1 files changed, 171 insertions, 0 deletions
diff --git a/libc/test/src/stdlib/mbstowcs_test.cpp b/libc/test/src/stdlib/mbstowcs_test.cpp
new file mode 100644
index 000000000000..125683a3eca9
--- /dev/null
+++ b/libc/test/src/stdlib/mbstowcs_test.cpp
@@ -0,0 +1,171 @@
+//===-- Unittests for mbstowcs --------------------------------------------===//
+//
+// 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/errno_macros.h"
+#include "hdr/types/wchar_t.h"
+#include "src/__support/macros/null_check.h"
+#include "src/stdlib/mbstowcs.h"
+#include "test/UnitTest/ErrnoCheckingTest.h"
+#include "test/UnitTest/Test.h"
+
+using LlvmLibcMBSToWCSTest = LIBC_NAMESPACE::testing::ErrnoCheckingTest;
+
+TEST_F(LlvmLibcMBSToWCSTest, OneByteOneChar) {
+  const char *ch = "A";
+  const char *original = ch;
+  wchar_t dest[2];
+  size_t n = LIBC_NAMESPACE::mbstowcs(dest, ch, 1);
+  ASSERT_EQ(static_cast<char>(*dest), 'A');
+  ASSERT_EQ(static_cast<int>(n), 1);
+  // Making sure the pointer is not getting updated
+  ASSERT_EQ(ch, original);
+  ASSERT_ERRNO_SUCCESS();
+
+  n = LIBC_NAMESPACE::mbstowcs(dest + 1, ch + 1, 1);
+  ASSERT_EQ(static_cast<char>(dest[1]), '\0');
+  // Should not include null terminator
+  ASSERT_EQ(static_cast<int>(n), 0);
+  // Making sure the pointer is not getting updated
+  ASSERT_EQ(ch, original);
+  ASSERT_ERRNO_SUCCESS();
+}
+
+TEST_F(LlvmLibcMBSToWCSTest, FourByteOneChar) {
+  const char *src = "\xf0\x9f\x98\xb9"; // laughing cat emoji 😹
+  const char *original = src;
+  wchar_t dest[2];
+  size_t n = LIBC_NAMESPACE::mbstowcs(dest, src, 2);
+  ASSERT_ERRNO_SUCCESS();
+  ASSERT_EQ(static_cast<int>(dest[0]), 128569);
+  ASSERT_TRUE(dest[1] == L'\0');
+  // Should not count null terminator in number
+  ASSERT_EQ(static_cast<int>(n), 1);
+  // Making sure the pointer is not getting updated
+  ASSERT_EQ(src, original);
+}
+
+TEST_F(LlvmLibcMBSToWCSTest, MultiByteTwoCharacters) {
+  // Two laughing cat emojis "😹😹"
+  const char *src = "\xf0\x9f\x98\xb9\xf0\x9f\x98\xb9";
+  const char *original = src;
+  wchar_t dest[3];
+  size_t n = LIBC_NAMESPACE::mbstowcs(dest, src, 3);
+  ASSERT_ERRNO_SUCCESS();
+  ASSERT_EQ(static_cast<int>(dest[0]), 128569);
+  ASSERT_EQ(static_cast<int>(dest[1]), 128569);
+  ASSERT_TRUE(dest[2] == L'\0');
+  // Should not count null terminator in number
+  ASSERT_EQ(static_cast<int>(n), 2);
+  // Making sure the pointer is not getting updated
+  ASSERT_EQ(src, original);
+}
+
+TEST_F(LlvmLibcMBSToWCSTest, MixedNumberOfBytes) {
+  // 'A', sigma symbol 'Σ', recycling symbol '♻', laughing cat emoji '😹'
+  const char *src = "A\xce\xa3\xe2\x99\xbb\xf0\x9f\x98\xb9";
+  const char *original = src;
+  wchar_t dest[5];
+  size_t n = LIBC_NAMESPACE::mbstowcs(dest, src, 5);
+  ASSERT_ERRNO_SUCCESS();
+  ASSERT_EQ(static_cast<char>(dest[0]), 'A');
+  ASSERT_EQ(static_cast<int>(dest[1]), 931);
+  ASSERT_EQ(static_cast<int>(dest[2]), 9851);
+  ASSERT_EQ(static_cast<int>(dest[3]), 128569);
+  ASSERT_TRUE(dest[4] == L'\0');
+  // Should not count null terminator in number
+  ASSERT_EQ(static_cast<int>(n), 4);
+  // Making sure the pointer is not getting updated
+  ASSERT_EQ(src, original);
+}
+
+TEST_F(LlvmLibcMBSToWCSTest, ReadLessThanStringLength) {
