Implement reading DOS namespace directories in FAT.

DiscImageChef.Filesystems/FAT/Dir.cs

@@ -32,7 +32,10 @@
 
 using System;
 using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
 using DiscImageChef.CommonTypes.Structs;
+using DiscImageChef.Helpers;
 
 namespace DiscImageChef.Filesystems.FAT
 {
@@ -59,7 +62,118 @@ namespace DiscImageChef.Filesystems.FAT
             contents = null;
             if(!mounted) return Errno.AccessDenied;
 
-            throw new NotImplementedException();
+            if(string.IsNullOrWhiteSpace(path) || path == "/")
+            {
+                contents = rootDirectoryCache.Keys.ToList();
+                return Errno.NoError;
+            }
+
+            string cutPath = path.StartsWith("/", StringComparison.Ordinal)
+                                 ? path.Substring(1).ToLower(cultureInfo)
+                                 : path.ToLower(cultureInfo);
+
+            if(directoryCache.TryGetValue(cutPath, out Dictionary<string, DirectoryEntry> currentDirectory))
+            {
+                contents = currentDirectory.Keys.ToList();
+                return Errno.NoError;
+            }
+
+            string[] pieces = cutPath.Split(new[] {'/'}, StringSplitOptions.RemoveEmptyEntries);
+
+            KeyValuePair<string, DirectoryEntry> entry =
+                rootDirectoryCache.FirstOrDefault(t => t.Key.ToLower(cultureInfo) == pieces[0]);
+
+            if(string.IsNullOrEmpty(entry.Key)) return Errno.NoSuchFile;
+
+            if(!entry.Value.attributes.HasFlag(FatAttributes.Subdirectory)) return Errno.NotDirectory;
+
+            string currentPath = pieces[0];
+
+            currentDirectory = rootDirectoryCache;
+
+            for(int p = 0; p < pieces.Length; p++)
+            {
+                entry = currentDirectory.FirstOrDefault(t => t.Key.ToLower(cultureInfo) == pieces[p]);
+
+                if(string.IsNullOrEmpty(entry.Key)) return Errno.NoSuchFile;
+
+                if(!entry.Value.attributes.HasFlag(FatAttributes.Subdirectory)) return Errno.NotDirectory;
+
+                currentPath = p == 0 ? pieces[0] : $"{currentPath}/{pieces[p]}";
+                uint currentCluster = entry.Value.start_cluster;
+
+                if(directoryCache.TryGetValue(currentPath, out currentDirectory)) continue;
+
+                uint[] clusters = GetClusters(currentCluster);
+
+                if(clusters is null) return Errno.InvalidArgument;
+
+                byte[] directoryBuffer = new byte[bytesPerCluster * clusters.Length];
+
+                for(int i = 0; i < clusters.Length; i++)
+                {
+                    byte[] buffer = image.ReadSectors(firstClusterSector + (clusters[i] - 2) * sectorsPerCluster,
+                                                      sectorsPerCluster);
+                    Array.Copy(buffer, 0, directoryBuffer, i * bytesPerCluster, bytesPerCluster);
+                }
+
+                currentDirectory = new Dictionary<string, DirectoryEntry>();
+
+                int pos = 0;
+                while(pos < directoryBuffer.Length)
+                {
+                    DirectoryEntry dirent =
+                        Marshal.ByteArrayToStructureLittleEndian<DirectoryEntry>(directoryBuffer, pos,
+                                                                                 Marshal.SizeOf<DirectoryEntry>());
+
+                    pos += Marshal.SizeOf<DirectoryEntry>();
+
+                    if(dirent.filename[0] == DIRENT_FINISHED) break;
+
+                    // Not a correct entry
+                    if(dirent.filename[0] < DIRENT_MIN && dirent.filename[0] != DIRENT_E5) continue;
+
+                    // Self
+                    if(Encoding.GetString(dirent.filename).TrimEnd() == ".") continue;
+
+                    // Parent
+                    if(Encoding.GetString(dirent.filename).TrimEnd() == "..") continue;
+
+                    // Deleted
+                    if(dirent.filename[0] == DIRENT_DELETED) continue;
+
+                    // TODO: LFN namespace
+                    if(dirent.attributes.HasFlag(FatAttributes.LFN)) continue;
+
+                    string filename;
+
+                    if(dirent.attributes.HasFlag(FatAttributes.VolumeLabel)) continue;
+
+                    if(dirent.filename[0] == DIRENT_E5) dirent.filename[0] = DIRENT_DELETED;
+
+                    string name      = Encoding.GetString(dirent.filename).TrimEnd();
+                    string extension = Encoding.GetString(dirent.extension).TrimEnd();
+
+                    if((dirent.caseinfo & FASTFAT_LOWERCASE_EXTENSION) > 0)
+                        extension = extension.ToLower(CultureInfo.CurrentCulture);
+
+                    if((dirent.caseinfo & FASTFAT_LOWERCASE_BASENAME) > 0)
+                        name = name.ToLower(CultureInfo.CurrentCulture);
+
+                    if(extension != "") filename = name + "." + extension;
+                    else filename                = name;
+
+                    // Using array accessor ensures that repeated entries just get substituted.
+                    // Repeated entries are not allowed but some bad implementations (e.g. FAT32.IFS)allow to create them
+                    // when using spaces
+                    currentDirectory[filename] = dirent;
+                }
+
+                directoryCache.Add(currentPath, currentDirectory);
+            }
+
+            contents = currentDirectory?.Keys.ToList();
+            return Errno.NoError;
         }
     }
 }