xfs_btree.hpp

1. Overview

The xfs_btree.hpp file implements traversal and decoding of XFS allocation and metadata B-trees.

This is an interface and data-contract file. It declares the public and internal types used by this subsystem, allowing implementation files and callers to share a stable compile-time contract.

Its paired source or interface file is xfs_btree.cpp.

Primary responsibilities:

  • Decode short and long B-tree headers
  • Read internal and leaf records
  • Traverse blocks safely
  • Support inode and extent recovery

2. File Identity and Scope

  • Source path: src/xfs_btree.hpp
  • Language: C++
  • File role: interface and data-contract file
  • Physical lines: 369
  • Non-empty lines: 336
  • SHA-256: 6936bbf6e8eb5a0bdf42470c48cbeb79ae921662170f81ec91a59fea32140c51

Declared namespaces:

  • xfs

3. Dependencies

3.1 Project Headers

  • xfs_format.hpp

3.2 Standard and External Headers

  • cstdint
  • functional
  • string
  • vector

These dependencies define the file’s compile-time integration with the recovery engine, GTK interface, on-disk format decoders, operating-system services, or C++ standard library.

4. Declared Types

  • struct BtreeNodeHeader.
  • struct InobtRec.
  • struct AllocatedInode.
  • struct BtreeLongHeader.

5. Constants and Configuration Values

  • constexpr uint32_t NULLAGBLOCK=0xFFFFFFFFu
  • constexpr uint64_t NULLFSBLOCK=0xFFFFFFFFFFFFFFFFull
  • constexpr uint32_t XFS_BMBT_MAGIC_V4=0x424D4150u
  • constexpr uint32_t XFS_BMBT_MAGIC_V5=0x424D4133u
  • constexpr uint32_t BMBT_KEY_SIZE_LONG=8
  • constexpr uint32_t BMBT_PTR_SIZE_LONG=8
  • constexpr uint32_t BMBT_REC_SIZE=16

5.1 Operational Strings, Paths, Formats, or Commands

The following code literals are operationally relevant and may identify filesystem paths, helper commands, formats, signatures, or subsystem labels:

  • xfs_format.hpp

6. Data Members and Persistent State

The interface declares the following state-bearing members:

  • constexpr uint32_t NULLAGBLOCK=0xFFFFFFFFu
  • constexpr uint64_t NULLFSBLOCK=0xFFFFFFFFFFFFFFFFull
  • uint32_t magic {0}
  • uint16_t level {0}
  • uint16_t numrecs {0}
  • uint32_t leftsib {NULLAGBLOCK}
  • uint32_t rightsib{NULLAGBLOCK}
  • uint64_t blkno {0}
  • uint64_t lsn {0}
  • uint32_t owner {0}
  • uint32_t crc {0}
  • bool is_v5_header{false}
  • uint32_t startino {0}
  • uint16_t holemask {0}
  • uint8_t count {64}
  • uint8_t freecount {0}
  • uint64_t freemask {0}
  • bool sparse {false}
  • uint64_t ino {0}
  • uint32_t agno {0}
  • uint32_t agbno {0}
  • uint32_t in_chunk_index {0}
  • uint64_t disk_offset {0}
  • constexpr uint32_t XFS_BMBT_MAGIC_V4=0x424D4150u
  • constexpr uint32_t XFS_BMBT_MAGIC_V5=0x424D4133u
  • constexpr uint32_t BMBT_KEY_SIZE_LONG=8
  • constexpr uint32_t BMBT_PTR_SIZE_LONG=8
  • constexpr uint32_t BMBT_REC_SIZE=16
  • uint64_t leftsib {NULLFSBLOCK}
  • uint64_t rightsib {NULLFSBLOCK}
  • uint64_t owner {0}
  • bool is_v5_header {false}

These members hold configuration, parser context, UI widgets, source references, progress state, recovered metadata, or temporary resources according to the owning type.

