index.h File Reference

On‑disk index block header and entry structures (versions 1, 2 and 3). More...

Go to the source code of this file.

Data Structures
struct	IndexHeader
	Index header (version 1) for legacy images (identifier == IndexBlock). More...
struct	IndexHeader2
	Index header (version 2) with 64‑bit entry counter (identifier == IndexBlock2). More...
struct	IndexHeader3
	Index header (version 3) adding hierarchical chaining (identifier == IndexBlock3). More...
struct	IndexEntry
	Single index entry describing a block's type, (optional) data classification, and file offset. More...

Typedefs
typedef struct IndexHeader	IndexHeader
typedef struct IndexHeader2	IndexHeader2
typedef struct IndexHeader3	IndexHeader3
typedef struct IndexEntry	IndexEntry

Detailed Description

On‑disk index block header and entry structures (versions 1, 2 and 3).

The index provides a directory of all blocks contained in an Aaru image. Each index block starts with a versioned header (IndexHeader / IndexHeader2 / IndexHeader3) followed by a contiguous array of fixed‑size IndexEntry records. Version 3 adds support for hierarchical (chained / nested) subindexes.

Version mapping by block identifier (see BlockType):

• IndexBlock (v1) -> IndexHeader followed by 16‑bit entry count entries.
• IndexBlock2 (v2) -> IndexHeader2 followed by 64‑bit entry count entries.
• IndexBlock3 (v3) -> IndexHeader3 with optional hierarchical subindex references.

CRC coverage & endianness:

• The crc64 field stores a CRC64-ECMA over the entries array ONLY (header bytes are excluded).
• For images with imageMajorVersion <= AARUF_VERSION_V1 a legacy writer byte-swapped the CRC; readers compensate (see verify_index_v1/v2/v3). The value in the header remains whatever was originally written.

Hierarchical (v3) behavior:

• Entries whose blockType == IndexBlock3 refer to subindex blocks; readers recursively load and flatten.
• IndexHeader3::previous can point to a preceding index segment (for append / incremental scenarios) or 0.
• CRC of the main index does NOT cover subindex contents; each subindex has its own header + CRC.

Invariants / validation recommendations:

• identifier must equal the expected BlockType variant for that version.
• entries > 0 implies the entries array byte size == entries * sizeof(IndexEntry).
• crc64 must match recomputed CRC64( entries array ) (after legacy byte swap handling if required).
• For v3, if previous != 0 it should point to another IndexBlock3 header (optional best‑effort check).

Notes:

• Structures are packed (1‑byte alignment). All multi-byte integers are little‑endian on disk.
• The index does not store per-entry CRC; integrity relies on each individual block's own CRC plus the index CRC.
• dataType in IndexEntry is meaningful only for block types that carry typed data (e.g. DataBlock, DumpHardwareBlock, etc.).

See also: verify_index_v1(), verify_index_v2(), verify_index_v3() for integrity procedures.

Definition in file index.h.

Typedef Documentation

IndexEntry

typedef struct IndexEntry IndexEntry

IndexHeader

typedef struct IndexHeader IndexHeader

IndexHeader2

typedef struct IndexHeader2 IndexHeader2

IndexHeader3

typedef struct IndexHeader3 IndexHeader3