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Diffstat (limited to 'chromium/v8/src/inspector/v8-string-conversions.cc')
| -rw-r--r-- | chromium/v8/src/inspector/v8-string-conversions.cc | 403 |
1 files changed, 403 insertions, 0 deletions
diff --git a/chromium/v8/src/inspector/v8-string-conversions.cc b/chromium/v8/src/inspector/v8-string-conversions.cc new file mode 100644 index 00000000000..0c75e66b972 --- /dev/null +++ b/chromium/v8/src/inspector/v8-string-conversions.cc @@ -0,0 +1,403 @@ +// Copyright 2019 the V8 project authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +#include "src/inspector/v8-string-conversions.h" + +#include <limits> +#include <vector> + +#include "src/base/logging.h" +#include "src/base/v8-fallthrough.h" + +namespace v8_inspector { +namespace { +using UChar = uint16_t; +using UChar32 = uint32_t; + +bool isASCII(UChar c) { return !(c & ~0x7F); } + +const UChar replacementCharacter = 0xFFFD; + +inline int inlineUTF8SequenceLengthNonASCII(char b0) { + if ((b0 & 0xC0) != 0xC0) return 0; + if ((b0 & 0xE0) == 0xC0) return 2; + if ((b0 & 0xF0) == 0xE0) return 3; + if ((b0 & 0xF8) == 0xF0) return 4; + return 0; +} + +inline int inlineUTF8SequenceLength(char b0) { + return isASCII(b0) ? 1 : inlineUTF8SequenceLengthNonASCII(b0); +} + +// Once the bits are split out into bytes of UTF-8, this is a mask OR-ed +// into the first byte, depending on how many bytes follow. There are +// as many entries in this table as there are UTF-8 sequence types. +// (I.e., one byte sequence, two byte... etc.). Remember that sequences +// for *legal* UTF-8 will be 4 or fewer bytes total. +static const unsigned char firstByteMark[7] = {0x00, 0x00, 0xC0, 0xE0, + 0xF0, 0xF8, 0xFC}; + +enum ConversionResult { + conversionOK, // conversion successful + sourceExhausted, // partial character in source, but hit end + targetExhausted, // insuff. room in target for conversion + sourceIllegal // source sequence is illegal/malformed +}; + +ConversionResult convertUTF16ToUTF8(const UChar** sourceStart, + const UChar* sourceEnd, char** targetStart, + char* targetEnd, bool strict) { + ConversionResult result = conversionOK; + const UChar* source = *sourceStart; + char* target = *targetStart; + while (source < sourceEnd) { + UChar32 ch; + uint32_t bytesToWrite = 0; + const UChar32 byteMask = 0xBF; + const UChar32 byteMark = 0x80; + const UChar* oldSource = + source; // In case we have to back up because of target overflow. + ch = static_cast<uint16_t>(*source++); + // If we have a surrogate pair, convert to UChar32 first. + if (ch >= 0xD800 && ch <= 0xDBFF) { + // If the 16 bits following the high surrogate are in the source buffer... + if (source < sourceEnd) { + UChar32 ch2 = static_cast<uint16_t>(*source); + // If it's a low surrogate, convert to UChar32. + if (ch2 >= 0xDC00 && ch2 <= 0xDFFF) { + ch = ((ch - 0xD800) << 10) + (ch2 - 0xDC00) + 0x0010000; + ++source; + } else if (strict) { // it's an unpaired high surrogate + --source; // return to the illegal value itself + result = sourceIllegal; + break; + } + } else { // We don't have the 16 bits following the high surrogate. + --source; // return to the high surrogate + result = sourceExhausted; + break; + } + } else if (strict) { + // UTF-16 surrogate values are illegal in UTF-32 + if (ch >= 0xDC00 && ch <= 0xDFFF) { + --source; // return to the illegal value itself + result = sourceIllegal; + break; + } + } + // Figure out how many bytes the result will require + if (ch < static_cast<UChar32>(0x80)) { + bytesToWrite = 1; + } else if (ch < static_cast<UChar32>(0x800)) { + bytesToWrite = 2; + } else if (ch < static_cast<UChar32>(0x10000)) { + bytesToWrite = 3; + } else if (ch < static_cast<UChar32>(0x110000)) { + bytesToWrite = 4; + } else { + bytesToWrite = 3; + ch = replacementCharacter; + } + + target += bytesToWrite; + if (target > targetEnd) { + source = oldSource; // Back up source pointer! + target -= bytesToWrite; + result = targetExhausted; + break; + } + switch (bytesToWrite) { + case 4: + *--target = static_cast<char>((ch | byteMark) & byteMask); + ch >>= 6; + V8_FALLTHROUGH; + case 3: + *--target = static_cast<char>((ch | byteMark) & byteMask); + ch >>= 6; + V8_FALLTHROUGH; + case 2: + *--target = static_cast<char>((ch | byteMark) & byteMask); + ch >>= 6; + V8_FALLTHROUGH; + case 