xref: /qemu/tests/qemu-iotests/qed.py (revision 72ac97cd) 
1#!/usr/bin/env python
2#
3# Tool to manipulate QED image files
4#
5# Copyright (C) 2010 IBM, Corp.
6#
7# Authors:
8#  Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
9#
10# This work is licensed under the terms of the GNU GPL, version 2 or later.
11# See the COPYING file in the top-level directory.
12
13import sys
14import struct
15import random
16import optparse
17
18# This can be used as a module
19__all__ = ['QED_F_NEED_CHECK', 'QED']
20
21QED_F_NEED_CHECK = 0x02
22
23header_fmt = '<IIIIQQQQQII'
24header_size = struct.calcsize(header_fmt)
25field_names = ['magic', 'cluster_size', 'table_size',
26               'header_size', 'features', 'compat_features',
27               'autoclear_features', 'l1_table_offset', 'image_size',
28               'backing_filename_offset', 'backing_filename_size']
29table_elem_fmt = '<Q'
30table_elem_size = struct.calcsize(table_elem_fmt)
31
32def err(msg):
33    sys.stderr.write(msg + '\n')
34    sys.exit(1)
35
36def unpack_header(s):
37    fields = struct.unpack(header_fmt, s)
38    return dict((field_names[idx], val) for idx, val in enumerate(fields))
39
40def pack_header(header):
41    fields = tuple(header[x] for x in field_names)
42    return struct.pack(header_fmt, *fields)
43
44def unpack_table_elem(s):
45    return struct.unpack(table_elem_fmt, s)[0]
46
47def pack_table_elem(elem):
48    return struct.pack(table_elem_fmt, elem)
49
50class QED(object):
51    def __init__(self, f):
52        self.f = f
53
54        self.f.seek(0, 2)
55        self.filesize = f.tell()
56
57        self.load_header()
58        self.load_l1_table()
59
60    def raw_pread(self, offset, size):
61        self.f.seek(offset)
62        return self.f.read(size)
63
64    def raw_pwrite(self, offset, data):
65        self.f.seek(offset)
66        return self.f.write(data)
67
68    def load_header(self):
69        self.header = unpack_header(self.raw_pread(0, header_size))
70
71    def store_header(self):
72        self.raw_pwrite(0, pack_header(self.header))
73
74    def read_table(self, offset):
75        size = self.header['table_size'] * self.header['cluster_size']
76        s = self.raw_pread(offset, size)
77        table = [unpack_table_elem(s[i:i + table_elem_size]) for i in xrange(0, size, table_elem_size)]
78        return table
79
80    def load_l1_table(self):
81        self.l1_table = self.read_table(self.header['l1_table_offset'])
82        self.table_nelems = self.header['table_size'] * self.header['cluster_size'] / table_elem_size
83
84    def write_table(self, offset, table):
85        s = ''.join(pack_table_elem(x) for x in table)
86        self.raw_pwrite(offset, s)
87
88def random_table_item(table):
89    vals = [(index, offset) for index, offset in enumerate(table) if offset != 0]
90    if not vals:
91        err('cannot pick random item because table is empty')
92    return random.choice(vals)
93
94def corrupt_table_duplicate(table):
95    '''Corrupt a table by introducing a duplicate offset'''
96    victim_idx, victim_val = random_table_item(table)
97    unique_vals = set(table)
98    if len(unique_vals) == 1:
99        err('no duplication corruption possible in table')
100    dup_val = random.choice(list(unique_vals.difference([victim_val])))
101    table[victim_idx] = dup_val
102
103def corrupt_table_invalidate(qed, table):
104    '''Corrupt a table by introducing an invalid offset'''
105    index, _ = random_table_item(table)
106    table[index] = qed.filesize + random.randint(0, 100 * 1024 * 1024 * 1024 * 1024)
107
108def cmd_show(qed, *args):
109    '''show [header|l1|l2 <offset>]- Show header or l1/l2 tables'''
110    if not args or args[0] == 'header':
111        print qed.header
112    elif args[0] == 'l1':
113        print qed.l1_table
114    elif len(args) == 2 and args[0] == 'l2':
115        offset = int(args[1])
116        print qed.read_table(offset)
