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[HFS] Brute-force finding the root directory node.

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This commit is contained in:
Natalia Portillo
2026-02-03 02:27:28 +00:00
parent 3aadf4db25
commit e430762c88
2 changed files with 118 additions and 54 deletions
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151
Aaru.Filesystems/AppleHFS/Catalog.cs
View File

@@ -56,7 +56,7 @@ public sealed partial class AppleHFS
if(bthdr.bthFNode <= bthdr.bthLNode)
{
AaruLogging.Debug(MODULE_NAME,
$"Scanning leaf nodes from {bthdr.bthFNode} to {bthdr.bthLNode} for CNID=2 (root)");
$"Scanning leaf nodes from {bthdr.bthFNode} to {bthdr.bthLNode} for CNID={kRootCnid} (root)");
for(uint leafNode = bthdr.bthFNode; leafNode <= bthdr.bthLNode; leafNode++)
{
@@ -80,7 +80,7 @@ public sealed partial class AppleHFS
_rootDirectory = rootRec;
AaruLogging.Debug(MODULE_NAME,
$"Found root directory (CNID=2) in leaf node {leafNode}: {rootRec.dirVal} entries");
$"Found root directory (CNID={kRootCnid}) in leaf node {leafNode}: {rootRec.dirVal} entries");
return ErrorNumber.NoError;
}
@@ -88,8 +88,41 @@ public sealed partial class AppleHFS
}
else
{
// Leaf range is invalid - do brute-force scan of ALL nodes
AaruLogging.Debug(MODULE_NAME,
$"Leaf node range invalid (firstLeaf={bthdr.bthFNode} > lastLeaf={bthdr.bthLNode}), skipping brute-force scan");
$"Leaf node range invalid (firstLeaf={bthdr.bthFNode} > lastLeaf={bthdr.bthLNode}), scanning ALL nodes for root");
uint maxNodes = bthdr.bthNNodes > 0 ? bthdr.bthNNodes : 2000;
for(uint nodeNum = 0; nodeNum < maxNodes; nodeNum++)
{
ErrorNumber scanErr = ReadNode(nodeNum, bthdr.bthNodeSize, out byte[] nodeData);
if(scanErr != ErrorNumber.NoError) continue;
NodeDescriptor nodeDesc =
Marshal.ByteArrayToStructureBigEndian<NodeDescriptor>(nodeData,
0,
System.Runtime.InteropServices.Marshal
.SizeOf(typeof(NodeDescriptor)));
if(nodeDesc.ndType != NodeType.ndLeafNode) continue;
// Search this leaf for CNID=2
ErrorNumber foundErr = FindRootInLeaf(nodeData, bthdr.bthNodeSize, out CdrDirRec rootRec);
if(foundErr == ErrorNumber.NoError)
{
_rootDirectory = rootRec;
AaruLogging.Debug(MODULE_NAME,
$"Found root directory (CNID={kRootCnid}) via brute-force in node {nodeNum}: {rootRec.dirVal} entries");
return ErrorNumber.NoError;
}
}
AaruLogging.Debug(MODULE_NAME, $"Brute-force scan of {maxNodes} nodes did not find root directory");
}
AaruLogging.Debug(MODULE_NAME,
@@ -749,48 +782,8 @@ public sealed partial class AppleHFS
AaruLogging.Debug(MODULE_NAME,
$"Record {i} (third pass/fallback): Found directory with parentID=1, CNID={rootRec.dirDirID}");
return ErrorNumber.NoError;
}
// Fourth pass: If NO directory with parentID=1 found, use the first available directory as root
// This handles severely malformed volumes
AaruLogging.Debug(MODULE_NAME, "Fourth pass: using first available directory as emergency fallback root");
for(ushort i = 0; i < nodeDesc.ndNRecs; i++)
{
var offsetPos = (ushort)(nodeSize - 2 - i * 2);
if(offsetPos < 14 || offsetPos >= nodeSize) continue;
var recordOffset = BigEndianBitConverter.ToUInt16(leafNode, offsetPos);
if(recordOffset < 14 || recordOffset >= nodeSize) continue;
// Parse the key
byte keyLen = leafNode[recordOffset];
// Calculate key size
