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Diffstat (limited to 'third_party/protobuf/3.6.0/java/core/src/main/java/com/google/protobuf/Utf8.java')
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diff --git a/third_party/protobuf/3.6.0/java/core/src/main/java/com/google/protobuf/Utf8.java b/third_party/protobuf/3.6.0/java/core/src/main/java/com/google/protobuf/Utf8.java new file mode 100644 index 0000000000..6968abb3c1 --- /dev/null +++ b/third_party/protobuf/3.6.0/java/core/src/main/java/com/google/protobuf/Utf8.java @@ -0,0 +1,2040 @@ +// Protocol Buffers - Google's data interchange format +// Copyright 2008 Google Inc. All rights reserved. +// https://developers.google.com/protocol-buffers/ +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +package com.google.protobuf; + +import static com.google.protobuf.UnsafeUtil.addressOffset; +import static com.google.protobuf.UnsafeUtil.hasUnsafeArrayOperations; +import static com.google.protobuf.UnsafeUtil.hasUnsafeByteBufferOperations; +import static java.lang.Character.MAX_SURROGATE; +import static java.lang.Character.MIN_HIGH_SURROGATE; +import static java.lang.Character.MIN_LOW_SURROGATE; +import static java.lang.Character.MIN_SUPPLEMENTARY_CODE_POINT; +import static java.lang.Character.MIN_SURROGATE; +import static java.lang.Character.isSurrogatePair; +import static java.lang.Character.toCodePoint; + +import java.nio.ByteBuffer; +import java.util.Arrays; + +/** + * A set of low-level, high-performance static utility methods related + * to the UTF-8 character encoding. This class has no dependencies + * outside of the core JDK libraries. + * + * <p>There are several variants of UTF-8. The one implemented by + * this class is the restricted definition of UTF-8 introduced in + * Unicode 3.1, which mandates the rejection of "overlong" byte + * sequences as well as rejection of 3-byte surrogate codepoint byte + * sequences. Note that the UTF-8 decoder included in Oracle's JDK + * has been modified to also reject "overlong" byte sequences, but (as + * of 2011) still accepts 3-byte surrogate codepoint byte sequences. + * + * <p>The byte sequences considered valid by this class are exactly + * those that can be roundtrip converted to Strings and back to bytes + * using the UTF-8 charset, without loss: <pre> {@code + * Arrays.equals(bytes, new String(bytes, Internal.UTF_8).getBytes(Internal.UTF_8)) + * }</pre> + * + * <p>See the Unicode Standard,</br> + * Table 3-6. <em>UTF-8 Bit Distribution</em>,</br> + * Table 3-7. <em>Well Formed UTF-8 Byte Sequences</em>. + * + * <p>This class supports decoding of partial byte sequences, so that the + * bytes in a complete UTF-8 byte sequences can be stored in multiple + * segments. Methods typically return {@link #MALFORMED} if the partial + * byte sequence is definitely not well-formed, {@link #COMPLETE} if it is + * well-formed in the absence of additional input, or if the byte sequence + * apparently terminated in the middle of a character, an opaque integer + * "state" value containing enough information to decode the character when + * passed to a subsequent invocation of a partial decoding method. + * + * @author martinrb@google.com (Martin Buchholz) + */ +// TODO(nathanmittler): Copy changes in this class back to Guava +final class Utf8 { + + /** + * UTF-8 is a runtime hot spot so we attempt to provide heavily optimized implementations + * depending on what is available on the platform. The processor is the platform-optimized + * delegate for which all methods are delegated directly to. + */ + private static final Processor processor = + UnsafeProcessor.isAvailable() ? new UnsafeProcessor() : new SafeProcessor(); + + /** + * A mask used when performing unsafe reads to determine if a long value contains any non-ASCII + * characters (i.e. any byte >= 0x80). + */ + private static final long ASCII_MASK_LONG = 0x8080808080808080L; + + /** + * Maximum number of bytes per Java UTF-16 char in UTF-8. + * @see java.nio.charset.CharsetEncoder#maxBytesPerChar() + */ + static final int MAX_BYTES_PER_CHAR = 3; + + /** + * State value indicating that the byte sequence is well-formed and + * complete (no further bytes are needed to complete a character). + */ + public static final int COMPLETE = 0; + + /** + * State value indicating that the byte sequence is definitely not + * well-formed. + */ + public static final int MALFORMED = -1; + + /** + * Used by {@code Unsafe} UTF-8 string validation logic to determine the minimum string length + * above which to employ an optimized algorithm for counting ASCII characters. The reason for this + * threshold is that for small strings, the optimization may not be beneficial or may even + * negatively impact performance since it requires additional logic to avoid unaligned reads + * (when calling {@code Unsafe.getLong}). This threshold guarantees that even if the initial + * offset is unaligned, we're guaranteed to make at least one call to {@code Unsafe.getLong()} + * which provides a performance improvement that entirely subsumes the cost of the additional + * logic. + */ + private static final int UNSAFE_COUNT_ASCII_THRESHOLD = 16; + + // Other state values include the partial bytes of the incomplete + // character to be decoded in the simplest way: we pack the bytes + // into the state int in little-endian order. For example: + // + // int state = byte1 ^ (byte2 << 8) ^ (byte3 << 16); + // + // Such a state is unpacked thus (note the ~ operation for byte2 to + // undo byte1's sign-extension bits): + // + // int byte1 = (byte) state; + // int byte2 = (byte) ~(state >> 8); + // int byte3 = (byte) (state >> 16); + // + // We cannot store a zero byte in the state because it would be + // indistinguishable from the absence of a byte. But we don't need + // to, because partial bytes must always be negative. When building + // a state, we ensure that byte1 is negative and subsequent bytes + // are valid trailing bytes. + + /** + * Returns {@code true} if the given byte array is a well-formed + * UTF-8 byte sequence. + * + * <p>This is a convenience method, equivalent to a call to {@code + * isValidUtf8(bytes, 0, bytes.length)}. + */ + public static boolean isValidUtf8(byte[] bytes) { + return processor.isValidUtf8(bytes, 0, bytes.length); + } + + /** + * Returns {@code true} if the given byte array slice is a + * well-formed UTF-8 byte sequence. The range of bytes to be + * checked extends from index {@code index}, inclusive, to {@code + * limit}, exclusive. + * + * <p>This is a convenience method, equivalent to {@code + * partialIsValidUtf8(bytes, index, limit) == Utf8.COMPLETE}. + */ + public static boolean isValidUtf8(byte[] bytes, int index, int limit) { + return processor.isValidUtf8(bytes, index, limit); + } + + /** + * Tells whether the given byte array slice is a well-formed, + * malformed, or incomplete UTF-8 byte sequence. The range of bytes + * to be checked extends from index {@code index}, inclusive, to + * {@code limit}, exclusive. + * + * @param state either {@link Utf8#COMPLETE} (if this is the initial decoding + * operation) or the value returned from a call to a partial decoding method + * for the previous bytes + * + * @return {@link #MALFORMED} if the partial byte sequence is + * definitely not well-formed, {@link #COMPLETE} if it is well-formed + * (no additional input needed), or if the byte sequence is + * "incomplete", i.e. apparently terminated in the middle of a character, + * an opaque integer "state" value containing enough information to + * decode the character when passed to a subsequent invocation of a + * partial decoding method. + */ + public static int partialIsValidUtf8(int state, byte[] bytes, int index, int limit) { + return processor.partialIsValidUtf8(state, bytes, index, limit); + } + + private static int incompleteStateFor(int byte1) { + return (byte1 > (byte) 0xF4) ? + MALFORMED : byte1; + } + + private static int incompleteStateFor(int byte1, int byte2) { + return (byte1 > (byte) 0xF4 || + byte2 > (byte) 0xBF) ? + MALFORMED : byte1 ^ (byte2 << 8); + } + + private static int incompleteStateFor(int byte1, int byte2, int byte3) { + return (byte1 > (byte) 0xF4 || + byte2 > (byte) 0xBF || + byte3 > (byte) 0xBF) ? + MALFORMED : byte1 ^ (byte2 << 8) ^ (byte3 << 16); + } + + private static int incompleteStateFor(byte[] bytes, int index, int limit) { + int byte1 = bytes[index - 1]; + switch (limit - index) { + case 0: return incompleteStateFor(byte1); + case 1: return incompleteStateFor(byte1, bytes[index]); + case 2: return incompleteStateFor(byte1, bytes[index], bytes[index + 1]); + default: throw new AssertionError(); + } + } + + private static int incompleteStateFor( + final ByteBuffer buffer, final int byte1, final int index, final int remaining) { + switch (remaining) { + case 