[libc] Add strncpy implementation.
Add libc strncpy implementation.
Reviewed By: sivachandra, gchatelet
Differential Revision: https://reviews.llvm.org/D91399
GitOrigin-RevId: 60cef893627be169f22dc540834c4d085847d94a
diff --git a/config/linux/aarch64/entrypoints.txt b/config/linux/aarch64/entrypoints.txt
index 3a34d95..1d8e5dd 100644
--- a/config/linux/aarch64/entrypoints.txt
+++ b/config/linux/aarch64/entrypoints.txt
@@ -29,6 +29,7 @@
libc.src.string.strcpy
libc.src.string.strcspn
libc.src.string.strlen
+ libc.src.string.strncpy
libc.src.string.strnlen
libc.src.string.strpbrk
libc.src.string.strrchr
diff --git a/config/linux/x86_64/entrypoints.txt b/config/linux/x86_64/entrypoints.txt
index 4eb964b..d6d56f2 100644
--- a/config/linux/x86_64/entrypoints.txt
+++ b/config/linux/x86_64/entrypoints.txt
@@ -47,6 +47,7 @@
libc.src.string.strcpy
libc.src.string.strcspn
libc.src.string.strlen
+ libc.src.string.strncpy
libc.src.string.strnlen
libc.src.string.strpbrk
libc.src.string.strrchr
diff --git a/src/string/CMakeLists.txt b/src/string/CMakeLists.txt
index 8a2adbe..94df8a9 100644
--- a/src/string/CMakeLists.txt
+++ b/src/string/CMakeLists.txt
@@ -75,6 +75,14 @@
)
add_entrypoint_object(
+ strncpy
+ SRCS
+ strncpy.cpp
+ HDRS
+ strncpy.h
+)
+
+add_entrypoint_object(
strnlen
SRCS
strnlen.cpp
diff --git a/src/string/strncpy.cpp b/src/string/strncpy.cpp
new file mode 100644
index 0000000..45255e3
--- /dev/null
+++ b/src/string/strncpy.cpp
@@ -0,0 +1,28 @@
+//===-- Implementation of strncpy -----------------------------------------===//
+//
+// 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/string/strncpy.h"
+
+#include "src/__support/common.h"
+#include <stddef.h> // For size_t.
+
+namespace __llvm_libc {
+
+char *LLVM_LIBC_ENTRYPOINT(strncpy)(char *__restrict dest,
+ const char *__restrict src, size_t n) {
+ size_t i = 0;
+ // Copy up until \0 is found.
+ for (; i < n && src[i] != '\0'; ++i)
+ dest[i] = src[i];
+ // When n>strlen(src), n-strlen(src) \0 are appended.
+ for (; i < n; ++i)
+ dest[i] = '\0';
+ return dest;
+}
+
+} // namespace __llvm_libc
diff --git a/src/string/strncpy.h b/src/string/strncpy.h
new file mode 100644
index 0000000..c419df9
--- /dev/null
+++ b/src/string/strncpy.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for strncpy -----------------------*- C++ -*-===//
+//
+// 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_STRING_STRNCPY_H
+#define LLVM_LIBC_SRC_STRING_STRNCPY_H
+
+#include <stddef.h>
+
+namespace __llvm_libc {
+
+char *strncpy(char *__restrict dest, const char *__restrict src, size_t n);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_STRING_STRNCPY_H
diff --git a/test/src/string/CMakeLists.txt b/test/src/string/CMakeLists.txt
index df824cd..8b78fcf 100644
--- a/test/src/string/CMakeLists.txt
+++ b/test/src/string/CMakeLists.txt
@@ -73,6 +73,16 @@
)
add_libc_unittest(
+ strncpy_test
+ SUITE
+ libc_string_unittests
+ SRCS
+ strncpy_test.cpp
+ DEPENDS
+ libc.src.string.strncpy
+)
+
+add_libc_unittest(
strnlen_test
SUITE
libc_string_unittests
diff --git a/test/src/string/strncpy_test.cpp b/test/src/string/strncpy_test.cpp
new file mode 100644
index 0000000..8148706
--- /dev/null
+++ b/test/src/string/strncpy_test.cpp
@@ -0,0 +1,57 @@
+//===-- Unittests for strncpy ---------------------------------------------===//
+//
+// 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/string/strncpy.h"
+#include "utils/CPP/ArrayRef.h"
+#include "utils/UnitTest/Test.h"
+#include <stddef.h> // For size_t.
+
+class StrncpyTest : public __llvm_libc::testing::Test {
+public:
+ void check_strncpy(__llvm_libc::cpp::MutableArrayRef<char> dst,
+ const __llvm_libc::cpp::ArrayRef<char> src, size_t n,
+ const __llvm_libc::cpp::ArrayRef<char> expected) {
+ // Making sure we don't overflow buffer.
+ ASSERT_GE(dst.size(), n);
+ // Making sure strncpy returns dst.
+ ASSERT_EQ(__llvm_libc::strncpy(dst.data(), src.data(), n), dst.data());
+ // Expected must be of the same size as dst.
+ ASSERT_EQ(dst.size(), expected.size());
+ // Expected and dst are the same.
+ for (size_t i = 0; i < expected.size(); ++i)
+ ASSERT_EQ(expected[i], dst[i]);
+ }
+};
+
+TEST_F(StrncpyTest, Untouched) {
+ char dst[] = {'a', 'b'};
+ const char src[] = {'x', '\0'};
+ const char expected[] = {'a', 'b'};
+ check_strncpy(dst, src, 0, expected);
+}
+
+TEST_F(StrncpyTest, CopyOne) {
+ char dst[] = {'a', 'b'};
+ const char src[] = {'x', 'y'};
+ const char expected[] = {'x', 'b'}; // no \0 is appended
+ check_strncpy(dst, src, 1, expected);
+}
+
+TEST_F(StrncpyTest, CopyNull) {
+ char dst[] = {'a', 'b'};
+ const char src[] = {'\0', 'y'};
+ const char expected[] = {'\0', 'b'};
+ check_strncpy(dst, src, 1, expected);
+}
+
+TEST_F(StrncpyTest, CopyPastSrc) {
+ char dst[] = {'a', 'b'};
+ const char src[] = {'\0', 'y'};
+ const char expected[] = {'\0', '\0'};
+ check_strncpy(dst, src, 2, expected);
+}
