| package org.codehaus.jackson.impl; |
| |
| import java.io.*; |
| |
| import org.codehaus.jackson.*; |
| import org.codehaus.jackson.io.*; |
| import org.codehaus.jackson.sym.BytesToNameCanonicalizer; |
| import org.codehaus.jackson.sym.CharsToNameCanonicalizer; |
| |
| /** |
| * This class is used to determine the encoding of byte stream |
| * that is to contain JSON content. Rules are fairly simple, and |
| * defined in JSON specification (RFC-4627 or newer), except |
| * for BOM handling, which is a property of underlying |
| * streams. |
| */ |
| public final class ByteSourceBootstrapper |
| { |
| /* |
| /********************************************************** |
| /* Configuration |
| /********************************************************** |
| */ |
| |
| final IOContext _context; |
| |
| final InputStream _in; |
| |
| /* |
| /********************************************************** |
| /* Input buffering |
| /********************************************************** |
| */ |
| |
| final byte[] _inputBuffer; |
| |
| private int _inputPtr; |
| |
| private int _inputEnd; |
| |
| /** |
| * Flag that indicates whether buffer above is to be recycled |
| * after being used or not. |
| */ |
| private final boolean _bufferRecyclable; |
| |
| /* |
| /********************************************************** |
| /* Input location |
| /********************************************************** |
| */ |
| |
| /** |
| * Current number of input units (bytes or chars) that were processed in |
| * previous blocks, |
| * before contents of current input buffer. |
| *<p> |
| * Note: includes possible BOMs, if those were part of the input. |
| */ |
| protected int _inputProcessed; |
| |
| /* |
| /********************************************************** |
| /* Data gathered |
| /********************************************************** |
| */ |
| |
| boolean _bigEndian = true; |
| int _bytesPerChar = 0; // 0 means "dunno yet" |
| |
| /* |
| /********************************************************** |
| /* Life-cycle |
| /********************************************************** |
| */ |
| |
| public ByteSourceBootstrapper(IOContext ctxt, InputStream in) |
| { |
| _context = ctxt; |
| _in = in; |
| _inputBuffer = ctxt.allocReadIOBuffer(); |
| _inputEnd = _inputPtr = 0; |
| _inputProcessed = 0; |
| _bufferRecyclable = true; |
| } |
| |
| public ByteSourceBootstrapper(IOContext ctxt, byte[] inputBuffer, int inputStart, int inputLen) |
| { |
| _context = ctxt; |
| _in = null; |
| _inputBuffer = inputBuffer; |
| _inputPtr = inputStart; |
| _inputEnd = (inputStart + inputLen); |
| // Need to offset this for correct location info |
| _inputProcessed = -inputStart; |
| _bufferRecyclable = false; |
| } |
| |
| /** |
| * Method that should be called after constructing an instace. |
| * It will figure out encoding that content uses, to allow |
| * for instantiating a proper scanner object. |
| */ |
| public JsonEncoding detectEncoding() |
| throws IOException, JsonParseException |
| { |
| boolean foundEncoding = false; |
| |
| // First things first: BOM handling |
| /* Note: we can require 4 bytes to be read, since no |
| * combination of BOM + valid JSON content can have |
| * shorter length (shortest valid JSON content is single |
| * digit char, but BOMs are chosen such that combination |
| * is always at least 4 chars long) |
| */ |
| if (ensureLoaded(4)) { |
| int quad = (_inputBuffer[_inputPtr] << 24) |
| | ((_inputBuffer[_inputPtr+1] & 0xFF) << 16) |
