[libc-commits] [libc] [libc] Implemented wcsnlen (PR #145610)
via libc-commits
libc-commits at lists.llvm.org
Thu Jun 26 10:01:46 PDT 2025
https://github.com/sribee8 updated https://github.com/llvm/llvm-project/pull/145610
>From 21f31c6f7460902a33783ca742f9bd36bf7400e8 Mon Sep 17 00:00:00 2001
From: Sriya Pratipati <sriyap at google.com>
Date: Tue, 24 Jun 2025 22:36:46 +0000
Subject: [PATCH 1/3] [libc] Implemented wcsnlen
Implemented wcsnlen and tests for the function.
---
libc/config/linux/x86_64/entrypoints.txt | 1 +
libc/include/wchar.yaml | 7 ++++
libc/src/wchar/CMakeLists.txt | 12 +++++++
libc/src/wchar/wcsnlen.cpp | 24 +++++++++++++
libc/src/wchar/wcsnlen.h | 22 ++++++++++++
libc/test/src/wchar/CMakeLists.txt | 12 +++++++
libc/test/src/wchar/wcsnlen_test.cpp | 46 ++++++++++++++++++++++++
7 files changed, 124 insertions(+)
create mode 100644 libc/src/wchar/wcsnlen.cpp
create mode 100644 libc/src/wchar/wcsnlen.h
create mode 100644 libc/test/src/wchar/wcsnlen_test.cpp
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index c8a6d6e648af9..01bd6ce195bca 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -366,6 +366,7 @@ set(TARGET_LIBC_ENTRYPOINTS
# wchar.h entrypoints
libc.src.wchar.btowc
libc.src.wchar.wcslen
+ libc.src.wchar.wcsnlen
libc.src.wchar.wctob
libc.src.wchar.wmemmove
libc.src.wchar.wmemset
diff --git a/libc/include/wchar.yaml b/libc/include/wchar.yaml
index 98cb3bdaf0ac9..a9f785a45b9a2 100644
--- a/libc/include/wchar.yaml
+++ b/libc/include/wchar.yaml
@@ -17,6 +17,13 @@ functions:
return_type: size_t
arguments:
- type: const wchar_t *
+ - name: wcsnlen
+ standards:
+ - stdc
+ return_type: size_t
+ arguments:
+ - type: const wchar_t *
+ - type: size_t
- name: wctob
standards:
- stdc
diff --git a/libc/src/wchar/CMakeLists.txt b/libc/src/wchar/CMakeLists.txt
index f390785e5817b..3be70b0422377 100644
--- a/libc/src/wchar/CMakeLists.txt
+++ b/libc/src/wchar/CMakeLists.txt
@@ -10,6 +10,18 @@ add_entrypoint_object(
libc.src.string.string_utils
)
+add_entrypoint_object(
+ wcsnlen
+ SRCS
+ wcsnlen.cpp
+ HDRS
+ wcsnlen.h
+ DEPENDS
+ libc.hdr.types.size_t
+ libc.hdr.types.wchar_t
+ libc.src.string.string_utils
+)
+
add_entrypoint_object(
wctob
SRCS
diff --git a/libc/src/wchar/wcsnlen.cpp b/libc/src/wchar/wcsnlen.cpp
new file mode 100644
index 0000000000000..d54301b210b6d
--- /dev/null
+++ b/libc/src/wchar/wcsnlen.cpp
@@ -0,0 +1,24 @@
+//===-- Implementation of wcsnlen -----------------------------------------===//
+//
+// 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/wcsnlen.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" // string_length_trivial
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(size_t, wcsnlen, (const wchar_t *src, size_t maxlen)) {
+ size_t temp = internal::string_length(src);
+ return temp > maxlen ? maxlen : temp;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/wchar/wcsnlen.h b/libc/src/wchar/wcsnlen.h
