private Inode GetInode(uint inodeNum)
{
uint index = inodeNum - 1;
SuperBlock superBlock = Context.SuperBlock;
uint group = index / superBlock.InodesPerGroup;
uint groupOffset = index - group * superBlock.InodesPerGroup;
BlockGroup inodeBlockGroup = GetBlockGroup(group);
uint inodesPerBlock = superBlock.BlockSize / superBlock.InodeSize;
uint block = groupOffset / inodesPerBlock;
uint blockOffset = groupOffset - block * inodesPerBlock;
Context.RawStream.Position = (inodeBlockGroup.InodeTableBlock + block) * (long)superBlock.BlockSize +
blockOffset * superBlock.InodeSize;
byte[] inodeData = StreamUtilities.ReadFully(Context.RawStream, superBlock.InodeSize);
return(EndianUtilities.ToStruct <Inode>(inodeData, 0));
}
public VfsExtFileSystem(Stream stream, FileSystemParameters parameters)
: base(new ExtFileSystemOptions(parameters))
{
stream.Position = 1024;
byte[] superblockData = StreamUtilities.ReadFully(stream, 1024);
SuperBlock superblock = new SuperBlock();
superblock.ReadFrom(superblockData, 0);
if (superblock.Magic != SuperBlock.Ext2Magic)
{
throw new IOException("Invalid superblock magic - probably not an Ext file system");
}
if (superblock.RevisionLevel == SuperBlock.OldRevision)
{
throw new IOException("Old ext revision - not supported");
}
if ((superblock.IncompatibleFeatures & ~SupportedIncompatibleFeatures) != 0)
{
throw new IOException("Incompatible ext features present: " +
(superblock.IncompatibleFeatures & ~SupportedIncompatibleFeatures));
}
Context = new Context
{
RawStream = stream,
SuperBlock = superblock,
Options = (ExtFileSystemOptions)Options
};
uint numGroups = MathUtilities.Ceil(superblock.BlocksCount, superblock.BlocksPerGroup);
long blockDescStart = (superblock.FirstDataBlock + 1) * (long)superblock.BlockSize;
stream.Position = blockDescStart;
var bgDescSize = superblock.Has64Bit ? BlockGroup64.DescriptorSize64 : BlockGroup.DescriptorSize;
byte[] blockDescData = StreamUtilities.ReadFully(stream, (int)numGroups * bgDescSize);
_blockGroups = new BlockGroup[numGroups];
for (int i = 0; i < numGroups; ++i)
{
BlockGroup bg = superblock.Has64Bit ? new BlockGroup64() : new BlockGroup();
bg.ReadFrom(blockDescData, i * bgDescSize);
_blockGroups[i] = bg;
}
var journalSuperBlock = new JournalSuperBlock();
if (superblock.JournalInode != 0)
{
var journalInode = GetInode(superblock.JournalInode);
var journalDataStream = journalInode.GetContentBuffer(Context);
var journalData = StreamUtilities.ReadFully(journalDataStream, 0, 1024 + 12);
journalSuperBlock.ReadFrom(journalData, 0);
Context.JournalSuperblock = journalSuperBlock;
}
RootDirectory = new Directory(Context, 2, GetInode(2));
}