0: + return incompleteStateFor(byte1); + case 1: + return incompleteStateFor(byte1, buffer.get(index)); + case 2: + return incompleteStateFor(byte1, buffer.get(index), buffer.get(index + 1)); + default: + throw new AssertionError(); + } + } + + // These UTF-8 handling methods are copied from Guava's Utf8 class with a modification to throw + // a protocol buffer local exception. This exception is then caught in CodedOutputStream so it can + // fallback to more lenient behavior. + + static class UnpairedSurrogateException extends IllegalArgumentException { + UnpairedSurrogateException(int index, int length) { + super("Unpaired surrogate at index " + index + " of " + length); + } + } + + /** + * Returns the number of bytes in the UTF-8-encoded form of {@code sequence}. For a string, + * this method is equivalent to {@code string.getBytes(UTF_8).length}, but is more efficient in + * both time and space. + * + * @throws IllegalArgumentException if {@code sequence} contains ill-formed UTF-16 (unpaired + * surrogates) + */ + static int encodedLength(CharSequence sequence) { + // Warning to maintainers: this implementation is highly optimized. + int utf16Length = sequence.length(); + int utf8Length = utf16Length; + int i = 0; + + // This loop optimizes for pure ASCII. + while (i < utf16Length && sequence.charAt(i) < 0x80) { + i++; + } + + // This loop optimizes for chars less than 0x800. + for (; i < utf16Length; i++) { + char c = sequence.charAt(i); + if (c < 0x800) { + utf8Length += ((0x7f - c) >>> 31); // branch free! + } else { + utf8Length += encodedLengthGeneral(sequence, i); + break; + } + } + + if (utf8Length < utf16Length) { + // Necessary and sufficient condition for overflow because of maximum 3x expansion + throw new IllegalArgumentException("UTF-8 length does not fit in int: " + + (utf8Length + (1L << 32))); + } + return utf8Length; + } + + private static int encodedLengthGeneral(CharSequence sequence, int start) { + int utf16Length = sequence.length(); + int utf8Length = 0; + for (int i = start; i < utf16Length; i++) { + char c = sequence.charAt(i); + if (c < 0x800) { + utf8Length += (0x7f - c) >>> 31; // branch free! + } else { + utf8Length += 2; + // jdk7+: if (Character.isSurrogate(c)) { + if (Character.MIN_SURROGATE <= c && c <= Character.MAX_SURROGATE) { + // Check that we have a well-formed surrogate pair. + int cp = Character.codePointAt(sequence, i); + if (cp < MIN_SUPPLEMENTARY_CODE_POINT) { + throw new UnpairedSurrogateException(i, utf16Length); + } + i++; + } + } + } + return utf8Length; + } + + static int encode(CharSequence in, byte[] out, int offset, int length) { + return processor.encodeUtf8(in, out, offset, length); + } + // End Guava UTF-8 methods. + + /** + * Determines if the given {@link ByteBuffer} is a valid UTF-8 string. + * + * <p>Selects an optimal algorithm based on the type of {@link ByteBuffer} (i.e. heap or direct) + * and the capabilities of the platform. + * + * @param buffer the buffer to check. + * @see Utf8#isValidUtf8(byte[], int, int) + */ + static boolean isValidUtf8(ByteBuffer buffer) { + return processor.isValidUtf8(buffer, buffer.position(), buffer.remaining()); + } + + /** + * Determines if the given {@link ByteBuffer} is a partially valid UTF-8 string. + * + * <p>Selects an optimal algorithm based on the type of {@link ByteBuffer} (i.e. heap or direct) + * and the capabilities of the platform. + * + * @param buffer the buffer to check. + * @see Utf8#partialIsValidUtf8(int, byte[], int, int) + */ + static int partialIsValidUtf8(int state, ByteBuffer buffer, int index, int limit) { + return processor.partialIsValidUtf8(state, buffer, index, limit); + } + + /** + * Decodes the given UTF-8 portion of the {@link ByteBuffer} into a {@link String}. + * + * @throws InvalidProtocolBufferException if the input is not valid UTF-8. + */ + static String decodeUtf8(ByteBuffer buffer, int index, int size) + throws InvalidProtocolBufferException { + return processor.decodeUtf8(buffer, index, size); + } + + /** + * Decodes the given UTF-8 encoded byte array slice into a {@link String}. + * + * @throws InvalidProtocolBufferException if the input is not valid UTF-8. + */ + static String decodeUtf8(byte[] bytes, int index, int size) + throws InvalidProtocolBufferException { + return processor.decodeUtf8(bytes, index, size); + } + + /** + * Encodes the given characters to the target {@link ByteBuffer} using UTF-8 encoding. + * + * <p>Selects an optimal algorithm based on the type of {@link ByteBuffer} (i.e. heap or direct) + * and the capabilities of the platform. + * + * @param in the source string to be encoded + * @param out the target buffer to receive the encoded string. + * @see Utf8#encode(CharSequence, byte[], int, int) + */ + static void encodeUtf8(CharSequence in, ByteBuffer out) { + processor.encodeUtf8(in, out); + } + + /** + * Counts (approximately) the number of consecutive ASCII characters in the given buffer. + * The byte order of the {@link ByteBuffer} does not matter, so performance can be improved if + * native byte order is used (i.e. no byte-swapping in {@link ByteBuffer#getLong(int)}). + * + * @param buffer the buffer to be scanned for ASCII chars + * @param index the starting index of the scan + * @param limit the limit within buffer for the scan + * @return the number of ASCII characters found. The stopping position will be at or + * before the first non-ASCII byte. + */ + private static int estimateConsecutiveAscii(ByteBuffer buffer, int index, int limit) { + int i = index; + final int lim = limit - 7; + // This simple loop stops when we encounter a byte >= 0x80 (i.e. non-ASCII). + // To speed things up further, we're reading longs instead of bytes so we use a mask to + // determine if any byte in the current long is non-ASCII. + for (; i < lim && (buffer.getLong(i) & ASCII_MASK_LONG) == 0; i += 8) {} + return i - index; + } + + /** + * A processor of UTF-8 strings, providing methods for checking validity and encoding. + */ + // TODO(nathanmittler): Add support for Memory/MemoryBlock on Android. + abstract static class Processor { + /** + * Returns {@code true} if the given byte array slice is a + * well-formed UTF-8 byte sequence. The range of bytes to be + * checked extends from index {@code index}, inclusive, to {@code + * limit}, exclusive. + * + * <p>This is a convenience method, equivalent to {@code + * partialIsValidUtf8(bytes, index, limit) == Utf8.COMPLETE}. + */ + final boolean isValidUtf8(byte[] bytes, int index, int limit) { + return partialIsValidUtf8(COMPLETE, bytes, index, limit) == COMPLETE; + } + + /** + * Tells whether the given byte array slice is a well-formed, + * malformed, or incomplete UTF-8 byte sequence. The range of bytes + * to be checked extends from index {@code index}, inclusive, to + * {@code limit}, exclusive. + * + * @param state either {@link Utf8#COMPLETE} (if this is the initial decoding + * operation) or the value returned from a call to a partial decoding method + * for the previous bytes + * + * @return {@link #MALFORMED} if the partial byte sequence is + * definitely not well-formed, {@link #COMPLETE} if it is well-formed + * (no additional input needed), or if the byte sequence is + * "incomplete", i.e. apparently terminated in the middle of a character, + * an opaque integer "state" value containing enough information to + * decode the character when passed to a subsequent invocation of a + * partial decoding method. + */ + abstract int partialIsValidUtf8(int state, byte[] bytes, int index, int limit); + + /** + * Returns {@code true} if the given portion of the {@link ByteBuffer} is a + * well-formed UTF-8 byte sequence. The range of bytes to be + * checked extends from index {@code index}, inclusive, to {@code + * limit}, exclusive. + * + * <p>This is a convenience method, equivalent to {@code + * partialIsValidUtf8(bytes, index, limit) == Utf8.COMPLETE}. + */ + final boolean isValidUtf8(ByteBuffer buffer, int index, int limit) { + return partialIsValidUtf8(COMPLETE, buffer, index, limit) == COMPLETE; + } + + /** + * Indicates whether or not the given buffer contains a valid UTF-8 string. + * + * @param buffer the buffer to check. + * @return {@code true} if the given buffer contains a valid UTF-8 string. + */ + final int partialIsValidUtf8( + final int state, final ByteBuffer buffer, int index, final int limit) { + if (buffer.hasArray()) { + final int offset = buffer.arrayOffset(); + return partialIsValidUtf8(state, buffer.array(), offset + index, offset + limit); + } else if (buffer.isDirect()){ + return partialIsValidUtf8Direct(state, buffer, index, limit); + } + return partialIsValidUtf8Default(state, buffer, index, limit); + } + + /** + * Performs validation for direct {@link ByteBuffer} instances. + */ + abstract int