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Commit d86ea58b authored by Ryan Mitchell's avatar Ryan Mitchell
Browse files

AAPT2: Encode 4-byte strings in Modified UTF-8 

Codepoints that are encoded to 4 bytes in UTF-8 are not allowed in
Modified UTF-8. They instead should be encoded as surrogate pairs in the
same way that CESU-8 allows for surrogate pairs. This will also cause 4
byte UTF-8 codes to be represented in 6 bytes.

Bug: 37140916
Test: aapt2_tests
Change-Id: I155dc24f166139d1d36a16bac088dcfcd59eb321
parent af575383

tools/aapt2/StringPool.cpp

+1 −1
Original line number Original line Diff line number Diff line
@@ -367,7 +367,7 @@ const std::string kStringTooLarge = "STRING_TOO_LARGE"; 
static bool EncodeString(const std::string& str, const bool utf8, BigBuffer* out,

static bool EncodeString(const std::string& str, const bool utf8, BigBuffer* out,

                         IDiagnostics* diag) {

                         IDiagnostics* diag) {

  if (utf8) {

  if (utf8) {

    const std::string& encoded = str;

    const std::string& encoded = util::Utf8ToModifiedUtf8(str);

    const ssize_t utf16_length = utf8_to_utf16_length(

    const ssize_t utf16_length = utf8_to_utf16_length(

        reinterpret_cast<const uint8_t*>(encoded.data()), encoded.size());

        reinterpret_cast<const uint8_t*>(encoded.data()), encoded.size());

    CHECK(utf16_length >= 0);

    CHECK(utf16_length >= 0);

tools/aapt2/StringPool_test.cpp

+19 −0
Original line number Original line Diff line number Diff line
@@ -303,6 +303,25 @@ TEST(StringPoolTest, Flatten) { 
  }

  }

}

}





TEST(StringPoolTest, FlattenModifiedUTF8) {

  using namespace android;  // For NO_ERROR on Windows.

  StdErrDiagnostics diag;

  StringPool pool;

  StringPool::Ref ref_a = pool.MakeRef("\xF0\x90\x90\x80"); // 𐐀 (U+10400)

  StringPool::Ref ref_b = pool.MakeRef("foo \xF0\x90\x90\xB7 bar"); // 𐐷 (U+10437)

  StringPool::Ref ref_c = pool.MakeRef("\xF0\x90\x90\x80\xF0\x90\x90\xB7");



  BigBuffer buffer(1024);

  StringPool::FlattenUtf8(&buffer, pool, &diag);

  std::unique_ptr<uint8_t[]> data = util::Copy(buffer);



  // Check that the 4 byte utf-8 codepoint is encoded using 2 3 byte surrogate pairs

  ResStringPool test;

  ASSERT_EQ(test.setTo(data.get(), buffer.size()), NO_ERROR);

  EXPECT_THAT(util::GetString(test, 0), Eq("\xED\xA0\x81\xED\xB0\x80"));

  EXPECT_THAT(util::GetString(test, 1), Eq("foo \xED\xA0\x81\xED\xB0\xB7 bar"));

  EXPECT_THAT(util::GetString(test, 2), Eq("\xED\xA0\x81\xED\xB0\x80\xED\xA0\x81\xED\xB0\xB7"));

}





TEST(StringPoolTest, MaxEncodingLength) {

TEST(StringPoolTest, MaxEncodingLength) {

  StdErrDiagnostics diag;

  StdErrDiagnostics diag;

tools/aapt2/util/Util.cpp

+47 −0
Original line number Original line Diff line number Diff line
@@ -297,6 +297,53 @@ bool VerifyJavaStringFormat(const StringPiece& str) { 
  return true;

  return true;

}

}





std::string Utf8ToModifiedUtf8(const std::string& utf8) {

  // Java uses Modified UTF-8 which only supports the 1, 2, and 3 byte formats of UTF-8. To encode

  // 4 byte UTF-8 codepoints, Modified UTF-8 allows the use of surrogate pairs in the same format

  // of CESU-8 surrogate pairs. Calculate the size of the utf8 string with all 4 byte UTF-8

  // codepoints replaced with 2 3 byte surrogate pairs

  size_t modified_size = 0;

  const size_t size = utf8.size();

  for (size_t i = 0; i < size; i++) {

    if (((uint8_t) utf8[i] >> 4) == 0xF) {

      modified_size += 6;

      i += 3;

    } else {

      modified_size++;

    }

  }



  // Early out if no 4 byte codepoints are found

  if (size == modified_size) {

    return utf8;

  }



  std::string output;

  output.reserve(modified_size);

  for (size_t i = 0; i < size; i++) {

    if (((uint8_t) utf8[i] >> 4) == 0xF) {

      auto codepoint = (char32_t) utf32_from_utf8_at(utf8.data(), size, i, nullptr);



      // Calculate the high and low surrogates as UTF-16 would

      char32_t high = ((codepoint - 0x10000) / 0x400) + 0xD800;

      char32_t low = ((codepoint - 0x10000) % 0x400) + 0xDC00;



      // Encode each surrogate in UTF-8

      output.push_back((char) (0xE4 | ((high >> 12) & 0xF)));

      output.push_back((char) (0x80 | ((high >> 6) & 0x3F)));

      output.push_back((char) (0x80 | (high & 0x3F)));

      output.push_back((char) (0xE4 | ((low >> 12) & 0xF)));

      output.push_back((char) (0x80 | ((low >> 6) & 0x3F)));

      output.push_back((char) (0x80 | (low & 0x3F)));

      i += 3;

    } else {

      output.push_back(utf8[i]);

    }

  }



  return output;

}



std::u16string Utf8ToUtf16(const StringPiece& utf8) {

std::u16string Utf8ToUtf16(const StringPiece& utf8) {

  ssize_t utf16_length = utf8_to_utf16_length(

  ssize_t utf16_length = utf8_to_utf16_length(

      reinterpret_cast<const uint8_t*>(utf8.data()), utf8.length());

      reinterpret_cast<const uint8_t*>(utf8.data()), utf8.length());

tools/aapt2/util/Util.h

+3 −0
Original line number Original line Diff line number Diff line
@@ -197,6 +197,9 @@ inline StringBuilder::operator bool() const { 
  return error_.empty();

  return error_.empty();

}

}





// Converts a UTF8 string into Modified UTF8

std::string Utf8ToModifiedUtf8(const std::string& utf8);



// Converts a UTF8 string to a UTF16 string.

// Converts a UTF8 string to a UTF16 string.

std::u16string Utf8ToUtf16(const android::StringPiece& utf8);

std::u16string Utf8ToUtf16(const android::StringPiece& utf8);

std::string Utf16ToUtf8(const android::StringPiece16& utf16);

std::string Utf16ToUtf8(const android::StringPiece16& utf16);