From b77291cc0af674ab98e1ea6192bd6a9205027b10 Mon Sep 17 00:00:00 2001 From: Michael Wedl Date: Thu, 7 Apr 2022 13:58:51 +0200 Subject: [PATCH] Fix LBA calculation for EBR --- src/pyreadpartitions/__init__.py | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/src/pyreadpartitions/__init__.py b/src/pyreadpartitions/__init__.py index 4c07047..123c7fd 100644 --- a/src/pyreadpartitions/__init__.py +++ b/src/pyreadpartitions/__init__.py @@ -41,9 +41,9 @@ # http://en.wikipedia.org/wiki/Master_boot_record#Partition_table_entries MBR_PARTITION_FORMAT = [ (b'B', 'status'), # > 0x80 => active - (b'3p', 'chs_first'), # 8*h + 2*c + 6*s + 8*c + (b'3s', 'chs_first'), # 8*h + 2*c + 6*s + 8*c (b'B', 'type'), - (b'3p', 'chs_last'), # 8*h + 2*c + 6*s + 8*c + (b'3s', 'chs_last'), # 8*h + 2*c + 6*s + 8*c (b'L', 'lba'), (b'L', 'sectors'), ] @@ -218,9 +218,9 @@ } -def make_fmt(name, fmt, extras=[]): +def make_fmt(name, fmt, extras=None): packfmt = b'<' + b''.join(t for t, n in fmt) - tupletype = namedtuple(name, [n for t, n in fmt if n != '_'] + extras) + tupletype = namedtuple(name, [n for t, n in fmt if n != '_'] + (extras or [])) return (packfmt, tupletype) @@ -268,6 +268,10 @@ def read_ebr_partition(fp, extended_lba, lba, num): if ebr.signature != b'\x55\xAA': raise MBRError('Bad EBR signature') parts = [read_mbr_partition(ebr.partition, num)] + + # LBA of EBRs are relative offsets from to the start of EBR to the partition. Calculate the absolute LBA. + parts[0] = parts[0]._replace(lba=extended_lba + parts[0].lba) + if ebr.next_ebr != 16 * b'\x00': part_next_ebr = read_mbr_partition(ebr.next_ebr, 0) next_lba = part_next_ebr.lba @@ -465,3 +469,4 @@ def main(): if __name__ == '__main__': exit(main()) +