partialIsValidUtf8Direct( + final int state, final ByteBuffer buffer, int index, final int limit); + + /** + * Performs validation for {@link ByteBuffer} instances using the {@link ByteBuffer} API rather + * than potentially faster approaches. This first completes validation for the current + * character (provided by {@code state}) and then finishes validation for the sequence. + */ + final int partialIsValidUtf8Default( + final int state, final ByteBuffer buffer, int index, final int limit) { + if (state != COMPLETE) { + // The previous decoding operation was incomplete (or malformed). + // We look for a well-formed sequence consisting of bytes from + // the previous decoding operation (stored in state) together + // with bytes from the array slice. + // + // We expect such "straddler characters" to be rare. + + if (index >= limit) { // No bytes? No progress. + return state; + } + + byte byte1 = (byte) state; + // byte1 is never ASCII. + if (byte1 < (byte) 0xE0) { + // two-byte form + + // Simultaneously checks for illegal trailing-byte in + // leading position and overlong 2-byte form. + if (byte1 < (byte) 0xC2 + // byte2 trailing-byte test + || buffer.get(index++) > (byte) 0xBF) { + return MALFORMED; + } + } else if (byte1 < (byte) 0xF0) { + // three-byte form + + // Get byte2 from saved state or array + byte byte2 = (byte) ~(state >> 8); + if (byte2 == 0) { + byte2 = buffer.get(index++); + if (index >= limit) { + return incompleteStateFor(byte1, byte2); + } + } + if (byte2 > (byte) 0xBF + // overlong? 5 most significant bits must not all be zero + || (byte1 == (byte) 0xE0 && byte2 < (byte) 0xA0) + // illegal surrogate codepoint? + || (byte1 == (byte) 0xED && byte2 >= (byte) 0xA0) + // byte3 trailing-byte test + || buffer.get(index++) > (byte) 0xBF) { + return MALFORMED; + } + } else { + // four-byte form + + // Get byte2 and byte3 from saved state or array + byte byte2 = (byte) ~(state >> 8); + byte byte3 = 0; + if (byte2 == 0) { + byte2 = buffer.get(index++); + if (index >= limit) { + return incompleteStateFor(byte1, byte2); + } + } else { + byte3 = (byte) (state >> 16); + } + if (byte3 == 0) { + byte3 = buffer.get(index++); + if (index >= limit) { + return incompleteStateFor(byte1, byte2, byte3); + } + } + + // If we were called with state == MALFORMED, then byte1 is 0xFF, + // which never occurs in well-formed UTF-8, and so we will return + // MALFORMED again below. + + if (byte2 > (byte) 0xBF + // Check that 1 <= plane <= 16. Tricky optimized form of: + // if (byte1 > (byte) 0xF4 || + // byte1 == (byte) 0xF0 && byte2 < (byte) 0x90 || + // byte1 == (byte) 0xF4 && byte2 > (byte) 0x8F) + || (((byte1 << 28) + (byte2 - (byte) 0x90)) >> 30) != 0 + // byte3 trailing-byte test + || byte3 > (byte) 0xBF + // byte4 trailing-byte test + || buffer.get(index++) > (byte) 0xBF) { + return MALFORMED; + } + } + } + + // Finish validation for the sequence. + return partialIsValidUtf8(buffer, index, limit); + } + + /** + * Performs validation for {@link ByteBuffer} instances using the {@link ByteBuffer} API rather + * than potentially faster approaches. + */ + private static int partialIsValidUtf8(final ByteBuffer buffer, int index, final int limit) { + index += estimateConsecutiveAscii(buffer, index, limit); + + for (;;) { + // Optimize for interior runs of ASCII bytes. + // TODO(nathanmittler): Consider checking 8 bytes at a time after some threshold? + // Maybe after seeing a few in a row that are ASCII, go back to fast mode? + int byte1; + do { + if (index >= limit) { + return COMPLETE; + } + } while ((byte1 = buffer.get(index++)) >= 0); + + // If we're here byte1 is not ASCII. Only need to handle 2-4 byte forms. + if (byte1 < (byte) 0xE0) { + // Two-byte form (110xxxxx 10xxxxxx) + if (index >= limit) { + // Incomplete sequence + return byte1; + } + + // Simultaneously checks for illegal trailing-byte in + // leading position and overlong 2-byte form. + if (byte1 < (byte) 0xC2 || buffer.get(index) > (byte) 0xBF) { + return MALFORMED; + } + index++; + } else if (byte1 < (byte) 0xF0) { + // Three-byte form (1110xxxx 10xxxxxx 10xxxxxx) + if (index >= limit - 1) { + // Incomplete sequence + return incompleteStateFor(buffer, byte1, index, limit - index); + } + + final byte byte2 = buffer.get(index++); + if (byte2 > (byte) 0xBF + // overlong? 5 most significant bits must not all be zero + || (byte1 == (byte) 0xE0 && byte2 < (byte) 0xA0) + // check for illegal surrogate codepoints + || (byte1 == (byte) 0xED && byte2 >= (byte) 0xA0) + // byte3 trailing-byte test + || buffer.get(index) > (byte) 0xBF) { + return MALFORMED; + } + index++; + } else { + // Four-byte form (1110xxxx 10xxxxxx 10xxxxxx 10xxxxxx) + if (index >= limit - 2) { + // Incomplete sequence + return incompleteStateFor(buffer, byte1, index, limit - index); + } + + // TODO(nathanmittler): Consider using getInt() to improve performance. + final int byte2 = buffer.get(index++); + if (byte2 > (byte) 0xBF + // Check that 1 <= plane <= 16. Tricky optimized form of: + // if (byte1 > (byte) 0xF4 || + // byte1 == (byte) 0xF0 && byte2 < (byte) 0x90 || + // byte1 == (byte) 0xF4 && byte2 > (byte) 0x8F) + || (((byte1 << 28) + (byte2 - (byte) 0x90)) >> 30) != 0 + // byte3 trailing-byte test + || buffer.get(index++) > (byte) 0xBF + // byte4 trailing-byte test + || buffer.get(index++) > (byte) 0xBF) { + return MALFORMED; + } + } + } + } + + /** + * Decodes the given byte array slice into a {@link String}. + * + * @throws InvalidProtocolBufferException if the byte array slice is not valid UTF-8. + */ + abstract String decodeUtf8(byte[] bytes, int index, int size) + throws InvalidProtocolBufferException; + + /** + * Decodes the given portion of the {@link ByteBuffer} into a {@link String}. + * + * @throws InvalidProtocolBufferException if the portion of the buffer is not valid UTF-8. + */ + final String decodeUtf8(ByteBuffer buffer, int index, int size) + throws InvalidProtocolBufferException { + if (buffer.hasArray()) { + final int offset = buffer.arrayOffset(); + return decodeUtf8(buffer.array(), offset + index, size); + } else if (buffer.isDirect()) { + return decodeUtf8Direct(buffer, index, size); + } + return decodeUtf8Default(buffer, index, size); + } + + /** + * Decodes direct {@link ByteBuffer} instances into {@link String}. + */ + abstract String decodeUtf8Direct(ByteBuffer buffer, int index, int size) + throws InvalidProtocolBufferException; + + /** + * Decodes {@link ByteBuffer} instances using the {@link ByteBuffer} API rather than + * potentially faster approaches. + */ + final String decodeUtf8Default(ByteBuffer buffer, int index, int size) + throws InvalidProtocolBufferException { + // Bitwise OR combines the sign bits so any negative value fails the check. + if ((index | size | buffer.limit() - index - size) < 0) { + throw new ArrayIndexOutOfBoundsException( + String.format("buffer limit=%d, index=%d, limit=%d", buffer.limit(), index, size)); + } + + int offset = index; + final int limit = offset + size; + + // The longest possible resulting String is the same as the number of input bytes, when it is + // all ASCII. For other cases, this over-allocates and we will truncate in the end. + char[] resultArr = new char[size]; + int resultPos = 0; + + // Optimize for 100% ASCII (Hotspot loves small simple top-level loops like this). + // This simple loop stops when we encounter a byte >= 0x80 (i.e. non-ASCII). + while (offset < limit) { + byte b = buffer.get(offset); + if (!DecodeUtil.isOneByte(b)) { + break; + } + offset++; + DecodeUtil.handleOneByte(b, resultArr, resultPos++); + } + + while (offset < limit) { + byte byte1 = buffer.get(offset++); + if (DecodeUtil.isOneByte(byte1)) { + DecodeUtil.handleOneByte(byte1, resultArr, resultPos++); + // It's common for there to be multiple ASCII characters in a run mixed in, so add an + // extra optimized loop to take care of these runs. + while (offset < limit) { + byte b = buffer.get(offset); + if (!DecodeUtil.isOneByte(b)) { + break; + } + offset++; + DecodeUtil.handleOneByte(b, resultArr, resultPos++); + } + } else if (DecodeUtil.isTwoBytes(byte1)) { + if (offset >= limit) { + throw InvalidProtocolBufferException.invalidUtf8(); + } + DecodeUtil.handleTwoBytes( + byte1, /* byte2 */ buffer.get(offset++), resultArr, resultPos++); + } else if (DecodeUtil.isThreeBytes(byte1)) { + if (offset >= limit - 1) { + throw InvalidProtocolBufferException.invalidUtf8(); + } + DecodeUtil.handleThreeBytes( + byte1, + /* byte2 */ buffer.get(offset++), + /* byte3 */ buffer.get(offset++), + resultArr, + resultPos++); + } else { + if (offset >= limit - 2) { + throw InvalidProtocolBufferException.invalidUtf8(); + } + DecodeUtil.handleFourBytes( + byte1, + /* byte2 */ buffer.get(offset++), + /* byte3 */ buffer.get(offset++), + /* byte4 */ buffer.get(offset++), + resultArr, + resultPos++); + // 