mirror of
https://github.com/eledio-devices/thirdparty-littlefs.git
synced 2025-10-31 00:32:38 +01:00
f4b6a6b328
The root of the problem was some assumptions about what tags could be sent to lfs_dir_commit. - The first assumption is that there could be only one splice (create/delete) tag at a time, which is trivially broken by the core commit in lfs_rename. - The second assumption is that there is at most one create and one delete in a single commit. This is less obvious but turns out to not be true in the case that we rename a file such that it overwrites another file in the same directory (1 delete for source file, 1 delete for destination). - The third assumption was that there was an ordering to the delete/creates passed to lfs_dir_commit. It may be possible to force all deletes to follow creates by rearranging the tags in lfs_rename, but this risks overflowing tag ids. The way the lfs_dir_commit first collected the "deletetag" and "createtag" broke all three of these assumptions. And because we lose the ordering information we can no longer apply the directory changes to open files correctly. The file ids may be shifted in a way that doesn't reflect the actual operations on disk. These problems were made worst by lfs_dir_commit cleaning up moves implicitly, which also creates deletes implicitly. While cleaning up moves in lfs_dir_commit may save some code size, it makes the commit logic much more difficult to implement correctly. This bug turned into pulling out a dead tree stump, roots and all. I ended up reworking how lfs_dir_commit updates open files so that it has less assumptions, now it just traverses the commit tags multiple times in order to update file ids after a successful commit in the correct order. This also got rid of the dir copy by carefully updating split dirs after all files have an up-to-date copy of the original dir. I also just removed the implicit move cleanup. It turns out the only commits that can occur before we have cleaned up the move is in lfs_fs_relocate, so it was simple enough to explicitly handle this case when we update our parent and pred during a relocate. Cases where we may need to fix moves: - In lfs_rename when we move a file/dir - In lfs_demove if we lose power - In lfs_fs_relocate if we have to relocate our parent and we find it had a pending move (or else the move will be outdated) - In lfs_fs_relocate if we have to relocate our predecessor and we find it had a pending move (or else the move will be outdated) Note the two cases in lfs_fs_relocate may be recursive. But lfs_fs_relocate can only trigger other lfs_fs_relocates so it's not possible for pending moves to spill out into other filesystem commits And of couse, I added several tests to cover these situations. Hopefully the rename-with-open-files logic should be fairly locked down now. found with initial fix by eastmoutain
279 lines
10 KiB
Python
Executable File
279 lines
10 KiB
Python
Executable File
#!/usr/bin/env python3
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import struct
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import sys
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import json
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import io
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import itertools as it
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from readmdir import Tag, MetadataPair
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def popc(x):
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return bin(x).count('1')
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def ctz(x):
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return len(bin(x)) - len(bin(x).rstrip('0'))
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def dumptags(args, mdir, f):
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if args.all:
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tags = mdir.all_
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elif args.log:
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tags = mdir.log
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else:
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tags = mdir.tags
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for k, tag in enumerate(tags):
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f.write("tag %08x %s" % (tag, tag.typerepr()))
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if tag.id != 0x3ff:
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f.write(" id %d" % tag.id)
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if tag.size != 0x3ff:
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f.write(" size %d" % tag.size)
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if tag.is_('name'):
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f.write(" name %s" %
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json.dumps(tag.data.decode('utf8')))
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if tag.is_('dirstruct'):
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f.write(" dir {%#x, %#x}" % struct.unpack(
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'<II', tag.data[:8].ljust(8, b'\xff')))
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if tag.is_('ctzstruct'):
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f.write(" ctz {%#x} size %d" % struct.unpack(
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'<II', tag.data[:8].ljust(8, b'\xff')))
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if tag.is_('inlinestruct'):
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f.write(" inline size %d" % tag.size)
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if tag.is_('gstate'):
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f.write(" 0x%s" % ''.join('%02x' % c for c in tag.data))
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if tag.is_('tail'):
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f.write(" tail {%#x, %#x}" % struct.unpack(
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'<II', tag.data[:8].ljust(8, b'\xff')))
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f.write("\n")
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if args.data:
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for i in range(0, len(tag.data), 16):
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f.write(" %-47s %-16s\n" % (
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' '.join('%02x' % c for c in tag.data[i:i+16]),
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''.join(c if c >= ' ' and c <= '~' else '.'
