Fix mszip relying on exceptions (#52)

* Better fix

* initial

* Fixed

* Move function to proper location, clear memory better

* work so far

* more

* more work

* No more per file seeking

* Finished work for now.

* First round of fixes.

* Return if array is empty too

SabreTools.Serialization/Readers/MicrosoftCabinet.cs

@@ -203,13 +203,13 @@ namespace SabreTools.Serialization.Readers
             dataBlock.Checksum = data.ReadUInt32LittleEndian();
             dataBlock.CompressedSize = data.ReadUInt16LittleEndian();
             dataBlock.UncompressedSize = data.ReadUInt16LittleEndian();
-
+            
             if (dataReservedSize > 0)
-                dataBlock.ReservedData = data.ReadBytes(dataReservedSize);
+                data.SeekIfPossible(dataReservedSize, SeekOrigin.Current);
 
             if (dataBlock.CompressedSize > 0)
-                dataBlock.CompressedData = data.ReadBytes(dataBlock.CompressedSize);
-
+                data.SeekIfPossible(dataBlock.CompressedSize, SeekOrigin.Current);
+            
             return dataBlock;
         }
 

SabreTools.Serialization/Wrappers/MicrosoftCabinet.Extraction.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.IO;
 using SabreTools.Data.Models.MicrosoftCabinet;
 using SabreTools.IO.Extensions;
@@ -174,12 +175,22 @@ namespace SabreTools.Serialization.Wrappers
                     // Loop through the current folders
                     for (int f = 0; f < cabinet.Folders.Length; f++)
                     {
+                        if (f == 0 && (cabinet.Files[0].FolderIndex == FolderIndex.CONTINUED_PREV_AND_NEXT
+                            || cabinet.Files[0].FolderIndex == FolderIndex.CONTINUED_FROM_PREV))
+                            continue;
+                        
                         var folder = cabinet.Folders[f];
                         allExtracted &= cabinet.ExtractFolder(Filename, outputDirectory, folder, f, ignorePrev, includeDebug);
                     }
 
                     // Move to the next cabinet, if possible
+                    Array.ForEach(cabinet.Folders, folder => folder.DataBlocks = []);
+                    
                     cabinet = cabinet.Next;
+                    cabinet?.Prev = null;
+                    
+                    // TODO: already-extracted data isn't being cleared from memory, at least not nearly enough.
+                    
                     if (cabinet?.Folders == null || cabinet.Folders.Length == 0)
                         break;
                 }
@@ -192,7 +203,7 @@ namespace SabreTools.Serialization.Wrappers
                 return false;
             }
         }
-
+        
         /// <summary>
         /// Extract the contents of a single folder
         /// </summary>
@@ -217,15 +228,77 @@ namespace SabreTools.Serialization.Wrappers
 
             // Loop through the files
             bool allExtracted = true;
-            var files = GetFiles(folderIndex, ignorePrev);
+            var filterFiles = GetSpannedFiles(filename, folderIndex, ignorePrev);
+            List<CFFILE> fileList = [];
+
+            // Filtering, add debug output eventually
+            for (int i = 0; i < filterFiles.Length; i++)
+            {
+                var file = filterFiles[i];
+
+                if (file.FolderIndex == FolderIndex.CONTINUED_PREV_AND_NEXT ||
+                    file.FolderIndex == FolderIndex.CONTINUED_FROM_PREV)
+                {
+                    // debug output for inconsistencies would go here
+                    continue;
+                }
+                
+                fileList.Add(file);
+            }
+            
+            CFFILE[] files = fileList.ToArray();
+            blockStream.SeekIfPossible(0, SeekOrigin.Begin);
             for (int i = 0; i < files.Length; i++)
             {
                 var file = files[i];
-                allExtracted &= ExtractFile(outputDirectory, blockStream, file, includeDebug);
+                
+                allExtracted &= ExtractFiles(outputDirectory, blockStream, file, includeDebug);
             }
 
             return allExtracted;
         }
+        
+        // TODO: this will apparently improve memory usage/performance, but it's not clear if this implementation is enough for that to happen
+        /// <summary>
+        /// Extract the contents of a single file, intended to be used with all files in a straight shot
+        /// </summary>
+        /// <param name="outputDirectory">Path to the output directory</param>
+        /// <param name="blockStream">Stream representing the uncompressed block data</param>
+        /// <param name="file">File information</param>
+        /// <param name="includeDebug">True to include debug data, false otherwise</param>
+        /// <returns>True if the file extracted, false otherwise</returns>
+        private static bool ExtractFiles(string outputDirectory, Stream blockStream, CFFILE file, bool includeDebug)
+        {
+            try
+            {
+                byte[] fileData = blockStream.ReadBytes((int)file.FileSize);
+
+                // Ensure directory separators are consistent
+                string filename = file.Name;
+                if (Path.DirectorySeparatorChar == '\\')
+                    filename = filename.Replace('/', '\\');
+                else if (Path.DirectorySeparatorChar == '/')
+                    filename = filename.Replace('\\', '/');
+
+                // Ensure the full output directory exists
+                filename = Path.Combine(outputDirectory, filename);
+                var directoryName = Path.GetDirectoryName(filename);
+                if (directoryName != null && !Directory.Exists(directoryName))
+                    Directory.CreateDirectory(directoryName);
+
+                // Open the output file for writing
+                using var fs = File.Open(filename, FileMode.Create, FileAccess.Write, FileShare.None);
+                fs.Write(fileData, 0, fileData.Length);
+                fs.Flush();
+            }
+            catch (Exception ex)
+            {
+                if (includeDebug) Console.Error.WriteLine(ex);
+                return false;
+            }
+
+            return true;
+        }
 
