tests/qemu-iotests/qed.py

   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
  13 import sys
  14 import struct
  15 import random
  16 import optparse
  17
  18 # This can be used as a module
  19 __all__ = ['QED_F_NEED_CHECK', 'QED']
  20
  21 QED_F_NEED_CHECK = 0x02
  22
  23 header_fmt = '<IIIIQQQQQII'
  24 header_size = struct.calcsize(header_fmt)
  25 field_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']
  29 table_elem_fmt = '<Q'
  30 table_elem_size = struct.calcsize(table_elem_fmt)
  31
  32 def err(msg):
  33     sys.stderr.write(msg + '\n')
  34     sys.exit(1)
  35
  36 def unpack_header(s):
  37     fields = struct.unpack(header_fmt, s)
  38     return dict((field_names[idx], val) for idx, val in enumerate(fields))
  39
  40 def pack_header(header):
  41     fields = tuple(header[x] for x in field_names)
  42     return struct.pack(header_fmt, *fields)
  43
  44 def unpack_table_elem(s):
  45     return struct.unpack(table_elem_fmt, s)[0]
  46
  47 def pack_table_elem(elem):
  48     return struct.pack(table_elem_fmt, elem)
  49
  50 class 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
  88 def 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
  94 def 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
 103 def 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
 108 def 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
 120 def 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
 133 def 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
 146 def 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
 160 def 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
 181 def 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
 210 def 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
 218 def 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
 234 if __name__ == '__main__':
 235     main()