchar_t *src = L"1234";
+ LIBC_NAMESPACE::wcsncpy(dest, src, 2);
+ ASSERT_TRUE(dest[0] == L'1');
+ ASSERT_TRUE(dest[1] == L'2');
+ ASSERT_TRUE(dest[2] == L'c');
+ ASSERT_TRUE(dest[3] == L'd');
+ ASSERT_TRUE(dest[4] == L'\0');
+}
+
+TEST(LlvmLibcWCSNCpyTest, CopyNullTerminator) {
+ // Null terminator should copy into dest.
+ wchar_t dest[] = {L'a', L'b', L'c', L'd', L'\0'};
+ const wchar_t src[] = {L'\0', L'y'};
+ LIBC_NAMESPACE::wcsncpy(dest, src, 1);
+ ASSERT_TRUE(dest[0] == L'\0');
+ ASSERT_TRUE(dest[1] == L'b');
+ ASSERT_TRUE(dest[2] == L'c');
+ ASSERT_TRUE(dest[3] == L'd');
+ ASSERT_TRUE(dest[4] == L'\0');
+}
+
+TEST(LlvmLibcWCSNCpyTest, CopyPastSrc) {
+ // Copying past src should fill with null terminator.
+ wchar_t dest[] = {L'a', L'b', L'c', L'd', L'\0'};
+ const wchar_t src[] = {L'x', L'\0'};
+ LIBC_NAMESPACE::wcsncpy(dest, src, 4);
+ ASSERT_TRUE(dest[0] == L'x');
+ ASSERT_TRUE(dest[1] == L'\0');
+ ASSERT_TRUE(dest[2] == L'\0');
+ ASSERT_TRUE(dest[3] == L'\0');
+ ASSERT_TRUE(dest[4] == L'\0');
+}
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