| | | 1 | | // Licensed to the .NET Foundation under one or more agreements. |
| | | 2 | | // The .NET Foundation licenses this file to you under the MIT license. |
| | | 3 | | |
| | | 4 | | using System.Diagnostics; |
| | | 5 | | using System.Diagnostics.CodeAnalysis; |
| | | 6 | | using System.Globalization; |
| | | 7 | | |
| | | 8 | | namespace System.Text |
| | | 9 | | { |
| | | 10 | | public abstract class DecoderFallback |
| | | 11 | | { |
| | | 12 | | // Default fallback, uses no best fit & "?" |
| | 6808 | 13 | | public static DecoderFallback ReplacementFallback => DecoderReplacementFallback.s_default; |
| | | 14 | | |
| | 10209 | 15 | | public static DecoderFallback ExceptionFallback => DecoderExceptionFallback.s_default; |
| | | 16 | | |
| | | 17 | | // Fallback |
| | | 18 | | // |
| | | 19 | | // Return the appropriate unicode string alternative to the character that need to fall back. |
| | | 20 | | // Most implementations will be: |
| | | 21 | | // return new MyCustomDecoderFallbackBuffer(this); |
| | | 22 | | |
| | | 23 | | public abstract DecoderFallbackBuffer CreateFallbackBuffer(); |
| | | 24 | | |
| | | 25 | | // Maximum number of characters that this instance of this fallback could return |
| | | 26 | | |
| | | 27 | | public abstract int MaxCharCount { get; } |
| | | 28 | | } |
| | | 29 | | |
| | | 30 | | |
| | | 31 | | public abstract class DecoderFallbackBuffer |
| | | 32 | | { |
| | | 33 | | // Most implementations will probably need an implementation-specific constructor |
| | | 34 | | |
| | | 35 | | // internal methods that cannot be overridden that let us do our fallback thing |
| | | 36 | | // These wrap the internal methods so that we can check for people doing stuff that's incorrect |
| | | 37 | | |
| | | 38 | | public abstract bool Fallback(byte[] bytesUnknown, int index); |
| | | 39 | | |
| | | 40 | | // Get next character |
| | | 41 | | |
| | | 42 | | public abstract char GetNextChar(); |
| | | 43 | | |
| | | 44 | | // Back up a character |
| | | 45 | | |
| | | 46 | | public abstract bool MovePrevious(); |
| | | 47 | | |
| | | 48 | | // How many chars left in this fallback? |
| | | 49 | | |
| | | 50 | | public abstract int Remaining { get; } |
| | | 51 | | |
| | | 52 | | // Clear the buffer |
| | | 53 | | |
| | | 54 | | public virtual void Reset() |
| | | 55 | | { |
| | | 56 | | while (GetNextChar() != (char)0) ; |
| | | 57 | | } |
| | | 58 | | |
| | | 59 | | // Internal items to help us figure out what we're doing as far as error messages, etc. |
| | | 60 | | // These help us with our performance and messages internally |
| | | 61 | | internal unsafe byte* byteStart; |
| | | 62 | | internal unsafe char* charEnd; |
| | | 63 | | |
| | | 64 | | internal Encoding? _encoding; |
| | | 65 | | internal DecoderNLS? _decoder; |
| | | 66 | | private int _originalByteCount; |
| | | 67 | | |
| | | 68 | | // Internal Reset |
| | | 69 | | internal unsafe void InternalReset() |
| | | 70 | | { |
| | | 71 | | byteStart = null; |
| | | 72 | | Reset(); |
| | | 73 | | } |
| | | 74 | | |
| | | 75 | | // Set the above values |
| | | 76 | | // This can't be part of the constructor because DecoderFallbacks would have to know how to implement these. |
| | | 77 | | internal unsafe void InternalInitialize(byte* byteStart, char* charEnd) |
| | | 78 | | { |
| | | 79 | | this.byteStart = byteStart; |
| | | 80 | | this.charEnd = charEnd; |
