Check if subtitle file contains only binary zeroes

LanguageMaster.xml

@@ -1278,6 +1278,9 @@ Continue?</SubtitleAppendPrompt>
     <ErrorLoadPng>This file seems to be a PNG image file. Subtitle Edit cannot open PNG files.</ErrorLoadPng>
     <ErrorLoadSrr>This file seems to be a ReScene .srr file - not a subtitle file.</ErrorLoadSrr>
     <ErrorLoadTorrent>This file seems to be a BitTorrent file - not a subtitle file.</ErrorLoadTorrent>
+    <ErrorLoadBinaryZeroes>Sorry, this file contains only binary zeroes!
+
+If you have edited this file with Subtitle Edit you might be alble to find a backup via the menu item File -&gt; Restore auto-backup...</ErrorLoadBinaryZeroes>
     <NoSupportEncryptedVobSub>Encrypted VobSub content is not supported.</NoSupportEncryptedVobSub>
     <NoSupportHereBluRaySup>Blu-ray sup files are not supported here.</NoSupportHereBluRaySup>
     <NoSupportHereDvdSup>DVD sup files are not supported here.</NoSupportHereDvdSup>

src/Core/FileUtil.cs

@@ -292,5 +292,29 @@ namespace Nikse.SubtitleEdit.Core
             }
         }
 
+        public static bool IsSubtitleFileAllBinaryZeroes(string fileName)
+        {
+            using (var fs = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
+            {
+                if (fs.Length < 10)
+                    return false; // too short to be a proper subtitle file
+
+                int numberOfBytes = 1;
+                var buffer = new byte[1024];
+                while (numberOfBytes > 0)
+                {
+                    numberOfBytes = fs.Read(buffer, 0, buffer.Length);
+                    for (int i = 0; i < numberOfBytes; i++)
+                    {
+                        if (buffer[i] > 0)
+                        {
+                            return false;
+                        }
+                    }
+                }
+            }
+            return true;
+        }
+
     }
 }

src/Forms/Main.cs

@@ -2357,6 +2357,13 @@ namespace Nikse.SubtitleEdit.Forms
                     return;
                 }
 
+                // check for all binary zeroes (I've heard about this a few times... perhaps related to crashes?)
+                if (format == null && fi.Length > 50 && FileUtil.IsSubtitleFileAllBinaryZeroes(fileName))
+                {
+                    MessageBox.Show(_language.ErrorLoadBinaryZeroes);
+                    return;
+                }
+
                 if (format == null && fi.Length < 100 * 1000000 && TransportStreamParser.IsDvbSup(fileName))
                 {
                     ImportSubtitleFromDvbSupFile(fileName);

src/Logic/Language.cs

@@ -1181,6 +1181,7 @@ namespace Nikse.SubtitleEdit.Logic
                 ErrorLoadPng = "This file seems to be a PNG image file. Subtitle Edit cannot open PNG files.",
                 ErrorLoadSrr = "This file seems to be a ReScene .srr file - not a subtitle file.",
                 ErrorLoadTorrent = "This file seems to be a BitTorrent file - not a subtitle file.",
+                ErrorLoadBinaryZeroes = "Sorry, this file contains only binary zeroes!\r\n\r\nIf you have edited this file with Subtitle Edit you might be alble to find a backup via the menu item File -> Restore auto-backup...",
                 NoSupportEncryptedVobSub = "Encrypted VobSub content is not supported.",
                 NoSupportHereBluRaySup = "Blu-ray sup files are not supported here.",
                 NoSupportHereDvdSup = "DVD sup files are not supported here.",

src/Logic/LanguageDeserializer.cs

@@ -2622,6 +2622,9 @@ namespace Nikse.SubtitleEdit.Logic
                 case "Main/ErrorLoadTorrent":
                     language.Main.ErrorLoadTorrent = reader.Value;
                     break;
+                case "Main/ErrorLoadBinaryZeroes":
+                    language.Main.ErrorLoadBinaryZeroes = reader.Value;
+                    break;
                 case "Main/NoSupportEncryptedVobSub":
                     language.Main.NoSupportEncryptedVobSub = reader.Value;
                     break;

src/Logic/LanguageStructure.cs

@@ -1057,6 +1057,7 @@
             public string ErrorLoadPng { get; set; }
             public string ErrorLoadSrr { get; set; }
             public string ErrorLoadTorrent { get; set; }
+            public string ErrorLoadBinaryZeroes { get; set; }
             public string NoSupportEncryptedVobSub { get; set; }
             public string NoSupportHereBluRaySup { get; set; }
             public string NoSupportHereDvdSup { get; set; }