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03e188102c
PEP 8 calls for it, because it's forward compatible with Python 3.
Supported since Python 2.6, which we require (commit fec2103).
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <1450425164-24969-5-git-send-email-armbru@redhat.com>
236 lines
7.0 KiB
Python
Executable File
236 lines
7.0 KiB
Python
Executable File
#!/usr/bin/env python
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#
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# Tool to manipulate QED image files
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#
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# Copyright (C) 2010 IBM, Corp.
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#
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# Authors:
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# Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
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#
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# This work is licensed under the terms of the GNU GPL, version 2 or later.
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# See the COPYING file in the top-level directory.
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import sys
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import struct
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import random
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import optparse
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# This can be used as a module
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__all__ = ['QED_F_NEED_CHECK', 'QED']
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QED_F_NEED_CHECK = 0x02
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header_fmt = '<IIIIQQQQQII'
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header_size = struct.calcsize(header_fmt)
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field_names = ['magic', 'cluster_size', 'table_size',
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'header_size', 'features', 'compat_features',
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'autoclear_features', 'l1_table_offset', 'image_size',
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'backing_filename_offset', 'backing_filename_size']
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table_elem_fmt = '<Q'
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table_elem_size = struct.calcsize(table_elem_fmt)
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def err(msg):
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sys.stderr.write(msg + '\n')
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sys.exit(1)
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def unpack_header(s):
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fields = struct.unpack(header_fmt, s)
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return dict((field_names[idx], val) for idx, val in enumerate(fields))
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def pack_header(header):
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fields = tuple(header[x] for x in field_names)
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return struct.pack(header_fmt, *fields)
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def unpack_table_elem(s):
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return struct.unpack(table_elem_fmt, s)[0]
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def pack_table_elem(elem):
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return struct.pack(table_elem_fmt, elem)
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class QED(object):
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def __init__(self, f):
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self.f = f
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self.f.seek(0, 2)
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self.filesize = f.tell()
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self.load_header()
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self.load_l1_table()
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def raw_pread(self, offset, size):
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self.f.seek(offset)
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return self.f.read(size)
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def raw_pwrite(self, offset, data):
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self.f.seek(offset)
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return self.f.write(data)
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def load_header(self):
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self.header = unpack_header(self.raw_pread(0, header_size))
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def store_header(self):
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self.raw_pwrite(0, pack_header(self.header))
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def read_table(self, offset):
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size = self.header['table_size'] * self.header['cluster_size']
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s = self.raw_pread(offset, size)
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table = [unpack_table_elem(s[i:i + table_elem_size]) for i in xrange(0, size, table_elem_size)]
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return table
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def load_l1_table(self):
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self.l1_table = self.read_table(self.header['l1_table_offset'])
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self.table_nelems = self.header['table_size'] * self.header['cluster_size'] / table_elem_size
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def write_table(self, offset, table):
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s = ''.join(pack_table_elem(x) for x in table)
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self.raw_pwrite(offset, s)
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def random_table_item(table):
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vals = [(index, offset) for index, offset in enumerate(table) if offset != 0]
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if not vals:
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err('cannot pick random item because table is empty')
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return random.choice(vals)
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def corrupt_table_duplicate(table):
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'''Corrupt a table by introducing a duplicate offset'''
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victim_idx, victim_val = random_table_item(table)
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unique_vals = set(table)
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if len(unique_vals) == 1:
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err('no duplication corruption possible in table')
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dup_val = random.choice(list(unique_vals.difference([victim_val])))
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table[victim_idx] = dup_val
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def corrupt_table_invalidate(qed, table):
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'''Corrupt a table by introducing an invalid offset'''
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index, _ = random_table_item(table)
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table[index] = qed.filesize + random.randint(0, 100 * 1024 * 1024 * 1024 * 1024)
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def cmd_show(qed, *args):
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'''show [header|l1|l2 <offset>]- Show header or l1/l2 tables'''
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if not args or args[0] == 'header':
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print qed.header
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elif args[0] == 'l1':
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print qed.l1_table
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elif len(args) == 2 and args[0] == 'l2':
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offset = int(args[1])
