[libc] mbtowc implementation (#145405)
Implemented mbtowcs and tests for the function.
---------
Co-authored-by: Sriya Pratipati <sriyap@google.com>
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index e1a2a26..f0e17d6 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -1248,6 +1248,7 @@
# wchar.h entrypoints
libc.src.wchar.mbrtowc
+ libc.src.wchar.mbtowc
libc.src.wchar.wcrtomb
)
endif()
diff --git a/libc/include/wchar.yaml b/libc/include/wchar.yaml
index 0a6a75e..d5044e1 100644
--- a/libc/include/wchar.yaml
+++ b/libc/include/wchar.yaml
@@ -38,6 +38,14 @@
- type: const char *__restrict
- type: size_t
- type: mbstate_t *__restrict
+ - name: mbtowc
+ standards:
+ - stdc
+ return_type: int
+ arguments:
+ - type: wchar_t *__restrict
+ - type: const char *__restrict
+ - type: size_t
- name: wmemset
standards:
- stdc
diff --git a/libc/src/wchar/CMakeLists.txt b/libc/src/wchar/CMakeLists.txt
index 476cf38..983e426 100644
--- a/libc/src/wchar/CMakeLists.txt
+++ b/libc/src/wchar/CMakeLists.txt
@@ -66,6 +66,22 @@
)
add_entrypoint_object(
+ mbtowc
+ SRCS
+ mbtowc.cpp
+ HDRS
+ mbtowc.h
+ DEPENDS
+ libc.hdr.types.size_t
+ libc.hdr.types.wchar_t
+ libc.src.__support.common
+ libc.src.__support.macros.config
+ libc.src.__support.libc_errno
+ libc.src.__support.wchar.mbrtowc
+ libc.src.__support.wchar.mbstate
+)
+
+add_entrypoint_object(
wmemset
SRCS
wmemset.cpp
diff --git a/libc/src/wchar/mbtowc.cpp b/libc/src/wchar/mbtowc.cpp
new file mode 100644
index 0000000..eae39ba
--- /dev/null
+++ b/libc/src/wchar/mbtowc.cpp
@@ -0,0 +1,40 @@
+//===-- Implementation of mbtowc -----------------------------------------===//
+//
+// 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/mbtowc.h"
+
+#include "hdr/types/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/__support/common.h"
+#include "src/__support/libc_errno.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/wchar/mbrtowc.h"
+#include "src/__support/wchar/mbstate.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(int, mbtowc,
+ (wchar_t *__restrict pwc, const char *__restrict s,
+ size_t n)) {
+ // returns 0 since UTF-8 encoding is not state-dependent
+ if (s == nullptr)
+ return 0;
+ internal::mbstate internal_mbstate;
+ // temp ptr to use if pwc is nullptr
+ wchar_t buf[1];
+ auto ret =
+ internal::mbrtowc(pwc == nullptr ? buf : pwc, s, n, &internal_mbstate);
+ if (!ret.has_value() || static_cast<int>(ret.value()) == -2) {
+ // Encoding failure
+ libc_errno = EILSEQ;
+ return -1;
+ }
+ return static_cast<int>(ret.value());
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/wchar/mbtowc.h b/libc/src/wchar/mbtowc.h
new file mode 100644
index 0000000..f974197f
--- /dev/null
+++ b/libc/src/wchar/mbtowc.h
@@ -0,0 +1,22 @@
+//===-- Implementation header for mbtowc ---------------------------------===//
+//
+// 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_MBTOWC_H
