Bug fix: properly handle overridden compressed objects

When caching objects in an object stream, only cache objects that
still resolve to that stream.  See Changelog mod from this commit for
details.

5 files changed, 28 insertions, 1 deletions

diff --git a/qpdf/qpdf.testcov b/qpdf/qpdf.testcov
index b09e966c..31e15495 100644
--- a/qpdf/qpdf.testcov
+++ b/qpdf/qpdf.testcov
@@ -261,3 +261,4 @@ qpdf-c called qpdf_set_r5_encryption_parameters 0
 qpdf-c called qpdf_set_r6_encryption_parameters 0
 QPDFObjectHandle EOF in inline image 0
 QPDFObjectHandle inline image token 0
+QPDF not caching overridden objstm object 0
diff --git a/qpdf/qtest/qpdf.test b/qpdf/qtest/qpdf.test
index f447bd83..8375e5f2 100644
--- a/qpdf/qtest/qpdf.test
+++ b/qpdf/qtest/qpdf.test
@@ -199,7 +199,7 @@ $td->runtest("remove page we don't have",
 show_ntests();
 # ----------
 $td->notify("--- Miscellaneous Tests ---");
-$n_tests += 60;
+$n_tests += 61;
 
 $td->runtest("qpdf version",
 	     {$td->COMMAND => "qpdf --version"},
@@ -484,6 +484,18 @@ $td->runtest("content stream errors",
               $td->EXIT_STATUS => 2},
              $td->NORMALIZE_NEWLINES);
 
+# The file override-compressed-object.pdf contains an object stream
+# with four strings in it.  The file is then appended.  The appended
+# section overrides one of the four strings with a string in another
+# object stream and another one in an uncompressed object.  The other
+# two strings are left alone.  The test case exercises that all four
+# objects have the correct value.
+$td->runtest("overridden compressed objects",
+             {$td->COMMAND => "test_driver 38 override-compressed-object.pdf"},
+             {$td->FILE => "override-compressed-object.out",
+              $td->EXIT_STATUS => 0},
+             $td->NORMALIZE_NEWLINES);
+
 show_ntests();
 # ----------
 $td->notify("--- Numeric range parsing tests ---");
diff --git a/qpdf/qtest/qpdf/override-compressed-object.out b/qpdf/qtest/qpdf/override-compressed-object.out
new file mode 100644
index 00000000..a3fbd51d
--- /dev/null
+++ b/qpdf/qtest/qpdf/override-compressed-object.out
@@ -0,0 +1,5 @@
+(orig-1)
+(override-2)
+(override-3)
+(orig-4)
+test 38 done
diff --git a/qpdf/qtest/qpdf/override-compressed-object.pdf b/qpdf/qtest/qpdf/override-compressed-object.pdf
new file mode 100644
index 00000000..0647b7fe
--- /dev/null
+++ b/qpdf/qtest/qpdf/override-compressed-object.pdf
diff --git a/qpdf/test_driver.cc b/qpdf/test_driver.cc
index 799ea4ba..d6534abf 100644
--- a/qpdf/test_driver.cc
+++ b/qpdf/test_driver.cc
@@ -1302,6 +1302,15 @@ void runtest(int n, char const* filename1, char const* arg2)
             QPDFObjectHandle::parseContentStream(contents, &cb);
         }
     }
+    else if (n == 38)
+    {
+        // Designed for override-compressed-object.pdf
+        QPDFObjectHandle qtest = pdf.getRoot().getKey("/QTest");
+        for (int i = 0; i < qtest.getArrayNItems(); ++i)
+        {
+            std::cout << qtest.getArrayItem(i).unparseResolved() << std::endl;
+        }
+    }
     else
     {
 	throw std::runtime_error(std::string("invalid test ") +