| | | 81 | | } |
| | | 82 | | |
| | | 83 | | internal static DecoderFallbackBuffer CreateAndInitialize(Encoding encoding, DecoderNLS? decoder, int originalBy |
| | | 84 | | { |
| | | 85 | | // The original byte count is only used for keeping track of what 'index' value needs |
| | | 86 | | // to be passed to the abstract Fallback method. The index value is calculated by subtracting |
| | | 87 | | // 'bytes.Length' (where bytes is expected to be the entire remaining input buffer) |
| | | 88 | | // from the 'originalByteCount' value specified here. |
| | | 89 | | |
| | | 90 | | DecoderFallbackBuffer fallbackBuffer = (decoder is null) ? encoding.DecoderFallback.CreateFallbackBuffer() : |
| | | 91 | | |
| | | 92 | | fallbackBuffer._encoding = encoding; |
| | | 93 | | fallbackBuffer._decoder = decoder; |
| | | 94 | | fallbackBuffer._originalByteCount = originalByteCount; |
| | | 95 | | |
| | | 96 | | return fallbackBuffer; |
| | | 97 | | } |
| | | 98 | | |
| | | 99 | | // Fallback the current byte by sticking it into the remaining char buffer. |
| | | 100 | | // This can only be called by our encodings (other have to use the public fallback methods), so |
| | | 101 | | // we can use our DecoderNLS here too (except we don't). |
| | | 102 | | // Returns true if we are successful, false if we can't fallback the character (no buffer space) |
| | | 103 | | // So caller needs to throw buffer space if return false. |
| | | 104 | | // Right now this has both bytes and bytes[], since we might have extra bytes, hence the |
| | | 105 | | // array, and we might need the index, hence the byte* |
| | | 106 | | // Don't touch ref chars unless we succeed |
| | | 107 | | internal unsafe bool InternalFallback(byte[] bytes, byte* pBytes, ref char* chars) |
| | | 108 | | { |
| | | 109 | | Debug.Assert(byteStart != null, "[DecoderFallback.InternalFallback]Used InternalFallback without calling Int |
| | | 110 | | |
| | | 111 | | // See if there's a fallback character and we have an output buffer then copy our string. |
| | | 112 | | if (this.Fallback(bytes, (int)(pBytes - byteStart - bytes.Length))) |
| | | 113 | | { |
| | | 114 | | // Copy the chars to our output |
| | | 115 | | char ch; |
| | | 116 | | char* charTemp = chars; |
| | | 117 | | bool bHighSurrogate = false; |
| | | 118 | | while ((ch = GetNextChar()) != 0) |
| | | 119 | | { |
| | | 120 | | // Make sure no mixed up surrogates |
| | | 121 | | if (char.IsSurrogate(ch)) |
| | | 122 | | { |
| | | 123 | | if (char.IsHighSurrogate(ch)) |
| | | 124 | | { |
| | | 125 | | // High Surrogate |
| | | 126 | | if (bHighSurrogate) |
| | | 127 | | throw new ArgumentException(SR.Argument_InvalidCharSequenceNoIndex); |
| | | 128 | | bHighSurrogate = true; |
| | | 129 | | } |
| | | 130 | | else |
| | | 131 | | { |
| | | 132 | | // Low surrogate |
| | | 133 | | if (!bHighSurrogate) |
| | | 134 | | throw new ArgumentException(SR.Argument_InvalidCharSequenceNoIndex); |
| | | 135 | | bHighSurrogate = false; |
| | | 136 | | } |
| | | 137 | | } |
| | | 138 | | |
| | | 139 | | if (charTemp >= charEnd) |
| | | 140 | | { |
| | | 141 | | // No buffer space |
| | | 142 | | return false; |
| | | 143 | | } |
| | | 144 | | |
| | | 145 | | *(charTemp++) = ch; |
| | | 146 | | } |
| | | 147 | | |
| | | 148 | | // Need to make sure that bHighSurrogate isn't true |
| | | 149 | | if (bHighSurrogate) |