+  // Four laughing cat emojis "😹😹😹😹"
+  const char *src =
+      "\xf0\x9f\x98\xb9\xf0\x9f\x98\xb9\xf0\x9f\x98\xb9\xf0\x9f\x98\xb9";
+  const char *original = src;
+  wchar_t dest[5] = {L'a', L'b', L'c', L'd', L'e'};
+  size_t n = LIBC_NAMESPACE::mbstowcs(dest, src, 3);
+  ASSERT_ERRNO_SUCCESS();
+  // Should have read 3 emojis
+  ASSERT_EQ(static_cast<int>(n), 3);
+  ASSERT_EQ(static_cast<int>(dest[0]), 128569);
+  ASSERT_EQ(static_cast<int>(dest[1]), 128569);
+  ASSERT_EQ(static_cast<int>(dest[2]), 128569);
+  ASSERT_TRUE(dest[3] == L'd');
+  ASSERT_TRUE(dest[4] == L'e');
+  // Making sure the pointer is not getting updated
+  ASSERT_EQ(src, original);
+}
+
+TEST_F(LlvmLibcMBSToWCSTest, InvalidFirstByte) {
+  // 0x80 is invalid first byte of mb character
+  const char *src =
+      "\x80\x9f\x98\xb9\xf0\x9f\x98\xb9\xf0\x9f\x98\xb9\xf0\x9f\x98\xb9";
+  wchar_t dest[3];
+  size_t n = LIBC_NAMESPACE::mbstowcs(dest, src, 3);
+  // Should return error and set errno
+  ASSERT_EQ(static_cast<int>(n), -1);
+  ASSERT_ERRNO_EQ(EILSEQ);
+}
+
+TEST_F(LlvmLibcMBSToWCSTest, InvalidMiddleByte) {
+  // The 7th byte is invalid for a 4 byte character
+  const char *src =
+      "\xf0\x9f\x98\xb9\xf0\x9f\xf0\xb9\xf0\x9f\x98\xb9\xf0\x9f\x98\xb9";
+  const char *original = src;
+  wchar_t dest[3];
+  size_t n = LIBC_NAMESPACE::mbstowcs(dest, src, 5);
+  // Should return error and set errno
+  ASSERT_EQ(static_cast<int>(n), -1);
+  ASSERT_ERRNO_EQ(EILSEQ);
+  // Making sure the pointer is not getting updated
+  ASSERT_EQ(src, original);
+}
+
+TEST_F(LlvmLibcMBSToWCSTest, NullDestination) {
+  // Four laughing cat emojis "😹😹😹😹"
+  const char *src =
+      "\xf0\x9f\x98\xb9\xf0\x9f\x98\xb9\xf0\x9f\x98\xb9\xf0\x9f\x98\xb9";
+  const char *original = src;
+  size_t n = LIBC_NAMESPACE::mbstowcs(nullptr, src, 2);
+  ASSERT_ERRNO_SUCCESS();
+  // Null destination should ignore len and read till end of string
+  ASSERT_EQ(static_cast<int>(n), 4);
+  // Making sure the pointer is not getting updated
+  ASSERT_EQ(src, original);
+}
+
+TEST_F(LlvmLibcMBSToWCSTest, ErrnoChecks) {
+  // Two laughing cat emojis and invalid 3rd mb char (3rd byte of it)
+  const char *src =
+      "\xf0\x9f\x98\xb9\xf0\x9f\x98\xb9\xf0\x9f\xf0\xb9\xf0\x9f\x98\xb9";
+  const char *original = src;
+  wchar_t dest[5];
+  // First two bytes are valid --> should not set errno
+  size_t n = LIBC_NAMESPACE::mbstowcs(dest, src, 2);
+  ASSERT_ERRNO_SUCCESS();
+  ASSERT_EQ(static_cast<int>(n), 2);
+  ASSERT_EQ(static_cast<int>(dest[0]), 128569);
+  ASSERT_EQ(static_cast<int>(dest[1]), 128569);
+  // Making sure the pointer is not getting updated
+  ASSERT_EQ(src, original);
+  // Trying to read the 3rd byte should set errno
+  n = LIBC_NAMESPACE::mbstowcs(dest, src + 2, 2);
+  ASSERT_ERRNO_EQ(EILSEQ);
+  ASSERT_EQ(static_cast<int>(n), -1);
+  // Making sure the pointer is not getting updated
+  ASSERT_EQ(src, original);
+}
+
+#if defined(LIBC_ADD_NULL_CHECKS)
+TEST(LlvmLibcMBSToWCSTest, NullptrCrash) {
+  // Passing in a nullptr should crash the program.
+  EXPECT_DEATH([] { LIBC_NAMESPACE::mbstowcs(nullptr, nullptr, 1); },
+               WITH_SIGNAL(-1));
+}
+#endif // LIBC_ADD_NULL_CHECKS