var keySize = (ushort)(keyLen + 1 + 1 & ~1);
int dataOffset = recordOffset + keySize;
if(dataOffset + 2 > leafNode.Length) continue;
byte recordType = leafNode[dataOffset];
// Only look at directory records (type 1)
if(recordType != kCatalogRecordTypeDirectory) continue;
// Parse the directory record
int cdrDirRecSize = System.Runtime.InteropServices.Marshal.SizeOf(typeof(CdrDirRec));
if(dataOffset + cdrDirRecSize > leafNode.Length) continue;
rootRec = Marshal.ByteArrayToStructureBigEndian<CdrDirRec>(leafNode, dataOffset, cdrDirRecSize);
AaruLogging.Debug(MODULE_NAME,
$"Record {i} (fourth pass/emergency): Using first directory as root, CNID={rootRec.dirDirID}");
return ErrorNumber.NoError;
// Only accept CNID=2 as the real root
if(rootRec.dirDirID == kRootCnid) return ErrorNumber.NoError;
}
return ErrorNumber.InvalidArgument;
@@ -808,6 +801,7 @@ public sealed partial class AppleHFS
AaruLogging.Debug(MODULE_NAME,
$"Caching root directory entries: CNID={targetParentID}, expectedCount={expectedCount}");
AaruLogging.Debug(MODULE_NAME,
$"Root directory details: dirDirID={_rootDirectory.dirDirID}, dirVal={_rootDirectory.dirVal}");
@@ -843,8 +837,7 @@ public sealed partial class AppleHFS
if(leafDesc.ndType != NodeType.ndLeafNode) continue;
AaruLogging.Debug(MODULE_NAME,
$"Processing leaf node {leafNode}, {leafDesc.ndNRecs} records");
AaruLogging.Debug(MODULE_NAME, $"Processing leaf node {leafNode}, {leafDesc.ndNRecs} records");
// Extract all entries with parentID = targetParentID from this leaf node
errno = ExtractDirectoryEntriesFromLeaf(leafData, bthdr.bthNodeSize, targetParentID, ref entriesFound);
@@ -874,9 +867,65 @@ public sealed partial class AppleHFS
return ErrorNumber.NoError;
}
// Leaf range is invalid, fall back to standard B-tree traversal
// Leaf range is invalid, fall back to brute-force scan of ALL nodes
AaruLogging.Debug(MODULE_NAME,
$"Leaf node range invalid (firstLeaf={bthdr.bthFNode} > lastLeaf={bthdr.bthLNode}), using standard B-tree traversal");
$"Leaf node range invalid (firstLeaf={bthdr.bthFNode} > lastLeaf={bthdr.bthLNode}), using brute-force scan of all nodes");
// Brute-force scan ALL nodes looking for leaf nodes with our targetParentID
{
ushort entriesFound = 0;
uint maxNodes = bthdr.bthNNodes > 0 ? bthdr.bthNNodes : 2000;
AaruLogging.Debug(MODULE_NAME,
$"CacheRootDirectoryEntries brute-force: bthNNodes={bthdr.bthNNodes}, maxNodes={maxNodes}, scanning for parentID={targetParentID}");
uint leafNodesScanned = 0;
for(uint nodeNum = 0; nodeNum < maxNodes; nodeNum++)
{
errno = ReadNode(nodeNum, bthdr.bthNodeSize, out byte[] nodeData);
if(errno != ErrorNumber.NoError) continue;
NodeDescriptor nodeDesc =
Marshal.ByteArrayToStructureBigEndian<NodeDescriptor>(nodeData,
0,
System.Runtime.InteropServices.Marshal
.SizeOf(typeof(NodeDescriptor)));
if(nodeDesc.ndType != NodeType.ndLeafNode) continue;
leafNodesScanned++;
ushort beforeCount = entriesFound;
// Extract all entries with parentID = targetParentID from this leaf node
errno = ExtractDirectoryEntriesFromLeaf(nodeData, bthdr.bthNodeSize, targetParentID, ref entriesFound);
if(entriesFound > beforeCount)
{
AaruLogging.Debug(MODULE_NAME,
$"Node {nodeNum}: Found {entriesFound - beforeCount} matching entries (total now: {entriesFound})");
}
