pdftops/XRef.cxx

   1 //========================================================================
   2 //
   3 // XRef.cc
   4 //
   5 // Copyright 1996-2003 Glyph & Cog, LLC
   6 //
   7 //========================================================================
   8
   9 #include <config.h>
  10
  11 #ifdef USE_GCC_PRAGMAS
  12 #pragma implementation
  13 #endif
  14
  15 #include <stdlib.h>
  16 #include <stddef.h>
  17 #include <string.h>
  18 #include <ctype.h>
  19 #include "gmem.h"
  20 #include "Object.h"
  21 #include "Stream.h"
  22 #include "Lexer.h"
  23 #include "Parser.h"
  24 #include "Dict.h"
  25 #include "Error.h"
  26 #include "ErrorCodes.h"
  27 #include "XRef.h"
  28
  29 //------------------------------------------------------------------------
  30
  31 #define xrefSearchSize 1024     // read this many bytes at end of file
  32                                 //   to look for 'startxref'
  33
  34 //------------------------------------------------------------------------
  35 // Permission bits
  36 //------------------------------------------------------------------------
  37
  38 #define permPrint    (1<<2)
  39 #define permChange   (1<<3)
  40 #define permCopy     (1<<4)
  41 #define permNotes    (1<<5)
  42 #define defPermFlags 0xfffc
  43
  44 //------------------------------------------------------------------------
  45 // ObjectStream
  46 //------------------------------------------------------------------------
  47
  48 class ObjectStream {
  49 public:
  50
  51   // Create an object stream, using object number <objStrNum>,
  52   // generation 0.
  53   ObjectStream(XRef *xref, int objStrNumA);
  54
  55   ~ObjectStream();
  56
  57   // Return the object number of this object stream.
  58   int getObjStrNum() { return objStrNum; }
  59
  60   // Get the <objIdx>th object from this stream, which should be
  61   // object number <objNum>, generation 0.
  62   Object *getObject(int objIdx, int objNum, Object *obj);
  63
  64 private:
  65
  66   int objStrNum;                // object number of the object stream
  67   int nObjects;                 // number of objects in the stream
  68   Object *objs;                 // the objects (length = nObjects)
  69   int *objNums;                 // the object numbers (length = nObjects)
  70 };
  71
  72 ObjectStream::ObjectStream(XRef *xref, int objStrNumA) {
  73   Stream *str;
  74   Parser *parser;
  75   int *offsets;
  76   Object objStr, obj1, obj2;
  77   int first, i;
  78
  79   objStrNum = objStrNumA;
  80   nObjects = 0;
  81   objs = NULL;
  82   objNums = NULL;
  83
  84   if (!xref->fetch(objStrNum, 0, &objStr)->isStream()) {
  85     goto err1;
  86   }
  87
  88   if (!objStr.streamGetDict()->lookup("N", &obj1)->isInt()) {
  89     obj1.free();
  90     goto err1;
  91   }
  92   nObjects = obj1.getInt();
  93   obj1.free();
  94   if (nObjects <= 0) {
  95     goto err1;
  96   }
  97
  98   if (!objStr.streamGetDict()->lookup("First", &obj1)->isInt()) {
  99     obj1.free();
 100     goto err1;
 101   }
 102   first = obj1.getInt();
 103   obj1.free();
 104   if (first < 0) {
 105     goto err1;
 106   }
 107
 108   objs = new Object[nObjects];
 109   objNums = (int *)gmallocn(nObjects, sizeof(int));
 110   offsets = (int *)gmallocn(nObjects, sizeof(int));
 111
 112   // parse the header: object numbers and offsets
 113   objStr.streamReset();
 114   obj1.initNull();
 115   str = new EmbedStream(objStr.getStream(), &obj1, gTrue, first);
 116   parser = new Parser(xref, new Lexer(xref, str));
 117   for (i = 0; i < nObjects; ++i) {
 118     parser->getObj(&obj1);
 119     parser->getObj(&obj2);
 120     if (!obj1.isInt() || !obj2.isInt()) {
 121       obj1.free();
 122       obj2.free();
 123       delete parser;
 124       gfree(offsets);
 125       goto err1;
 126     }
 127     objNums[i] = obj1.getInt();
 128     offsets[i] = obj2.getInt();
 129     obj1.free();
 130     obj2.free();
 131     if (objNums[i] < 0 || offsets[i] < 0 ||
 132         (i > 0 && offsets[i] < offsets[i-1])) {
 133       delete parser;
 134       gfree(offsets);
 135       goto err1;
 136     }
 137   }
 138   while (str->getChar() != EOF) ;
 139   delete parser;
 140
 141   // skip to the first object - this shouldn't be necessary because
 142   // the First key is supposed to be equal to offsets[0], but just in
 143   // case...