+#define LLVM_LIBC_SRC_WCHAR_MBTOWC_H
+
+#include "hdr/types/size_t.h"
+#include "hdr/types/wchar_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+int mbtowc(wchar_t *__restrict pwc, const char *__restrict s, size_t n);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_WCHAR_MBTOWC_H
diff --git a/libc/test/src/wchar/CMakeLists.txt b/libc/test/src/wchar/CMakeLists.txt
index c932f36..ac58693 100644
--- a/libc/test/src/wchar/CMakeLists.txt
+++ b/libc/test/src/wchar/CMakeLists.txt
@@ -38,6 +38,19 @@
)
add_libc_test(
+ mbtowc_test
+ SUITE
+ libc_wchar_unittests
+ SRCS
+ mbtowc_test.cpp
+ DEPENDS
+ libc.src.__support.libc_errno
+ libc.src.wchar.mbtowc
+ libc.hdr.types.wchar_t
+ libc.test.UnitTest.ErrnoCheckingTest
+)
+
+add_libc_test(
wctob_test
SUITE
libc_wchar_unittests
diff --git a/libc/test/src/wchar/mbtowc_test.cpp b/libc/test/src/wchar/mbtowc_test.cpp
new file mode 100644
index 0000000..b27b05c
--- /dev/null
+++ b/libc/test/src/wchar/mbtowc_test.cpp
@@ -0,0 +1,154 @@
+//===-- Unittests for mbtowc ---------------------------------------------===//
+//
+// 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/__support/libc_errno.h"
+#include "src/wchar/mbtowc.h"
+#include "test/UnitTest/ErrnoCheckingTest.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcMBToWCTest = LIBC_NAMESPACE::testing::ErrnoCheckingTest;
+
+TEST_F(LlvmLibcMBToWCTest, OneByte) {
+ const char *ch = "A";
+ wchar_t dest[2];
+ int n = LIBC_NAMESPACE::mbtowc(dest, ch, 1);
+ ASSERT_EQ(static_cast<char>(*dest), 'A');
+ ASSERT_EQ(n, 1);
+
+ // Should fail since we have not read enough
+ n = LIBC_NAMESPACE::mbtowc(dest, ch, 0);
+ ASSERT_EQ(n, -1);
+ ASSERT_ERRNO_EQ(EILSEQ);
+}
+
+TEST_F(LlvmLibcMBToWCTest, TwoByte) {
+ const char ch[2] = {static_cast<char>(0xC2),
+ static_cast<char>(0x8E)}; // car symbol
+ wchar_t dest[2];
+ int n = LIBC_NAMESPACE::mbtowc(dest, ch, 2);
+ ASSERT_EQ(static_cast<int>(*dest), 142);
+ ASSERT_EQ(n, 2);
+
+ // Should fail since we have not read enough
+ n = LIBC_NAMESPACE::mbtowc(dest, ch, 1);
+ ASSERT_EQ(n, -1);
+ // Should fail after trying to read next byte too
+ n = LIBC_NAMESPACE::mbtowc(dest, ch + 1, 1);
+ ASSERT_EQ(n, -1);
+ ASSERT_ERRNO_EQ(EILSEQ);
+}
+
+TEST_F(LlvmLibcMBToWCTest, ThreeByte) {
+ const char ch[3] = {static_cast<char>(0xE2), static_cast<char>(0x88),
+ static_cast<char>(0x91)}; // ∑ sigma symbol
+ wchar_t dest[2];
+ int n = LIBC_NAMESPACE::mbtowc(dest, ch, 3);
+ ASSERT_EQ(static_cast<int>(*dest), 8721);
+ ASSERT_EQ(n, 3);
+
+ // Should fail since we have not read enough
+ n = LIBC_NAMESPACE::mbtowc(dest, ch, 2);
+ ASSERT_EQ(n, -1);
+ ASSERT_ERRNO_EQ(EILSEQ);
+}
+
+TEST_F(LlvmLibcMBToWCTest, FourByte) {
+ const char ch[4] = {static_cast<char>(0xF0), static_cast<char>(0x9F),
+ static_cast<char>(0xA4),
+ static_cast<char>(0xA1)}; // 🤡 clown emoji
+ wchar_t dest[2];
