1 //========================================================================
5 // Copyright 1996-2002 Glyph & Cog, LLC
7 //========================================================================
11 #ifdef USE_GCC_PRAGMAS
12 #pragma implementation
29 #include "ErrorCodes.h"
32 //------------------------------------------------------------------------
34 #define xrefSearchSize 1024 // read this many bytes at end of file
35 // to look for 'startxref'
38 //------------------------------------------------------------------------
40 //------------------------------------------------------------------------
42 #define permPrint (1<<2)
43 #define permChange (1<<3)
44 #define permCopy (1<<4)
45 #define permNotes (1<<5)
46 #define defPermFlags 0xfffc
49 //------------------------------------------------------------------------
51 //------------------------------------------------------------------------
53 XRef::XRef(BaseStream *strA, GString *ownerPassword, GString *userPassword) {
66 start = str->getStart();
69 // if there was a problem with the trailer,
70 // try to reconstruct the xref table
72 if (!(ok = constructXRef())) {
77 // trailer is ok - read the xref table
79 entries = (XRefEntry *)gmalloc(size * sizeof(XRefEntry));
80 for (i = 0; i < size; ++i) {
81 entries[i].offset = 0xffffffff;
82 entries[i].used = gFalse;
84 while (readXRef(&pos)) ;
86 // if there was a problem with the xref table,
87 // try to reconstruct it
92 if (!(ok = constructXRef())) {
99 // now set the trailer dictionary's xref pointer so we can fetch
100 // indirect objects from it
101 trailerDict.getDict()->setXRef(this);
103 // check for encryption
104 #ifndef NO_DECRYPTION
107 if (checkEncrypted(ownerPassword, userPassword)) {
109 errCode = errEncrypted;
122 // Read startxref position, xref table size, and root. Returns
123 // first xref position.
124 Guint XRef::readTrailer() {
127 char buf[xrefSearchSize+1];
134 // read last xrefSearchSize bytes
135 str->setPos(xrefSearchSize, -1);
136 for (n = 0; n < xrefSearchSize; ++n) {
137 if ((c = str->getChar()) == EOF)
144 for (i = n - 9; i >= 0; --i) {
145 if (!strncmp(&buf[i], "startxref", 9))
150 for (p = &buf[i+9]; isspace(*p); ++p) ;
151 pos = lastXRefPos = strToUnsigned(p);
153 // find trailer dict by looking after first xref table
154 // (NB: we can't just use the trailer dict at the end of the file --
155 // this won't work for linearized files.)
156 str->setPos(start + pos);
157 for (i = 0; i < 4; ++i)
158 buf[i] = str->getChar();
159 if (strncmp(buf, "xref", 4))
163 str->setPos(start + pos1);
164 for (i = 0; i < 35; ++i) {
165 if ((c = str->getChar()) == EOF)
169 if (!strncmp(buf, "trailer", 7))
172 while (isspace(*p)) ++p;
173 while ('0' <= *p && *p <= '9') ++p;
174 while (isspace(*p)) ++p;
176 while ('0' <= *p && *p <= '9') ++p;
177 while (isspace(*p)) ++p;
180 pos1 += (p - buf) + n * 20;
186 parser = new Parser(NULL,
188 str->makeSubStream(start + pos1, gFalse, 0, &obj)));
189 parser->getObj(&trailerDict);
190 if (trailerDict.isDict()) {
191 trailerDict.dictLookupNF("Size", &obj);
197 trailerDict.dictLookupNF("Root", &obj);
199 rootNum = obj.getRefNum();
200 rootGen = obj.getRefGen();
210 // return first xref position
214 // Read an xref table and the prev pointer from the trailer.
