Return results rather than using reference parameters.
Fixes bug in #1272 where parameters were not reinitialized when calling
read_bad_entry from read_entry.
Optimistically read subsection headers without reading individual object
entries, assuming that they are 20 bytes long as per the PDF spec. If
problems are encountered, fall back to calling bad_subsections.
Split reconstruction into two passes - scanning of input for objects and
insertion of objects into the xref table. This allows insertion to take
place in the usual reverse order and removes the need for a separate
insert_reconstructed method.
Rename to Xref_table::subsection.
Return results instead of using out parameters.
Take on responsibility for throwing exception and calculation of offset of
first subsection entry.
1. Make class final
2. Pass og parameter by value
3. Properly initialize qpdf and og
Also, tweak QPDF::replaceObject to allow stream replacement without
violating the requirement that streams must always be indirect objects.
Also, remove QPDF::reserveStream as it does not do what the name implies
and having this as a separate methods does not aid code readability.
QPDF::read_xrefTable ignores type 0 entries for objects in a section if an
associates XRefStm has an entry for the same object.
The spec states:
When the conforming reader searches for an object, if an entry is not
found in any given standard cross-reference section, the search shall
proceed to a cross-reference stream specified by the XRefStm entry
before looking in the previous cross-reference section,
If a deleted entry is found in a section, the XRefStm is not searched
according to the standard.
Create unresolved objects only for objects in the xref table (except during
parsing of the xref table). Do not add indirect nulls into the the object
cache as the result of a cache miss during a call to getObject except
during parsing or creation/updating from JSON. To support this behaviour,
add new private methods getObjectForParser and getObjectForJSON.
As a result of this change, dangling references are treated as direct nulls
rather than indirect nulls.
Prepare for treating indirect references differently depending on whether
we are parsing a PDF file (in which case reference to objects not in the
xref table are null even if they are in the object cache) or whether parse
from user code (in which case an indirect reference can refer to a user
created object).
