file/magic/Magdir/dwarfs

#------------------------------------------------------------------------------
# $File: dwarfs,v 1.2 2023/05/23 13:37:32 christos Exp $
# dwarfs: file(1) magic for DwarFS File System Image files
# URL: https://github.com/mhx/dwarfs for details about DwarFS
# From: Marcus Holland-Moritz <github@mhxnet.de>

#### DwarFS Version Macro
0			name		dwarfsversion
>&0			byte		x		\b, version %d
>&1			byte		x		\b.%d

#### DwarFS Compression Macro
0			name		dwarfscompression
>&0			leshort		=0		\b, uncompressed
>&0			leshort		=1		\b, LZMA compression
>&0			leshort		=2		\b, ZSTD compression
>&0			leshort		=3		\b, LZ4 compression
>&0			leshort		=4		\b, LZ4HC compression
>&0			leshort		=5		\b, BROTLI compression

#### DwarFS files without header
## We first check against a DWARFS magic at the start of the file, then
## validate by checking the block count / section type to be all zeros
## for the first block. Finally, we check that the *next* block also
## has the correct DWARFS magic.
0			string		DWARFS
>&0x2A			string/b	\0\0\0\0\0\0
>>&(&0x02.q+0x0A)	string		DWARFS		DwarFS File System Image
>>>&0			use		dwarfsversion
>>&0			use		dwarfscompression

#### DwarFS files with header
## We search for a DWARFS magic in the first 64k of the file (images with
## headers longer than 64k won't be recognized), then  validate by checking
## the block count / section type to be all zeros for the first block.
## Finally, we check that the *next* block also has the correct DWARFS magic.
## If we find a DWARFS magic that doesn't pass validation, we continue with
## an indirect match recursively.
1			search/65536/b	DWARFS
>&0x2A			string/b	\0\0\0\0\0\0
>>&(&0x02.q+0x0A)	string		DWARFS		DwarFS File System Image (with header)
>>>&0			use		dwarfsversion
>>&0			use		dwarfscompression
>&-1			indirect	x