 144   for (i = first; i < offsets[0]; ++i) {
 145     objStr.getStream()->getChar();
 146   }
 147
 148   // parse the objects
 149   for (i = 0; i < nObjects; ++i) {
 150     obj1.initNull();
 151     if (i == nObjects - 1) {
 152       str = new EmbedStream(objStr.getStream(), &obj1, gFalse, 0);
 153     } else {
 154       str = new EmbedStream(objStr.getStream(), &obj1, gTrue,
 155                             offsets[i+1] - offsets[i]);
 156     }
 157     parser = new Parser(xref, new Lexer(xref, str));
 158     parser->getObj(&objs[i]);
 159     while (str->getChar() != EOF) ;
 160     delete parser;
 161   }
 162
 163   gfree(offsets);
 164
 165  err1:
 166   objStr.free();
 167   return;
 168 }
 169
 170 ObjectStream::~ObjectStream() {
 171   int i;
 172
 173   if (objs) {
 174     for (i = 0; i < nObjects; ++i) {
 175       objs[i].free();
 176     }
 177     delete[] objs;
 178   }
 179   gfree(objNums);
 180 }
 181
 182 Object *ObjectStream::getObject(int objIdx, int objNum, Object *obj) {
 183   if (objIdx < 0 || objIdx >= nObjects || objNum != objNums[objIdx]) {
 184     return obj->initNull();
 185   }
 186   return objs[objIdx].copy(obj);
 187 }
 188
 189 //------------------------------------------------------------------------
 190 // XRef
 191 //------------------------------------------------------------------------
 192
 193 XRef::XRef(BaseStream *strA) {
 194   Guint pos;
 195   Object obj;
 196
 197   ok = gTrue;
 198   errCode = errNone;
 199   size = 0;
 200   entries = NULL;
 201   streamEnds = NULL;
 202   streamEndsLen = 0;
 203   objStr = NULL;
 204
 205   encrypted = gFalse;
 206   permFlags = defPermFlags;
 207   ownerPasswordOk = gFalse;
 208
 209   // read the trailer
 210   str = strA;
 211   start = str->getStart();
 212   pos = getStartXref();
 213
 214   // if there was a problem with the 'startxref' position, try to
 215   // reconstruct the xref table
 216   if (pos == 0) {
 217     if (!(ok = constructXRef())) {
 218       errCode = errDamaged;
 219       return;
 220     }
 221
 222   // read the xref table
 223   } else {
 224     while (readXRef(&pos)) ;
 225
 226     // if there was a problem with the xref table,
 227     // try to reconstruct it
 228     if (!ok) {
 229       if (!(ok = constructXRef())) {
 230         errCode = errDamaged;
 231         return;
 232       }
 233     }
 234   }
 235
 236   // get the root dictionary (catalog) object
 237   trailerDict.dictLookupNF("Root", &obj);
 238   if (obj.isRef()) {
 239     rootNum = obj.getRefNum();
 240     rootGen = obj.getRefGen();
 241     obj.free();
 242   } else {
 243     obj.free();
 244     if (!(ok = constructXRef())) {
 245       errCode = errDamaged;
 246       return;
 247     }
 248   }
 249
 250   // now set the trailer dictionary's xref pointer so we can fetch
 251   // indirect objects from it
 252   trailerDict.getDict()->setXRef(this);
 253 }
 254
 255 XRef::~XRef() {
 256   gfree(entries);
 257   trailerDict.free();
 258   if (streamEnds) {
 259     gfree(streamEnds);
 260   }
 261   if (objStr) {
 262     delete objStr;
 263   }
 264 }
 265
 266 // Read the 'startxref' position.