117    else:
118        err('unrecognized sub-command')
119
120def cmd_duplicate(qed, table_level):
121    '''duplicate l1|l2 - Duplicate a random table element'''
122    if table_level == 'l1':
123        offset = qed.header['l1_table_offset']
124        table = qed.l1_table
125    elif table_level == 'l2':
126        _, offset = random_table_item(qed.l1_table)
127        table = qed.read_table(offset)
128    else:
129        err('unrecognized sub-command')
130    corrupt_table_duplicate(table)
131    qed.write_table(offset, table)
132
133def cmd_invalidate(qed, table_level):
134    '''invalidate l1|l2 - Plant an invalid table element at random'''
135    if table_level == 'l1':
136        offset = qed.header['l1_table_offset']
137        table = qed.l1_table
138    elif table_level == 'l2':
139        _, offset = random_table_item(qed.l1_table)
140        table = qed.read_table(offset)
141    else:
142        err('unrecognized sub-command')
143    corrupt_table_invalidate(qed, table)
144    qed.write_table(offset, table)
145
146def cmd_need_check(qed, *args):
147    '''need-check [on|off] - Test, set, or clear the QED_F_NEED_CHECK header bit'''
148    if not args:
149        print bool(qed.header['features'] & QED_F_NEED_CHECK)
150        return
151
152    if args[0] == 'on':
153        qed.header['features'] |= QED_F_NEED_CHECK
154    elif args[0] == 'off':
155        qed.header['features'] &= ~QED_F_NEED_CHECK
156    else:
157        err('unrecognized sub-command')
158    qed.store_header()
159
160def cmd_zero_cluster(qed, pos, *args):
161    '''zero-cluster <pos> [<n>] - Zero data clusters'''
162    pos, n = int(pos), 1
163    if args:
164        if len(args) != 1:
165            err('expected one argument')
166        n = int(args[0])
167
168    for i in xrange(n):
169        l1_index = pos / qed.header['cluster_size'] / len(qed.l1_table)
170        if qed.l1_table[l1_index] == 0:
171            err('no l2 table allocated')
172
173        l2_offset = qed.l1_table[l1_index]
174        l2_table = qed.read_table(l2_offset)
175
176        l2_index = (pos / qed.header['cluster_size']) % len(qed.l1_table)
177        l2_table[l2_index] = 1 # zero the data cluster
178        qed.write_table(l2_offset, l2_table)
179        pos += qed.header['cluster_size']
180
181def cmd_copy_metadata(qed, outfile):
182    '''copy-metadata <outfile> - Copy metadata only (for scrubbing corrupted images)'''
183    out = open(outfile, 'wb')
184
185    # Match file size
186    out.seek(qed.filesize - 1)
187    out.write('\0')
188
189    # Copy header clusters
190    out.seek(0)
191    header_size_bytes = qed.header['header_size'] * qed.header['cluster_size']
192    out.write(qed.raw_pread(0, header_size_bytes))
193
194    # Copy L1 table
195    out.seek(qed.header['l1_table_offset'])
196    s = ''.join(pack_table_elem(x) for x in qed.l1_table)
197    out.write(s)
198
199    # Copy L2 tables
200    for l2_offset in qed.l1_table:
201        if l2_offset == 0:
202            continue
203        l2_table = qed.read_table(l2_offset)
204        out.seek(l2_offset)
205        s = ''.join(pack_table_elem(x) for x in l2_table)
206        out.write(s)
207
208    out.close()
209
210def usage():
211    print 'Usage: %s <file> <cmd> [<arg>, ...]' % sys.argv[0]
212    print
213    print 'Supported commands:'
214    for cmd in sorted(x for x in globals() if x.startswith('cmd_')):
215        print globals()[cmd].__doc__
216    sys.exit(1)
217
218def main():
219    if len(sys.argv) < 3:
220        usage()
221    filename, cmd = sys.argv[1:3]
222
223    cmd = 'cmd_' + cmd.replace('-', '_')
224    if cmd not in globals():
225        usage()
226
227    qed = QED(open(filename, 'r+b'))
228    try:
229        globals()[cmd](qed, *sys.argv[3:])
230    except TypeError, e:
231        sys.stderr.write(globals()[cmd].__doc__ + '\n')
232        sys.exit(1)
233
234if __name__ == '__main__':
235    main()
236