From 4fe267b6b46bdd97cd0b221ff9d91d1618e537e9 Mon Sep 17 00:00:00 2001
From: LostDragonist <lost.dragonist@gmail.com>
Date: Sat, 28 Sep 2019 08:11:29 -0500
Subject: [PATCH] Fix md5 hashing for large download files

Previously, the md5 hashing was broken for download files larger
than about 2GB.  This was due to the maximum size of a QByteArray.
The hashing was broken up into 10MB chunks to correct this issue.

Additionally, a progress bar was added as hashing large files would
lock up the GUI.
---
 src/downloadmanager.cpp | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/src/downloadmanager.cpp b/src/downloadmanager.cpp
index 56238ef30..35f60d7af 100644
--- a/src/downloadmanager.cpp
+++ b/src/downloadmanager.cpp
@@ -985,16 +985,39 @@ void DownloadManager::queryInfoMd5(int index)
     downloadFile.setFileName(m_OrganizerCore->downloadsPath() + "\\" + info->m_FileName);
   }
   if (!downloadFile.exists()) {
-    log::debug("Can't find download file {}", info->m_FileName);
+    log::error("Can't find download file '{}'", info->m_FileName);
     return;
   }
   if (!downloadFile.open(QIODevice::ReadOnly)) {
-    log::debug("Can't open download file {}", info->m_FileName);
+    log::error("Can't open download file '{}'", info->m_FileName);
     return;
   }
-  info->m_Hash = QCryptographicHash::hash(downloadFile.readAll(), QCryptographicHash::Md5);
+
+  QCryptographicHash hash(QCryptographicHash::Md5);
+  const qint64 progressStep = 10 * 1024 * 1024;
+  QProgressDialog progress(tr("Hashing download file '%1'").arg(info->m_FileName),
+                           tr("Cancel"), 
+                           0, 
+                           downloadFile.size() / progressStep);
+  progress.setWindowModality(Qt::WindowModal);
+  progress.setMinimumDuration(1000);
+
+  for (qint64 i = 0; i < downloadFile.size(); i += progressStep) {
+    progress.setValue(progress.value()+1);
+    if (progress.wasCanceled()) {
+      break;
+    }
+    hash.addData(downloadFile.read(progressStep));
+  }
+  if (progress.wasCanceled()) {
+    downloadFile.close();
+    return;
+  }
+
+  progress.close();
   downloadFile.close();
 
+  info->m_Hash = hash.result();
   info->m_ReQueried = true;
   setState(info, STATE_FETCHINGMODINFO_MD5);
 }