 267 Guint XRef::getStartXref() {
 268   char buf[xrefSearchSize+1];
 269   char *p;
 270   int c, n, i;
 271
 272   // read last xrefSearchSize bytes
 273   str->setPos(xrefSearchSize, -1);
 274   for (n = 0; n < xrefSearchSize; ++n) {
 275     if ((c = str->getChar()) == EOF) {
 276       break;
 277     }
 278     buf[n] = c;
 279   }
 280   buf[n] = '\0';
 281
 282   // find startxref
 283   for (i = n - 9; i >= 0; --i) {
 284     if (!strncmp(&buf[i], "startxref", 9)) {
 285       break;
 286     }
 287   }
 288   if (i < 0) {
 289     return 0;
 290   }
 291   for (p = &buf[i+9]; isspace(*p); ++p) ;
 292   lastXRefPos = strToUnsigned(p);
 293
 294   return lastXRefPos;
 295 }
 296
 297 // Read one xref table section.  Also reads the associated trailer
 298 // dictionary, and returns the prev pointer (if any).
 299 GBool XRef::readXRef(Guint *pos) {
 300   Parser *parser;
 301   Object obj;
 302   GBool more;
 303
 304   // start up a parser, parse one token
 305   obj.initNull();
 306   parser = new Parser(NULL,
 307              new Lexer(NULL,
 308                str->makeSubStream(start + *pos, gFalse, 0, &obj)));
 309   parser->getObj(&obj);
 310
 311   // parse an old-style xref table
 312   if (obj.isCmd("xref")) {
 313     obj.free();
 314     more = readXRefTable(parser, pos);
 315
 316   // parse an xref stream
 317   } else if (obj.isInt()) {
 318     obj.free();
 319     if (!parser->getObj(&obj)->isInt()) {
 320       goto err1;
 321     }
 322     obj.free();
 323     if (!parser->getObj(&obj)->isCmd("obj")) {
 324       goto err1;
 325     }
 326     obj.free();
 327     if (!parser->getObj(&obj)->isStream()) {
 328       goto err1;
 329     }
 330     more = readXRefStream(obj.getStream(), pos);
 331     obj.free();
 332
 333   } else {
 334     goto err1;
 335   }
 336
 337   delete parser;
 338   return more;
 339
 340  err1:
 341   obj.free();
 342   delete parser;
 343   ok = gFalse;
 344   return gFalse;
 345 }
 346
 347 GBool XRef::readXRefTable(Parser *parser, Guint *pos) {
 348   XRefEntry entry;
 349   GBool more;
 350   Object obj, obj2;
 351   Guint pos2;
 352   int first, n, newSize, i;
 353
 354   while (1) {
 355     parser->getObj(&obj);
 356     if (obj.isCmd("trailer")) {
 357       obj.free();
 358       break;
 359     }
 360     if (!obj.isInt()) {
 361       goto err1;
 362     }
 363     first = obj.getInt();
 364     obj.free();
 365     if (!parser->getObj(&obj)->isInt()) {
 366       goto err1;
 367     }
 368     n = obj.getInt();
 369     obj.free();
 370     if (first < 0 || n < 0 || first + n < 0) {
 371       goto err1;
 372     }
 373     if (first + n > size) {
 374       for (newSize = size ? 2 * size : 1024;
 375            first + n > newSize && newSize > 0;
 376            newSize <<= 1) ;
 377       if (newSize < 0) {
 378         goto err1;
 379       }
 380       entries = (XRefEntry *)greallocn(entries, newSize, sizeof(XRefEntry));
 381       for (i = size; i < newSize; ++i) {
 382         entries[i].offset = 0xffffffff;
 383         entries[i].type = xrefEntryFree;
 384       }
 385       size = newSize;
 386     }
 387     for (i = first; i < first + n; ++i) {
 388       if (!parser->getObj(&obj)->isInt()) {
 389         goto err1;
 390       }
 391       entry.offset = (Guint)obj.getInt();
 392       obj.free();
 393       if (!parser->getObj(&obj)->isInt()) {
 394         goto err1;
 395       }
 396       entry.gen = obj.getInt();
 397       obj.free();
 398       parser->getObj(&obj);
 399       if (obj.isCmd("n")) {
 400         entry.type = xrefEntryUncompressed;
 401       } else if (obj.isCmd("f")) {
 402         entry.type = xrefEntryFree;
 403       } else {
 404         goto err1;
 405       }
 406       obj.free();
 407       if (entries[i].offset == 0xffffffff) {
 408         entries[i] = entry;
 409         // PDF files of patents from the IBM Intellectual Property
 410         // Network have a bug: the xref table claims to start at 1
 411         // instead of 0.