215 GBool XRef::readXRef(Guint *pos) {
220 int first, newSize, n, i, j;
223 // seek to xref in stream
224 str->setPos(start + *pos);
226 // make sure it's an xref table
227 while ((c = str->getChar()) != EOF && isspace(c)) ;
229 s[1] = (char)str->getChar();
230 s[2] = (char)str->getChar();
231 s[3] = (char)str->getChar();
232 if (!(s[0] == 'x' && s[1] == 'r' && s[2] == 'e' && s[3] == 'f')) {
238 while ((c = str->lookChar()) != EOF && isspace(c)) {
244 for (i = 0; (c = str->getChar()) != EOF && isdigit(c) && i < 20; ++i) {
252 while ((c = str->lookChar()) != EOF && isspace(c)) {
255 for (i = 0; (c = str->getChar()) != EOF && isdigit(c) && i < 20; ++i) {
263 while ((c = str->lookChar()) != EOF && isspace(c)) {
266 // check for buggy PDF files with an incorrect (too small) xref
268 if (first + n > size) {
269 newSize = size + 256;
270 entries = (XRefEntry *)grealloc(entries, newSize * sizeof(XRefEntry));
271 for (i = size; i < newSize; ++i) {
272 entries[i].offset = 0xffffffff;
273 entries[i].used = gFalse;
277 for (i = first; i < first + n; ++i) {
278 for (j = 0; j < 20; ++j) {
279 if ((c = str->getChar()) == EOF) {
284 if (entries[i].offset == 0xffffffff) {
286 entries[i].offset = strToUnsigned(s);
288 entries[i].gen = atoi(&s[11]);
290 entries[i].used = gTrue;
291 } else if (s[17] == 'f') {
292 entries[i].used = gFalse;
296 // PDF files of patents from the IBM Intellectual Property
297 // Network have a bug: the xref table claims to start at 1
299 if (i == 1 && first == 1 &&
300 entries[1].offset == 0 && entries[1].gen == 65535 &&
303 entries[0] = entries[1];
304 entries[1].offset = 0xffffffff;
310 // read prev pointer from trailer dictionary
312 parser = new Parser(NULL,
314 str->makeSubStream(str->getPos(), gFalse, 0, &obj)));
315 parser->getObj(&obj);
316 if (!obj.isCmd("trailer")) {
320 parser->getObj(&obj);
324 obj.getDict()->lookupNF("Prev", &obj2);
326 *pos = (Guint)obj2.getInt();
344 // Attempt to construct an xref table for a damaged file.
345 GBool XRef::constructXRef() {
357 error(0, "PDF file is damaged - attempting to reconstruct xref table...");
359 streamEndsLen = streamEndsSize = 0;
364 if (!str->getLine(buf, 256)) {
369 // got trailer dictionary
370 if (!strncmp(p, "trailer", 7)) {
372 parser = new Parser(NULL,
374 str->makeSubStream(start + pos + 7, gFalse, 0, &obj)));
375 if (!trailerDict.isNone())
377 parser->getObj(&trailerDict);
378 if (trailerDict.isDict()) {
379 trailerDict.dictLookupNF("Root", &obj);
381 rootNum = obj.getRefNum();
382 rootGen = obj.getRefGen();
392 } else if (isdigit(*p)) {
396 } while (*p && isdigit(*p));
400 } while (*p && isspace(*p));
405 } while (*p && isdigit(*p));
409 } while (*p && isspace(*p));
410 if (!strncmp(p, "obj", 3)) {
412 newSize = (num + 1 + 255) & ~255;
413 entries = (XRefEntry *)
414 grealloc(entries, newSize * sizeof(XRefEntry));
415 for (i = size; i < newSize; ++i) {
416 entries[i].offset = 0xffffffff;
417 entries[i].used = gFalse;
421 if (!entries[num].used || gen >= entries[num].gen) {
422 entries[num].offset = pos - start;
423 entries[num].gen = gen;
424 entries[num].used = gTrue;
431 } else if (!strncmp(p, "endstream", 9)) {
432 if (streamEndsLen == streamEndsSize) {
433 streamEndsSize += 64;
434 streamEnds = (Guint *)grealloc(streamEnds,
435 streamEndsSize * sizeof(int));
437 streamEnds[streamEndsLen++] = pos;
444 error(-1, "Couldn't find trailer dictionary");
448 #ifndef NO_DECRYPTION
449 GBool XRef::checkEncrypted(GString *ownerPassword, GString *userPassword) {
450 Object encrypt, filterObj, versionObj, revisionObj, lengthObj;
451 Object ownerKey, userKey, permissions, fileID, fileID1;
457 permFlags = defPermFlags;
458 ownerPasswordOk = gFalse;
459 trailerDict.dictLookup("Encrypt", &encrypt);
460 if ((encrypted1 = encrypt.isDict())) {