4-byte case requires two chars. + resultPos++; + } + } + + return new String(resultArr, 0, resultPos); + } + + /** + * Encodes an input character sequence ({@code in}) to UTF-8 in the target array ({@code out}). + * For a string, this method is similar to + * <pre>{@code + * byte[] a = string.getBytes(UTF_8); + * System.arraycopy(a, 0, bytes, offset, a.length); + * return offset + a.length; + * }</pre> + * + * but is more efficient in both time and space. One key difference is that this method + * requires paired surrogates, and therefore does not support chunking. + * While {@code String.getBytes(UTF_8)} replaces unpaired surrogates with the default + * replacement character, this method throws {@link UnpairedSurrogateException}. + * + * <p>To ensure sufficient space in the output buffer, either call {@link #encodedLength} to + * compute the exact amount needed, or leave room for + * {@code Utf8.MAX_BYTES_PER_CHAR * sequence.length()}, which is the largest possible number + * of bytes that any input can be encoded to. + * + * @param in the input character sequence to be encoded + * @param out the target array + * @param offset the starting offset in {@code bytes} to start writing at + * @param length the length of the {@code bytes}, starting from {@code offset} + * @throws UnpairedSurrogateException if {@code sequence} contains ill-formed UTF-16 (unpaired + * surrogates) + * @throws ArrayIndexOutOfBoundsException if {@code sequence} encoded in UTF-8 is longer than + * {@code bytes.length - offset} + * @return the new offset, equivalent to {@code offset + Utf8.encodedLength(sequence)} + */ + abstract int encodeUtf8(CharSequence in, byte[] out, int offset, int length); + + /** + * Encodes an input character sequence ({@code in}) to UTF-8 in the target buffer ({@code out}). + * Upon returning from this method, the {@code out} position will point to the position after + * the last encoded byte. This method requires paired surrogates, and therefore does not + * support chunking. + * + * <p>To ensure sufficient space in the output buffer, either call {@link #encodedLength} to + * compute the exact amount needed, or leave room for + * {@code Utf8.MAX_BYTES_PER_CHAR * in.length()}, which is the largest possible number + * of bytes that any input can be encoded to. + * + * @param in the source character sequence to be encoded + * @param out the target buffer + * @throws UnpairedSurrogateException if {@code in} contains ill-formed UTF-16 (unpaired + * surrogates) + * @throws ArrayIndexOutOfBoundsException if {@code in} encoded in UTF-8 is longer than + * {@code out.remaining()} + */ + final void encodeUtf8(CharSequence in, ByteBuffer out) { + if (out.hasArray()) { + final int offset = out.arrayOffset(); + int endIndex = + Utf8.encode(in, out.array(), offset + out.position(), out.remaining()); + out.position(endIndex - offset); + } else if (out.isDirect()) { + encodeUtf8Direct(in, out); + } else { + encodeUtf8Default(in, out); + } + } + + /** + * Encodes the input character sequence to a direct {@link ByteBuffer} instance. + */ + abstract void encodeUtf8Direct(CharSequence in, ByteBuffer out); + + /** + * Encodes the input character sequence to a {@link ByteBuffer} instance using the {@link + * ByteBuffer} API, rather than potentially faster approaches. + */ + final void encodeUtf8Default(CharSequence in, ByteBuffer out) { + final int inLength = in.length(); + int outIx = out.position(); + int inIx = 0; + + // Since ByteBuffer.putXXX() already checks boundaries for us, no need to explicitly check + // access. Assume the buffer is big enough and let it handle the out of bounds exception + // if it occurs. + try { + // Designed to take advantage of + // https://wikis.oracle.com/display/HotSpotInternals/RangeCheckElimination + for (char c; inIx < inLength && (c = in.charAt(inIx)) < 0x80; ++inIx) { + out.put(outIx + inIx, (byte) c); + } + if (inIx == inLength) { + // Successfully encoded the entire string. + out.position(outIx + inIx); + return; + } + + outIx += inIx; + for (char c; inIx < inLength; ++inIx, ++outIx) { + c = in.charAt(inIx); + if (c < 0x80) { + // One byte (0xxx xxxx) + out.put(outIx, (byte) c); + } else if (c < 0x800) { + // Two bytes (110x xxxx 10xx xxxx) + + // Benchmarks show put performs better than putShort here (for HotSpot). + out.put(outIx++, (byte) (0xC0 | (c >>> 6))); + out.put(outIx, (byte) (0x80 | (0x3F & c))); + } else if (c < MIN_SURROGATE || MAX_SURROGATE < c) { + // Three bytes (1110 xxxx 10xx xxxx 10xx xxxx) + // Maximum single-char code point is 0xFFFF, 16 bits. + + // Benchmarks show put performs better than putShort here (for HotSpot). + out.put(outIx++, (byte) (0xE0 | (c >>> 12))); + out.put(outIx++, (byte) (0x80 | (0x3F & (c >>> 6)))); + out.put(outIx, (byte) (0x80 | (0x3F & c))); + } else { + // Four bytes (1111 xxxx 10xx xxxx 10xx xxxx 10xx xxxx) + + // Minimum code point represented by a surrogate pair is 0x10000, 17 bits, four UTF-8 + // bytes + final char low; + if (inIx + 1 == inLength || !isSurrogatePair(c, (low = in.charAt(++inIx)))) { + throw new UnpairedSurrogateException(inIx, inLength); + } + // TODO(nathanmittler): Consider using putInt() to improve performance. + int codePoint = toCodePoint(c, low); + out.put(outIx++, (byte) ((0xF << 4) | (codePoint >>> 18))); + out.put(outIx++, (byte) (0x80 | (0x3F & (codePoint >>> 12)))); + out.put(outIx++, (byte) (0x80 | (0x3F & (codePoint >>> 6)))); + out.put(outIx, (byte) (0x80 | (0x3F & codePoint))); + } + } + + // Successfully encoded the entire string. + out.position(outIx); + } catch (IndexOutOfBoundsException e) { + // TODO(nathanmittler): Consider making the API throw IndexOutOfBoundsException instead. + + // If we failed in the outer ASCII loop, outIx will not have been updated. In this case, + // use inIx to determine the bad write index. + int badWriteIndex = out.position() + Math.max(inIx, outIx - out.position() + 1); + throw new ArrayIndexOutOfBoundsException( + "Failed writing " + in.charAt(inIx) + " at index " + badWriteIndex); + } + } + } + + /** + * {@link Processor} implementation that does not use any {@code sun.misc.Unsafe} methods. + */ + static final class SafeProcessor extends Processor { + @Override + int partialIsValidUtf8(int state, byte[] bytes, int index, int limit) { + if (state != COMPLETE) { + // The previous decoding operation was incomplete (or malformed). + // We look for a well-formed sequence consisting of bytes from + // the previous decoding operation (stored in state) together + // with bytes from the array slice. + // + // We expect such "straddler characters" to be rare. + + if (index >= limit) { // No bytes? No progress. + return state; + } + int byte1 = (byte) state; + // byte1 is never ASCII. + if (byte1 < (byte) 0xE0) { + // two-byte form + + // Simultaneously checks for illegal trailing-byte in + // leading position and overlong 2-byte form. + if (byte1 < (byte) 0xC2 + // byte2 trailing-byte test + || bytes[index++] > (byte) 0xBF) { + return MALFORMED; + } + } else if (byte1 < (byte) 0xF0) { + // three-byte form + + // Get byte2 from saved state or array + int byte2 = (byte) ~(state >> 8); + if (byte2 == 0) { + byte2 = bytes[index++]; + if (index >= limit) { + return incompleteStateFor(byte1, byte2); + } + } + if (byte2 > (byte) 0xBF + // overlong? 5 most significant bits must not all be zero + || (byte1 == (byte) 0xE0 && byte2 < (byte) 0xA0) + // illegal surrogate codepoint? + || (byte1 == (byte) 0xED && byte2 >= (byte) 0xA0) + // byte3 trailing-byte test + || bytes[index++] > (byte) 0xBF) { + return MALFORMED; + } + } else { + // four-byte form + + // Get byte2 and byte3 from saved state or array + int byte2 = (byte) ~(state >> 8); + int byte3 = 0; + if (byte2 == 0) { + byte2 = bytes[index++]; + if (index >= limit) { + return incompleteStateFor(byte1, byte2); + } + } else { + byte3 = (byte) (state >> 16); + } + if (byte3 == 0) { + byte3 = bytes[index++]; + if (index >= limit) { + return incompleteStateFor(byte1, byte2, byte3); + } + } + + // If we were called with state == MALFORMED, then byte1 is 0xFF, + // which never occurs in well-formed UTF-8, and so we will return + // MALFORMED again below. + + if (byte2 > (byte) 0xBF + // Check that 1 <= plane <= 16. Tricky optimized form of: + // if (byte1 > (byte) 0xF4 || + // byte1 == (byte) 0xF0 && byte2 < (byte) 0x90 || + // byte1 == (byte) 0xF4 && byte2 > (byte) 0x8F) + || (((byte1 << 28) + (byte2 - (byte) 0x90)) >> 30) != 0 + // byte3 trailing-byte test + || byte3 > (byte) 0xBF + // byte4 trailing-byte test + || bytes[index++] > (byte) 0xBF) { + return MALFORMED; + } + } + } + + return partialIsValidUtf8(bytes, index, limit); + } + + @Override + int partialIsValidUtf8Direct(int state, ByteBuffer buffer, int index, int limit) { + // For safe processing, we