From e1cd5891af199dc6d926a1792c9add182b39fc56 Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Sun, 5 Aug 2018 15:42:01 -0400
Subject: [PATCH] Fix infinite loop on small files with progress reporting
 (fixes #230)

Turns out you can keep adding zero to a number over and over again and
it just doesn't get any bigger. Who would have known?
---
 ChangeLog                          |  5 +++++
 libqpdf/QPDFWriter.cc              |  3 ++-
 qpdf/qtest/qpdf.test               | 11 +++++++++++
 qpdf/qtest/qpdf/small-progress.out |  3 +++
 4 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 qpdf/qtest/qpdf/small-progress.out

diff --git a/ChangeLog b/ChangeLog
index 7888293f..42598e8a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2018-08-05  Jay Berkenbilt  <ejb@ql.org>
+
+	* Bug fix: infinite loop on progress reporting for very small
+	files. Fixes #230.
+
 2018-08-04  Jay Berkenbilt  <ejb@ql.org>
 
 	* Performance fix: optimize page merging operation to avoid
diff --git a/libqpdf/QPDFWriter.cc b/libqpdf/QPDFWriter.cc
index 447b6627..30ba6f1f 100644
--- a/libqpdf/QPDFWriter.cc
+++ b/libqpdf/QPDFWriter.cc
@@ -3357,9 +3357,10 @@ QPDFWriter::indicateProgress(bool decrement, bool finished)
                                 this->m->events_expected)));
         this->m->progress_reporter->reportProgress(percentage);
     }
+    int increment = std::max(1, (this->m->events_expected / 100));
     while (this->m->events_seen >= this->m->next_progress_report)
     {
-        this->m->next_progress_report += (this->m->events_expected / 100);
+        this->m->next_progress_report += increment;
     }
 }
 
diff --git a/qpdf/qtest/qpdf.test b/qpdf/qtest/qpdf.test
index 603bbe01..bab7ec1c 100644
--- a/qpdf/qtest/qpdf.test
+++ b/qpdf/qtest/qpdf.test
@@ -925,6 +925,17 @@ $td->runtest("don't overwrite self",
              {$td->REGEXP => "input file and output file are the same.*",
               $td->EXIT_STATUS => 2});
 
+show_ntests();
+# ----------
+$td->notify("--- Progress reporting ---");
+$n_tests += 1;
+
+$td->runtest("progress report on small file",
+             {$td->COMMAND => "qpdf --progress minimal.pdf a.pdf",
+                  $td->FILTER => "perl filter-progress.pl"},
+             {$td->FILE => "small-progress.out", $td->EXIT_STATUS => 0},
+             $td->NORMALIZE_NEWLINES);
+
 show_ntests();
 # ----------
 $td->notify("--- Type checks ---");
diff --git a/qpdf/qtest/qpdf/small-progress.out b/qpdf/qtest/qpdf/small-progress.out
new file mode 100644
index 00000000..5845dec2
--- /dev/null
+++ b/qpdf/qtest/qpdf/small-progress.out
@@ -0,0 +1,3 @@
+qpdf: a.pdf: write progress: 0%
+....other write progress....
+qpdf: a.pdf: write progress: 100%