 412         if (i == 1 && first == 1 &&
 413             entries[1].offset == 0 && entries[1].gen == 65535 &&
 414             entries[1].type == xrefEntryFree) {
 415           i = first = 0;
 416           entries[0] = entries[1];
 417           entries[1].offset = 0xffffffff;
 418         }
 419       }
 420     }
 421   }
 422
 423   // read the trailer dictionary
 424   if (!parser->getObj(&obj)->isDict()) {
 425     goto err1;
 426   }
 427
 428   // get the 'Prev' pointer
 429   obj.getDict()->lookupNF("Prev", &obj2);
 430   if (obj2.isInt()) {
 431     *pos = (Guint)obj2.getInt();
 432     more = gTrue;
 433   } else if (obj2.isRef()) {
 434     // certain buggy PDF generators generate "/Prev NNN 0 R" instead
 435     // of "/Prev NNN"
 436     *pos = (Guint)obj2.getRefNum();
 437     more = gTrue;
 438   } else {
 439     more = gFalse;
 440   }
 441   obj2.free();
 442
 443   // save the first trailer dictionary
 444   if (trailerDict.isNone()) {
 445     obj.copy(&trailerDict);
 446   }
 447
 448   // check for an 'XRefStm' key
 449   if (obj.getDict()->lookup("XRefStm", &obj2)->isInt()) {
 450     pos2 = (Guint)obj2.getInt();
 451     readXRef(&pos2);
 452     if (!ok) {
 453       obj2.free();
 454       goto err1;
 455     }
 456   }
 457   obj2.free();
 458
 459   obj.free();
 460   return more;
 461
 462  err1:
 463   obj.free();
 464   ok = gFalse;
 465   return gFalse;
 466 }
 467
 468 GBool XRef::readXRefStream(Stream *xrefStr, Guint *pos) {
 469   Dict *dict;
 470   int w[3];
 471   GBool more;
 472   Object obj, obj2, idx;
 473   int newSize, first, n, i;
 474
 475   dict = xrefStr->getDict();
 476
 477   if (!dict->lookupNF("Size", &obj)->isInt()) {
 478     goto err1;
 479   }
 480   newSize = obj.getInt();
 481   obj.free();
 482   if (newSize < 0) {
 483     goto err1;
 484   }
 485   if (newSize > size) {
 486     entries = (XRefEntry *)greallocn(entries, newSize, sizeof(XRefEntry));
 487     for (i = size; i < newSize; ++i) {
 488       entries[i].offset = 0xffffffff;
 489       entries[i].type = xrefEntryFree;
 490     }
 491     size = newSize;
 492   }
 493
 494   if (!dict->lookupNF("W", &obj)->isArray() ||
 495       obj.arrayGetLength() < 3) {
 496     goto err1;
 497   }
 498   for (i = 0; i < 3; ++i) {
 499     if (!obj.arrayGet(i, &obj2)->isInt()) {
 500       obj2.free();
 501       goto err1;
 502     }
 503     w[i] = obj2.getInt();
 504     obj2.free();
 505     if (w[i] < 0 || w[i] > 4) {
 506       goto err1;
 507     }
 508   }
 509   obj.free();
 510
 511   xrefStr->reset();
 512   dict->lookupNF("Index", &idx);
 513   if (idx.isArray()) {
 514     for (i = 0; i+1 < idx.arrayGetLength(); i += 2) {
 515       if (!idx.arrayGet(i, &obj)->isInt()) {
 516         idx.free();
 517         goto err1;
 518       }
 519       first = obj.getInt();
 520       obj.free();
 521       if (!idx.arrayGet(i+1, &obj)->isInt()) {
 522         idx.free();
 523         goto err1;
