Files
Aaru/Aaru.Filesystems/exFAT/File.cs

293 lines
11 KiB
C#

// /***************************************************************************
// Aaru Data Preservation Suite
// ----------------------------------------------------------------------------
//
// Filename : File.cs
// Author(s) : Natalia Portillo <claunia@claunia.com>
//
// Component : Microsoft exFAT filesystem plugin.
//
// --[ License ] --------------------------------------------------------------
//
// This library is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 2.1 of the
// License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, see <http://www.gnu.org/licenses/>.
//
// ----------------------------------------------------------------------------
// Copyright © 2011-2026 Natalia Portillo
// ****************************************************************************/
using System;
using System.Collections.Generic;
using Aaru.CommonTypes.Enums;
using Aaru.CommonTypes.Interfaces;
using Aaru.CommonTypes.Structs;
using Aaru.Helpers;
namespace Aaru.Filesystems;
// Information from https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src/FileIO/exfat-specification.md
/// <inheritdoc />
public sealed partial class exFAT
{
/// <inheritdoc />
public ErrorNumber OpenFile(string path, out IFileNode node)
{
node = null;
if(!_mounted) return ErrorNumber.AccessDenied;
ErrorNumber errno = GetFileEntry(path, out CompleteDirectoryEntry entry);
if(errno != ErrorNumber.NoError) return errno;
if(entry.IsDirectory) return ErrorNumber.IsDirectory;
node = new ExFatFileNode
{
Path = path,
Length = (long)entry.DataLength,
Offset = 0,
FirstCluster = entry.FirstCluster,
IsContiguous = entry.IsContiguous
};
return ErrorNumber.NoError;
}
/// <inheritdoc />
public ErrorNumber CloseFile(IFileNode node)
{
if(!_mounted) return ErrorNumber.AccessDenied;
if(node is not ExFatFileNode myNode) return ErrorNumber.InvalidArgument;
myNode.Offset = -1;
return ErrorNumber.NoError;
}
/// <inheritdoc />
public ErrorNumber ReadFile(IFileNode node, long length, byte[] buffer, out long read)
{
read = 0;
if(!_mounted) return ErrorNumber.AccessDenied;
if(buffer is null || buffer.Length < length) return ErrorNumber.InvalidArgument;
if(node is not ExFatFileNode myNode) return ErrorNumber.InvalidArgument;
if(myNode.Offset < 0) return ErrorNumber.InvalidArgument;
if(length < 0) return ErrorNumber.InvalidArgument;
// End of file reached
if(myNode.Offset >= myNode.Length) return ErrorNumber.NoError;
// Adjust length if it would read past end of file
if(myNode.Offset + length > myNode.Length) length = myNode.Length - myNode.Offset;
if(length == 0) return ErrorNumber.NoError;
// Calculate which clusters we need to read
long firstCluster = myNode.Offset / _bytesPerCluster;
long offsetInCluster = myNode.Offset % _bytesPerCluster;
long bytesToRead = length;
long sizeInClusters = (bytesToRead + offsetInCluster + _bytesPerCluster - 1) / _bytesPerCluster;
long bufferOffset = 0;
for(long i = 0; i < sizeInClusters; i++)
{
// Get the cluster number for this position
uint clusterNumber;
if(myNode.IsContiguous)
{
// For contiguous files, clusters are sequential starting from FirstCluster
clusterNumber = (uint)(myNode.FirstCluster + firstCluster + i);
}
else
{
// For non-contiguous files, follow the FAT chain
clusterNumber = GetClusterAtPosition(myNode.FirstCluster, (uint)(firstCluster + i));
if(clusterNumber < 2 || clusterNumber > _clusterCount + 1) return ErrorNumber.InvalidArgument;
}
// Calculate sector for this cluster
ulong sector = _clusterHeapOffset + (ulong)(clusterNumber - 2) * _sectorsPerCluster;
// Read the cluster
ErrorNumber errno = _image.ReadSectors(sector, false, _sectorsPerCluster, out byte[] clusterData, out _);
if(errno != ErrorNumber.NoError) return errno;
// Calculate how much to copy from this cluster
long clusterOffset = i == 0 ? offsetInCluster : 0;
long bytesFromThisCluster = _bytesPerCluster - clusterOffset;
if(bytesFromThisCluster > bytesToRead - bufferOffset) bytesFromThisCluster = bytesToRead - bufferOffset;
// Copy data to buffer
Array.Copy(clusterData, clusterOffset, buffer, bufferOffset, bytesFromThisCluster);