| | ((_inputBuffer[_inputPtr+2] & 0xFF) << 8) |
| | (_inputBuffer[_inputPtr+3] & 0xFF); |
| |
| if (handleBOM(quad)) { |
| foundEncoding = true; |
| } else { |
| /* If no BOM, need to auto-detect based on first char; |
| * this works since it must be 7-bit ascii (wrt. unicode |
| * compatible encodings, only ones JSON can be transferred |
| * over) |
| */ |
| // UTF-32? |
| if (checkUTF32(quad)) { |
| foundEncoding = true; |
| } else if (checkUTF16(quad >>> 16)) { |
| foundEncoding = true; |
| } |
| } |
| } else if (ensureLoaded(2)) { |
| int i16 = ((_inputBuffer[_inputPtr] & 0xFF) << 8) |
| | (_inputBuffer[_inputPtr+1] & 0xFF); |
| if (checkUTF16(i16)) { |
| foundEncoding = true; |
| } |
| } |
| |
| JsonEncoding enc; |
| |
| /* Not found yet? As per specs, this means it must be UTF-8. */ |
| if (!foundEncoding) { |
| enc = JsonEncoding.UTF8; |
| } else if (_bytesPerChar == 2) { |
| enc = _bigEndian ? JsonEncoding.UTF16_BE : JsonEncoding.UTF16_LE; |
| } else if (_bytesPerChar == 4) { |
| enc = _bigEndian ? JsonEncoding.UTF32_BE : JsonEncoding.UTF32_LE; |
| } else { |
| throw new RuntimeException("Internal error"); // should never get here |
| } |
| _context.setEncoding(enc); |
| return enc; |
| } |
| |
| public Reader constructReader() |
| throws IOException |
| { |
| JsonEncoding enc = _context.getEncoding(); |
| switch (enc) { |
| case UTF32_BE: |
| case UTF32_LE: |
| return new UTF32Reader(_context, _in, _inputBuffer, _inputPtr, _inputEnd, |
| _context.getEncoding().isBigEndian()); |
| |
| case UTF16_BE: |
| case UTF16_LE: |
| case UTF8: // only in non-common case where we don't want to do direct mapping |
| { |
| // First: do we have a Stream? If not, need to create one: |
| InputStream in = _in; |
| |
| if (in == null) { |
| in = new ByteArrayInputStream(_inputBuffer, _inputPtr, _inputEnd); |
| } else { |
| /* Also, if we have any read but unused input (usually true), |
| * need to merge that input in: |
| */ |
| if (_inputPtr < _inputEnd) { |
| in = new MergedStream(_context, in, _inputBuffer, _inputPtr, _inputEnd); |
| } |
| } |
| return new InputStreamReader(in, enc.getJavaName()); |
| } |
| } |
| throw new RuntimeException("Internal error"); // should never get here |
| } |
| |
| public JsonParser constructParser(int features, ObjectCodec codec, BytesToNameCanonicalizer rootByteSymbols, CharsToNameCanonicalizer rootCharSymbols) |
| throws IOException, JsonParseException |
| { |
| JsonEncoding enc = detectEncoding(); |
| |
| // As per [JACKSON-259], may want to fully disable canonicalization: |
| boolean canonicalize = JsonParser.Feature.CANONICALIZE_FIELD_NAMES.enabledIn(features); |
| boolean intern = JsonParser.Feature.INTERN_FIELD_NAMES.enabledIn(features); |
| if (enc == JsonEncoding.UTF8) { |
| /* and without canonicalization, byte-based approach is not performance; just use std UTF-8 reader |
| * (which is ok for larger input; not so hot for smaller; but this is not a common case) |
| */ |
| if (canonicalize) { |
| BytesToNameCanonicalizer can = rootByteSymbols.makeChild(canonicalize, intern); |
| return new Utf8StreamParser(_context, features, _in, codec, can, _inputBuffer, _inputPtr, _inputEnd, _bufferRecyclable); |
| } |
| } |
| return new ReaderBasedParser(_context, features, constructReader(), codec, rootCharSymbols.makeChild(canonicalize, intern)); |
| } |
| |
| /* |
| /********************************************************** |
| /* Internal methods, parsing |
| /********************************************************** |
| */ |
| |
| /** |
