pdftops/Parser.cxx

   1 //========================================================================
   2 //
   3 // Parser.cc
   4 //
   5 // Copyright 1996 Derek B. Noonburg
   6 //
   7 //========================================================================
   8
   9 #ifdef __GNUC__
  10 #pragma implementation
  11 #endif
  12
  13 #include <stddef.h>
  14 #include "Object.h"
  15 #include "Array.h"
  16 #include "Dict.h"
  17 #include "Parser.h"
  18 #include "XRef.h"
  19 #include "Error.h"
  20 #ifndef NO_DECRYPTION
  21 #include "Decrypt.h"
  22 #endif
  23
  24 Parser::Parser(XRef *xrefA, Lexer *lexerA) {
  25   xref = xrefA;
  26   lexer = lexerA;
  27   inlineImg = 0;
  28   lexer->getObj(&buf1);
  29   lexer->getObj(&buf2);
  30 }
  31
  32 Parser::~Parser() {
  33   buf1.free();
  34   buf2.free();
  35   delete lexer;
  36 }
  37
  38 #ifndef NO_DECRYPTION
  39 Object *Parser::getObj(Object *obj,
  40                        Guchar *fileKey, int keyLength,
  41                        int objNum, int objGen) {
  42 #else
  43 Object *Parser::getObj(Object *obj) {
  44 #endif
  45   char *key;
  46   Stream *str;
  47   Object obj2;
  48   int num;
  49 #ifndef NO_DECRYPTION
  50   Decrypt *decrypt;
  51   GString *s;
  52   char *p;
  53   int i;
  54 #endif
  55
  56   // refill buffer after inline image data
  57   if (inlineImg == 2) {
  58     buf1.free();
  59     buf2.free();
  60     lexer->getObj(&buf1);
  61     lexer->getObj(&buf2);
  62     inlineImg = 0;
  63   }
  64
  65   // array
  66   if (buf1.isCmd("[")) {
  67     shift();
  68     obj->initArray(xref);
  69     while (!buf1.isCmd("]") && !buf1.isEOF())
  70 #ifndef NO_DECRYPTION
  71       obj->arrayAdd(getObj(&obj2, fileKey, keyLength, objNum, objGen));
  72 #else
  73       obj->arrayAdd(getObj(&obj2));
  74 #endif
  75     if (buf1.isEOF())
  76       error(getPos(), "End of file inside array");
  77     shift();
  78
  79   // dictionary or stream
  80   } else if (buf1.isCmd("<<")) {
  81     shift();
  82     obj->initDict(xref);
  83     while (!buf1.isCmd(">>") && !buf1.isEOF()) {
  84       if (!buf1.isName()) {
  85         error(getPos(), "Dictionary key must be a name object");
  86         shift();
  87       } else {
  88         key = copyString(buf1.getName());
  89         shift();
  90         if (buf1.isEOF() || buf1.isError())
  91           break;
  92 #ifndef NO_DECRYPTION
  93         obj->dictAdd(key, getObj(&obj2, fileKey, keyLength, objNum, objGen));
  94 #else
  95         obj->dictAdd(key, getObj(&obj2));
  96 #endif
  97       }
  98     }
  99     if (buf1.isEOF())
 100       error(getPos(), "End of file inside dictionary");
 101     if (buf2.isCmd("stream")) {
 102       if ((str = makeStream(obj))) {
 103         obj->initStream(str);
 104 #ifndef NO_DECRYPTION
 105         if (fileKey) {
 106           str->getBaseStream()->doDecryption(fileKey, keyLength,
 107                                              objNum, objGen);
 108         }
 109 #endif
 110       } else {
 111         obj->free();
 112         obj->initError();
 113       }
 114     } else {
 115       shift();
 116     }
 117
 118   // indirect reference or integer
 119   } else if (buf1.isInt()) {
 120     num = buf1.getInt();
 121     shift();
 122     if (buf1.isInt() && buf2.isCmd("R")) {
 123       obj->initRef(num, buf1.getInt());
 124       shift();
 125       shift();
 126     } else {
 127       obj->initInt(num);
 128     }
 129
 130 #ifndef NO_DECRYPTION
 131   // string
 132   } else if (buf1.isString() && fileKey) {
 133     buf1.copy(obj);
 134     s = obj->getString();
 135     decrypt = new Decrypt(fileKey, keyLength, objNum, objGen);
 136     for (i = 0, p = obj->getString()->getCString();
 137          i < s->getLength();
 138          ++i, ++p) {
 139       *p = decrypt->decryptByte(*p);
 140     }
 141     delete decrypt;
 142     shift();
 143 #endif
 144
 145   // simple object
 146   } else {
 147     buf1.copy(obj);
 148     shift();
 149   }
 150
 151   return obj;
 152 }
 153
 154 Stream *Parser::makeStream(Object *dict) {
 155   Object obj;
 156   Stream *str;
 157   int pos, endPos, length;
 158
 159   // get stream start position
 160   lexer->skipToNextLine();
 161   pos = lexer->getPos();
 162
 163   // get length
 164   dict->dictLookup("Length", &obj);
 165   if (obj.isInt()) {
 166     length = obj.getInt();
 167     obj.free();
 168   } else {
 169     error(getPos(), "Bad 'Length' attribute in stream");
 170     obj.free();
 171     return NULL;
 172   }
 173
 174   // check for length in damaged file
 175   if ((endPos = xref->getStreamEnd(pos)) >= 0) {
 176     length = endPos - pos;
 177   }
 178
 179   // make base stream
 180   str = lexer->getStream()->getBaseStream()->makeSubStream(pos, length, dict);
 181
 182   // get filters
 183   str = str->addFilters(dict);
 184
 185   // skip over stream data
 186   lexer->setPos(pos + length);
 187
 188   // refill token buffers and check for 'endstream'
 189   shift();  // kill '>>'
 190   shift();  // kill 'stream'
 191   if (buf1.isCmd("endstream"))
 192     shift();
 193   else
 194     error(getPos(), "Missing 'endstream'");
 195
 196   return str;
 197 }
 198
 199 void Parser::shift() {
 200   if (inlineImg > 0) {
 201     ++inlineImg;
 202   } else if (buf2.isCmd("ID")) {
 203     lexer->skipChar();          // skip char after 'ID' command
 204     inlineImg = 1;
 205   }
 206   buf1.free();
 207   buf1 = buf2;
 208   if (inlineImg > 0)            // don't buffer inline image data
 209     buf2.initNull();
 210   else
 211     lexer->getObj(&buf2);
 212 }