mcs/class/System.XML/System.Xml/XmlInputStream.cs

   1 //
   2 // System.Xml.XmlInputStream
   3 //      encoding-specification-wise XML input stream and reader
   4 //
   5 // Author:
   6 //      Atsushi Enomoto (ginga@kit.hi-ho.ne.jp)
   7 //
   8 //      (C)2003 Atsushi Enomoto
   9 //
  10 using System;\r
  11 using System.IO;\r
  12 using System.Text;\r
  13 \r
  14 namespace System.Xml\r
  15 {\r
  16         #region XmlStreamReader
  17         internal class XmlStreamReader : StreamReader
  18         {
  19                 public XmlStreamReader (XmlInputStream input)
  20                         : base (input, input.ActualEncoding != null ? input.ActualEncoding : Encoding.UTF8)
  21                 {
  22                 }
  23         }
  24         #endregion
  25 \r
  26         public class XmlInputStream : Stream\r
  27         {\r
  28                 Encoding enc;\r
  29                 Stream stream;\r
  30                 byte[] buffer = new byte[256];\r
  31                 int bufLength;\r
  32                 int bufPos;\r
  33 \r
  34                 static XmlException encodingException = new XmlException ("invalid encoding specification.");\r
  35 \r
  36                 public XmlInputStream (string uri)\r
  37                 {\r
  38                         Initialize (new System.Net.WebClient ().OpenRead (uri));\r
  39                 }\r
  40 \r
  41                 public XmlInputStream (Stream stream)\r
  42                 {\r
  43                         Initialize (stream);\r
  44                 }\r
  45 \r
  46                 private void Initialize (Stream stream)\r
  47                 {\r
  48                         // FIXME: seems too waste...\r
  49                         MemoryStream ms = new MemoryStream ();\r
  50                         this.stream = stream;\r
  51                         int c = stream.ReadByte ();\r
  52                         switch (c) {\r
  53                         case 0xFF:\r
  54                                 c = stream.ReadByte ();\r
  55                                 if (c == 0xFE) {\r
  56                                         // BOM-ed little endian utf-16\r
  57                                         enc = Encoding.Unicode;\r
  58                                 } else {\r
  59                                         // It doesn't start from "<?xml" then its encoding is utf-8\r
  60                                         enc = Encoding.UTF8;\r
  61                                         ms.WriteByte ((byte)0xFF);\r
  62                                         ms.WriteByte ((byte)c);\r
  63                                 }\r
  64                                 break;\r
  65                         case 0xFE:\r
  66                                 c = stream.ReadByte ();\r
  67                                 if (c == 0xFF) {\r
  68                                         // BOM-ed big endian utf-16\r
  69                                         enc = Encoding.BigEndianUnicode;\r
  70                                         return;\r
  71                                 } else {\r
  72                                         // It doesn't start from "<?xml" then its encoding is utf-8\r
  73                                         enc = Encoding.UTF8;\r
  74                                         ms.WriteByte ((byte)0xFE);\r
  75                                         ms.WriteByte ((byte)c);\r
  76                                 }\r
  77                                 break;\r
  78                         case 0xEF:\r
  79                                 enc = Encoding.UTF8;\r
  80                                 c = ReadByte ();\r
  81                                 if (c == 0xBB) {\r
  82                                         c = ReadByte ();\r
  83                                         if (c != 0xBF) {\r
  84                                                 ms.WriteByte ((byte)0xEF);\r
  85                                                 ms.WriteByte ((byte)0xBB);\r
  86                                                 ms.WriteByte ((byte)c);\r
  87                                         }\r
  88                                 } else {\r
  89                                         ms.WriteByte ((byte)0xEF);\r
  90                                 }\r
  91                                 break;\r
  92                         case '<':\r
  93                                 // try to get encoding name from XMLDecl.\r
  94                                 ms.WriteByte ((byte)'<');\r
  95                                 int size = stream.Read (buffer, 1, 4);\r
  96                                 ms.Write (buffer, 1, 4);\r
  97                                 if (Encoding.ASCII.GetString (buffer, 1, 4) == "?xml") {\r
  98                                         int loop = 0;\r
  99                                         c = SkipWhitespace (ms);\r
 100                                         // version\r
 101                                         if (c != 'v' || stream.ReadByte () != 'e')\r
 102                                                 throw new XmlException ("invalid xml declaration.");\r
 103                                         ms.WriteByte ((byte)'v');\r
 104                                         ms.WriteByte ((byte)'e');\r
 105                                         while (loop++ >= 0) {\r
 106                                                 c = stream.ReadByte ();\r
 107                                                 ms.WriteByte ((byte)c);\r
 108                                                 if (c == '0') {\r
 109                                                         ms.WriteByte ((byte)stream.ReadByte ());\r
 110                                                         break;\r
 111                                                 }\r
 112                                         }\r
 113                                         c = SkipWhitespace (ms);\r
 114                                         if (c == 'e') {\r
 115                                                 ms.WriteByte ((byte)'e');\r
 116                                                 size = stream.Read (buffer, 0, 7);\r
 117                                                 ms.Write (buffer, 0, 7);\r
 118                                                 if (Encoding.ASCII.GetString(buffer, 0, 7) == "ncoding") {\r
 119                                                         c = this.SkipWhitespace(ms);\r
 120                                                         if (c != '=')\r
 121                                                                 throw encodingException;\r
 122                                                         ms.WriteByte ((byte)'=');\r
 123                                                         c = this.SkipWhitespace (ms);\r
 124                                                         int quoteChar = c;\r
 125                                                         ms.WriteByte ((byte)c);\r
 126                                                         int start = (int)ms.Position;\r
 127                                                         while (loop++ >= 0) {\r
 128                                                                 c = stream.ReadByte ();\r
 129                                                                 if (c == quoteChar)\r
