39 lines
1.3 KiB
Python
39 lines
1.3 KiB
Python
import struct
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with open('/tmp/fs_meta.img', 'r+b') as f:
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f.seek(1024)
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sb = bytearray(f.read(1024))
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ro_compat = struct.unpack_from('<I', sb, 100)[0]
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incompat = struct.unpack_from('<I', sb, 96)[0]
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compat = struct.unpack_from('<I', sb, 92)[0]
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print(f'Before: compat=0x{compat:08x} incompat=0x{incompat:08x} ro_compat=0x{ro_compat:08x}')
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incompat &= ~0x004 # clear HAS_JOURNAL
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ro_compat &= ~0x400 # clear METADATA_CSUM
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ro_compat &= ~0x010 # clear GDT_CSUM
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compat &= ~0x004 # clear HAS_JOURNAL from compat too
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# Zero the journal inode number so e2fsck ignores it
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struct.pack_into('<I', sb, 180, 0) # s_journal_inum = 0
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struct.pack_into('<I', sb, 92, compat)
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struct.pack_into('<I', sb, 96, incompat)
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struct.pack_into('<I', sb, 100, ro_compat)
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struct.pack_into('<I', sb, 1020, 0) # clear sb checksum
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f.seek(1024)
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f.write(bytes(sb))
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print(f'After: compat=0x{compat:08x} incompat=0x{incompat:08x} ro_compat=0x{ro_compat:08x}')
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# Zero all GDT checksums
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with open('/tmp/fs_meta.img', 'r+b') as f:
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f.seek(4096)
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gdt = bytearray(f.read(35728 * 64))
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for g in range(35728):
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struct.pack_into('<H', gdt, g*64+30, 0)
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f.seek(4096)
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f.write(bytes(gdt))
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print('GDT checksums zeroed')
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