Add test case for self-referential object streams

Previous test case was lost in #1221. Test file was created from
object-stream.pdf by adding a reference to itself into object stream 1 0.

ChangeLog

@@ -17,6 +17,11 @@
 	* Add static option to Pl_DCT to control whether decompression of
 	corrupt JPEG data is attempted.
 
+2024-07-01  M Holger  <m.holger@qpdf.org>
+
+	* Bug fix: certain invalid object streams caused the insertion of
+	invalid entries into in the xref table.
+
 2024-06-29  M Holger  <m.holger@qpdf.org>
 
 	* Bug fix: in QPDFOutlineObjectHelper detect loops in the list of 

libqpdf/QPDF.cc

@@ -1938,6 +1938,7 @@ QPDF::resolveObjectsInStream(int obj_stream_number)
             continue;
         }
         if (num == obj_stream_number) {
+            QTC::TC("qpdf", "QPDF ignore self-referential object stream");
             warn(damagedPDF(
                 input,
                 m->last_object_description,

qpdf/qpdf.testcov

@@ -4,6 +4,7 @@ QPDF err wrong objid/generation 0
 QPDF check objid 1
 QPDF check generation 1
 QPDF check obj 1
+QPDF ignore self-referential object stream 0
 QPDF hint table length indirect 0
 QPDF hint table length direct 0
 QPDF P absent in lindict 0

qpdf/qtest/object-stream.test

@@ -16,7 +16,7 @@ cleanup();
 
 my $td = new TestDriver('object-stream');
 
-my $n_tests = 7 + (36 * 4) + (12 * 2);
+my $n_tests = 9 + (36 * 4) + (12 * 2);
 my $n_compare_pdfs = 36;
 
 for (my $n = 16; $n <= 19; ++$n)
@@ -107,5 +107,16 @@ $td->runtest("check file",
              {$td->FILE => "a.pdf"},
              {$td->FILE => "recover-xref-stream-recovered.pdf"});
 
+# Self-referential object stream
+$td->runtest("self-referential object stream",
+             {$td->COMMAND => "qpdf --static-id --qdf" .
+                  " object-stream-self-ref.pdf a.pdf"},
+             {$td->FILE => "object-stream-self-ref.out", $td->EXIT_STATUS => 3},
+             $td->NORMALIZE_NEWLINES);
+$td->runtest("check file",
+             {$td->FILE => "a.pdf"},
+             {$td->FILE => "object-stream-self-ref.out.pdf"});
+
+
 cleanup();
 $td->report(calc_ntests($n_tests, $n_compare_pdfs));

qpdf/qtest/qpdf/object-stream-self-ref.out

@@ -0,0 +1,2 @@
+WARNING: object-stream-self-ref.pdf object stream 1 (object 1 0, offset 2): object stream claims to contain itself
+qpdf: operation succeeded with warnings; resulting file may have some problems