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for c in map(chr, tag.data[i:i+16]))))
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def dumpentries(args, mdir, f):
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for k, id_ in enumerate(mdir.ids):
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name = mdir[Tag('name', id_, 0)]
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struct_ = mdir[Tag('struct', id_, 0)]
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f.write("id %d %s %s" % (
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id_, name.typerepr(),
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json.dumps(name.data.decode('utf8'))))
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if struct_.is_('dirstruct'):
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f.write(" dir {%#x, %#x}" % struct.unpack(
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'<II', struct_.data[:8].ljust(8, b'\xff')))
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if struct_.is_('ctzstruct'):
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f.write(" ctz {%#x} size %d" % struct.unpack(
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'<II', struct_.data[:8].ljust(8, b'\xff')))
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if struct_.is_('inlinestruct'):
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f.write(" inline size %d" % struct_.size)
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f.write("\n")
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if args.data and struct_.is_('inlinestruct'):
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for i in range(0, len(struct_.data), 16):
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f.write(" %-47s %-16s\n" % (
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' '.join('%02x' % c for c in struct_.data[i:i+16]),
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''.join(c if c >= ' ' and c <= '~' else '.'
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for c in map(chr, struct_.data[i:i+16]))))
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elif args.data and struct_.is_('ctzstruct'):
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block, size = struct.unpack(
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'<II', struct_.data[:8].ljust(8, b'\xff'))
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data = []
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i = 0 if size == 0 else (size-1) // (args.block_size - 8)
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if i != 0:
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i = ((size-1) - 4*popc(i-1)+2) // (args.block_size - 8)
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with open(args.disk, 'rb') as f2:
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while i >= 0:
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f2.seek(block * args.block_size)
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dat = f2.read(args.block_size)
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data.append(dat[4*(ctz(i)+1) if i != 0 else 0:])
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block, = struct.unpack('<I', dat[:4].ljust(4, b'\xff'))
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i -= 1
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data = bytes(it.islice(
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it.chain.from_iterable(reversed(data)), size))
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for i in range(0, min(len(data), 256)
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if not args.no_truncate else len(data), 16):
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f.write(" %-47s %-16s\n" % (
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' '.join('%02x' % c for c in data[i:i+16]),
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''.join(c if c >= ' ' and c <= '~' else '.'
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for c in map(chr, data[i:i+16]))))
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for tag in mdir.tags:
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if tag.id==id_ and tag.is_('userattr'):
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f.write("id %d %s size %d\n" % (
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id_, tag.typerepr(), tag.size))
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if args.data:
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for i in range(0, len(tag.data), 16):
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f.write(" %-47s %-16s\n" % (
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' '.join('%02x' % c for c in tag.data[i:i+16]),
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''.join(c if c >= ' ' and c <= '~' else '.'
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for c in map(chr, tag.data[i:i+16]))))
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def main(args):
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with open(args.disk, 'rb') as f:
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dirs = []
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superblock = None
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gstate = b''
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mdirs = []
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tail = (args.block1, args.block2)
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hard = False
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while True:
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# load mdir
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data = []
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blocks = {}
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for block in tail:
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f.seek(block * args.block_size)
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data.append(f.read(args.block_size)
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.ljust(args.block_size, b'\xff'))
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blocks[id(data[-1])] = block
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mdir = MetadataPair(data)
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mdir.blocks = tuple(blocks[id(p.data)] for p in mdir.pair)
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# fetch some key metadata as a we scan
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try:
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mdir.tail = mdir[Tag('tail', 0, 0)]
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if mdir.tail.size != 8 or mdir.tail.data == 8*b'\xff':
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mdir.tail = None
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except KeyError:
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mdir.tail = None
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# have superblock?
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try:
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nsuperblock = mdir[
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Tag(0x7ff, 0x3ff, 0), Tag('superblock', 0, 0)]
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superblock = nsuperblock, mdir[Tag('inlinestruct', 0, 0)]
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except KeyError:
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pass
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# have gstate?