if(errno != ErrorNumber.NoError) continue;
// Check if we've found all entries
if(entriesFound >= expectedCount)
{
AaruLogging.Debug(MODULE_NAME, $"Found all expected entries: {entriesFound}/{expectedCount}");
break;
}
}
AaruLogging.Debug(MODULE_NAME,
$"Root directory caching complete: scanned {leafNodesScanned} leaf nodes, {entriesFound} entries found, cache has {_rootDirectoryCache.Count} items");
if(entriesFound > 0 || _rootDirectoryCache.Count > 0) return ErrorNumber.NoError;
}
// If brute-force failed, try standard B-tree traversal as last resort
AaruLogging.Debug(MODULE_NAME, "Brute-force scan found no entries, trying standard B-tree traversal");
// Navigate B-Tree to find entries with parentID = targetParentID
uint currentNode = bthdr.bthRoot;
@@ -1080,8 +1129,7 @@ public sealed partial class AppleHFS
// Only process records with parentID = targetParentID
if(keyParentID != targetParentID) continue;
AaruLogging.Debug(MODULE_NAME,
$"Record {i}: MATCH! Processing record with matching parentID");
AaruLogging.Debug(MODULE_NAME, $"Record {i}: MATCH! Processing record with matching parentID");
// Calculate key size for reading data
@@ -1253,6 +1301,7 @@ public sealed partial class AppleHFS
var directoryEntries = new Dictionary<string, CatalogEntry>();
ErrorNumber errno;
// This is robust against malformed B-tree structures like the one in this image
// Skip if leaf range is invalid
if(bthdr.bthFNode <= bthdr.bthLNode)

21
Aaru.Filesystems/AppleHFS/Mount.cs
View File

@@ -280,9 +280,24 @@ public sealed partial class AppleHFS
}
}
}
// If still not found, assume kRootCnid (2) is the root
// This handles cases where the root directory record doesn't exist but files with parentID=2 do
if(_rootDirectory.dirDirID == 0)
{
AaruLogging.Debug(MODULE_NAME, $"Root directory record not found, assuming CNID={kRootCnid} is the root");
_rootDirectory = new CdrDirRec
{
dirDirID = kRootCnid,
dirVal = 0 // Unknown valence, will be populated by CacheRootDirectoryEntries
};
}
else
{
AaruLogging.Debug(MODULE_NAME,
$"Root directory already found: CNID={_rootDirectory.dirDirID}, entries={_rootDirectory.dirVal}");
}
// Cache root directory entries
errno = CacheRootDirectoryEntries();
@@ -407,8 +422,8 @@ public sealed partial class AppleHFS
HfsOffsetToDeviceSector(firstAllocBlockSector512, out ulong startDeviceSector, out uint startByteOffset);
// Read enough data to cover the full extent
var sectorsToRead = (startByteOffset + firstExtent.xdrNumABlks * _mdb.drAlBlkSiz + _sectorSize - 1) /
_sectorSize;
uint sectorsToRead = (startByteOffset + firstExtent.xdrNumABlks * _mdb.drAlBlkSiz + _sectorSize - 1) /
_sectorSize;
ErrorNumber errno =
_imagePlugin.ReadSectors(startDeviceSector, false, sectorsToRead, out byte[] catalogData, out _);
@@ -657,7 +672,7 @@ public sealed partial class AppleHFS
// Re-read from the correct location
ulong sectorToRead = bruteForceOffset / _sectorSize;
var newByteOffset = (uint)(bruteForceOffset % _sectorSize);
var sectorCount = (_sectorSize - newByteOffset + 512 + _sectorSize - 1) / _sectorSize;
uint sectorCount = (_sectorSize - newByteOffset + 512 + _sectorSize - 1) / _sectorSize;
AaruLogging.Debug(MODULE_NAME,
$"ReadAndValidateCatalog: Re-reading sector {sectorToRead}, count={sectorCount}, byteOffset={newByteOffset}");