 130                                                                         break;\r
 131                                                                 else if (c < 0)\r
 132                                                                         throw encodingException;\r
 133                                                                 ms.WriteByte ((byte)c);\r
 134                                                         }\r
 135                                                         string encodingName = Encoding.UTF8.GetString (ms.GetBuffer (), start, (int)ms.Position - start);\r
 136                                                         if (!XmlConstructs.IsValidIANAEncoding (encodingName))\r
 137                                                                 throw encodingException;\r
 138                                                         ms.WriteByte ((byte)quoteChar);\r
 139                                                         enc = Encoding.GetEncoding (encodingName);\r
 140                                                 }\r
 141                                                 else\r
 142                                                         ms.Write (buffer, 0, size);\r
 143                                         }\r
 144                                         else\r
 145                                                 ms.WriteByte ((byte)c);\r
 146                                 }\r
 147                                 buffer = ms.ToArray ();\r
 148                                 bufLength = buffer.Length;\r
 149                                 bufPos = 0;\r
 150                                 break;\r
 151                         default:\r
 152                                 buffer [0] = (byte)c;\r
 153                                 bufLength = 1;\r
 154                                 enc = Encoding.UTF8;\r
 155                                 break;\r
 156                         }\r
 157                 }\r
 158 \r
 159                 // skips whitespace and returns misc char that was read from stream\r
 160                 private int SkipWhitespace (MemoryStream ms)    // ms may be null\r
 161                 {\r
 162                         int loop = 0;\r
 163                         int c;\r
 164                         while (loop++ >= 0) { // defends infinite loop (expecting overflow)\r
 165                                 c = stream.ReadByte ();\r
 166                                 switch (c) {\r
 167                                 case '\r': goto case ' ';\r
 168                                 case '\n': goto case ' ';\r
 169                                 case '\t': goto case ' ';\r
 170                                 case ' ':\r
 171                                         if (ms != null)\r
 172                                                 ms.WriteByte ((byte)c);\r
 173                                         continue;\r
 174                                 default:\r
 175                                         return c;\r
 176                                 }\r
 177                         }\r
 178                         throw new InvalidOperationException ();\r
 179                 }\r
 180 \r
 181                 public Encoding ActualEncoding {\r
 182                         get { return enc; }\r
 183                 }\r
 184 \r
 185                 #region Public Overrides\r
 186                 public override bool CanRead {\r
 187                         get { return stream.CanRead; }\r
 188                 }\r
 189 \r
 190                 public override bool CanSeek {\r
 191                         get { return false; } //stream.CanSeek; }\r
 192                 }\r
 193 \r
 194                 public override bool CanWrite {\r
 195                         get { return false; }\r
 196                 }\r
 197 \r
 198                 public override long Length {\r
 199                         get {\r
 200                                 return stream.Length;\r
 201                         }\r
 202                 }\r
 203 \r
 204                 public override long Position {\r
 205                         get {\r
 206                                 return stream.Position + bufLength;\r
 207                         }\r
 208                         set {\r
 209                                 if(value < bufLength)\r
 210                                         bufPos = (int)value;\r
 211                                 else\r
 212                                         stream.Position = value - bufLength;\r
 213                         }\r
 214                 }\r
 215 \r
 216                 public override void Flush()\r
 217                 {\r
 218                         stream.Flush ();\r
 219                 }\r
 220 \r
 221                 public override int Read (byte[] buffer, int offset, int count)\r
 222                 {\r
 223                         int ret;\r
 224                         if (count <= bufLength - bufPos)        {       // all from buffer\r
 225                                 Array.Copy (this.buffer, bufPos, buffer, offset, count);\r
 226                                 bufPos += count;\r
 227                                 ret = count;\r
 228                         } else {\r
 229                                 int bufRest = bufLength - bufPos;\r
 230                                 if (bufLength > bufPos) {\r
 231                                         Array.Copy (this.buffer, bufPos, buffer, offset, bufRest);\r
 232                                         bufPos += bufRest;\r
 233                                 }\r
 234                                 ret = bufRest +\r
 235                                         stream.Read (buffer, offset + bufRest, count - bufRest);\r
 236                         }\r
 237                         return ret;\r
 238                 }\r
 239 \r
 240                 public override int ReadByte ()\r
 241                 {\r
 242                         if (bufLength > bufPos) {\r
 243                                 return buffer [bufPos++];\r
 244                         }\r
 245                         return stream.ReadByte ();\r
 246                 }\r
 247 \r
 248                 public override long Seek (long offset, System.IO.SeekOrigin origin)\r
 249                 {\r
 250                         int bufRest = bufLength - bufPos;\r
 251                         if (origin == SeekOrigin.Current)\r
 252                                 if (offset < bufRest)\r
 253                                         return buffer [bufPos + offset];\r
 254                                 else\r
 255                                         return stream.Seek (offset - bufRest, origin);\r
 256                         else\r
 257                                 return stream.Seek (offset, origin);\r
 258                 }\r
 259 \r
 260                 public override void SetLength (long value)\r
 261                 {\r
 262                         stream.SetLength (value);\r
 263                 }\r
 264 \r
 265                 public override void Write (byte[] buffer, int offset, int count)\r
 266                 {\r
 267                         throw new NotSupportedException ();\r
 268                 }\r
 269                 #endregion\r
 270         }\r
 271 }\r