internal static bool Detect(Stream stream)
{
if (stream.Length < 2048)
{
return(false);
}
stream.Position = 1024;
byte[] superblockData = Utilities.ReadFully(stream, 1024);
SuperBlock superblock = new SuperBlock();
superblock.ReadFrom(superblockData, 0);
return(superblock.Magic == SuperBlock.Ext2Magic);
}
public VfsExtFileSystem(Stream stream)
: base(new DiscFileSystemOptions())
{
stream.Position = 1024;
byte[] superblockData = Utilities.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
};
uint numGroups = Utilities.Ceil(superblock.BlocksCount, superblock.BlocksPerGroup);
long blockDescStart = (superblock.FirstDataBlock + 1) * (long)superblock.BlockSize;
stream.Position = blockDescStart;
byte[] blockDescData = Utilities.ReadFully(stream, (int)numGroups * BlockGroup.DescriptorSize);
_blockGroups = new BlockGroup[numGroups];
for (int i = 0; i < numGroups; ++i)
{
BlockGroup bg = new BlockGroup();
bg.ReadFrom(blockDescData, i * BlockGroup.DescriptorSize);
_blockGroups[i] = bg;
}
RootDirectory = new Directory(Context, 2, GetInode(2));
}
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 = Utilities.ReadFully(Context.RawStream, superBlock.InodeSize);
return(Utilities.ToStruct <Inode>(inodeData, 0));
}