have to use the ByteBuffer API. + return partialIsValidUtf8Default(state, buffer, index, limit); + } + + @Override + String decodeUtf8(byte[] bytes, int index, int size) throws InvalidProtocolBufferException { + // Bitwise OR combines the sign bits so any negative value fails the check. + if ((index | size | bytes.length - index - size) < 0) { + throw new ArrayIndexOutOfBoundsException( + String.format("buffer length=%d, index=%d, size=%d", bytes.length, index, size)); + } + + int offset = index; + final int limit = offset + size; + + // The longest possible resulting String is the same as the number of input bytes, when it is + // all ASCII. For other cases, this over-allocates and we will truncate in the end. + char[] resultArr = new char[size]; + int resultPos = 0; + + // Optimize for 100% ASCII (Hotspot loves small simple top-level loops like this). + // This simple loop stops when we encounter a byte >= 0x80 (i.e. non-ASCII). + while (offset < limit) { + byte b = bytes[offset]; + if (!DecodeUtil.isOneByte(b)) { + break; + } + offset++; + DecodeUtil.handleOneByte(b, resultArr, resultPos++); + } + + while (offset < limit) { + byte byte1 = bytes[offset++]; + if (DecodeUtil.isOneByte(byte1)) { + DecodeUtil.handleOneByte(byte1, resultArr, resultPos++); + // It's common for there to be multiple ASCII characters in a run mixed in, so add an + // extra optimized loop to take care of these runs. + while (offset < limit) { + byte b = bytes[offset]; + if (!DecodeUtil.isOneByte(b)) { + break; + } + offset++; + DecodeUtil.handleOneByte(b, resultArr, resultPos++); + } + } else if (DecodeUtil.isTwoBytes(byte1)) { + if (offset >= limit) { + throw InvalidProtocolBufferException.invalidUtf8(); + } + DecodeUtil.handleTwoBytes(byte1, /* byte2 */ bytes[offset++], resultArr, resultPos++); + } else if (DecodeUtil.isThreeBytes(byte1)) { + if (offset >= limit - 1) { + throw InvalidProtocolBufferException.invalidUtf8(); + } + DecodeUtil.handleThreeBytes( + byte1, + /* byte2 */ bytes[offset++], + /* byte3 */ bytes[offset++], + resultArr, + resultPos++); + } else { + if (offset >= limit - 2) { + throw InvalidProtocolBufferException.invalidUtf8(); + } + DecodeUtil.handleFourBytes( + byte1, + /* byte2 */ bytes[offset++], + /* byte3 */ bytes[offset++], + /* byte4 */ bytes[offset++], + resultArr, + resultPos++); + // 4-byte case requires two chars. + resultPos++; + } + } + + return new String(resultArr, 0, resultPos); + } + + @Override + String decodeUtf8Direct(ByteBuffer buffer, int index, int size) + throws InvalidProtocolBufferException { + // For safe processing, we have to use the ByteBufferAPI. + return decodeUtf8Default(buffer, index, size); + } + + @Override + int encodeUtf8(CharSequence in, byte[] out, int offset, int length) { + int utf16Length = in.length(); + int j = offset; + int i = 0; + int limit = offset + length; + // Designed to take advantage of + // https://wikis.oracle.com/display/HotSpotInternals/RangeCheckElimination + for (char c; i < utf16Length && i + j < limit && (c = in.charAt(i)) < 0x80; i++) { + out[j + i] = (byte) c; + } + if (i == utf16Length) { + return j + utf16Length; + } + j += i; + for (char c; i < utf16Length; i++) { + c = in.charAt(i); + if (c < 0x80 && j < limit) { + out[j++] = (byte) c; + } else if (c < 0x800 && j <= limit - 2) { // 11 bits, two UTF-8 bytes + out[j++] = (byte) ((0xF << 6) | (c >>> 6)); + out[j++] = (byte) (0x80 | (0x3F & c)); + } else if ((c < Character.MIN_SURROGATE || Character.MAX_SURROGATE < c) && j <= limit - 3) { + // Maximum single-char code point is 0xFFFF, 16 bits, three UTF-8 bytes + out[j++] = (byte) ((0xF << 5) | (c >>> 12)); + out[j++] = (byte) (0x80 | (0x3F & (c >>> 6))); + out[j++] = (byte) (0x80 | (0x3F & c)); + } else if (j <= limit - 4) { + // Minimum code point represented by a surrogate pair is 0x10000, 17 bits, + // four UTF-8 bytes + final char low; + if (i + 1 == in.length() + || !Character.isSurrogatePair(c, (low = in.charAt(++i)))) { + throw new UnpairedSurrogateException((i - 1), utf16Length); + } + int codePoint = Character.toCodePoint(c, low); + out[j++] = (byte) ((0xF << 4) | (codePoint >>> 18)); + out[j++] = (byte) (0x80 | (0x3F & (codePoint >>> 12))); + out[j++] = (byte) (0x80 | (0x3F & (codePoint >>> 6))); + out[j++] = (byte) (0x80 | (0x3F & codePoint)); + } else { + // If we are surrogates and we're not a surrogate pair, always throw an + // UnpairedSurrogateException instead of an ArrayOutOfBoundsException. + if ((Character.MIN_SURROGATE <= c && c <= Character.MAX_SURROGATE) + && (i + 1 == in.length() + || !Character.isSurrogatePair(c, in.charAt(i + 1)))) { + throw new UnpairedSurrogateException(i, utf16Length); + } + throw new ArrayIndexOutOfBoundsException("Failed writing " + c + " at index " + j); + } + } + return j; + } + + @Override + void encodeUtf8Direct(CharSequence in, ByteBuffer out) { + // For safe processing, we have to use the ByteBuffer API. + encodeUtf8Default(in, out); + } + + private static int partialIsValidUtf8(byte[] bytes, int index, int limit) { + // Optimize for 100% ASCII (Hotspot loves small simple top-level loops like this). + // This simple loop stops when we encounter a byte >= 0x80 (i.e. non-ASCII). + while (index < limit && bytes[index] >= 0) { + index++; + } + + return (index >= limit) ? COMPLETE : partialIsValidUtf8NonAscii(bytes, index, limit); + } + + private static int partialIsValidUtf8NonAscii(byte[] bytes, int index, int limit) { + for (;;) { + int byte1, byte2; + + // Optimize for interior runs of ASCII bytes. + do { + if (index >= limit) { + return COMPLETE; + } + } while ((byte1 = bytes[index++]) >= 0); + + if (byte1 < (byte) 0xE0) { + // two-byte form + + if (index >= limit) { + // Incomplete sequence + return byte1; + } + + // Simultaneously checks for illegal trailing-byte in + // leading position and overlong 2-byte form. + if (byte1 < (byte) 0xC2 + || bytes[index++] > (byte) 0xBF) { + return MALFORMED; + } + } else if (byte1 < (byte) 0xF0) { + // three-byte form + + if (index >= limit - 1) { // incomplete sequence + return incompleteStateFor(bytes, index, limit); + } + if ((byte2 = bytes[index++]) > (byte) 0xBF + // overlong? 5 most significant bits must not all be zero + || (byte1 == (byte) 0xE0 && byte2 < (byte) 0xA0) + // check for illegal surrogate codepoints + || (byte1 == (byte) 0xED && byte2 >= (byte) 0xA0) + // byte3 trailing-byte test + || bytes[index++] > (byte) 0xBF) { + return MALFORMED; + } + } else { + // four-byte form + + if (index >= limit - 2) { // incomplete sequence + return incompleteStateFor(bytes, index, limit); + } + if ((byte2 = bytes[index++]) > (byte) 0xBF + // Check that 1 <= plane <= 16. Tricky optimized form of: + // if (byte1 > (byte) 0xF4 || + // byte1 == (byte) 0xF0 && byte2 < (byte) 0x90 || + // byte1 == (byte) 0xF4 && byte2 > (byte) 0x8F) + || (((byte1 << 28) + (byte2 - (byte) 0x90)) >> 30) != 0 + // byte3 trailing-byte test + || bytes[index++] > (byte) 0xBF + // byte4 trailing-byte test + || bytes[index++] > (byte) 0xBF) { + return MALFORMED; + } + } + } + } + } + + /** + * {@link Processor} that uses {@code sun.misc.Unsafe} where possible to improve performance. + */ + static final class UnsafeProcessor extends Processor { + /** + * Indicates whether or not all required unsafe operations are supported on this platform. + */ + static boolean isAvailable() { + return hasUnsafeArrayOperations() && hasUnsafeByteBufferOperations(); + } + + @Override + int partialIsValidUtf8(int state, byte[] bytes, final int index, final int limit) { + // Bitwise OR combines the sign bits so any negative value fails the check. + if ((index | limit | bytes.length - limit) < 0) { + throw new ArrayIndexOutOfBoundsException( + String.format("Array length=%d, index=%d, limit=%d", bytes.length, index, limit)); + } + long offset = index; + final long offsetLimit = limit; + if (state != COMPLETE) { + // The previous decoding operation was incomplete (or malformed). + // We look for a well-formed sequence consisting of bytes from + // the previous decoding operation (stored in state) together + // with bytes from the array slice. + // + // We expect such "straddler characters" to be rare. + + if (offset >= offsetLimit) { // No bytes? No progress. + return state; + } + int byte1 = (byte) state; + // byte1 is never ASCII. + if (byte1 < (byte) 0xE0) { + // two-byte form + + // Simultaneously checks for illegal trailing-byte in + // leading position and overlong 2-byte form. + if (byte1 < (byte) 0xC2 + // byte2 trailing-byte test + || UnsafeUtil.getByte(bytes, offset++) > (byte) 0xBF) { + return MALFORMED; + } + } else if (byte1 < (byte) 0xF0) { + // three-byte form + + // Get byte2 from saved state or array + int byte2 = (byte) ~(state >> 8); + if (byte2 == 0) { + byte2 = UnsafeUtil.getByte(bytes, offset++); + if (offset >= offsetLimit) { + return incompleteStateFor(byte1, byte2); + } + } + if (byte2 > (byte) 0xBF + // overlong? 