| | | 150 | | throw new ArgumentException(SR.Argument_InvalidCharSequenceNoIndex); |
| | | 151 | | |
| | | 152 | | // Now we aren't going to be false, so its OK to update chars |
| | | 153 | | chars = charTemp; |
| | | 154 | | } |
| | | 155 | | |
| | | 156 | | return true; |
| | | 157 | | } |
| | | 158 | | |
| | | 159 | | // This version just counts the fallback and doesn't actually copy anything. |
| | | 160 | | internal virtual unsafe int InternalFallback(byte[] bytes, byte* pBytes) |
| | | 161 | | // Right now this has both bytes and bytes[], since we might have extra bytes, hence the |
| | | 162 | | // array, and we might need the index, hence the byte* |
| | | 163 | | { |
| | | 164 | | Debug.Assert(byteStart != null, "[DecoderFallback.InternalFallback]Used InternalFallback without calling Int |
| | | 165 | | |
| | | 166 | | // See if there's a fallback character and we have an output buffer then copy our string. |
| | | 167 | | if (this.Fallback(bytes, (int)(pBytes - byteStart - bytes.Length))) |
| | | 168 | | { |
| | | 169 | | int count = 0; |
| | | 170 | | |
| | | 171 | | char ch; |
| | | 172 | | bool bHighSurrogate = false; |
| | | 173 | | while ((ch = GetNextChar()) != 0) |
| | | 174 | | { |
| | | 175 | | // Make sure no mixed up surrogates |
| | | 176 | | if (char.IsSurrogate(ch)) |
| | | 177 | | { |
| | | 178 | | if (char.IsHighSurrogate(ch)) |
| | | 179 | | { |
| | | 180 | | // High Surrogate |
| | | 181 | | if (bHighSurrogate) |
| | | 182 | | throw new ArgumentException(SR.Argument_InvalidCharSequenceNoIndex); |
| | | 183 | | bHighSurrogate = true; |
| | | 184 | | } |
| | | 185 | | else |
| | | 186 | | { |
| | | 187 | | // Low surrogate |
| | | 188 | | if (!bHighSurrogate) |
| | | 189 | | throw new ArgumentException(SR.Argument_InvalidCharSequenceNoIndex); |
| | | 190 | | bHighSurrogate = false; |
| | | 191 | | } |
| | | 192 | | } |
| | | 193 | | |
| | | 194 | | count++; |
| | | 195 | | } |
| | | 196 | | |
| | | 197 | | // Need to make sure that bHighSurrogate isn't true |
| | | 198 | | if (bHighSurrogate) |
| | | 199 | | throw new ArgumentException(SR.Argument_InvalidCharSequenceNoIndex); |
| | | 200 | | |
| | | 201 | | return count; |
| | | 202 | | } |
| | | 203 | | |
| | | 204 | | // If no fallback return 0 |
| | | 205 | | return 0; |
| | | 206 | | } |
| | | 207 | | |
| | | 208 | | internal int InternalFallbackGetCharCount(ReadOnlySpan<byte> remainingBytes, int fallbackLength) |
| | | 209 | | { |
| | | 210 | | return (Fallback(remainingBytes.Slice(0, fallbackLength).ToArray(), index: _originalByteCount - remainingByt |
| | | 211 | | ? DrainRemainingDataForGetCharCount() |
| | | 212 | | : 0; |
| | | 213 | | } |
| | | 214 | | |
| | | 215 | | internal bool TryInternalFallbackGetChars(ReadOnlySpan<byte> remainingBytes, int fallbackLength, Span<char> char |
| | | 216 | | { |
| | | 217 | | if (Fallback(remainingBytes.Slice(0, fallbackLength).ToArray(), index: _originalByteCount - remainingBytes.L |
| | | 218 | | { |
| | | 219 | | return TryDrainRemainingDataForGetChars(chars, out charsWritten); |
| | | 220 | | } |
| | | 221 | | else |
| | | 222 | | { |
| | | 223 | | // Return true because we weren't asked to write anything, so this is a "success" in the sense that |
| | | 224 | | // the output buffer was large enough to hold the desired 0 chars of output. |
| | | 225 | | |
| | | 226 | | charsWritten = 0; |
| | | 227 | | return true; |
| | | 228 | | } |
