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54 lines
1.6 KiB
Plaintext
54 lines
1.6 KiB
Plaintext
=== Snapshot Block (`SNAP`)
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The snapshot block holds a list of historical indexes, representing earlier versions of the media captured within the image.
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This feature enables users to manually preserve a specific media state, allowing reversion to previous versions or comparison between multiple data capture attempts.
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The active index used by the image must always be the one referenced by the image header.
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If any snapshot block references the current index, it must be ignored and treated as non-existent during image save operations.
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Generation 0 refers to the initial image state, where only a single index—pointed to by the header—is present.
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The latest image header should reference all available snapshots, unless individual blocks have been explicitly discarded by the user.
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Once discarded, such blocks become orphaned and are no longer reachable within the image structure.
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During conversion from AaruFormat, only one snapshot (or the latest index) should be included, based on user selection.
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==== Structure Definition
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[source,c]
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/* Undefined */
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==== Field Descriptions
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[cols="2,2,2,6",options="header"]
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|===
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|Type
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|Size
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|Name
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|Description
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|uint32_t
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|4 bytes
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|identifier
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|The snapshot block identifier, always 'SNAP'
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|uint32_t
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|4 bytes
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|length
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|The length in bytes of the data following this header.
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|uint16_t
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|2 bytes
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|generation
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|The generation, starting from 1, of this snapshot. Every snapshot gets a generation incremented in one from the lastest recorded one.
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|int64_t
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|8 bytes
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|creationTime
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|Creation time of this snapshot.
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|uint64_t
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|8 bytes
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|index
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|Offset in bytes where the index marked by this snapshot resides.
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|=== |