462 encrypt.dictLookup("Filter", &filterObj);
463 if (filterObj.isName("Standard")) {
464 encrypt.dictLookup("V", &versionObj);
465 encrypt.dictLookup("R", &revisionObj);
466 encrypt.dictLookup("Length", &lengthObj);
467 encrypt.dictLookup("O", &ownerKey);
468 encrypt.dictLookup("U", &userKey);
469 encrypt.dictLookup("P", &permissions);
470 trailerDict.dictLookup("ID", &fileID);
471 if (versionObj.isInt() &&
472 revisionObj.isInt() &&
473 ownerKey.isString() && ownerKey.getString()->getLength() == 32 &&
474 userKey.isString() && userKey.getString()->getLength() == 32 &&
475 permissions.isInt() &&
477 encVersion = versionObj.getInt();
478 encRevision = revisionObj.getInt();
479 if (lengthObj.isInt()) {
480 keyLength = lengthObj.getInt() / 8;
484 permFlags = permissions.getInt();
485 if (encVersion >= 1 && encVersion <= 2 &&
486 encRevision >= 2 && encRevision <= 3) {
487 fileID.arrayGet(0, &fileID1);
488 if (fileID1.isString()) {
489 if (Decrypt::makeFileKey(encVersion, encRevision, keyLength,
490 ownerKey.getString(), userKey.getString(),
491 permFlags, fileID1.getString(),
492 ownerPassword, userPassword, fileKey,
494 if (ownerPassword && !ownerPasswordOk) {
495 error(-1, "Incorrect owner password");
499 error(-1, "Incorrect password");
502 error(-1, "Weird encryption info");
506 error(-1, "Unsupported version/revision (%d/%d) of Standard security handler",
507 encVersion, encRevision);
510 error(-1, "Weird encryption info");
520 error(-1, "Unknown security handler '%s'",
521 filterObj.isName() ? filterObj.getName() : "???");
527 // this flag has to be set *after* we read the O/U/P strings
528 encrypted = encrypted1;
533 GBool XRef::checkEncrypted(GString *ownerPassword, GString *userPassword) {
537 trailerDict.dictLookup("Encrypt", &obj);
538 if ((encrypted = !obj.isNull())) {
539 error(-1, "PDF file is encrypted and this version of the Xpdf tools");
540 error(-1, "was built without decryption support.");
547 GBool XRef::okToPrint(GBool ignoreOwnerPW) {
548 #ifndef NO_DECRYPTION
549 if ((ignoreOwnerPW || !ownerPasswordOk) && !(permFlags & permPrint)) {
556 GBool XRef::okToChange(GBool ignoreOwnerPW) {
557 #ifndef NO_DECRYPTION
558 if ((ignoreOwnerPW || !ownerPasswordOk) && !(permFlags & permChange)) {
565 GBool XRef::okToCopy(GBool ignoreOwnerPW) {
566 #ifndef NO_DECRYPTION
567 if ((ignoreOwnerPW || !ownerPasswordOk) && !(permFlags & permCopy)) {
574 GBool XRef::okToAddNotes(GBool ignoreOwnerPW) {
575 #ifndef NO_DECRYPTION
576 if ((ignoreOwnerPW || !ownerPasswordOk) && !(permFlags & permNotes)) {
583 Object *XRef::fetch(int num, int gen, Object *obj) {
586 Object obj1, obj2, obj3;
588 // check for bogus ref - this can happen in corrupted PDF files
589 if (num < 0 || num >= size) {
595 if (e->gen == gen && e->offset != 0xffffffff) {
597 parser = new Parser(this,
599 str->makeSubStream(start + e->offset, gFalse, 0, &obj1)));
600 parser->getObj(&obj1);
601 parser->getObj(&obj2);
602 parser->getObj(&obj3);
603 if (obj1.isInt() && obj1.getInt() == num &&
604 obj2.isInt() && obj2.getInt() == gen &&
606 #ifndef NO_DECRYPTION
607 parser->getObj(obj, encrypted ? fileKey : (Guchar *)NULL, keyLength,
625 Object *XRef::getDocInfo(Object *obj) {
626 return trailerDict.dictLookup("Info", obj);
629 // Added for the pdftex project.
630 Object *XRef::getDocInfoNF(Object *obj) {
631 return trailerDict.dictLookupNF("Info", obj);
634 GBool XRef::getStreamEnd(Guint streamStart, Guint *streamEnd) {
637 if (streamEndsLen == 0 ||
638 streamStart > streamEnds[streamEndsLen - 1]) {
643 b = streamEndsLen - 1;
644 // invariant: streamEnds[a] < streamStart <= streamEnds[b]
647 if (streamStart <= streamEnds[m]) {
653 *streamEnd = streamEnds[b];
657 Guint XRef::strToUnsigned(char *s) {
663 for (p = s, i = 0; *p && isdigit(*p) && i < 10; ++p, ++i) {
664 x = 10 * x + (*p - '0');