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Added dbgrbyd.py script, fixed some small things in rbyd commit

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- We need to actually write the perturb bit
- It helps to encode the crc's leb128 length field correctly
This commit is contained in:
Christopher Haster
2022-12-20 18:59:39 -06:00
parent 2802880eaa
commit ad00ca79e2
2 changed files with 227 additions and 2 deletions
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lfs.c
+2 -2
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@@ -1424,13 +1424,13 @@ static int lfs_rbyd_commit(lfs_t *lfs, lfs_rbyd_t *rbyd,
// get around this catch-22 we just always write a fully-expanded leb128
// encoding
uint8_t buffer[1+5+4];
buffer[0] = LFS_MKRTAG(CRC0, 0, 0) << 1;
buffer[0] = (LFS_MKRTAG(CRC0, 0, 0) << 1) | (lfs_popc(crc) & 1);
lfs_off_t padding = aligned - (off + 1+5);
buffer[1] = 0x80 | (0x7f & (padding >> 0));
buffer[2] = 0x80 | (0x7f & (padding >> 7));
buffer[3] = 0x80 | (0x7f & (padding >> 14));
buffer[4] = 0x00 | (0x7f & (padding >> 21));
buffer[4] = 0x80 | (0x7f & (padding >> 21));
buffer[5] = 0x00 | (0x7f & (padding >> 28));
crc = lfs_crc32c(crc, buffer, 1+5);
scripts/dbgrbyd.py
Executable
+225
View File
@@ -0,0 +1,225 @@
#!/usr/bin/env python3
import itertools as it
import math as m
import struct
def crc32c(data, crc=0):
crc ^= 0xffffffff
for b in data:
crc ^= b
for j in range(8):
crc = (crc >> 1) ^ ((crc & 1) * 0x82f63b78)
return 0xffffffff ^ crc
def fromleb128(data):
word = 0
for i, b in enumerate(data):
word |= ((b & 0x7f) << 7*i)
word &= 0xffffffff
if not b & 0x80:
return word, i+1
return word, len(data)
def fromtag(data):
tag, delta1 = fromleb128(data)
size, delta2 = fromleb128(data[delta1:])
return tag & 1, tag >> 1, size, delta1+delta2
def popc(x):
return bin(x).count('1')
def xxd(data, width=16, crc=False):
for i in range(0, len(data), width):
yield '%-*s %-*s' % (
3*width,
' '.join('%02x' % b for b in data[i:i+width]),
width,
''.join(
b if b >= ' ' and b <= '~' else '.'
for b in map(chr, data[i:i+width])))
def tagrepr(tag, size, off=None):
type1 = tag & 0x7f
type2 = (tag >> 7) & 0xff
id = (tag >> 15) & 0xffff
if type1 & 1:
return 'alt %s %s x%x %s' % (
'r' if type1 & 4 else 'b',
'gt' if type1 & 2 else 'lt',
tag >> 3,
'x%x' % (0xffffffff & (off-size))
if off is not None
else '-%d' % off)
elif type1 == 0x40:
return 'create x%02x id%d %d' % (type2, id, size)
elif type1 == 0x48:
return 'delete x%02x id%d %d' % (type2, id, size)
elif type1 == 0x50:
return 'struct x%02x id%d %d' % (type2, id, size)
elif type1 == 0x60:
return 'uattr x%02x id%d %d' % (type2, id, size)
elif type1 == 0x08:
if type2 == 0:
return 'tail %d' % size
else:
return 'tail x%02x %d' % (type2, size)
elif type1 == 0x10:
return 'gstate x%02x %d' % (type2, size)
elif type1 == 0x02 or type1 == 0x0a:
if type2 == 0:
return 'crc%x %d' % (type1 >> 3, size)
else:
return 'crc%x x%02x %d' % (type1 >> 3, type2, size)
elif type1 == 0x12:
if type2 == 0:
return 'fcrc %d' % (size)
else:
return 'fcrc x%02x %d' % (type2, size)
else:
return 'x%02x x%02x id%d %d' % (type1, type2, id, size)
def main(disk, block_size, block1, block2=None, **args):
# read each block
blocks = [block for block in [block1, block2] if block is not None]
with open(disk, 'rb') as f:
datas = []
for block in blocks:
f.seek(block * block_size)
datas.append(f.read(block_size))
# first figure out which block as the most recent revision
def fetch(data):
rev, = struct.unpack('<I', data[0:4])
crc = crc32c(data[0:4])
off = 0
j = 4
while j < block_size:
v, tag, size, delta = fromtag(data[j:])
if v != popc(crc) & 1:
break
crc = crc32c(data[j:j+delta], crc)
j += delta
if not tag & 0x1:
if (tag & 0x37) != 0x2:
crc = crc32c(data[j:j+size], crc)
