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sribee8Sriya Pratipati
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Anthony Tran
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[libc] mbtowc implementation (llvm#145405)
Implemented mbtowcs and tests for the function. --------- Co-authored-by: Sriya Pratipati <[email protected]>
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‎libc/config/linux/x86_64/entrypoints.txt‎

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@@ -1248,6 +1248,7 @@ if(LLVM_LIBC_FULL_BUILD)
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# wchar.h entrypoints
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libc.src.wchar.mbrtowc
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libc.src.wchar.mbtowc
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libc.src.wchar.wcrtomb
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)
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endif()

‎libc/include/wchar.yaml‎

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@@ -38,6 +38,14 @@ functions:
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- type: const char *__restrict
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- type: size_t
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- type: mbstate_t *__restrict
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- name: mbtowc
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standards:
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- stdc
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return_type: int
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arguments:
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- type: wchar_t *__restrict
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- type: const char *__restrict
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- type: size_t
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- name: wmemset
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standards:
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- stdc

‎libc/src/wchar/CMakeLists.txt‎

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@@ -65,6 +65,22 @@ add_entrypoint_object(
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libc.src.__support.wchar.mbstate
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)
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add_entrypoint_object(
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mbtowc
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SRCS
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mbtowc.cpp
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HDRS
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mbtowc.h
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DEPENDS
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libc.hdr.types.size_t
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libc.hdr.types.wchar_t
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libc.src.__support.common
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libc.src.__support.macros.config
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libc.src.__support.libc_errno
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libc.src.__support.wchar.mbrtowc
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libc.src.__support.wchar.mbstate
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)
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add_entrypoint_object(
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wmemset
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SRCS

‎libc/src/wchar/mbtowc.cpp‎

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//===-- Implementation of mbtowc -----------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "src/wchar/mbtowc.h"
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#include "hdr/types/size_t.h"
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#include "hdr/types/wchar_t.h"
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#include "src/__support/common.h"
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#include "src/__support/libc_errno.h"
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#include "src/__support/macros/config.h"
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#include "src/__support/wchar/mbrtowc.h"
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#include "src/__support/wchar/mbstate.h"
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namespace LIBC_NAMESPACE_DECL {
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LLVM_LIBC_FUNCTION(int, mbtowc,
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(wchar_t *__restrict pwc, const char *__restrict s,
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size_t n)) {
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// returns 0 since UTF-8 encoding is not state-dependent
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if (s == nullptr)
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return 0;
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internal::mbstate internal_mbstate;
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// temp ptr to use if pwc is nullptr
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wchar_t buf[1];
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auto ret =
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internal::mbrtowc(pwc == nullptr ? buf : pwc, s, n, &internal_mbstate);
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if (!ret.has_value() || static_cast<int>(ret.value()) == -2) {
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// Encoding failure
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libc_errno = EILSEQ;
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return -1;
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}
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return static_cast<int>(ret.value());
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}
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} // namespace LIBC_NAMESPACE_DECL

‎libc/src/wchar/mbtowc.h‎

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//===-- Implementation header for mbtowc ---------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_SRC_WCHAR_MBTOWC_H
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#define LLVM_LIBC_SRC_WCHAR_MBTOWC_H
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#include "hdr/types/size_t.h"
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#include "hdr/types/wchar_t.h"
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#include "src/__support/macros/config.h"
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namespace LIBC_NAMESPACE_DECL {
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int mbtowc(wchar_t *__restrict pwc, const char *__restrict s, size_t n);
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} // namespace LIBC_NAMESPACE_DECL
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#endif // LLVM_LIBC_SRC_WCHAR_MBTOWC_H

‎libc/test/src/wchar/CMakeLists.txt‎

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@@ -37,6 +37,19 @@ add_libc_test(
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libc.hdr.types.wchar_t
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)
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add_libc_test(
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mbtowc_test
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SUITE
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libc_wchar_unittests
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SRCS
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mbtowc_test.cpp
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DEPENDS
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libc.src.__support.libc_errno
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libc.src.wchar.mbtowc
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libc.hdr.types.wchar_t
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libc.test.UnitTest.ErrnoCheckingTest
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)
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add_libc_test(
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wctob_test
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SUITE