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try:
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ngstate = mdir[Tag('movestate', 0, 0)]
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gstate = bytes((a or 0) ^ (b or 0)
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for a,b in it.zip_longest(gstate, ngstate.data))
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except KeyError:
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pass
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# add to directories
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mdirs.append(mdir)
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if mdir.tail is None or not mdir.tail.is_('hardtail'):
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dirs.append(mdirs)
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mdirs = []
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if mdir.tail is None:
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break
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tail = struct.unpack('<II', mdir.tail.data)
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hard = mdir.tail.is_('hardtail')
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# find paths
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dirtable = {}
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for dir in dirs:
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dirtable[tuple(sorted(dir[0].blocks))] = dir
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pending = [("/", dirs[0])]
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while pending:
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path, dir = pending.pop(0)
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for mdir in dir:
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for tag in mdir.tags:
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if tag.is_('dir'):
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try:
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npath = tag.data.decode('utf8')
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dirstruct = mdir[Tag('dirstruct', tag.id, 0)]
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nblocks = struct.unpack('<II', dirstruct.data)
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nmdir = dirtable[tuple(sorted(nblocks))]
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pending.append(((path + '/' + npath), nmdir))
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except KeyError:
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pass
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dir[0].path = path.replace('//', '/')
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# dump tree
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if not args.superblock and not args.gstate and not args.mdirs:
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args.superblock = True
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args.gstate = True
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args.mdirs = True
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if args.superblock and superblock:
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print("superblock %s" % json.dumps(superblock[0].data.decode('utf8')))
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print(
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" version v{1}.{0}\n"
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" block_size {2}\n"
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" block_count {3}\n"
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" name_max {4}\n"
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" file_max {5}\n"
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" attr_max {6}"
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.format(*struct.unpack(
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'<HHIIIII', superblock[1].data[:24].ljust(24, b'\xff'))))
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if args.gstate and gstate:
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print("gstate 0x%s" % ''.join('%02x' % c for c in gstate))
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tag = Tag(struct.unpack('<I', gstate[0:4].ljust(4, b'\xff'))[0])
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blocks = struct.unpack('<II', gstate[4:4+8].ljust(8, b'\xff'))
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if tag.size:
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print(" orphans %d" % tag.size)
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if tag.type:
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print(" move dir {%#x, %#x} id %d" % (
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blocks[0], blocks[1], tag.id))
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if args.mdirs:
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for i, dir in enumerate(dirs):
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print("dir %s" % (json.dumps(dir[0].path)
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if hasattr(dir[0], 'path') else '(orphan)'))
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for j, mdir in enumerate(dir):
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print("mdir {%#x, %#x} rev %d%s" % (
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mdir.blocks[0], mdir.blocks[1], mdir.rev,
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' (corrupted)' if not mdir else ''))
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f = io.StringIO()
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if args.tags or args.all or args.log:
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dumptags(args, mdir, f)
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else:
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dumpentries(args, mdir, f)
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lines = list(filter(None, f.getvalue().split('\n')))
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for k, line in enumerate(lines):
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print("%s %s" % (
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' ' if j == len(dir)-1 else
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'v' if k == len(lines)-1 else
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'|',
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line))
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return 0 if all(mdir for dir in dirs for mdir in dir) else 1
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if __name__ == "__main__":
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import argparse
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import sys
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parser = argparse.ArgumentParser(
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description="Dump semantic info about the metadata tree in littlefs")
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parser.add_argument('disk',
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help="File representing the block device.")
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parser.add_argument('block_size', type=lambda x: int(x, 0),
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help="Size of a block in bytes.")
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parser.add_argument('block1', nargs='?', default=0,
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type=lambda x: int(x, 0),
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help="Optional first block address for finding the root.")
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parser.add_argument('block2', nargs='?', default=1,
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type=lambda x: int(x, 0),
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help="Optional second block address for finding the root.")
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parser.add_argument('-s', '--superblock', action='store_true',
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help="Show contents of the superblock.")
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parser.add_argument('-g', '--gstate', action='store_true',
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help="Show contents of global-state.")
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parser.add_argument('-m', '--mdirs', action='store_true',
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help="Show contents of metadata-pairs/directories.")
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parser.add_argument('-t', '--tags', action='store_true',
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help="Show metadata tags instead of reconstructing entries.")
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parser.add_argument('-a', '--all', action='store_true',
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help="Show all tags in log, included tags in corrupted commits.")
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parser.add_argument('-l', '--log', action='store_true',
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help="Show tags in log.")
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parser.add_argument('-d', '--data', action='store_true',
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help="Also show the raw contents of files/attrs/tags.")
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parser.add_argument('-T', '--no-truncate', action='store_true',
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help="Don't truncate large amounts of data in files.")
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sys.exit(main(parser.parse_args()))
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