# found a crc?
else:
crc_, = struct.unpack('<I', data[j:j+4])
if crc != crc_:
break
# commit what we have
off = j + size
j += size
return rev, off
revs, offs = [], []
i = 0
for block, data in zip(blocks, datas):
rev, off = fetch(data)
revs.append(rev)
offs.append(off)
# compare with sequence arithmetic
if off and ((rev - revs[i]) & 0x80000000):
i = len(revs)-1
# print contents of the winning metadata block
block, data, rev, off = blocks[i], datas[i], revs[i], offs[i]
print('mdir 0x%x, rev %d, size %d (was 0x%x, %d, %d)' % (
block, rev, off,
blocks[len(blocks)-1-i],
revs[len(revs)-1-i],
offs[len(offs)-1-i]))
print('%-8s %-22s %s' % (
'off', 'tag',
'data (truncated)'
if not args.get('no_truncate') else ''))
# print revision count
crc = crc32c(data[0:4])
if args.get('raw'):
print('%08x: %s' % (0, next(xxd(data[0:4]))))
# print tags
j = 4
while j < (block_size if args.get('all') else off):
notes = []
v, tag, size, delta = fromtag(data[j:])
if v != popc(crc) & 1:
notes.append('v!=%x' % (popc(crc) & 1))
crc = crc32c(data[j:j+delta], crc)
j += delta
if not tag & 0x1:
if (tag & 0x37) != 0x2:
crc = crc32c(data[j:j+size], crc)
# found a crc?
else:
crc_, = struct.unpack('<I', data[j:j+4])
if crc != crc_:
notes.append('crc!=%08x' % crc)
j += size
print('%08x: %-57s%s' % (
j-delta-size,
'%-22s%s' % (
tagrepr(tag, size, j),
' %s' % next(xxd(data[j-size:j-size+min(size, 8)], 8), '')
if not tag & 1 and not args.get('no_truncate') else ''),
' (%s)' % ', '.join(notes)
if notes else ''))
if args.get('raw'):
for o, line in enumerate(xxd(data[j-delta-size:j-size])):
print('%8s: %s' % ('%04x' % (j-delta-size + o*16), line))
if not tag & 0x1:
if args.get('raw') or args.get('no_truncate'):
for o, line in enumerate(xxd(data[j-size:j])):
print('%8s: %s' % ('%04x' % (j-size + o*16), line))
if __name__ == "__main__":
import argparse
import sys
parser = argparse.ArgumentParser(
description="Debug rbyd metadata.",
allow_abbrev=False)
parser.add_argument(
'disk',
help="File containing the block device.")
parser.add_argument(
'block_size',
type=lambda x: int(x, 0),
help="Block size in bytes.")
parser.add_argument(
'block1',
type=lambda x: int(x, 0),
help="Block address of the first metadata block.")
parser.add_argument(
'block2',
nargs='?',
type=lambda x: int(x, 0),
help="Block address of the second metadata block.")
parser.add_argument(
'-a', '--all',
action='store_true',
help="Don't stop parsing on bad commits.")
parser.add_argument(
'-R', '--raw',
action='store_true',
help="Show the raw data including tag encodings.")
parser.add_argument(
'-T', '--no-truncate',
action='store_true',
help="Don't truncate, show the full contents.")
sys.exit(main(**{k: v
for k, v in vars(parser.parse_intermixed_args()).items()
if v is not None}))