‎libc/test/src/wchar/mbtowc_test.cpp‎

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//===-- Unittests for mbtowc ---------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "hdr/types/wchar_t.h"
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#include "src/__support/libc_errno.h"
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#include "src/wchar/mbtowc.h"
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#include "test/UnitTest/ErrnoCheckingTest.h"
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#include "test/UnitTest/Test.h"
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using LlvmLibcMBToWCTest = LIBC_NAMESPACE::testing::ErrnoCheckingTest;
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TEST_F(LlvmLibcMBToWCTest, OneByte) {
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const char *ch = "A";
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wchar_t dest[2];
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int n = LIBC_NAMESPACE::mbtowc(dest, ch, 1);
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ASSERT_EQ(static_cast<char>(*dest), 'A');
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ASSERT_EQ(n, 1);
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// Should fail since we have not read enough
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n = LIBC_NAMESPACE::mbtowc(dest, ch, 0);
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ASSERT_EQ(n, -1);
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ASSERT_ERRNO_EQ(EILSEQ);
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}
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TEST_F(LlvmLibcMBToWCTest, TwoByte) {
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const char ch[2] = {static_cast<char>(0xC2),
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static_cast<char>(0x8E)}; // Ž car symbol
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wchar_t dest[2];
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int n = LIBC_NAMESPACE::mbtowc(dest, ch, 2);
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ASSERT_EQ(static_cast<int>(*dest), 142);
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ASSERT_EQ(n, 2);
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// Should fail since we have not read enough
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n = LIBC_NAMESPACE::mbtowc(dest, ch, 1);
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ASSERT_EQ(n, -1);
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// Should fail after trying to read next byte too
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n = LIBC_NAMESPACE::mbtowc(dest, ch + 1, 1);
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ASSERT_EQ(n, -1);
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ASSERT_ERRNO_EQ(EILSEQ);
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}
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TEST_F(LlvmLibcMBToWCTest, ThreeByte) {
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const char ch[3] = {static_cast<char>(0xE2), static_cast<char>(0x88),
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static_cast<char>(0x91)}; // ∑ sigma symbol
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wchar_t dest[2];
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int n = LIBC_NAMESPACE::mbtowc(dest, ch, 3);
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ASSERT_EQ(static_cast<int>(*dest), 8721);
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ASSERT_EQ(n, 3);
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// Should fail since we have not read enough
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n = LIBC_NAMESPACE::mbtowc(dest, ch, 2);
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ASSERT_EQ(n, -1);
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ASSERT_ERRNO_EQ(EILSEQ);
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}
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TEST_F(LlvmLibcMBToWCTest, FourByte) {
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const char ch[4] = {static_cast<char>(0xF0), static_cast<char>(0x9F),
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static_cast<char>(0xA4),
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static_cast<char>(0xA1)}; // 🤡 clown emoji
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wchar_t dest[2];
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int n = LIBC_NAMESPACE::mbtowc(dest, ch, 4);
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ASSERT_EQ(static_cast<int>(*dest), 129313);
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ASSERT_EQ(n, 4);
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// Should fail since we have not read enough
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n = LIBC_NAMESPACE::mbtowc(dest, ch, 2);
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ASSERT_EQ(n, -1);
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ASSERT_ERRNO_EQ(EILSEQ);
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}
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TEST_F(LlvmLibcMBToWCTest, InvalidByte) {
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const char ch[1] = {static_cast<char>(0x80)};
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wchar_t dest[2];
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int n = LIBC_NAMESPACE::mbtowc(dest, ch, 1);
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ASSERT_EQ(n, -1);
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ASSERT_ERRNO_EQ(EILSEQ);
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}
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TEST_F(LlvmLibcMBToWCTest, InvalidMultiByte) {
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const char ch[4] = {static_cast<char>(0x80), static_cast<char>(0x00),
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static_cast<char>(0x80),
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static_cast<char>(0x00)}; // invalid sequence of bytes
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wchar_t dest[2];
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// Trying to push all 4 should error
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int n = LIBC_NAMESPACE::mbtowc(dest, ch, 4);
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ASSERT_EQ(n, -1);
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ASSERT_ERRNO_EQ(EILSEQ);
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// Trying to push the second and third should correspond to null wc
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n = LIBC_NAMESPACE::mbtowc(dest, ch + 1, 2);
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ASSERT_EQ(n, 0);
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ASSERT_TRUE(*dest == L'\0');
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}
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TEST_F(LlvmLibcMBToWCTest, InvalidLastByte) {
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// Last byte is invalid since it does not have correct starting sequence.
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// 0xC0 --> 11000000 starting sequence should be 10xxxxxx
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const char ch[4] = {static_cast<char>(0xF1), static_cast<char>(0x80),
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static_cast<char>(0x80), static_cast<char>(0xC0)};
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wchar_t dest[2];
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// Trying to push all 4 should error
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int n = LIBC_NAMESPACE::mbtowc(dest, ch, 4);
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ASSERT_EQ(n, -1);
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ASSERT_ERRNO_EQ(EILSEQ);
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}
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TEST_F(LlvmLibcMBToWCTest, ValidTwoByteWithExtraRead) {
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const char ch[3] = {static_cast<char>(0xC2), static_cast<char>(0x8E),
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static_cast<char>(0x80)};
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wchar_t dest[2];
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// Trying to push all 3 should return valid 2 byte
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int n = LIBC_NAMESPACE::mbtowc(dest, ch, 3);
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ASSERT_EQ(n, 2);
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ASSERT_EQ(static_cast<int>(*dest), 142);
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}
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TEST_F(LlvmLibcMBToWCTest, TwoValidTwoBytes) {
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const char ch[4] = {static_cast<char>(0xC2), static_cast<char>(0x8E),
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static_cast<char>(0xC7), static_cast<char>(0x8C)};
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wchar_t dest[2];
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int n = LIBC_NAMESPACE::mbtowc(dest, ch, 2);
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ASSERT_EQ(n, 2);
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ASSERT_EQ(static_cast<int>(*dest), 142);
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n = LIBC_NAMESPACE::mbtowc(dest + 1, ch + 2, 2);
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ASSERT_EQ(n, 2);
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ASSERT_EQ(static_cast<int>(*(dest + 1)), 460);
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}
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TEST_F(LlvmLibcMBToWCTest, NullString) {
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wchar_t dest[2] = {L'O', L'K'};
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// reading on nullptr should return 0
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int n = LIBC_NAMESPACE::mbtowc(dest, nullptr, 2);
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ASSERT_EQ(n, 0);
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ASSERT_TRUE(dest[0] == L'O');
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// reading a null terminator should return 0
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const char *ch = "\0";
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n = LIBC_NAMESPACE::mbtowc(dest, ch, 1);
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ASSERT_EQ(n, 0);
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}
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TEST_F(LlvmLibcMBToWCTest, NullWCPtr) {
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const char ch[2] = {
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static_cast<char>(0xC2),
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static_cast<char>(0x8E),
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};
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// a null destination should still return the number of read bytes
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int n = LIBC_NAMESPACE::mbtowc(nullptr, ch, 2);
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ASSERT_EQ(n, 2);
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}

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