new file mode 100644
index 0000000000000..5a4c92d368a54
--- /dev/null
+++ b/libc/src/wchar/wcsnlen.h
@@ -0,0 +1,22 @@
+//===-- Implementation header for wcsnlen ---------------------------------===//
+//
+// 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_WCSNLEN_H
+#define LLVM_LIBC_SRC_WCHAR_WCSNLEN_H
+
+#include "hdr/types/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+size_t wcsnlen(const wchar_t *src, size_t maxlen);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_WCHAR_WCSNLEN_H
diff --git a/libc/test/src/wchar/CMakeLists.txt b/libc/test/src/wchar/CMakeLists.txt
index 48688b3bdd1f3..8dd5d8fc6399f 100644
--- a/libc/test/src/wchar/CMakeLists.txt
+++ b/libc/test/src/wchar/CMakeLists.txt
@@ -12,6 +12,18 @@ add_libc_test(
libc.src.wchar.wcslen
)
+add_libc_test(
+ wcsnlen_test
+ SUITE
+ libc_wchar_unittests
+ SRCS
+ wcsnlen_test.cpp
+ DEPENDS
+ libc.hdr.types.size_t
+ libc.hdr.types.wchar_t
+ libc.src.wchar.wcsnlen
+)
+
add_libc_test(
btowc_test
SUITE
diff --git a/libc/test/src/wchar/wcsnlen_test.cpp b/libc/test/src/wchar/wcsnlen_test.cpp
new file mode 100644
index 0000000000000..771df44d81641
--- /dev/null
+++ b/libc/test/src/wchar/wcsnlen_test.cpp
@@ -0,0 +1,46 @@
+//===-- Unittests for wcsnlen ---------------------------------------------===//
+//
+// 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/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/wchar/wcsnlen.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcWCSNLenTest, EmptyString) {
+ ASSERT_EQ(static_cast<size_t>(0), LIBC_NAMESPACE::wcsnlen(L"", 0));
+ // If N is greater than string length, this should still return 0.
+ ASSERT_EQ(static_cast<size_t>(0), LIBC_NAMESPACE::wcsnlen(L"", 1));
+}
+
+TEST(LlvmLibcWCSNLenTest, OneCharacterString) {
+ const wchar_t *src = L"A";
+ ASSERT_EQ(static_cast<size_t>(1), LIBC_NAMESPACE::wcsnlen(src, 1));
+ // If N is 0, this should return 0.
+ ASSERT_EQ(static_cast<size_t>(0), LIBC_NAMESPACE::wcsnlen(src, 0));
+ // If N is greater than string length, this should still return 1.
+ ASSERT_EQ(static_cast<size_t>(1), LIBC_NAMESPACE::wcsnlen(src, 3));
+}
+
+TEST(LlvmLibcWCSNLenTest, ManyCharacterString) {
+ const wchar_t *src = L"123456789";
+ ASSERT_EQ(static_cast<size_t>(9), LIBC_NAMESPACE::wcsnlen(src, 9));
+ // If N is 0, this should return 0.
+ ASSERT_EQ(static_cast<size_t>(0), LIBC_NAMESPACE::wcsnlen(src, 0));
+ // If N is smaller than the string length, it should return N.
+ ASSERT_EQ(static_cast<size_t>(3), LIBC_NAMESPACE::wcsnlen(src, 3));
+ // If N is greater than string length, this should still return 9.
+ ASSERT_EQ(static_cast<size_t>(9), LIBC_NAMESPACE::wcsnlen(src, 42));
+}
+
+TEST(LlvmLibcWCSNLenTest, IgnoreCharactersAfterNullTerminator) {
+ const wchar_t src[5] = {L'a', L'b', L'c', L'\0', L'd'};
+ ASSERT_EQ(static_cast<size_t>(3), LIBC_NAMESPACE::wcsnlen(src, 3));
+ // This should only read up to the null terminator.