+ int n = LIBC_NAMESPACE::mbtowc(dest, ch, 4);
+ ASSERT_EQ(static_cast<int>(*dest), 129313);
+ ASSERT_EQ(n, 4);
+
+ // Should fail since we have not read enough
+ n = LIBC_NAMESPACE::mbtowc(dest, ch, 2);
+ ASSERT_EQ(n, -1);
+ ASSERT_ERRNO_EQ(EILSEQ);
+}
+
+TEST_F(LlvmLibcMBToWCTest, InvalidByte) {
+ const char ch[1] = {static_cast<char>(0x80)};
+ wchar_t dest[2];
+ int n = LIBC_NAMESPACE::mbtowc(dest, ch, 1);
+ ASSERT_EQ(n, -1);
+ ASSERT_ERRNO_EQ(EILSEQ);
+}
+
+TEST_F(LlvmLibcMBToWCTest, InvalidMultiByte) {
+ const char ch[4] = {static_cast<char>(0x80), static_cast<char>(0x00),
+ static_cast<char>(0x80),
+ static_cast<char>(0x00)}; // invalid sequence of bytes
+ wchar_t dest[2];
+ // Trying to push all 4 should error
+ int n = LIBC_NAMESPACE::mbtowc(dest, ch, 4);
+ ASSERT_EQ(n, -1);
+ ASSERT_ERRNO_EQ(EILSEQ);
+
+ // Trying to push the second and third should correspond to null wc
+ n = LIBC_NAMESPACE::mbtowc(dest, ch + 1, 2);
+ ASSERT_EQ(n, 0);
+ ASSERT_TRUE(*dest == L'\0');
+}
+
+TEST_F(LlvmLibcMBToWCTest, InvalidLastByte) {
+ // Last byte is invalid since it does not have correct starting sequence.
+ // 0xC0 --> 11000000 starting sequence should be 10xxxxxx
+ const char ch[4] = {static_cast<char>(0xF1), static_cast<char>(0x80),
+ static_cast<char>(0x80), static_cast<char>(0xC0)};
+ wchar_t dest[2];
+ // Trying to push all 4 should error
+ int n = LIBC_NAMESPACE::mbtowc(dest, ch, 4);
+ ASSERT_EQ(n, -1);
+ ASSERT_ERRNO_EQ(EILSEQ);
+}
+
+TEST_F(LlvmLibcMBToWCTest, ValidTwoByteWithExtraRead) {
+ const char ch[3] = {static_cast<char>(0xC2), static_cast<char>(0x8E),
+ static_cast<char>(0x80)};
+ wchar_t dest[2];
+ // Trying to push all 3 should return valid 2 byte
+ int n = LIBC_NAMESPACE::mbtowc(dest, ch, 3);
+ ASSERT_EQ(n, 2);
+ ASSERT_EQ(static_cast<int>(*dest), 142);
+}
+
+TEST_F(LlvmLibcMBToWCTest, TwoValidTwoBytes) {
+ const char ch[4] = {static_cast<char>(0xC2), static_cast<char>(0x8E),
+ static_cast<char>(0xC7), static_cast<char>(0x8C)};
+ wchar_t dest[2];
+ int n = LIBC_NAMESPACE::mbtowc(dest, ch, 2);
+ ASSERT_EQ(n, 2);
+ ASSERT_EQ(static_cast<int>(*dest), 142);
+ n = LIBC_NAMESPACE::mbtowc(dest + 1, ch + 2, 2);
+ ASSERT_EQ(n, 2);
+ ASSERT_EQ(static_cast<int>(*(dest + 1)), 460);
+}
+
+TEST_F(LlvmLibcMBToWCTest, NullString) {
+ wchar_t dest[2] = {L'O', L'K'};
+ // reading on nullptr should return 0
+ int n = LIBC_NAMESPACE::mbtowc(dest, nullptr, 2);
+ ASSERT_EQ(n, 0);
+ ASSERT_TRUE(dest[0] == L'O');
+ // reading a null terminator should return 0
+ const char *ch = "\0";
+ n = LIBC_NAMESPACE::mbtowc(dest, ch, 1);
+ ASSERT_EQ(n, 0);
+}
+
+TEST_F(LlvmLibcMBToWCTest, NullWCPtr) {
+ const char ch[2] = {
+ static_cast<char>(0xC2),
+ static_cast<char>(0x8E),
+ };
+ // a null destination should still return the number of read bytes
+ int n = LIBC_NAMESPACE::mbtowc(nullptr, ch, 2);
+ ASSERT_EQ(n, 2);
+}
