mirror of
https://github.com/commaai/agnos-builder.git
synced 2026-07-10 09:12:05 +08:00
Cameron Clough
77 lines
2.3 KiB
Python
Executable File
77 lines
2.3 KiB
Python
Executable File
#!/usr/bin/env python3
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import argparse
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import sys
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import struct
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from enum import IntEnum
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# https://android.googlesource.com/platform/system/core/+/master/libsparse/sparse_format.h
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class ChunkType(IntEnum):
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RAW = 0xCAC1
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FILL = 0xCAC2
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DONT_CARE = 0xCAC3
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CRC32 = 0xCAC4
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ChunkHeader = struct.Struct("<2H2I")
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def process_image(input_image: str, output_image: str) -> None:
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with open(input_image, "rb") as inf, open(output_image, "wb") as outf:
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dat = inf.read(28)
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outf.write(dat)
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header = struct.unpack("<I4H4I", dat)
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magic = header[0]
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major_version = header[1]
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minor_version = header[2]
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file_hdr_sz = header[3]
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chunk_hdr_sz = header[4]
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total_chunks = header[7]
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image_checksum = header[8]
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assert magic == 0xED26FF3A
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assert major_version == 1 and minor_version == 0
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assert file_hdr_sz == 28
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assert chunk_hdr_sz == 12
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for _ in range(1, total_chunks+1):
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header_bin = inf.read(12)
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header = ChunkHeader.unpack(header_bin)
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chunk_type = ChunkType(header[0])
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chunk_sz = header[2]
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total_sz = header[3]
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data_sz = total_sz - 12
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# replace fill 0s with DONT_CARE chunks
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if chunk_type == ChunkType.FILL:
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assert data_sz == 4
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fill_bin = inf.read(4)
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fill = struct.unpack("<I", fill_bin)[0]
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if fill == 0:
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# https://coral.googlesource.com/img2simg/+/refs/heads/master/libsparse/output_file.c#351
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dat = ChunkHeader.pack(ChunkType.DONT_CARE, 0, chunk_sz, ChunkHeader.size)
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outf.write(dat)
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continue
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else:
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inf.seek(inf.tell() - data_sz)
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# pass through other chunk types
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outf.write(header_bin)
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dat = inf.read(data_sz)
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outf.write(dat)
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if __name__ == "__main__":
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parser = argparse.ArgumentParser(description="Replace FILL 0 chunks in a sparse image with DONT_CARE chunks",
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formatter_class=argparse.ArgumentDefaultsHelpFormatter)
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parser.add_argument("input_image", nargs="?", help="Input sparse image")
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parser.add_argument("output_image", nargs="?", help="Output sparse image")
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args = parser.parse_args(sys.argv[1:])
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if args.input_image is None or args.output_image is None:
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parser.print_help()
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exit(1)
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process_image(args.input_image, args.output_image)
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