+ ASSERT_EQ(static_cast<size_t>(3), LIBC_NAMESPACE::wcsnlen(src, 4));
+ ASSERT_EQ(static_cast<size_t>(3), LIBC_NAMESPACE::wcsnlen(src, 5));
+}
>From e5e4455322c8cd6069a084629ab6e50a0b39b623 Mon Sep 17 00:00:00 2001
From: Sriya Pratipati <sriyap at google.com>
Date: Tue, 24 Jun 2025 22:51:42 +0000
Subject: [PATCH 2/3] fixed behavior for case with no null terminator
---
libc/src/wchar/wcsnlen.cpp | 6 ++++--
libc/test/src/wchar/wcsnlen_test.cpp | 8 ++++++++
2 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/libc/src/wchar/wcsnlen.cpp b/libc/src/wchar/wcsnlen.cpp
index d54301b210b6d..0fd839d6412b3 100644
--- a/libc/src/wchar/wcsnlen.cpp
+++ b/libc/src/wchar/wcsnlen.cpp
@@ -17,8 +17,10 @@
namespace LIBC_NAMESPACE_DECL {
LLVM_LIBC_FUNCTION(size_t, wcsnlen, (const wchar_t *src, size_t maxlen)) {
- size_t temp = internal::string_length(src);
- return temp > maxlen ? maxlen : temp;
+ size_t i = 0;
+ for (; i < maxlen && src[i]; ++i)
+ ;
+ return i;
}
} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/test/src/wchar/wcsnlen_test.cpp b/libc/test/src/wchar/wcsnlen_test.cpp
index 771df44d81641..efb7198a31154 100644
--- a/libc/test/src/wchar/wcsnlen_test.cpp
+++ b/libc/test/src/wchar/wcsnlen_test.cpp
@@ -44,3 +44,11 @@ TEST(LlvmLibcWCSNLenTest, IgnoreCharactersAfterNullTerminator) {
ASSERT_EQ(static_cast<size_t>(3), LIBC_NAMESPACE::wcsnlen(src, 4));
ASSERT_EQ(static_cast<size_t>(3), LIBC_NAMESPACE::wcsnlen(src, 5));
}
+
+TEST(LlvmLibcWCSNLenTest, NoNullTerminator) {
+ const wchar_t src[4] = {L'a', L'b', L'c', L'd'};
+ // Should return 4
+ ASSERT_EQ(static_cast<size_t>(4), LIBC_NAMESPACE::wcsnlen(src, 4));
+ // Should return 2 since N is smaller than string length
+ ASSERT_EQ(static_cast<size_t>(2), LIBC_NAMESPACE::wcsnlen(src, 2));
+}
>From b772f17d8a6d6aafc96e4ec2e5d25117eae06e7f Mon Sep 17 00:00:00 2001
From: Sriya Pratipati <sriyap at google.com>
Date: Thu, 26 Jun 2025 17:01:27 +0000
Subject: [PATCH 3/3] removed unnecessary include
---
libc/src/wchar/CMakeLists.txt | 1 -
libc/src/wchar/wcsnlen.cpp | 1 -
2 files changed, 2 deletions(-)
diff --git a/libc/src/wchar/CMakeLists.txt b/libc/src/wchar/CMakeLists.txt
index 3be70b0422377..6a43105421def 100644
--- a/libc/src/wchar/CMakeLists.txt
+++ b/libc/src/wchar/CMakeLists.txt
@@ -19,7 +19,6 @@ add_entrypoint_object(
DEPENDS
libc.hdr.types.size_t
libc.hdr.types.wchar_t
- libc.src.string.string_utils
)
add_entrypoint_object(
diff --git a/libc/src/wchar/wcsnlen.cpp b/libc/src/wchar/wcsnlen.cpp
index 0fd839d6412b3..4613006ff203e 100644
--- a/libc/src/wchar/wcsnlen.cpp
+++ b/libc/src/wchar/wcsnlen.cpp
@@ -12,7 +12,6 @@
#include "hdr/types/wchar_t.h"
#include "src/__support/common.h"
#include "src/__support/macros/config.h"
-#include "src/string/string_utils.h" // string_length_trivial
namespace LIBC_NAMESPACE_DECL {
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