OpenSystemsDevelopment / qpdf

Commit 4499e04b5714747eb954420f8133e650a5137d45

Authored by Jay Berkenbilt
1 parent 35d72c82

better recovery for appended files with damaged cross-reference tables 

git-svn-id: svn+q:///qpdf/trunk@649 71b93d88-0707-0410-a8cf-f5a4172ac649
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Showing 4 changed files with 37 additions and 6 deletions
ChangeLog
  View file @4499e04
  1 +2009-02-20 Jay Berkenbilt <ejb@ql.org>
  2 +
  3 + * libqpdf/QPDF.cc (QPDF::insertXrefEntry): when recovering the
  4 + cross-reference table, have objects we encounter later in the file
  5 + supersede those we found earlier. This improves the chances of
  6 + being able to recover appended files with damaged cross-reference
  7 + tables.
  8 +
1 9 2009-02-19 Jay Berkenbilt <ejb@ql.org>
2 10  
3 11 * libqpdf/Pl_LZWDecoder.cc: correct logic error for previously
... ...
  1 +2.0.4
  2 +=====
  3 +
  4 + * Spell check to fix types in messages and comments. Known type in
  5 + "damanged".
  6 +
  7 + * Exit with a different exit code if warning are found during check
  8 + mode.
  9 +
  10 +
1 11 General
2 12 =======
3 13  
... ...
include/qpdf/QPDF.hh
  View file @4499e04
... ... @@ -333,7 +333,8 @@ class QPDF
333 333 int read_xrefTable(off_t offset);
334 334 int read_xrefStream(off_t offset);
335 335 int processXRefStream(off_t offset, QPDFObjectHandle& xref_stream);
336   - void insertXrefEntry(int obj, int f0, int f1, int f2);
  336 + void insertXrefEntry(int obj, int f0, int f1, int f2,
  337 + bool overwrite = false);
337 338 QPDFObjectHandle readObject(
338 339 InputSource*, int objid, int generation,
339 340 bool in_object_stream);
... ...
libqpdf/QPDF.cc
  View file @4499e04
... ... @@ -435,7 +435,7 @@ QPDF::reconstruct_xref(QPDFExc&amp; e)
435 435 int obj = atoi(m.getMatch(1).c_str());
436 436 int gen = atoi(m.getMatch(2).c_str());
437 437 int offset = this->file.getLastOffset();
438   - insertXrefEntry(obj, 1, offset, gen);
  438 + insertXrefEntry(obj, 1, offset, gen, true);
439 439 }
440 440 else if ((! this->trailer.isInitialized()) &&
441 441 trailer_re.match(line.c_str()))
... ... @@ -865,11 +865,15 @@ QPDF::processXRefStream(off_t xref_offset, QPDFObjectHandle&amp; xref_obj)
865 865 }
866 866  
867 867 void
868   -QPDF::insertXrefEntry(int obj, int f0, int f1, int f2)
  868 +QPDF::insertXrefEntry(int obj, int f0, int f1, int f2, bool overwrite)
869 869 {
870 870 // Populate the xref table in such a way that the first reference
871 871 // to an object that we see, which is the one in the latest xref
872   - // table in which it appears, is the one that gets stored.
  872 + // table in which it appears, is the one that gets stored. This
  873 + // works because we are reading more recent appends before older
  874 + // ones. Exception: if overwrite is true, then replace any
  875 + // existing object. This is used in xref recovery mode, which
  876 + // reads the file from beginning to end.
873 877  
874 878 // If there is already an entry for this object and generation in
875 879 // the table, it means that a later xref table has registered this
... ... @@ -879,8 +883,16 @@ QPDF::insertXrefEntry(int obj, int f0, int f1, int f2)
879 883 ObjGen og(obj, gen);
880 884 if (this->xref_table.count(og))
881 885 {
882   - QTC::TC("qpdf", "QPDF xref reused object");
883   - return;
  886 + if (overwrite)
  887 + {
  888 + QTC::TC("qpdf", "QPDF xref overwrite object");
  889 + this->xref_table.erase(og);
  890 + }
  891 + else
  892 + {
  893 + QTC::TC("qpdf", "QPDF xref reused object");
  894 + return;
  895 + }
884 896 }
885 897 if (this->deleted_objects.count(obj))
886 898 {
... ...