| * @return True if a BOM was succesfully found, and encoding |
| * thereby recognized. |
| */ |
| private boolean handleBOM(int quad) |
| throws IOException |
| { |
| /* Handling of (usually) optional BOM (required for |
| * multi-byte formats); first 32-bit charsets: |
| */ |
| switch (quad) { |
| case 0x0000FEFF: |
| _bigEndian = true; |
| _inputPtr += 4; |
| _bytesPerChar = 4; |
| return true; |
| case 0xFFFE0000: // UCS-4, LE? |
| _inputPtr += 4; |
| _bytesPerChar = 4; |
| _bigEndian = false; |
| return true; |
| case 0x0000FFFE: // UCS-4, in-order... |
| reportWeirdUCS4("2143"); // throws exception |
| case 0xFEFF0000: // UCS-4, in-order... |
| reportWeirdUCS4("3412"); // throws exception |
| } |
| // Ok, if not, how about 16-bit encoding BOMs? |
| int msw = quad >>> 16; |
| if (msw == 0xFEFF) { // UTF-16, BE |
| _inputPtr += 2; |
| _bytesPerChar = 2; |
| _bigEndian = true; |
| return true; |
| } |
| if (msw == 0xFFFE) { // UTF-16, LE |
| _inputPtr += 2; |
| _bytesPerChar = 2; |
| _bigEndian = false; |
| return true; |
| } |
| // And if not, then UTF-8 BOM? |
| if ((quad >>> 8) == 0xEFBBBF) { // UTF-8 |
| _inputPtr += 3; |
| _bytesPerChar = 1; |
| _bigEndian = true; // doesn't really matter |
| return true; |
| } |
| return false; |
| } |
| |
| private boolean checkUTF32(int quad) |
| throws IOException |
| { |
| /* Handling of (usually) optional BOM (required for |
| * multi-byte formats); first 32-bit charsets: |
| */ |
| if ((quad >> 8) == 0) { // 0x000000?? -> UTF32-BE |
| _bigEndian = true; |
| } else if ((quad & 0x00FFFFFF) == 0) { // 0x??000000 -> UTF32-LE |
| _bigEndian = false; |
| } else if ((quad & ~0x00FF0000) == 0) { // 0x00??0000 -> UTF32-in-order |
| reportWeirdUCS4("3412"); |
| } else if ((quad & ~0x0000FF00) == 0) { // 0x0000??00 -> UTF32-in-order |
| reportWeirdUCS4("2143"); |
| } else { |
| // Can not be valid UTF-32 encoded JSON... |
| return false; |
| } |
| // Not BOM (just regular content), nothing to skip past: |
| //_inputPtr += 4; |
| _bytesPerChar = 4; |
| return true; |
| } |
| |
| private boolean checkUTF16(int i16) |
| { |
| if ((i16 & 0xFF00) == 0) { // UTF-16BE |
| _bigEndian = true; |
| } else if ((i16 & 0x00FF) == 0) { // UTF-16LE |
| _bigEndian = false; |
| } else { // nope, not UTF-16 |
| return false; |
| } |
| // Not BOM (just regular content), nothing to skip past: |
| //_inputPtr += 2; |
| _bytesPerChar = 2; |
| return true; |
| } |
| |
| /* |
| /********************************************************** |
| /* Internal methods, problem reporting |
| /********************************************************** |
| */ |
| |
| private void reportWeirdUCS4(String type) |
| throws IOException |
| { |
| throw new CharConversionException("Unsupported UCS-4 endianness ("+type+") detected"); |
| } |
| |
| /* |
| /********************************************************** |
| /* Internal methods, raw input access |
| /********************************************************** |
| */ |
| |
| protected boolean ensureLoaded(int minimum) |
| throws IOException |
| { |
| /* Let's assume here buffer has enough room -- this will always |
| * be true for the limited used this method gets |
| */ |
| int gotten = (_inputEnd - _inputPtr); |
| while (gotten < minimum) { |
| int count; |
| |
| if (_in == null) { // block source |
| count = -1; |
| } else { |
| count = _in.read(_inputBuffer, _inputEnd, _inputBuffer.length - _inputEnd); |
| } |
| if (count < 1) { |
| return false; |
| } |
| _inputEnd += count; |
| gotten += count; |
| } |
| return true; |
| } |
| } |
| |
