From 10c2f72720628c952138bc87dffd6505576fdcd0 Mon Sep 17 00:00:00 2001
From: webzwo0i <webzwo0i@c3d2.de>
Date: Thu, 4 Dec 2014 16:01:39 +0100
Subject: [PATCH 1/4] dont remove more lines than exist in the whole text

---
 src/static/js/Changeset.js | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/static/js/Changeset.js b/src/static/js/Changeset.js
index 355bef4a9..366ad15f9 100644
--- a/src/static/js/Changeset.js
+++ b/src/static/js/Changeset.js
@@ -903,6 +903,8 @@ exports.pack = function (oldLen, newLen, opsStr, bank) {
  * @params str {string} String to which a Changeset should be applied
  */
 exports.applyToText = function (cs, str) {
+  var totalNrOfLines = str.split("\n").length;
+  var removedLines = 0;
   var unpacked = exports.unpack(cs);
   exports.assert(str.length == unpacked.oldLen, "mismatched apply: ", str.length, " / ", unpacked.oldLen);
   var csIter = exports.opIterator(unpacked.ops);
@@ -916,6 +918,7 @@ exports.applyToText = function (cs, str) {
       assem.append(bankIter.take(op.chars));
       break;
     case '-':
+      removedLines += op.lines;
       strIter.skip(op.chars);
       break;
     case '=':
@@ -923,6 +926,7 @@ exports.applyToText = function (cs, str) {
       break;
     }
   }
+  exports.assert(totalNrOfLines >= removedLines,"cannot remove ", removedLines, " lines from text with ", totalNrOfLines, " lines");
   assem.append(strIter.take(strIter.remaining()));
   return assem.toString();
 };

From 5306f0c98af051b790bcf8344077e781b10f3eb7 Mon Sep 17 00:00:00 2001
From: webzwo0i <webzwo0i@c3d2.de>
Date: Thu, 4 Dec 2014 16:05:02 +0100
Subject: [PATCH 2/4] wrap appendRevision in try-catch block

---
 src/node/handler/PadMessageHandler.js | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/node/handler/PadMessageHandler.js b/src/node/handler/PadMessageHandler.js
index bc8f5d629..1d89288cf 100644
--- a/src/node/handler/PadMessageHandler.js
+++ b/src/node/handler/PadMessageHandler.js
@@ -742,7 +742,16 @@ function handleUserChanges(data, cb)
         return callback(new Error("Can't apply USER_CHANGES "+changeset+" with oldLen " + Changeset.oldLen(changeset) + " to document of length " + prevText.length));
       }
 
-      pad.appendRevision(changeset, thisSession.author);
+      try
+      {
+        pad.appendRevision(changeset, thisSession.author);
+      }
+      catch(e)
+      {
+        client.json.send({disconnect:"badChangeset"});
+        stats.meter('failedChangesets').mark();
+        return callback(e)
+      }
 
       var correctionChangeset = _correctMarkersInPad(pad.atext, pad.pool);
       if (correctionChangeset) {

From 22803da42f4f8c6aeccc15d0a916bae6332a8652 Mon Sep 17 00:00:00 2001
From: webzwo0i <webzwo0i@c3d2.de>
Date: Thu, 4 Dec 2014 16:12:13 +0100
Subject: [PATCH 3/4] be more strict in checkRep

---
 src/static/js/Changeset.js | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/static/js/Changeset.js b/src/static/js/Changeset.js
index 366ad15f9..4d5487f82 100644
--- a/src/static/js/Changeset.js
+++ b/src/static/js/Changeset.js
@@ -255,20 +255,20 @@ exports.checkRep = function (cs) {
     var o = iter.next();
     switch (o.opcode) {
     case '=':
+      exports.assert(o.chars >= o.lines, o.chars, " chars and ", o.lines, " lines in op ",cs);
       oldPos += o.chars;
       calcNewLen += o.chars;
       break;
     case '-':
+      exports.assert(o.chars >= o.lines, o.chars, " chars and ", o.lines, " lines in op ",cs);
       oldPos += o.chars;
       exports.assert(oldPos < oldLen, oldPos, " >= ", oldLen, " in ", cs);
       break;
     case '+':
-      {
-        calcNewLen += o.chars;
-        numInserted += o.chars;
-        exports.assert(calcNewLen < newLen, calcNewLen, " >= ", newLen, " in ", cs);
-        break;
-      }
+      exports.assert(o.chars >= o.lines, o.chars, " chars and ", o.lines, " lines in op ",cs);
+      calcNewLen += o.chars;
+      exports.assert(calcNewLen < newLen, calcNewLen, " >= ", newLen, " in ", cs);
+      break;
     }
     assem.append(o);
   }

From 07a6702363a2b3cb195422cbc618de221a83b278 Mon Sep 17 00:00:00 2001
From: webzwo0i <webzwo0i@c3d2.de>
Date: Sat, 27 Dec 2014 17:56:20 +0100
Subject: [PATCH 4/4] Revert "be more strict in checkRep"

This reverts commit 22803da42f4f8c6aeccc15d0a916bae6332a8652.
---
 src/static/js/Changeset.js | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/static/js/Changeset.js b/src/static/js/Changeset.js
index 4d5487f82..366ad15f9 100644
--- a/src/static/js/Changeset.js
+++ b/src/static/js/Changeset.js
@@ -255,20 +255,20 @@ exports.checkRep = function (cs) {
     var o = iter.next();
     switch (o.opcode) {
     case '=':
-      exports.assert(o.chars >= o.lines, o.chars, " chars and ", o.lines, " lines in op ",cs);
       oldPos += o.chars;
       calcNewLen += o.chars;
       break;
     case '-':
-      exports.assert(o.chars >= o.lines, o.chars, " chars and ", o.lines, " lines in op ",cs);
       oldPos += o.chars;
       exports.assert(oldPos < oldLen, oldPos, " >= ", oldLen, " in ", cs);
       break;
     case '+':
-      exports.assert(o.chars >= o.lines, o.chars, " chars and ", o.lines, " lines in op ",cs);
-      calcNewLen += o.chars;
-      exports.assert(calcNewLen < newLen, calcNewLen, " >= ", newLen, " in ", cs);
-      break;
+      {
+        calcNewLen += o.chars;
+        numInserted += o.chars;
+        exports.assert(calcNewLen < newLen, calcNewLen, " >= ", newLen, " in ", cs);
+        break;
+      }
     }
     assem.append(o);
   }