From bcea54fcaa16a7d5feff0c4cd038fea51d1359ea Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Tue, 27 Oct 2020 10:51:41 -0400
Subject: Revert removal of unreadCh change for performance

Turns out unreadCh is much more efficient than seek(-1, SEEK_CUR).
Update comments and code to reflect this.
---
 libqpdf/QPDF.cc | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

(limited to 'libqpdf/QPDF.cc')

diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc
index d256e444..d4d7d519 100644
--- a/libqpdf/QPDF.cc
+++ b/libqpdf/QPDF.cc
@@ -632,7 +632,7 @@ QPDF::read_xref(qpdf_offset_t xref_offset)
                 }
                 else
                 {
-                    this->m->file->seek(-1, SEEK_CUR);
+                    this->m->file->unreadCh(ch);
                     done = true;
                 }
             }
@@ -1604,7 +1604,7 @@ QPDF::readObject(PointerHolder<InputSource> input,
                             // start reading stream data in spite
                             // of not having seen a newline.
                             QTC::TC("qpdf", "QPDF stream with CR only");
-                            input->seek(-1, SEEK_CUR);
+                            input->unreadCh(ch);
                             warn(QPDFExc(
                                      qpdf_e_damaged_pdf,
                                      input->getName(),
@@ -1629,7 +1629,7 @@ QPDF::readObject(PointerHolder<InputSource> input,
                 else
                 {
                     QTC::TC("qpdf", "QPDF stream without newline");
-                    input->seek(-1, SEEK_CUR);
+                    input->unreadCh(ch);
                     warn(QPDFExc(qpdf_e_damaged_pdf, input->getName(),
                                  this->m->last_object_description,
                                  input->tell(),
-- 
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