5 most significant bits must not all be zero + || (byte1 == (byte) 0xE0 && byte2 < (byte) 0xA0) + // illegal surrogate codepoint? + || (byte1 == (byte) 0xED && byte2 >= (byte) 0xA0) + // byte3 trailing-byte test + || UnsafeUtil.getByte(bytes, offset++) > (byte) 0xBF) { + return MALFORMED; + } + } else { + // four-byte form + + // Get byte2 and byte3 from saved state or array + int byte2 = (byte) ~(state >> 8); + int byte3 = 0; + if (byte2 == 0) { + byte2 = UnsafeUtil.getByte(bytes, offset++); + if (offset >= offsetLimit) { + return incompleteStateFor(byte1, byte2); + } + } else { + byte3 = (byte) (state >> 16); + } + if (byte3 == 0) { + byte3 = UnsafeUtil.getByte(bytes, offset++); + if (offset >= offsetLimit) { + return incompleteStateFor(byte1, byte2, byte3); + } + } + + // If we were called with state == MALFORMED, then byte1 is 0xFF, + // which never occurs in well-formed UTF-8, and so we will return + // MALFORMED again below. + + if (byte2 > (byte) 0xBF + // Check that 1 <= plane <= 16. Tricky optimized form of: + // if (byte1 > (byte) 0xF4 || + // byte1 == (byte) 0xF0 && byte2 < (byte) 0x90 || + // byte1 == (byte) 0xF4 && byte2 > (byte) 0x8F) + || (((byte1 << 28) + (byte2 - (byte) 0x90)) >> 30) != 0 + // byte3 trailing-byte test + || byte3 > (byte) 0xBF + // byte4 trailing-byte test + || UnsafeUtil.getByte(bytes, offset++) > (byte) 0xBF) { + return MALFORMED; + } + } + } + + return partialIsValidUtf8(bytes, offset, (int) (offsetLimit - offset)); + } + + @Override + int partialIsValidUtf8Direct( + final int state, ByteBuffer buffer, final int index, final int limit) { + // Bitwise OR combines the sign bits so any negative value fails the check. + if ((index | limit | buffer.limit() - limit) < 0) { + throw new ArrayIndexOutOfBoundsException( + String.format("buffer limit=%d, index=%d, limit=%d", buffer.limit(), index, limit)); + } + long address = addressOffset(buffer) + index; + final long addressLimit = address + (limit - index); + if (state != COMPLETE) { + // The previous decoding operation was incomplete (or malformed). + // We look for a well-formed sequence consisting of bytes from + // the previous decoding operation (stored in state) together + // with bytes from the array slice. + // + // We expect such "straddler characters" to be rare. + + if (address >= addressLimit) { // No bytes? No progress. + return state; + } + + final int byte1 = (byte) state; + // byte1 is never ASCII. + if (byte1 < (byte) 0xE0) { + // two-byte form + + // Simultaneously checks for illegal trailing-byte in + // leading position and overlong 2-byte form. + if (byte1 < (byte) 0xC2 + // byte2 trailing-byte test + || UnsafeUtil.getByte(address++) > (byte) 0xBF) { + return MALFORMED; + } + } else if (byte1 < (byte) 0xF0) { + // three-byte form + + // Get byte2 from saved state or array + int byte2 = (byte) ~(state >> 8); + if (byte2 == 0) { + byte2 = UnsafeUtil.getByte(address++); + if (address >= addressLimit) { + return incompleteStateFor(byte1, byte2); + } + } + if (byte2 > (byte) 0xBF + // overlong? 5 most significant bits must not all be zero + || (byte1 == (byte) 0xE0 && byte2 < (byte) 0xA0) + // illegal surrogate codepoint? + || (byte1 == (byte) 0xED && byte2 >= (byte) 0xA0) + // byte3 trailing-byte test + || UnsafeUtil.getByte(address++) > (byte) 0xBF) { + return MALFORMED; + } + } else { + // four-byte form + + // Get byte2 and byte3 from saved state or array + int byte2 = (byte) ~(state >> 8); + int byte3 = 0; + if (byte2 == 0) { + byte2 = UnsafeUtil.getByte(address++); + if (address >= addressLimit) { + return incompleteStateFor(byte1, byte2); + } + } else { + byte3 = (byte) (state >> 16); + } + if (byte3 == 0) { + byte3 = UnsafeUtil.getByte(address++); + if (address >= addressLimit) { + return incompleteStateFor(byte1, byte2, byte3); + } + } + + // If we were called with state == MALFORMED, then byte1 is 0xFF, + // which never occurs in well-formed UTF-8, and so we will return + // MALFORMED again below. + + if (byte2 > (byte) 0xBF + // Check that 1 <= plane <= 16. Tricky optimized form of: + // if (byte1 > (byte) 0xF4 || + // byte1 == (byte) 0xF0 && byte2 < (byte) 0x90 || + // byte1 == (byte) 0xF4 && byte2 > (byte) 0x8F) + || (((byte1 << 28) + (byte2 - (byte) 0x90)) >> 30) != 0 + // byte3 trailing-byte test + || byte3 > (byte) 0xBF + // byte4 trailing-byte test + || UnsafeUtil.getByte(address++) > (byte) 0xBF) { + return MALFORMED; + } + } + } + + return partialIsValidUtf8(address, (int) (addressLimit - address)); + } + + @Override + String decodeUtf8(byte[] bytes, int index, int size) throws InvalidProtocolBufferException { + if ((index | size | bytes.length - index - size) < 0) { + throw new ArrayIndexOutOfBoundsException( + String.format("buffer length=%d, index=%d, size=%d", bytes.length, index, size)); + } + + int offset = index; + final int limit = offset + size; + + // The longest possible resulting String is the same as the number of input bytes, when it is + // all ASCII. For other cases, this over-allocates and we will truncate in the end. + char[] resultArr = new char[size]; + int resultPos = 0; + + // Optimize for 100% ASCII (Hotspot loves small simple top-level loops like this). + // This simple loop stops when we encounter a byte >= 0x80 (i.e. non-ASCII). + while (offset < limit) { + byte b = UnsafeUtil.getByte(bytes, offset); + if (!DecodeUtil.isOneByte(b)) { + break; + } + offset++; + DecodeUtil.handleOneByte(b, resultArr, resultPos++); + } + + while (offset < limit) { + byte byte1 = UnsafeUtil.getByte(bytes, offset++); + if (DecodeUtil.isOneByte(byte1)) { + DecodeUtil.handleOneByte(byte1, resultArr, resultPos++); + // It's common for there to be multiple ASCII characters in a run mixed in, so add an + // extra optimized loop to take care of these runs. + while (offset < limit) { + byte b = UnsafeUtil.getByte(bytes, offset); + if (!DecodeUtil.isOneByte(b)) { + break; + } + offset++; + DecodeUtil.handleOneByte(b, resultArr, resultPos++); + } + } else if (DecodeUtil.isTwoBytes(byte1)) { + if (offset >= limit) { + throw InvalidProtocolBufferException.invalidUtf8(); + } + DecodeUtil.handleTwoBytes( + byte1, /* byte2 */ UnsafeUtil.getByte(bytes, offset++), resultArr, resultPos++); + } else if (DecodeUtil.isThreeBytes(byte1)) { + if (offset >= limit - 1) { + throw InvalidProtocolBufferException.invalidUtf8(); + } + DecodeUtil.handleThreeBytes( + byte1, + /* byte2 */ UnsafeUtil.getByte(bytes, offset++), + /* byte3 */ UnsafeUtil.getByte(bytes, offset++), + resultArr, + resultPos++); + } else { + if (offset >= limit - 2) { + throw InvalidProtocolBufferException.invalidUtf8(); + } + DecodeUtil.handleFourBytes( + byte1, + /* byte2 */ UnsafeUtil.getByte(bytes, offset++), + /* byte3 */ UnsafeUtil.getByte(bytes, offset++), + /* byte4 */ UnsafeUtil.getByte(bytes, offset++), + resultArr, + resultPos++); + // 4-byte case requires two chars. + resultPos++; + } + } + + if (resultPos < resultArr.length) { + resultArr = Arrays.copyOf(resultArr, resultPos); + } + return UnsafeUtil.moveToString(resultArr); + } + + @Override + String decodeUtf8Direct(ByteBuffer buffer, int index, int size) + throws InvalidProtocolBufferException { + // Bitwise OR combines the sign bits so any negative value fails the check. + if ((index | size | buffer.limit() - index - size) < 0) { + throw new ArrayIndexOutOfBoundsException( + String.format("buffer limit=%d, index=%d, limit=%d", buffer.limit(), index, size)); + } + long address = UnsafeUtil.addressOffset(buffer) + index; + final long addressLimit = address + size; + + // The longest possible resulting String is the same as the number of input bytes, when it is + // all ASCII. For other cases, this over-allocates and we will truncate in the end. + char[] resultArr = new char[size]; + int resultPos = 0; + + // Optimize for 100% ASCII (Hotspot loves small simple top-level loops like this). + // This simple loop stops when we encounter a byte >= 0x80 (i.e. non-ASCII). + while (address < addressLimit) { + byte b = UnsafeUtil.getByte(address); + if (!DecodeUtil.isOneByte(b)) { + break; + } + address++; + DecodeUtil.handleOneByte(b, resultArr, resultPos++); + } + + while (address < addressLimit) { + byte byte1 = UnsafeUtil.getByte(address++); + if (DecodeUtil.isOneByte(byte1)) { + DecodeUtil.handleOneByte(byte1, resultArr, resultPos++); + // It's common for there to be multiple ASCII characters in a run mixed in, so add an + // extra optimized loop to take care of these runs. + while (address < addressLimit) { + byte b = UnsafeUtil.getByte(address); + if (!DecodeUtil.isOneByte(b)) { + break; + } + address++; + DecodeUtil.handleOneByte(b, resultArr, resultPos++); + } + } else if (DecodeUtil.isTwoBytes(byte1)) { + if (address >= addressLimit) { + throw InvalidProtocolBufferException.invalidUtf8(); + } + DecodeUtil.handleTwoBytes( + byte1, /* byte2 */ UnsafeUtil.getByte(address++), resultArr, resultPos++); + } else if (DecodeUtil.isThreeBytes(byte1)) { + if (address >= addressLimit - 1) { + throw InvalidProtocolBufferException.invalidUtf8(); + } + DecodeUtil.handleThreeBytes( + byte1, + /* byte2 */ UnsafeUtil.getByte(address++), + /* byte3 */ UnsafeUtil.getByte(address++), + resultArr, + resultPos++); + } else { + if (address >= addressLimit - 2) { + throw InvalidProtocolBufferException.invalidUtf8(); + } + DecodeUtil.handleFourBytes( + byte1, + /* byte2 */ UnsafeUtil.getByte(address++), + /* byte3 */ UnsafeUtil.getByte(address++), + /* byte4 */ UnsafeUtil.getByte(address++), + resultArr, + resultPos++); + // 4-byte case requires two chars. + resultPos++; + } + } + + if (resultPos < resultArr.length) { + resultArr = Arrays.copyOf(resultArr, resultPos); + } + return UnsafeUtil.moveToString(resultArr); + } + + @Override + int encodeUtf8(final CharSequence in, final byte[] out, final int offset, final int length) { + long outIx = offset; + final long outLimit = outIx + length; + final int inLimit = in.length(); + if (inLimit > length || out.length - length < offset) { + // Not even enough room for an ASCII-encoded string. + throw new ArrayIndexOutOfBoundsException( + "Failed writing " + in.charAt(inLimit - 1) + " at index " + (offset + length)); + } + + // Designed to take advantage of + // https://wikis.oracle.com/display/HotSpotInternals/RangeCheckElimination + int inIx = 0; + for (char c; inIx < inLimit && (c = in.charAt(inIx)) < 0x80; ++inIx) { + UnsafeUtil.putByte(out, outIx++, (byte) c); + } + if (inIx == inLimit) { + // We're done, it was ASCII encoded. + return (int) outIx; + } + + for (char c; inIx < inLimit; ++inIx) { + c = in.charAt(inIx); + if (c < 0x80 && outIx < outLimit) { + UnsafeUtil.putByte(out, outIx++, (byte) c); + } else if (c < 0x800 && outIx <= outLimit - 2L) { // 11 bits, two UTF-8 bytes + UnsafeUtil.putByte(out, outIx++, (byte) ((0xF << 6) | (c >>> 6))); + UnsafeUtil.putByte(out, outIx++, (byte) (0x80 | (0x3F & c))); + } else if ((c < MIN_SURROGATE || MAX_SURROGATE < c) && outIx <= outLimit - 3L) { + // Maximum single-char code point is 0xFFFF, 16 bits, three UTF-8 bytes + UnsafeUtil.putByte(out, outIx++, (byte) ((0xF << 5) | (c >>> 12))); + UnsafeUtil.putByte(out, outIx++, (byte) (0x80 | (0x3F & (c >>> 6)))); + UnsafeUtil.putByte(out, outIx++, (byte) (0x80 | (0x3F & c))); + } else if (outIx <= outLimit - 4L) { + // Minimum code point represented by a surrogate pair is 0x10000, 17 bits, four UTF-8 + // bytes + final char low; + if (inIx + 1 == inLimit || !isSurrogatePair(c, (low = in.charAt(++inIx)))) { + throw new UnpairedSurrogateException((inIx - 1), inLimit); + } + int codePoint = toCodePoint(c, low); + UnsafeUtil.putByte(out, outIx++, (byte) ((0xF << 4) | (codePoint >>> 18))); + UnsafeUtil.putByte(out, outIx++, (byte) (0x80 | (0x3F & (codePoint >>> 12)))); + UnsafeUtil.putByte(out, outIx++, (byte) (0x80 | (0x3F & (codePoint >>> 6)))); + UnsafeUtil.putByte(out, outIx++, (byte) (0x80 | (0x3F & codePoint))); + } else { + if ((MIN_SURROGATE <= c && c <= MAX_SURROGATE) + && (inIx + 1 == inLimit || !isSurrogatePair(c, in.charAt(inIx + 1)))) { + // We are surrogates and we're not a surrogate pair. + throw new UnpairedSurrogateException(inIx, inLimit); + } + // Not enough space in the output buffer. + throw new ArrayIndexOutOfBoundsException("Failed writing " + c + " at index " + outIx); + } + } + + // All bytes have been encoded. + return (int) outIx; + } + + @Override + void encodeUtf8Direct(CharSequence in, ByteBuffer out) { + final long address = addressOffset(out); + long outIx = address + out.position(); + final long outLimit = address + out.limit(); + final int inLimit = in.length(); + if (inLimit > outLimit - outIx) { + // Not even enough room for an ASCII-encoded string. + throw new ArrayIndexOutOfBoundsException( + "Failed writing " + in.charAt(inLimit - 1) + " at index " + out.limit()); + } + + // Designed to take advantage of + // https://wikis.oracle.com/display/HotSpotInternals/RangeCheckElimination + int inIx = 0; + for (char c; inIx < inLimit && (c = in.charAt(inIx)) < 0x80; ++inIx) { + UnsafeUtil.putByte(outIx++, (byte) c); + } + if (inIx == inLimit) { + // We're done, it was ASCII encoded. + out.position((int) (outIx - address)); + return; + } + + for (char c; inIx < inLimit; ++inIx) { + c = in.charAt(inIx); + if (c < 0x80 && outIx < outLimit) { + UnsafeUtil.putByte(outIx++, (byte) c); + } else if (c < 0x800 && outIx <= outLimit - 2L) { // 11 bits, two UTF-8 bytes + UnsafeUtil.putByte(outIx++, (byte) ((0xF << 6) | (c >>> 6))); + UnsafeUtil.putByte(outIx++, (byte) (0x80 | (0x3F & c))); + } else if ((c < MIN_SURROGATE || MAX_SURROGATE < c) && outIx <= outLimit - 3L) { + // Maximum single-char code point is 0xFFFF, 16 bits, three UTF-8 bytes + UnsafeUtil.putByte(outIx++, (byte) ((0xF << 5) | (c >>> 12))); + UnsafeUtil.putByte(outIx++, (byte) (0x80 | (0x3F & (c >>> 6)))); + UnsafeUtil.putByte(outIx++, (byte) (0x80 | (0x3F & c))); + } else if (outIx <= outLimit - 4L) { + // Minimum code point represented by a surrogate pair is 0x10000, 17 bits, four UTF-8 + // bytes + final char low; + if (inIx + 1 == inLimit || !isSurrogatePair(c, (low = in.charAt(++inIx)))) { + throw new UnpairedSurrogateException((inIx - 1), inLimit); + } + int codePoint = toCodePoint(c, low); + UnsafeUtil.putByte(outIx++, (byte) ((0xF << 4) | (codePoint >>> 18))); + UnsafeUtil.putByte(outIx++, (byte) (0x80 | (0x3F & (codePoint >>> 12)))); + UnsafeUtil.putByte(outIx++, (byte) (0x80 | (0x3F & (codePoint >>> 6)))); + UnsafeUtil.putByte(outIx++, (byte) (0x80 | (0x3F & codePoint))); + } else { + if ((MIN_SURROGATE <= c && c <= MAX_SURROGATE) + && (inIx + 1 == inLimit || !isSurrogatePair(c, in.charAt(inIx + 1)))) { + // We are surrogates and we're not a surrogate pair. + throw new UnpairedSurrogateException(inIx, inLimit); + } + // Not enough space in the output buffer. + throw new ArrayIndexOutOfBoundsException("Failed writing " + c + " at index " + outIx); + } + } + + // All bytes have been encoded. + out.position((int) (outIx - address)); + } + + /** + * Counts (approximately) the number of consecutive ASCII characters starting from the given + * position, using the most efficient method available to the platform. + * + * @param bytes the array containing the character sequence + * @param offset the offset position of the index (same as index + arrayBaseOffset) + * @param maxChars the maximum number of characters to count + * @return the number of ASCII characters found. The stopping position will be at or + * before the first non-ASCII byte. + */ + private static int unsafeEstimateConsecutiveAscii( + byte[] bytes, long offset, final int maxChars) { + if (maxChars < UNSAFE_COUNT_ASCII_THRESHOLD) { + // Don't bother with small strings. + return 0; + } + + for (int i = 0; i < maxChars; i++) { + if (UnsafeUtil.getByte(bytes, offset++) < 0) { + return i; + } + } + return maxChars; + } + + /** + * Same as {@link Utf8#estimateConsecutiveAscii(ByteBuffer, int, int)} except that it uses the + * most efficient method available to the platform. + */ + private static int unsafeEstimateConsecutiveAscii(long address, final int maxChars) { + int remaining = maxChars; + if (remaining < UNSAFE_COUNT_ASCII_THRESHOLD) { + // Don't bother with small strings. + return 0; + } + + // Read bytes until 8-byte aligned so that we can read longs in the loop below. + // We do this by ANDing the address with 7 to determine the number of bytes that need to + // be read before we're 8-byte aligned. + final int unaligned = 8 - ((int) address & 7); + for (int j = unaligned; j > 0; j--) { + if (UnsafeUtil.getByte(address++) < 0) { + return unaligned - j; + } + } + + // This simple loop stops when we encounter a byte >= 0x80 (i.e. non-ASCII). + // To speed things up further, we're reading longs instead of bytes so we use a mask to + // determine if any byte in the current long is non-ASCII. + remaining -= unaligned; + for (; remaining >= 8 && (UnsafeUtil.getLong(address) & ASCII_MASK_LONG) == 0; + address += 8, remaining -= 8) {} + return maxChars - remaining; + } + + private static int partialIsValidUtf8(final byte[] bytes, long offset, int remaining) { + // Skip past ASCII characters as quickly as possible. + final int skipped = unsafeEstimateConsecutiveAscii(bytes, offset, remaining); + remaining -= skipped; + offset += skipped; + + for (;;) { + // Optimize for interior runs of ASCII bytes. + // TODO(nathanmittler): Consider checking 8 bytes at a time after some threshold? + // Maybe after seeing a few in a row that are ASCII, go back to fast mode? + int byte1 = 0; + for (; remaining > 0 && (byte1 = UnsafeUtil.getByte(bytes, offset++)) >= 0; --remaining) { + } + if (remaining == 0) { + return COMPLETE; + } + remaining--; + + // If we're here byte1 is not ASCII. Only need to handle 2-4 byte forms. + if (byte1 < (byte) 0xE0) { + // Two-byte form (110xxxxx 10xxxxxx) + if (remaining == 0) { + // Incomplete sequence + return byte1; + } + remaining--; + + // Simultaneously checks for illegal trailing-byte in + // leading position and overlong 2-byte form. + if (byte1 < (byte) 0xC2 + || UnsafeUtil.getByte(bytes, offset++) > (byte) 0xBF) { + return MALFORMED; + } + } else if (byte1 < (byte) 0xF0) { + // Three-byte form (1110xxxx 10xxxxxx 10xxxxxx) + if (remaining < 2) { + // Incomplete sequence + return unsafeIncompleteStateFor(bytes, byte1, offset, remaining); + } + remaining -= 2; + + final int byte2; + if ((byte2 = UnsafeUtil.getByte(bytes, offset++)) > (byte) 0xBF + // overlong? 