1: + *--target = static_cast<char>(ch | firstByteMark[bytesToWrite]); + } + target += bytesToWrite; + } + *sourceStart = source; + *targetStart = target; + return result; +} + +/** + * Is this code point a BMP code point (U+0000..U+ffff)? + * @param c 32-bit code point + * @return TRUE or FALSE + * @stable ICU 2.8 + */ +#define U_IS_BMP(c) ((uint32_t)(c) <= 0xFFFF) + +/** + * Is this code point a supplementary code point (U+010000..U+10FFFF)? + * @param c 32-bit code point + * @return TRUE or FALSE + * @stable ICU 2.8 + */ +#define U_IS_SUPPLEMENTARY(c) ((uint32_t)((c)-0x010000) <= 0xFFFFF) + +/** + * Is this code point a surrogate (U+d800..U+dfff)? + * @param c 32-bit code point + * @return TRUE or FALSE + * @stable ICU 2.4 + */ +#define U_IS_SURROGATE(c) (((c)&0xFFFFF800) == 0xD800) + +/** + * Get the lead surrogate (0xD800..0xDBFF) for a + * supplementary code point (0x010000..0x10FFFF). + * @param supplementary 32-bit code point (U+010000..U+10FFFF) + * @return lead surrogate (U+D800..U+DBFF) for supplementary + * @stable ICU 2.4 + */ +#define U16_LEAD(supplementary) (UChar)(((supplementary) >> 10) + 0xD7C0) + +/** + * Get the trail surrogate (0xDC00..0xDFFF) for a + * supplementary code point (0x010000..0x10FFFF). + * @param supplementary 32-bit code point (U+010000..U+10FFFF) + * @return trail surrogate (U+DC00..U+DFFF) for supplementary + * @stable ICU 2.4 + */ +#define U16_TRAIL(supplementary) (UChar)(((supplementary)&0x3FF) | 0xDC00) + +// This must be called with the length pre-determined by the first byte. +// If presented with a length > 4, this returns false. The Unicode +// definition of UTF-8 goes up to 4-byte sequences. +static bool isLegalUTF8(const unsigned char* source, int length) { + unsigned char a; + const unsigned char* srcptr = source + length; + switch (length) { + default: + return false; + // Everything else falls through when "true"... + case 4: + if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return false; + V8_FALLTHROUGH; + case 3: + if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return false; + V8_FALLTHROUGH; + case 2: + if ((a = (*--srcptr)) > 0xBF) return false; + + // no fall-through in this inner switch + switch (*source) { + case 0xE0: + if (a < 0xA0) return false; + break; + case 0xED: + if (a > 0x9F) return false; + break; + case 0xF0: + if (a < 0x90) return false; + break; + case 0xF4: + if (a > 0x8F) return false; + break; + default: + if (a < 0x80) return false; + } + V8_FALLTHROUGH; + + case 1: + if (*source >= 0x80 && *source < 0xC2) return false; + } + if (*source > 0xF4) return false; + return true; +} + +// Magic values subtracted from a buffer value during UTF8 conversion. +// This table contains as many values as there might be trailing bytes +// in a UTF-8 sequence. +static const UChar32 offsetsFromUTF8[6] = {0x00000000UL, + 0x00003080UL, + 0x000E2080UL, + 0x03C82080UL, + static_cast<UChar32>(0xFA082080UL), + static_cast<UChar32>(0x82082080UL)}; + +static inline UChar32 readUTF8Sequence(const char*& sequence, size_t length) { + UChar32 character = 0; + + // The cases all fall through. + switch (length) { + case 6: + character += static_cast<unsigned char>(*sequence++); + character <<= 6; + V8_FALLTHROUGH; + case 5: + character += static_cast<unsigned char>(*sequence++); + character <<= 6; + V8_FALLTHROUGH; + case 4: + character += static_cast<unsigned char>(*sequence++); + character <<= 6; + V8_FALLTHROUGH; + case 3: + character += static_cast<unsigned char>(*sequence++); + character <<= 6; + V8_FALLTHROUGH; + case 2: + character += static_cast<unsigned char>(*sequence++); + character <<= 6; + V8_FALLTHROUGH; + case 1: + character += static_cast<unsigned char>(*sequence++); + } + + return character - offsetsFromUTF8[length - 1]; +} + +ConversionResult convertUTF8ToUTF16(const char** sourceStart, + const char* sourceEnd, UChar** targetStart, + UChar* targetEnd, bool* sourceAllASCII, + bool strict) { + ConversionResult result = conversionOK; + const char* source = *sourceStart; + UChar* target = *targetStart; + UChar orAllData = 0; + while (source < sourceEnd) { + int utf8SequenceLength = inlineUTF8SequenceLength(*source); + if (sourceEnd - source < utf8SequenceLength) { + result = sourceExhausted; + break; + } + // Do this check whether lenient or strict + if (!isLegalUTF8(reinterpret_cast<const unsigned char*>(source), + utf8SequenceLength)) { + result = sourceIllegal; + break; + } + + UChar32 character = readUTF8Sequence(source, utf8SequenceLength); + + if (target >= targetEnd) { + source -= utf8SequenceLength; // Back up source pointer! + result = targetExhausted; + break; + } + + if (U_IS_BMP(character)) { + // UTF-16 surrogate values are illegal in UTF-32 + if (U_IS_SURROGATE(character)) { + if (strict) { + source -= utf8SequenceLength; // return to the illegal value itself + result = sourceIllegal; + break; + } + *target++ = replacementCharacter; + orAllData |= replacementCharacter; + } else { + *target++ = static_cast<UChar>(character); // normal case + orAllData |= character; + } + } else if (U_IS_SUPPLEMENTARY(character)) { + // target is a character in range 0xFFFF - 0x10FFFF + if (target + 1 >= targetEnd) { + source -= utf8SequenceLength; // Back up source pointer! + result = targetExhausted; + break; + } + *target++ = U16_LEAD(character); + *target++ = U16_TRAIL(character); + orAllData = 0xFFFF; + } else { + if (strict) { + source -= utf8SequenceLength; // return to the start + result = sourceIllegal; + break; // Bail out; shouldn't continue + } else { + *target++ = replacementCharacter; + orAllData |= replacementCharacter; + } + } + } + *sourceStart = source; + *targetStart = target; + + if (sourceAllASCII) *sourceAllASCII = !(orAllData & ~0x7F); + + return result; +} + +// Helper to write a three-byte UTF-8 code point to the buffer, caller must +// check room is available. +static inline void putUTF8Triple(char*& buffer, UChar ch) { + *buffer++ = static_cast<char>(((ch >> 12) & 0x0F) | 0xE0); + *buffer++ = static_cast<char>(((ch >> 6) & 0x3F) | 0x80); + *buffer++ = static_cast<char>((ch & 0x3F) | 0x80); +} +} // namespace + +std::string UTF16ToUTF8(const UChar* stringStart, size_t length) { + if (!stringStart || !length) return std::string(); + + // Allocate a buffer big enough to hold all the characters + // (an individual UTF-16 UChar can only expand to 3 UTF-8 bytes). + // Optimization ideas, if we find this function is hot: + // * We could speculatively create a CStringBuffer to contain 'length' + // characters, and resize if necessary (i.e. if the buffer contains + // non-ascii characters). (Alternatively, scan the buffer first for + // ascii characters, so we know this will be sufficient). + // * We could allocate a CStringBuffer with an appropriate size to + // have a good chance of being able to write the string into the + // buffer without reallocing (say, 1.5 x length). + if (length > std::numeric_limits<unsigned>::max() / 3) return std::string(); + + std::string output(length * 3, '\0'); + const UChar* characters = stringStart; + const UChar* characters_end = characters + length; + char* buffer = &*output.begin(); + char* buffer_end = &*output.end(); + while (characters < characters_end) { + // Use strict conversion to detect unpaired surrogates. + ConversionResult result = convertUTF16ToUTF8( + &characters, characters_end, &buffer, buffer_end, /* strict= */ true); + DCHECK_NE(result, targetExhausted); + // Conversion fails when there is an unpaired surrogate. Put + // replacement character (U+FFFD) instead of the unpaired + // surrogate. + if (result != conversionOK) { + DCHECK_LE(0xD800, *characters); + DCHECK_LE(*characters, 0xDFFF); + // There should be room left, since one UChar hasn't been + // converted. + DCHECK_LE(buffer + 3, buffer_end); + putUTF8Triple(buffer, replacementCharacter); + ++characters; + } + } + + output.resize(buffer - output.data()); + return output; +} + +std::basic_string<UChar> UTF8ToUTF16(const char* stringStart, size_t length) { + if (!stringStart || !length) return std::basic_string<UChar>(); + std::vector<uint16_t> buffer(length); + UChar* bufferStart = buffer.data(); + + UChar* bufferCurrent = bufferStart; + const char* stringCurrent = reinterpret_cast<const char*>(stringStart); + if (convertUTF8ToUTF16(&stringCurrent, + reinterpret_cast<const char*>(stringStart + length), + &bufferCurrent, bufferCurrent + buffer.size(), nullptr, + true) != conversionOK) + return std::basic_string<uint16_t>(); + size_t utf16Length = bufferCurrent - bufferStart; + return std::basic_string<UChar>(bufferStart, bufferStart + utf16Length); +} + +} // namespace v8_inspector |