 524       }
 525       n = obj.getInt();
 526       obj.free();
 527       if (first < 0 || n < 0 ||
 528           !readXRefStreamSection(xrefStr, w, first, n)) {
 529         idx.free();
 530         goto err0;
 531       }
 532     }
 533   } else {
 534     if (!readXRefStreamSection(xrefStr, w, 0, newSize)) {
 535       idx.free();
 536       goto err0;
 537     }
 538   }
 539   idx.free();
 540
 541   dict->lookupNF("Prev", &obj);
 542   if (obj.isInt()) {
 543     *pos = (Guint)obj.getInt();
 544     more = gTrue;
 545   } else {
 546     more = gFalse;
 547   }
 548   obj.free();
 549   if (trailerDict.isNone()) {
 550     trailerDict.initDict(dict);
 551   }
 552
 553   return more;
 554
 555  err1:
 556   obj.free();
 557  err0:
 558   ok = gFalse;
 559   return gFalse;
 560 }
 561
 562 GBool XRef::readXRefStreamSection(Stream *xrefStr, int *w, int first, int n) {
 563   Guint offset;
 564   int type, gen, c, newSize, i, j;
 565
 566   if (first + n < 0) {
 567     return gFalse;
 568   }
 569   if (first + n > size) {
 570     for (newSize = size ? 2 * size : 1024;
 571          first + n > newSize && newSize > 0;
 572          newSize <<= 1) ;
 573     if (newSize < 0) {
 574       return gFalse;
 575     }
 576     entries = (XRefEntry *)greallocn(entries, newSize, sizeof(XRefEntry));
 577     for (i = size; i < newSize; ++i) {
 578       entries[i].offset = 0xffffffff;
 579       entries[i].type = xrefEntryFree;
 580     }
 581     size = newSize;
 582   }
 583   for (i = first; i < first + n; ++i) {
 584     if (w[0] == 0) {
 585       type = 1;
 586     } else {
 587       for (type = 0, j = 0; j < w[0]; ++j) {
 588         if ((c = xrefStr->getChar()) == EOF) {
 589           return gFalse;
 590         }
 591         type = (type << 8) + c;
 592       }
 593     }
 594     for (offset = 0, j = 0; j < w[1]; ++j) {
 595       if ((c = xrefStr->getChar()) == EOF) {
 596         return gFalse;
 597       }
 598       offset = (offset << 8) + c;
 599     }
 600     for (gen = 0, j = 0; j < w[2]; ++j) {
 601       if ((c = xrefStr->getChar()) == EOF) {
 602         return gFalse;
 603       }
 604       gen = (gen << 8) + c;
 605     }
 606     if (entries[i].offset == 0xffffffff) {
 607       switch (type) {
 608       case 0:
 609         entries[i].offset = offset;
 610         entries[i].gen = gen;
 611         entries[i].type = xrefEntryFree;
 612         break;
 613       case 1:
 614         entries[i].offset = offset;
 615         entries[i].gen = gen;
 616         entries[i].type = xrefEntryUncompressed;
 617         break;
 618       case 2:
 619         entries[i].offset = offset;
 620         entries[i].gen = gen;
 621         entries[i].type = xrefEntryCompressed;
 622         break;
 623       default:
 624         return gFalse;
 625       }
 626     }
 627   }
 628
 629   return gTrue;
 630 }
 631
 632 // Attempt to construct an xref table for a damaged file.