5 most significant bits must not all be zero + || (byte1 == (byte) 0xE0 && byte2 < (byte) 0xA0) + // check for illegal surrogate codepoints + || (byte1 == (byte) 0xED && byte2 >= (byte) 0xA0) + // byte3 trailing-byte test + || UnsafeUtil.getByte(bytes, offset++) > (byte) 0xBF) { + return MALFORMED; + } + } else { + // Four-byte form (1110xxxx 10xxxxxx 10xxxxxx 10xxxxxx) + if (remaining < 3) { + // Incomplete sequence + return unsafeIncompleteStateFor(bytes, byte1, offset, remaining); + } + remaining -= 3; + + final int byte2; + if ((byte2 = UnsafeUtil.getByte(bytes, offset++)) > (byte) 0xBF + // Check that 1 <= plane <= 16. Tricky optimized form of: + // if (byte1 > (byte) 0xF4 || + // byte1 == (byte) 0xF0 && byte2 < (byte) 0x90 || + // byte1 == (byte) 0xF4 && byte2 > (byte) 0x8F) + || (((byte1 << 28) + (byte2 - (byte) 0x90)) >> 30) != 0 + // byte3 trailing-byte test + || UnsafeUtil.getByte(bytes, offset++) > (byte) 0xBF + // byte4 trailing-byte test + || UnsafeUtil.getByte(bytes, offset++) > (byte) 0xBF) { + return MALFORMED; + } + } + } + } + + private static int partialIsValidUtf8(long address, int remaining) { + // Skip past ASCII characters as quickly as possible. + final int skipped = unsafeEstimateConsecutiveAscii(address, remaining); + address += skipped; + remaining -= skipped; + + for (;;) { + // Optimize for interior runs of ASCII bytes. + // TODO(nathanmittler): Consider checking 8 bytes at a time after some threshold? + // Maybe after seeing a few in a row that are ASCII, go back to fast mode? + int byte1 = 0; + for (; remaining > 0 && (byte1 = UnsafeUtil.getByte(address++)) >= 0; --remaining) { + } + if (remaining == 0) { + return COMPLETE; + } + remaining--; + + if (byte1 < (byte) 0xE0) { + // Two-byte form + + if (remaining == 0) { + // Incomplete sequence + return byte1; + } + remaining--; + + // Simultaneously checks for illegal trailing-byte in + // leading position and overlong 2-byte form. + if (byte1 < (byte) 0xC2 || UnsafeUtil.getByte(address++) > (byte) 0xBF) { + return MALFORMED; + } + } else if (byte1 < (byte) 0xF0) { + // Three-byte form + + if (remaining < 2) { + // Incomplete sequence + return unsafeIncompleteStateFor(address, byte1, remaining); + } + remaining -= 2; + + final byte byte2 = UnsafeUtil.getByte(address++); + if (byte2 > (byte) 0xBF + // overlong? 5 most significant bits must not all be zero + || (byte1 == (byte) 0xE0 && byte2 < (byte) 0xA0) + // check for illegal surrogate codepoints + || (byte1 == (byte) 0xED && byte2 >= (byte) 0xA0) + // byte3 trailing-byte test + || UnsafeUtil.getByte(address++) > (byte) 0xBF) { + return MALFORMED; + } + } else { + // Four-byte form + + if (remaining < 3) { + // Incomplete sequence + return unsafeIncompleteStateFor(address, byte1, remaining); + } + remaining -= 3; + + final byte byte2 = UnsafeUtil.getByte(address++); + if (byte2 > (byte) 0xBF + // Check that 1 <= plane <= 16. Tricky optimized form of: + // if (byte1 > (byte) 0xF4 || + // byte1 == (byte) 0xF0 && byte2 < (byte) 0x90 || + // byte1 == (byte) 0xF4 && byte2 > (byte) 0x8F) + || (((byte1 << 28) + (byte2 - (byte) 0x90)) >> 30) != 0 + // byte3 trailing-byte test + || UnsafeUtil.getByte(address++) > (byte) 0xBF + // byte4 trailing-byte test + || UnsafeUtil.getByte(address++) > (byte) 0xBF) { + return MALFORMED; + } + } + } + } + + private static int unsafeIncompleteStateFor(byte[] bytes, int byte1, long offset, + int remaining) { + switch (remaining) { + case 0: { + return incompleteStateFor(byte1); + } + case 1: { + return incompleteStateFor(byte1, UnsafeUtil.getByte(bytes, offset)); + } + case 2: { + return incompleteStateFor(byte1, UnsafeUtil.getByte(bytes, offset), + UnsafeUtil.getByte(bytes, offset + 1)); + } + default: { + throw new AssertionError(); + } + } + } + + private static int unsafeIncompleteStateFor(long address, final int byte1, int remaining) { + switch (remaining) { + case 0: { + return incompleteStateFor(byte1); + } + case 1: { + return incompleteStateFor(byte1, UnsafeUtil.getByte(address)); + } + case 2: { + return incompleteStateFor(byte1, UnsafeUtil.getByte(address), + UnsafeUtil.getByte(address + 1)); + } + default: { + throw new AssertionError(); + } + } + } + } + + /** + * Utility methods for decoding bytes into {@link String}. Callers are responsible for extracting + * bytes (possibly using Unsafe methods), and checking remaining bytes. All other UTF-8 validity + * checks and codepoint conversion happen in this class. + */ + private static class DecodeUtil { + + /** + * Returns whether this is a single-byte codepoint (i.e., ASCII) with the form '0XXXXXXX'. + */ + private static boolean isOneByte(byte b) { + return b >= 0; + } + + /** + * Returns whether this is a two-byte codepoint with the form '10XXXXXX'. + */ + private static boolean isTwoBytes(byte b) { + return b < (byte) 0xE0; + } + + /** + * Returns whether this is a three-byte codepoint with the form '110XXXXX'. + */ + private static boolean isThreeBytes(byte b) { + return b < (byte) 0xF0; + } + + private static void handleOneByte(byte byte1, char[] resultArr, int resultPos) { + resultArr[resultPos] = (char) byte1; + } + + private static void handleTwoBytes( + byte byte1, byte byte2, char[] resultArr, int resultPos) + throws InvalidProtocolBufferException { + // Simultaneously checks for illegal trailing-byte in leading position (<= '11000000') and + // overlong 2-byte, '11000001'. + if (byte1 < (byte) 0xC2 + || isNotTrailingByte(byte2)) { + throw InvalidProtocolBufferException.invalidUtf8(); + } + resultArr[resultPos] = (char) (((byte1 & 0x1F) << 6) | trailingByteValue(byte2)); + } + + private static void handleThreeBytes( + byte byte1, byte byte2, byte byte3, char[] resultArr, int resultPos) + throws InvalidProtocolBufferException { + if (isNotTrailingByte(byte2) + // overlong? 5 most significant bits must not all be zero + || (byte1 == (byte) 0xE0 && byte2 < (byte) 0xA0) + // check for illegal surrogate codepoints + || (byte1 == (byte) 0xED && byte2 >= (byte) 0xA0) + || isNotTrailingByte(byte3)) { + throw InvalidProtocolBufferException.invalidUtf8(); + } + resultArr[resultPos] = (char) + (((byte1 & 0x0F) << 12) | (trailingByteValue(byte2) << 6) | trailingByteValue(byte3)); + } + + private static void handleFourBytes( + byte byte1, byte byte2, byte byte3, byte byte4, char[] resultArr, int resultPos) + throws InvalidProtocolBufferException{ + if (isNotTrailingByte(byte2) + // Check that 1 <= plane <= 16. Tricky optimized form of: + // valid 4-byte leading byte? + // if (byte1 > (byte) 0xF4 || + // overlong? 4 most significant bits must not all be zero + // byte1 == (byte) 0xF0 && byte2 < (byte) 0x90 || + // codepoint larger than the highest code point (U+10FFFF)? + // byte1 == (byte) 0xF4 && byte2 > (byte) 0x8F) + || (((byte1 << 28) + (byte2 - (byte) 0x90)) >> 30) != 0 + || isNotTrailingByte(byte3) + || isNotTrailingByte(byte4)) { + throw InvalidProtocolBufferException.invalidUtf8(); + } + int codepoint = ((byte1 & 0x07) << 18) + | (trailingByteValue(byte2) << 12) + | (trailingByteValue(byte3) << 6) + | trailingByteValue(byte4); + resultArr[resultPos] = DecodeUtil.highSurrogate(codepoint); + resultArr[resultPos + 1] = DecodeUtil.lowSurrogate(codepoint); + } + + /** + * Returns whether the byte is not a valid continuation of the form '10XXXXXX'. + */ + private static boolean isNotTrailingByte(byte b) { + return b > (byte) 0xBF; + } + + /** + * Returns the actual value of the trailing byte (removes the prefix '10') for composition. + */ + private static int trailingByteValue(byte b) { + return b & 0x3F; + } + + private static char highSurrogate(int codePoint) { + return (char) ((MIN_HIGH_SURROGATE - (MIN_SUPPLEMENTARY_CODE_POINT >>> 10)) + + (codePoint >>> 10)); + } + + private static char lowSurrogate(int codePoint) { + return (char) (MIN_LOW_SURROGATE + (codePoint & 0x3ff)); + } + } + + private Utf8() {} +} |