Implement QPDFObjectHandle::parse

Move object parsing code from QPDF to QPDFObjectHandle and
parameterize the parts of it that are specific to a QPDF object.
Provide a version that can't handle indirect objects and that can be
called on an arbitrary string.

A side effect of this change is that the offset used when reporting
invalid stream length has changed, but since the new value seems like
a better value than the old one, the test suite has been updated
rather than making the code backward compatible.  This only effects
the offset reported for invalid streams that lack /Length or have an
invalid /Length key.

Updated some test code and exmaples to use QPDFObjectHandle::parse.

Supporting changes include adding a BufferInputSource constructor that
takes a string.

1 files changed, 15 insertions, 0 deletions

diff --git a/libqpdf/QPDF_Stream.cc b/libqpdf/QPDF_Stream.cc
index c089bcc1..970ee58b 100644
--- a/libqpdf/QPDF_Stream.cc
+++ b/libqpdf/QPDF_Stream.cc
@@ -464,3 +464,18 @@ QPDF_Stream::replaceFilterData(QPDFObjectHandle const& filter,
             "/Length", QPDFObjectHandle::newInteger((int)length));
     }
 }
+
+void
+QPDF_Stream::replaceDict(QPDFObjectHandle new_dict)
+{
+    this->stream_dict = new_dict;
+    QPDFObjectHandle length_obj = new_dict.getKey("/Length");
+    if (length_obj.isInteger())
+    {
+        this->length = length_obj.getIntValue();
+    }
+    else
+    {
+        this->length = 0;
+    }
+}