Bug fix: handle generation > 0 when generating object streams

Rework QPDFWriter to always track old object IDs and QPDFObjGen
instead of int, thus not discarding the generation number.  Switch to
QPDF::getCompressibleObjGen() to properly handle the case of an old
object eligible for compression that has a generation of other than
zero.

4 files changed, 90 insertions, 1 deletions

diff --git a/qpdf/qpdf.testcov b/qpdf/qpdf.testcov
index 31e15495..16650f73 100644
--- a/qpdf/qpdf.testcov
+++ b/qpdf/qpdf.testcov
@@ -262,3 +262,4 @@ 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
+QPDFWriter original obj non-zero gen 0
diff --git a/qpdf/qtest/qpdf.test b/qpdf/qtest/qpdf.test
index 5ae2ae3c..30200ca1 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 += 62;
+$n_tests += 64;
 
 $td->runtest("qpdf version",
 	     {$td->COMMAND => "qpdf --version"},
@@ -501,6 +501,14 @@ $td->runtest("overridden compressed objects",
               $td->EXIT_STATUS => 0},
              $td->NORMALIZE_NEWLINES);
 
+$td->runtest("generate object streams for gen > 0",
+             {$td->COMMAND => "qpdf --qdf --static-id" .
+		  " --object-streams=generate gen1.pdf a.pdf"},
+             {$td->STRING => "", $td->EXIT_STATUS => 0});
+$td->runtest("check file",
+             {$td->FILE => "a.pdf"},
+             {$td->FILE => "gen1.qdf"});
+
 show_ntests();
 # ----------
 $td->notify("--- Numeric range parsing tests ---");
@@ -1183,6 +1191,7 @@ my @to_linearize =
      'lin-delete-and-reuse',	# linearized, then delete and reuse
      'object-stream',		# contains object streams
      'hybrid-xref',	        # contains both xref tables and streams
+     'gen1',                    # has objects with generation > 0
      @linearized_files,		# we should be able to relinearize
      );
 
diff --git a/qpdf/qtest/qpdf/gen1.pdf b/qpdf/qtest/qpdf/gen1.pdf
new file mode 100644
index 00000000..6bfbbefe
--- /dev/null
+++ b/qpdf/qtest/qpdf/gen1.pdf
@@ -0,0 +1,79 @@
+%PDF-1.3
+1 1 obj
+<<
+  /Type /Catalog
+  /Pages 2 1 R
+>>
+endobj
+
+2 1 obj
+<<
+  /Type /Pages
+  /Kids [
+    3 1 R
+  ]
+  /Count 1
+>>
+endobj
+
+3 1 obj
+<<
+  /Type /Page
+  /Parent 2 1 R
+  /MediaBox [0 0 612 792]
+  /Contents 4 1 R
+  /Resources <<
+    /ProcSet 5 1 R
+    /Font <<
+      /F1 6 1 R
+    >>
+  >>
+>>
+endobj
+
+4 1 obj
+<<
+  /Length 44
+>>
+stream
+BT
+  /F1 24 Tf
+  72 720 Td
+  (Potato) Tj
+ET
+endstream
+endobj
+
+5 1 obj
+[
+  /PDF
+  /Text
+]
+endobj
+
+6 1 obj
+<<
+  /Type /Font
+  /Subtype /Type1
+  /Name /F1
+  /BaseFont /Helvetica
+  /Encoding /WinAnsiEncoding
+>>
+endobj
+
+xref
+0 7
+0000000000 65535 f 
+0000000009 00001 n 
+0000000063 00001 n 
+0000000135 00001 n 
+0000000307 00001 n 
+0000000403 00001 n 
+0000000438 00001 n 
+trailer <<
+  /Size 7
+  /Root 1 1 R
+>>
+startxref
+556
+%%EOF
diff --git a/qpdf/qtest/qpdf/gen1.qdf b/qpdf/qtest/qpdf/gen1.qdf
new file mode 100644
index 00000000..802bf2bc
--- /dev/null
+++ b/qpdf/qtest/qpdf/gen1.qdf