         /// <summary>
         /// Extract the contents of a single file

SabreTools.Serialization/Wrappers/MicrosoftCabinet.cs

@@ -2,6 +2,7 @@
 using System.IO;
 using SabreTools.Data.Models.MicrosoftCabinet;
 using SabreTools.IO.Compression.MSZIP;
+using SabreTools.IO.Extensions;
 
 namespace SabreTools.Serialization.Wrappers
 {
@@ -315,6 +316,8 @@ namespace SabreTools.Serialization.Wrappers
             if (folder?.DataBlocks == null || folder.DataBlocks.Length == 0)
                 return null;
 
+            GetData(folder);
+
             // Get all files for the folder
             var files = GetFiles(folderIndex);
             if (files.Length == 0)
@@ -335,7 +338,7 @@ namespace SabreTools.Serialization.Wrappers
                 // Get all blocks from Prev
                 if (Prev?.Header != null && Prev.Folders != null)
                 {
-                    int prevFolderIndex = Prev.FolderCount;
+                    int prevFolderIndex = Prev.FolderCount - 1;
                     var prevFolder = Prev.Folders[prevFolderIndex - 1];
                     prevBlocks = Prev.GetDataBlocks(filename, prevFolder, prevFolderIndex, skipNext: true) ?? [];
                 }
@@ -360,6 +363,106 @@ namespace SabreTools.Serialization.Wrappers
             // Return all found blocks in order
             return [.. prevBlocks, .. folder.DataBlocks, .. nextBlocks];
         }
+        
+        /// <summary>
+        /// Loads in all the datablocks for the current folder.
+        /// </summary>
+        /// <param name="folder">The folder to have the datablocks loaded for</param>
+        public void GetData(CFFOLDER folder)
+        {
+            if (folder.CabStartOffset <= 0)
+                return;
+
+            uint offset = folder.CabStartOffset;
+            for (int i = 0; i < folder.DataCount; i++)
+            {
+                offset += 8;
+
+                if (Header.DataReservedSize > 0)
+                {
+                    folder.DataBlocks[i].ReservedData = ReadRangeFromSource(offset, Header.DataReservedSize);
+                    offset += Header.DataReservedSize;
+                }
+
+                if (folder.DataBlocks[i].CompressedSize > 0)
+                {
+                    folder.DataBlocks[i].CompressedData = ReadRangeFromSource(offset, folder.DataBlocks[i].CompressedSize);
+                    offset += folder.DataBlocks[i].CompressedSize;
+                }
+            }
+            
+        }
+        
+        /// <summary>
+        /// Get all files for the current folder, plus connected spanned folders.
+        /// </summary>
+        /// <param name="folderIndex">Index of the folder in the cabinet</param>
+        /// <param name="ignorePrev">True to ignore previous links, false otherwise</param>
+        /// <returns>Array of all files for the folder</returns>
+        private CFFILE[] GetSpannedFiles(string? filename, int folderIndex, bool ignorePrev = false, bool skipPrev = false, bool skipNext = false)
+        {
+            // Ignore invalid archives
+            if (Files.IsNullOrEmpty())
+                return [];
+
+            // Get all files with a name and matching index
+            var files = Array.FindAll(Files, f =>
+            {
+                if (string.IsNullOrEmpty(f.Name))
+                    return false;
+
+                // Ignore links to previous cabinets, if required
+                if (ignorePrev)
+                {
+                    if (f.FolderIndex == FolderIndex.CONTINUED_FROM_PREV)
+                        return false;
+                    else if (f.FolderIndex == FolderIndex.CONTINUED_PREV_AND_NEXT)
+                        return false;
+                }
+
+                int fileFolder = GetFolderIndex(f);
+                return fileFolder == folderIndex;
+            });
+            
+            // Check if the folder spans in either direction
+            bool spanPrev = Array.Exists(files, f => f.FolderIndex == FolderIndex.CONTINUED_FROM_PREV || f.FolderIndex == FolderIndex.CONTINUED_PREV_AND_NEXT);
+            bool spanNext = Array.Exists(files, f => f.FolderIndex == FolderIndex.CONTINUED_TO_NEXT || f.FolderIndex == FolderIndex.CONTINUED_PREV_AND_NEXT);
+
+            // If the folder spans backward and Prev is not being skipped
+            CFFILE[] prevFiles = [];
+            if (!skipPrev && spanPrev)
+            {
+                // Try to get Prev if it doesn't exist
+                if (Prev?.Header == null)
+                    Prev = OpenPrevious(filename);
+
+                // Get all files from Prev
+                if (Prev?.Header != null && Prev.Folders != null)
+                {
+                    int prevFolderIndex = Prev.FolderCount - 1;
+                    prevFiles = Prev.GetSpannedFiles(filename, prevFolderIndex, skipNext: true) ?? [];
+                }
+            }
+            
+            // If the folder spans forward and Next is not being skipped
+            CFFILE[] nextFiles = [];
+            if (!skipNext && spanNext)
+            {
+                // Try to get Next if it doesn't exist
+                if (Next?.Header == null)
+                    Next = OpenNext(filename);
+
+                // Get all files from Prev
+                if (Next?.Header != null && Next.Folders != null)
+                {
+                    var nextFolder = Next.Folders[0];
+                    nextFiles = Next.GetSpannedFiles(filename, 0, skipPrev: true) ?? [];
+                }
+            }
+            
+            // Return all found files in order
+            return [.. prevFiles, .. files, .. nextFiles];
+        }
 
         /// <summary>
         /// Get all files for the current folder index