| | | 229 | | } |
| | | 230 | | |
| | | 231 | | private Rune GetNextRune() |
| | | 232 | | { |
| | | 233 | | // Call GetNextChar() and try treating it as a non-surrogate character. |
| | | 234 | | // If that fails, call GetNextChar() again and attempt to treat the two chars |
| | | 235 | | // as a surrogate pair. If that still fails, throw an exception since the fallback |
| | | 236 | | // mechanism is giving us a bad replacement character. |
| | | 237 | | |
| | | 238 | | char ch = GetNextChar(); |
| | | 239 | | if (!Rune.TryCreate(ch, out Rune rune) && !Rune.TryCreate(ch, GetNextChar(), out rune)) |
| | | 240 | | { |
| | | 241 | | throw new ArgumentException(SR.Argument_InvalidCharSequenceNoIndex); |
| | | 242 | | } |
| | | 243 | | |
| | | 244 | | return rune; |
| | | 245 | | } |
| | | 246 | | |
| | | 247 | | internal int DrainRemainingDataForGetCharCount() |
| | | 248 | | { |
| | | 249 | | int totalCharCount = 0; |
| | | 250 | | |
| | | 251 | | Rune thisRune; |
| | | 252 | | while ((thisRune = GetNextRune()).Value != 0) |
| | | 253 | | { |
| | | 254 | | // We need to check for overflow while tallying the fallback char count. |
| | | 255 | | |
| | | 256 | | totalCharCount += thisRune.Utf16SequenceLength; |
| | | 257 | | if (totalCharCount < 0) |
| | | 258 | | { |
| | | 259 | | InternalReset(); |
| | | 260 | | Encoding.ThrowConversionOverflow(); |
| | | 261 | | } |
| | | 262 | | } |
| | | 263 | | |
| | | 264 | | return totalCharCount; |
| | | 265 | | } |
| | | 266 | | |
| | | 267 | | internal bool TryDrainRemainingDataForGetChars(Span<char> chars, out int charsWritten) |
| | | 268 | | { |
| | | 269 | | int originalCharCount = chars.Length; |
| | | 270 | | |
| | | 271 | | Rune thisRune; |
| | | 272 | | while ((thisRune = GetNextRune()).Value != 0) |
| | | 273 | | { |
| | | 274 | | if (thisRune.TryEncodeToUtf16(chars, out int charsWrittenJustNow)) |
| | | 275 | | { |
| | | 276 | | chars = chars.Slice(charsWrittenJustNow); |
| | | 277 | | continue; |
| | | 278 | | } |
| | | 279 | | else |
| | | 280 | | { |
| | | 281 | | InternalReset(); |
| | | 282 | | charsWritten = default; |
| | | 283 | | return false; |
| | | 284 | | } |
| | | 285 | | } |
| | | 286 | | |
| | | 287 | | charsWritten = originalCharCount - chars.Length; |
| | | 288 | | return true; |
| | | 289 | | } |
| | | 290 | | |
| | | 291 | | // private helper methods |
| | | 292 | | [DoesNotReturn] |
| | | 293 | | internal static void ThrowLastBytesRecursive(byte[] bytesUnknown) |
| | | 294 | | { |
| | | 295 | | bytesUnknown ??= []; |
| | | 296 | | |
| | | 297 | | // Create a string representation of our bytes. |
| | | 298 | | StringBuilder strBytes = new StringBuilder(bytesUnknown.Length * 3); |
| | | 299 | | int i; |
| | | 300 | | for (i = 0; i < bytesUnknown.Length && i < 20; i++) |
| | | 301 | | { |
| | | 302 | | if (strBytes.Length > 0) |
| | | 303 | | strBytes.Append(' '); |
| | | 304 | | strBytes.Append($"\\x{bytesUnknown[i]:X2}"); |
| | | 305 | | } |
| | | 306 | | // In case the string's really long |
| | | 307 | | if (i == 20) |
| | | 308 | | strBytes.Append(" ..."); |
| | | 309 | | |
| | | 310 | | // Throw it, using our complete bytes |
| | | 311 | | throw new ArgumentException( |
| | | 312 | | SR.Format(SR.Argument_RecursiveFallbackBytes, |
| | | 313 | | strBytes.ToString()), nameof(bytesUnknown)); |
| | | 314 | | } |
| | | 315 | | } |
| | | 316 | | } |
| | | 317 | | |