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LeavaTail / debugfatfs

FAT/exFATのファイルシステム情報出力プログラム
GNU General Public License v2.0
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Consider NoFatChain Field in exFAT filesystem #35

Closed LeavaTail closed 3 years ago

LeavaTail commented 3 years ago

Is your feature request related to a problem? Please describe. According to exFAT specification,

The NoFatChain field shall indicate whether or not the active FAT describes the given allocation's cluster chain.

The valid values for this field shall be:

  • 0, which means the corresponding FAT entries for the allocation's cluster chain are valid and implementations shall interpret them; if the AllocationPossible field contains the value 0, or if the AllocationPossible field contains the value 1 and the FirstCluster field contains the value 0, then this field's only valid value is 0 1, which means the associated allocation is one contiguous series of clusters; the corresponding FAT entries for the clusters are invalid and implementations shall not interpret them; implementations may use the following equation to calculate the size of the associated allocation: DataLength / (2SectorsPerClusterShift* 2BytesPerSectorShift) rounded up to the nearest integer

If critical primary directory entry structures which derive from this template redefine the GeneralPrimaryFlags field, then the corresponding FAT entries for any associated allocation's cluster chain are valid.