Track whether certain page modifying methods have been called

We need to know whether pushInheritedAttributesToPage or getAllPages
have been called when generating JSON output. When reading the JSON
back in, we have to call the same methods so that object numbers will
line up properly.

TODO

@@ -9,10 +9,6 @@ Before Release:
 * Release qtest with updates to qtest-driver and copy back into qpdf
 
 Next:
-* QPDF -- track whether the pages tree was modified (whether
-  getAllPages was ever called. If so, consider generating a non-flat
-  pages tree before creating output to better handle files with lots
-  of pages.
 * JSON v2 fixes
 
 Pending changes:
@@ -44,6 +40,12 @@ Pending changes:
   drivers from the qpdf directory into the latter category as long
   as doing so isn't too troublesome from a coverage standpoint.
 * Consider adding fuzzer code for JSON
+* Consider generating a non-flat pages tree before creating output to
+  better handle files with lots of pages. If there are more than 256
+  pages, add a second layer with the second layer nodes having no more
+  than 256 nodes and being as evenly sizes as possible. Don't worry
+  about the case of more than 65,536 pages. If the top node has more
+  than 256 children, we'll live with it.
 
 Soon: Break ground on "Document-level work"
 
@@ -81,7 +83,8 @@ JSON v2 fixes
     "qpdf": [
       {
         "jsonversion": 2,
-        "repairpagestree": false,
+        "pushedinheritedpageresources": false,
+        "calledgetallpages": false,
         "maxobjectid": 10
       },
       {
@@ -110,6 +113,10 @@ JSON v2 fixes
     the same number of elements whose individual elements are
     validated according to the regular rules.
 
+  * When reading back in, we'll have to call
+    pushInheritedAttributesToPage or getAllPages based on the values
+    of the metadata.
+
 * Support json v2 in the C API. At a minimum, write_json,
   create_from_json, and update_from_json need to be there and should
   take the same kinds of functions as the C API for logger.

include/qpdf/QPDF.hh

@@ -709,6 +709,11 @@ class QPDF
     QPDF_DLL
     std::vector<QPDFObjectHandle> const& getAllPages();
 
+    QPDF_DLL
+    bool everCalledGetAllPages() const;
+    QPDF_DLL
+    bool everPushedInheritedAttributesToPages() const;
+
     // These methods, given a page object or its object/generation
     // number, returns the 0-based index into the array returned by
     // getAllPages() for that page. An exception is thrown if the page
@@ -1690,6 +1695,8 @@ class QPDF
         std::vector<QPDFObjectHandle> all_pages;
         std::map<QPDFObjGen, int> pageobj_to_pages_pos;
         bool pushed_inherited_attributes_to_pages;
+        bool ever_pushed_inherited_attributes_to_pages;
+        bool ever_called_get_all_pages;
         std::vector<QPDFExc> warnings;
         std::map<unsigned long long, ObjCopier> object_copiers;
         std::shared_ptr<QPDFObjectHandle::StreamDataProvider> copied_streams;

libqpdf/QPDF.cc

@@ -222,6 +222,8 @@ QPDF::Members::Members() :
     attempt_recovery(true),
     encp(new EncryptionParameters),
     pushed_inherited_attributes_to_pages(false),
+    ever_pushed_inherited_attributes_to_pages(false),
+    ever_called_get_all_pages(false),
     copied_stream_data_provider(0),
     reconstructed_xref(false),
     fixed_dangling_refs(false),
@@ -2879,3 +2881,15 @@ QPDF::stopOnError(std::string const& message)
         this->m->file->getLastOffset(),
         message);
 }
+
+bool
+QPDF::everCalledGetAllPages() const
+{
+    return this->m->ever_called_get_all_pages;
+}
+
+bool
+QPDF::everPushedInheritedAttributesToPages() const
+{
+    return this->m->ever_pushed_inherited_attributes_to_pages;
+}

libqpdf/QPDF_optimization.cc

@@ -162,6 +162,7 @@ QPDF::pushInheritedAttributesToPage(bool allow_changes, bool warn_skipped_keys)
                                " pushing inherited attributes to pages");
     }
     this->m->pushed_inherited_attributes_to_pages = true;
+    this->m->ever_pushed_inherited_attributes_to_pages = true;
 }
 
 void

libqpdf/QPDF_pages.cc

@@ -54,6 +54,7 @@ QPDF::getAllPages()
     // Note that pushInheritedAttributesToPage may also be used to
     // initialize this->m->all_pages.
     if (this->m->all_pages.empty()) {
+        this->m->ever_called_get_all_pages = true;
         std::set<QPDFObjGen> visited;
         std::set<QPDFObjGen> seen;
         QPDFObjectHandle pages = getRoot().getKey("/Pages");

qpdf/test_driver.cc

@@ -691,7 +691,9 @@ test_15(QPDF& pdf, char const* arg2)
     // Remove pages from various places, checking to make sure
     // that our pages reference is getting updated.
     assert(pages.size() == 10);
+    assert(!pdf.everPushedInheritedAttributesToPages());
     pdf.removePage(pages.back()); // original page 9
+    assert(pdf.everPushedInheritedAttributesToPages());
     assert(pages.size() == 9);
     pdf.removePage(*pages.begin()); // original page 0
     assert(pages.size() == 8);
@@ -767,7 +769,9 @@ static void
 test_16(QPDF& pdf, char const* arg2)
 {
     // Insert a page manually and then update the cache.
+    assert(!pdf.everCalledGetAllPages());
     std::vector<QPDFObjectHandle> const& all_pages = pdf.getAllPages();
+    assert(pdf.everCalledGetAllPages());
 
     QPDFObjectHandle contents = createPageContents(pdf, "New page 10");
     QPDFObjectHandle page =
@@ -785,6 +789,7 @@ test_16(QPDF& pdf, char const* arg2)
     kids.appendItem(page);
     assert(all_pages.size() == 10);
     pdf.updateAllPagesCache();
+    assert(pdf.everCalledGetAllPages());
     assert(all_pages.size() == 11);
     assert(all_pages.back().getObjGen() == page.getObjGen());