bufferOffset += bytesFromThisCluster;
}
read = bufferOffset;
myNode.Offset += read;
return ErrorNumber.NoError;
}
/// <inheritdoc />
public ErrorNumber GetAttributes(string path, out CommonTypes.Structs.FileAttributes attributes)
{
attributes = new CommonTypes.Structs.FileAttributes();
if(!_mounted) return ErrorNumber.AccessDenied;
ErrorNumber errno = GetFileEntry(path, out CompleteDirectoryEntry entry);
if(errno != ErrorNumber.NoError) return errno;
if(entry.IsDirectory)
attributes |= CommonTypes.Structs.FileAttributes.Directory;
else
attributes |= CommonTypes.Structs.FileAttributes.File;
if(entry.FileEntry.FileAttributes.HasFlag(FileAttributes.ReadOnly))
attributes |= CommonTypes.Structs.FileAttributes.ReadOnly;
if(entry.FileEntry.FileAttributes.HasFlag(FileAttributes.Hidden))
attributes |= CommonTypes.Structs.FileAttributes.Hidden;
if(entry.FileEntry.FileAttributes.HasFlag(FileAttributes.System))
attributes |= CommonTypes.Structs.FileAttributes.System;
if(entry.FileEntry.FileAttributes.HasFlag(FileAttributes.Archive))
attributes |= CommonTypes.Structs.FileAttributes.Archive;
return ErrorNumber.NoError;
}
/// <inheritdoc />
public ErrorNumber Stat(string path, out FileEntryInfo stat)
{
stat = null;
if(!_mounted) return ErrorNumber.AccessDenied;
ErrorNumber errno = GetFileEntry(path, out CompleteDirectoryEntry entry);
if(errno != ErrorNumber.NoError) return errno;
stat = new FileEntryInfo
{
Attributes = new CommonTypes.Structs.FileAttributes(),
BlockSize = _bytesPerCluster,
Length = (long)entry.DataLength,
Inode = entry.FirstCluster,
Links = 1
};
// Calculate blocks
stat.Blocks = (long)(entry.DataLength / _bytesPerCluster);
if(entry.DataLength % _bytesPerCluster > 0) stat.Blocks++;
// Convert timestamps
stat.CreationTimeUtc = DateHandlers.ExFatToDateTime(entry.FileEntry.CreateTimestamp,
entry.FileEntry.Create10msIncrement,
entry.FileEntry.CreateUtcOffset);
stat.LastWriteTimeUtc = DateHandlers.ExFatToDateTime(entry.FileEntry.LastModifiedTimestamp,
entry.FileEntry.LastModified10msIncrement,
entry.FileEntry.LastModifiedUtcOffset);
stat.AccessTimeUtc = DateHandlers.ExFatToDateTime(entry.FileEntry.LastAccessedTimestamp,
0,
entry.FileEntry.LastAccessedUtcOffset);
// Set file attributes
if(entry.IsDirectory)
stat.Attributes |= CommonTypes.Structs.FileAttributes.Directory;
else
stat.Attributes |= CommonTypes.Structs.FileAttributes.File;
if(entry.FileEntry.FileAttributes.HasFlag(FileAttributes.ReadOnly))
stat.Attributes |= CommonTypes.Structs.FileAttributes.ReadOnly;
if(entry.FileEntry.FileAttributes.HasFlag(FileAttributes.Hidden))
stat.Attributes |= CommonTypes.Structs.FileAttributes.Hidden;
if(entry.FileEntry.FileAttributes.HasFlag(FileAttributes.System))
stat.Attributes |= CommonTypes.Structs.FileAttributes.System;
if(entry.FileEntry.FileAttributes.HasFlag(FileAttributes.Archive))
stat.Attributes |= CommonTypes.Structs.FileAttributes.Archive;
return ErrorNumber.NoError;
}
// ...existing code...
/// <param name="path">Path to the file or directory.</param>
/// <param name="entry">The directory entry if found.</param>
/// <returns>Error number.</returns>
ErrorNumber GetFileEntry(string path, out CompleteDirectoryEntry entry)
{
entry = null;
if(string.IsNullOrWhiteSpace(path) || path == "/") return ErrorNumber.IsDirectory;
string cutPath = path.StartsWith("/", StringComparison.Ordinal) ? path[1..] : path;
string[] pieces = cutPath.Split('/', StringSplitOptions.RemoveEmptyEntries);
if(pieces.Length == 0) return ErrorNumber.IsDirectory;
// Get parent directory
string parentPath;
string fileName;
if(pieces.Length == 1)
{
parentPath = "/";
fileName = pieces[0];
}
else
{
parentPath = string.Join("/", pieces, 0, pieces.Length - 1);
fileName = pieces[^1];
}
ErrorNumber errno =
GetDirectoryEntries(parentPath, out Dictionary<string, CompleteDirectoryEntry> parentEntries);
if(errno != ErrorNumber.NoError) return errno;
// Find the entry (case-insensitive per exFAT spec)
foreach(KeyValuePair<string, CompleteDirectoryEntry> kvp in parentEntries)
{
if(kvp.Key.Equals(fileName, StringComparison.OrdinalIgnoreCase))
{
entry = kvp.Value;
return ErrorNumber.NoError;
}
}
return ErrorNumber.NoSuchFile;
}
}