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print qed.read_table(offset)
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else:
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err('unrecognized sub-command')
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def cmd_duplicate(qed, table_level):
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'''duplicate l1|l2 - Duplicate a random table element'''
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if table_level == 'l1':
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offset = qed.header['l1_table_offset']
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table = qed.l1_table
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elif table_level == 'l2':
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_, offset = random_table_item(qed.l1_table)
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table = qed.read_table(offset)
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else:
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err('unrecognized sub-command')
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corrupt_table_duplicate(table)
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qed.write_table(offset, table)
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def cmd_invalidate(qed, table_level):
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'''invalidate l1|l2 - Plant an invalid table element at random'''
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if table_level == 'l1':
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offset = qed.header['l1_table_offset']
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table = qed.l1_table
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elif table_level == 'l2':
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_, offset = random_table_item(qed.l1_table)
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table = qed.read_table(offset)
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else:
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err('unrecognized sub-command')
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corrupt_table_invalidate(qed, table)
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qed.write_table(offset, table)
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def cmd_need_check(qed, *args):
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'''need-check [on|off] - Test, set, or clear the QED_F_NEED_CHECK header bit'''
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if not args:
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print bool(qed.header['features'] & QED_F_NEED_CHECK)
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return
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if args[0] == 'on':
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qed.header['features'] |= QED_F_NEED_CHECK
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elif args[0] == 'off':
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qed.header['features'] &= ~QED_F_NEED_CHECK
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else:
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err('unrecognized sub-command')
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qed.store_header()
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def cmd_zero_cluster(qed, pos, *args):
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'''zero-cluster <pos> [<n>] - Zero data clusters'''
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pos, n = int(pos), 1
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if args:
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if len(args) != 1:
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err('expected one argument')
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n = int(args[0])
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for i in xrange(n):
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l1_index = pos / qed.header['cluster_size'] / len(qed.l1_table)
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if qed.l1_table[l1_index] == 0:
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err('no l2 table allocated')
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l2_offset = qed.l1_table[l1_index]
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l2_table = qed.read_table(l2_offset)
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l2_index = (pos / qed.header['cluster_size']) % len(qed.l1_table)
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l2_table[l2_index] = 1 # zero the data cluster
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qed.write_table(l2_offset, l2_table)
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pos += qed.header['cluster_size']
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def cmd_copy_metadata(qed, outfile):
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'''copy-metadata <outfile> - Copy metadata only (for scrubbing corrupted images)'''
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out = open(outfile, 'wb')
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# Match file size
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out.seek(qed.filesize - 1)
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out.write('\0')
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# Copy header clusters
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out.seek(0)
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header_size_bytes = qed.header['header_size'] * qed.header['cluster_size']
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out.write(qed.raw_pread(0, header_size_bytes))
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# Copy L1 table
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out.seek(qed.header['l1_table_offset'])
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s = ''.join(pack_table_elem(x) for x in qed.l1_table)
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out.write(s)
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# Copy L2 tables
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for l2_offset in qed.l1_table:
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if l2_offset == 0:
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continue
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l2_table = qed.read_table(l2_offset)
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out.seek(l2_offset)
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s = ''.join(pack_table_elem(x) for x in l2_table)
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out.write(s)
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out.close()
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def usage():
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print 'Usage: %s <file> <cmd> [<arg>, ...]' % sys.argv[0]
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print
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print 'Supported commands:'
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for cmd in sorted(x for x in globals() if x.startswith('cmd_')):
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print globals()[cmd].__doc__
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sys.exit(1)
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def main():
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if len(sys.argv) < 3:
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usage()
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filename, cmd = sys.argv[1:3]
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cmd = 'cmd_' + cmd.replace('-', '_')
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if cmd not in globals():
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usage()
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qed = QED(open(filename, 'r+b'))
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try:
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globals()[cmd](qed, *sys.argv[3:])
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except TypeError as e:
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sys.stderr.write(globals()[cmd].__doc__ + '\n')
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sys.exit(1)
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if __name__ == '__main__':
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main()
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