 633 GBool XRef::constructXRef() {
 634   Parser *parser;
 635   Object newTrailerDict, obj;
 636   char buf[256];
 637   Guint pos;
 638   int num, gen;
 639   int newSize;
 640   int streamEndsSize;
 641   char *p;
 642   int i;
 643   GBool gotRoot;
 644
 645   gfree(entries);
 646   size = 0;
 647   entries = NULL;
 648
 649   error(0, "PDF file is damaged - attempting to reconstruct xref table...");
 650   gotRoot = gFalse;
 651   streamEndsLen = streamEndsSize = 0;
 652
 653   str->reset();
 654   while (1) {
 655     pos = str->getPos();
 656     if (!str->getLine(buf, 256)) {
 657       break;
 658     }
 659     p = buf;
 660
 661     // got trailer dictionary
 662     if (!strncmp(p, "trailer", 7)) {
 663       obj.initNull();
 664       parser = new Parser(NULL,
 665                  new Lexer(NULL,
 666                    str->makeSubStream(pos + 7, gFalse, 0, &obj)));
 667       parser->getObj(&newTrailerDict);
 668       if (newTrailerDict.isDict()) {
 669         newTrailerDict.dictLookupNF("Root", &obj);
 670         if (obj.isRef()) {
 671           rootNum = obj.getRefNum();
 672           rootGen = obj.getRefGen();
 673           if (!trailerDict.isNone()) {
 674             trailerDict.free();
 675           }
 676           newTrailerDict.copy(&trailerDict);
 677           gotRoot = gTrue;
 678         }
 679         obj.free();
 680       }
 681       newTrailerDict.free();
 682       delete parser;
 683
 684     // look for object
 685     } else if (isdigit(*p)) {
 686       num = atoi(p);
 687       if (num > 0) {
 688         do {
 689           ++p;
 690         } while (*p && isdigit(*p));
 691         if (isspace(*p)) {
 692           do {
 693             ++p;
 694           } while (*p && isspace(*p));
 695           if (isdigit(*p)) {
 696             gen = atoi(p);
 697             do {
 698               ++p;
 699             } while (*p && isdigit(*p));
 700             if (isspace(*p)) {
 701               do {
 702                 ++p;
 703               } while (*p && isspace(*p));
 704               if (!strncmp(p, "obj", 3)) {
 705                 if (num >= size) {
 706                   newSize = (num + 1 + 255) & ~255;
 707                   if (newSize < 0) {
 708                     error(-1, "Bad object number");
 709                     return gFalse;
 710                   }
 711                   entries = (XRefEntry *)
 712                       greallocn(entries, newSize, sizeof(XRefEntry));
 713                   for (i = size; i < newSize; ++i) {
 714                     entries[i].offset = 0xffffffff;
 715                     entries[i].type = xrefEntryFree;
 716                   }
 717                   size = newSize;
 718                 }
 719                 if (entries[num].type == xrefEntryFree ||
 720                     gen >= entries[num].gen) {
 721                   entries[num].offset = pos - start;
 722                   entries[num].gen = gen;
 723                   entries[num].type = xrefEntryUncompressed;
 724                 }
 725               }
 726             }
 727           }
 728         }
 729       }
 730
 731     } else if (!strncmp(p, "endstream", 9)) {
 732       if (streamEndsLen == streamEndsSize) {
 733         streamEndsSize += 64;
 734         streamEnds = (Guint *)greallocn(streamEnds,
 735                                         streamEndsSize, sizeof(int));
 736       }
 737       streamEnds[streamEndsLen++] = pos;
 738     }
 739   }
 740
 741   if (gotRoot)
 742     return gTrue;
 743
 744   error(-1, "Couldn't find trailer dictionary");
 745   return gFalse;
 746 }
 747
 748 void XRef::setEncryption(int permFlagsA, GBool ownerPasswordOkA,