7. API and Function Inventory

The following callable interfaces or definitions were detected:

  • inline uint32_t btree_header_size(bool is_v5) – Implements the operation identified by this API and updates or returns the associated state.
  • bool parse_btree_header(const unsigned char*buf,uint32_t expected_magic_v4,uint32_t expected_magic_v5,BtreeNodeHeader&out) – Reads or derives the requested information and returns or stores the decoded result.
  • void parse_inobt_record(const unsigned char*buf,bool is_v5_sparse,InobtRec&out) – Reads or derives the requested information and returns or stores the decoded result.
  • bool walk_inode_btree(DiskReader&reader,const VolumeContext&vol,uint32_t agno,const InobtRecordCallback&on_record,std::vector<std::string>&logs,std::string&error) – Implements the operation identified by this API and updates or returns the associated state.
  • bool walk_all_inode_records(DiskReader&reader,const VolumeContext&vol,const InobtRecordCallback&on_record,std::vector<std::string>&logs) – Implements the operation identified by this API and updates or returns the associated state.
  • bool walk_free_inode_btree(DiskReader&reader,const VolumeContext&vol,uint32_t agno,const InobtRecordCallback&on_record,std::vector<std::string>&logs,std::string&error) – Implements the operation identified by this API and updates or returns the associated state.
  • bool walk_all_free_inode_records(DiskReader&reader,const VolumeContext&vol,const InobtRecordCallback&on_record,std::vector<std::string>&logs) – Implements the operation identified by this API and updates or returns the associated state.
  • void expand_chunk(const InobtRec&rec,uint32_t agno,const VolumeContext&vol,std::vector<AllocatedInode>&out) – Implements the operation identified by this API and updates or returns the associated state.
  • void expand_chunk_free(const InobtRec&rec,uint32_t agno,const VolumeContext&vol,std::vector<AllocatedInode>&out) – Implements the operation identified by this API and updates or returns the associated state.
  • inline uint32_t btree_long_header_size(bool is_v5) – Implements the operation identified by this API and updates or returns the associated state.
  • bool parse_btree_long_header(const unsigned char*buf,uint32_t expected_magic_v4,uint32_t expected_magic_v5,BtreeLongHeader&out) – Reads or derives the requested information and returns or stores the decoded result.
  • bool walk_extent_btree_root(DiskReader&reader,const VolumeContext&vol,const unsigned char*root_buf,uint32_t root_len,bool is_v5_volume,uint32_t max_extents,std::vector<Extent>&out,std::vector<std::string>&logs,std::string&error) – Implements the operation identified by this API and updates or returns the associated state.

8. Operational Flow

The subsystem represented by this file normally participates in the following flow:

  1. Decode short and long B-tree headers.
  2. Read internal and leaf records.
  3. Traverse blocks safely.
  4. Support inode and extent recovery.
  5. Expose or execute the detected APIs: btree_header_size, parse_btree_header, parse_inobt_record, walk_inode_btree, walk_all_inode_records, walk_free_inode_btree, walk_all_free_inode_records, expand_chunk, expand_chunk_free, btree_long_header_size, parse_btree_long_header, walk_extent_btree_root.
  6. Return explicit results, progress data, recovered records, or diagnostics to the calling layer.

9. Validation and Error Handling

  • Errors are propagated through Boolean results, error strings, logs, exceptions, or status records depending on the API.
  • Byte offsets, sizes and lengths must be validated before arithmetic and before every read to avoid overflow and out-of-bounds access.
  • On-disk structures are accepted only after validating signatures, magic values and structural constraints.
  • Input and output paths require existence checks, permission handling and safe destination construction.

10. Runtime, Concurrency, and Resource Management

  • Deterministic behavior: callers depend on explicit return values and stable data structures to distinguish successful recovery from partial or invalid results.

11. Security and Data-Recovery Considerations

  • Recovery code should prefer read-only source access and avoid writing to the original damaged medium.
  • Raw devices and image files are treated as untrusted binary input; every offset and length must remain bounded by the source size.

12. Implementation Considerations

  • Changes to public declarations can affect every translation unit that includes this header and should preserve binary and source compatibility where required.
  • State-bearing members should have explicit ownership and initialization semantics, especially for references, pointers, file descriptors and GTK widgets.
  • Large-device arithmetic uses 64-bit values; additions and multiplications should be checked before use as offsets or allocation sizes.

13. Integration with the Recovery Pipeline

  • The file belongs to the source-discovery, parsing or support layer.
  • Its results feed scanner, recovery or reporting modules through shared models.
  • The API should remain deterministic so higher layers can combine results safely.

14. Licensing and Provenance

No explicit copyright or software-license statement was detected in the opening section of this individual file. Distribution terms should therefore be verified against the project-level license and repository metadata.

The SHA-256 value in this document can be used to associate the generated documentation with the exact source version analyzed.

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