add_inode: read compressed $DATA by compression unit

maharmstone · Jan 1, 2021 · e538754 · e538754
1 parent 1e8fc7a
commit e538754
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Showing 2 changed files with 56 additions and 13 deletions.
diff --git a/src/ntfs.h b/src/ntfs.h
@@ -104,7 +104,8 @@ typedef struct {
  uint64_t LowestVcn;
  uint64_t HighestVcn;
  uint16_t MappingPairsOffset;
- uint8_t Reserved[6];
+ uint16_t CompressionUnit;
+ uint32_t Padding;
  uint64_t AllocatedLength;
  uint64_t FileSize;
  uint64_t ValidDataLength;

diff --git a/src/ntfs2btrfs.cpp b/src/ntfs2btrfs.cpp
@@ -1691,27 +1691,69 @@ static void add_inode(root& r, uint64_t inode, uint64_t ntfs_inode, bool& is_dir
  file_size = att->Form.Resident.ValueLength;
 
  inline_data = res_data;
-
- // ATTRIBUTE_FLAG_COMPRESSION_MASK can be set in flags, but doesn't seem to do anything
  } else {
- file_size = att->Form.Nonresident.FileSize;
+ if (file_size == 0)
+ file_size = att->Form.Nonresident.FileSize;
 
- if (att->Flags & ATTRIBUTE_FLAG_COMPRESSION_MASK) {
+ if (att->Form.Nonresident.CompressionUnit != 0) {
  list<mapping> comp_mappings;
  string compdata;
+ uint64_t cus = 1 << att->Form.Nonresident.CompressionUnit;
 
  read_nonresident_mappings(att, comp_mappings, cluster_size);
 
- compdata.resize(att->Form.Nonresident.TotalAllocated);
- memset(compdata.data(), 0, compdata.length());
-
- for (const auto& m : comp_mappings) {
- dev.seek(m.lcn * cluster_size);
- dev.read(compdata.data() + (m.vcn * cluster_size), m.length * cluster_size);
- }
+ compdata.resize(cus * cluster_size);
 
  try {
- inline_data = lznt1_decompress(compdata, file_size);
+ uint64_t vcn = att->Form.Nonresident.LowestVcn;
+
+ while (true) {
+ uint64_t clusters = 0;
+
+ while (clusters < cus) {
+ if (comp_mappings.empty()) {
+ memset(compdata.data() + (clusters * cluster_size), 0, (cus - clusters) * cluster_size);
+ break;
+ }
+
+ auto& m = comp_mappings.front();
+ auto l = min(m.length, cus - clusters);
+
+ if (m.lcn == 0) {
+ memset(compdata.data() + (clusters * cluster_size), 0, l * cluster_size);
+
+ if (l < m.length) {
+ m.vcn += l;
+ m.length -= l;
+ } else
+ comp_mappings.pop_front();
+ } else {
+ dev.seek(m.lcn * cluster_size);
+ dev.read(compdata.data() + (clusters * cluster_size), l * cluster_size);
+
+ if (l < m.length) {
+ m.lcn += l;
+ m.vcn += l;
+ m.length -= l;
+ } else
+ comp_mappings.pop_front();
+ }
+
+ clusters += l;
+ }
+
+ inline_data += lznt1_decompress(compdata, compdata.length());
+
+ if (inline_data.length() >= file_size) {
+ inline_data.resize(file_size);
+ break;
+ }
+
+ vcn += cus;
+
+ if (vcn >= att->Form.Nonresident.HighestVcn)
+ break;
+ }
  } catch (const exception& e) {
  if (filename.empty())
  filename = f.get_filename();