 749                          Guchar *fileKeyA, int keyLengthA, int encVersionA) {
 750   int i;
 751
 752   encrypted = gTrue;
 753   permFlags = permFlagsA;
 754   ownerPasswordOk = ownerPasswordOkA;
 755   if (keyLengthA <= 16) {
 756     keyLength = keyLengthA;
 757   } else {
 758     keyLength = 16;
 759   }
 760   for (i = 0; i < keyLength; ++i) {
 761     fileKey[i] = fileKeyA[i];
 762   }
 763   encVersion = encVersionA;
 764 }
 765
 766 GBool XRef::okToPrint(GBool ignoreOwnerPW) {
 767   return (!ignoreOwnerPW && ownerPasswordOk) || (permFlags & permPrint);
 768 }
 769
 770 GBool XRef::okToChange(GBool ignoreOwnerPW) {
 771   return (!ignoreOwnerPW && ownerPasswordOk) || (permFlags & permChange);
 772 }
 773
 774 GBool XRef::okToCopy(GBool ignoreOwnerPW) {
 775   return (!ignoreOwnerPW && ownerPasswordOk) || (permFlags & permCopy);
 776 }
 777
 778 GBool XRef::okToAddNotes(GBool ignoreOwnerPW) {
 779   return (!ignoreOwnerPW && ownerPasswordOk) || (permFlags & permNotes);
 780 }
 781
 782 Object *XRef::fetch(int num, int gen, Object *obj) {
 783   XRefEntry *e;
 784   Parser *parser;
 785   Object obj1, obj2, obj3;
 786
 787   // check for bogus ref - this can happen in corrupted PDF files
 788   if (num < 0 || num >= size) {
 789     goto err;
 790   }
 791
 792   e = &entries[num];
 793   switch (e->type) {
 794
 795   case xrefEntryUncompressed:
 796     if (e->gen != gen) {
 797       goto err;
 798     }
 799     obj1.initNull();
 800     parser = new Parser(this,
 801                new Lexer(this,
 802                  str->makeSubStream(start + e->offset, gFalse, 0, &obj1)));
 803     parser->getObj(&obj1);
 804     parser->getObj(&obj2);
 805     parser->getObj(&obj3);
 806     if (!obj1.isInt() || obj1.getInt() != num ||
 807         !obj2.isInt() || obj2.getInt() != gen ||
 808         !obj3.isCmd("obj")) {
 809       obj1.free();
 810       obj2.free();
 811       obj3.free();
 812       delete parser;
 813       goto err;
 814     }
 815     parser->getObj(obj, encrypted ? fileKey : (Guchar *)NULL, keyLength,
 816                    num, gen);
 817     obj1.free();
 818     obj2.free();
 819     obj3.free();
 820     delete parser;
 821     break;
 822
 823   case xrefEntryCompressed:
 824     if (gen != 0) {
 825       goto err;
 826     }
 827     if (!objStr || objStr->getObjStrNum() != (int)e->offset) {
 828       if (objStr) {
 829         delete objStr;
 830       }
 831       objStr = new ObjectStream(this, e->offset);
 832     }
 833     objStr->getObject(e->gen, num, obj);
 834     break;
 835
 836   default:
 837     goto err;
 838   }
 839
 840   return obj;
 841
 842  err:
 843   return obj->initNull();
 844 }
 845
 846 Object *XRef::getDocInfo(Object *obj) {
 847   return trailerDict.dictLookup("Info", obj);
 848 }
 849
 850 // Added for the pdftex project.
 851 Object *XRef::getDocInfoNF(Object *obj) {
 852   return trailerDict.dictLookupNF("Info", obj);
 853 }
 854
 855 GBool XRef::getStreamEnd(Guint streamStart, Guint *streamEnd) {
 856   int a, b, m;
 857
 858   if (streamEndsLen == 0 ||
 859       streamStart > streamEnds[streamEndsLen - 1]) {
 860     return gFalse;
 861   }
 862
 863   a = -1;
 864   b = streamEndsLen - 1;
 865   // invariant: streamEnds[a] < streamStart <= streamEnds[b]
 866   while (b - a > 1) {
 867     m = (a + b) / 2;
 868     if (streamStart <= streamEnds[m]) {
 869       b = m;
 870     } else {
 871       a = m;
 872     }
 873   }
 874   *streamEnd = streamEnds[b];
 875   return gTrue;
 876 }
 877
 878 Guint XRef::strToUnsigned(char *s) {
 879   Guint x;
 880   char *p;
 881   int i;
 882
 883   x = 0;
 884   for (p = s, i = 0; *p && isdigit(*p) && i < 10; ++p, ++i) {
 885     x = 10 * x + (*p - '0');
 886   }
 887   return x;
 888 }