tests/qemu-iotests/qcow2.py

   1 #!/usr/bin/env python
   2
   3 from __future__ import print_function
   4 import sys
   5 import struct
   6 import string
   7
   8 class QcowHeaderExtension:
   9
  10     def __init__(self, magic, length, data):
  11         if length % 8 != 0:
  12             padding = 8 - (length % 8)
  13             data += b"\0" * padding
  14
  15         self.magic  = magic
  16         self.length = length
  17         self.data   = data
  18
  19     @classmethod
  20     def create(cls, magic, data):
  21         return QcowHeaderExtension(magic, len(data), data)
  22
  23 class QcowHeader:
  24
  25     uint32_t = 'I'
  26     uint64_t = 'Q'
  27
  28     fields = [
  29         # Version 2 header fields
  30         [ uint32_t, '%#x',  'magic' ],
  31         [ uint32_t, '%d',   'version' ],
  32         [ uint64_t, '%#x',  'backing_file_offset' ],
  33         [ uint32_t, '%#x',  'backing_file_size' ],
  34         [ uint32_t, '%d',   'cluster_bits' ],
  35         [ uint64_t, '%d',   'size' ],
  36         [ uint32_t, '%d',   'crypt_method' ],
  37         [ uint32_t, '%d',   'l1_size' ],
  38         [ uint64_t, '%#x',  'l1_table_offset' ],
  39         [ uint64_t, '%#x',  'refcount_table_offset' ],
  40         [ uint32_t, '%d',   'refcount_table_clusters' ],
  41         [ uint32_t, '%d',   'nb_snapshots' ],
  42         [ uint64_t, '%#x',  'snapshot_offset' ],
  43
  44         # Version 3 header fields
  45         [ uint64_t, 'mask', 'incompatible_features' ],
  46         [ uint64_t, 'mask', 'compatible_features' ],
  47         [ uint64_t, 'mask', 'autoclear_features' ],
  48         [ uint32_t, '%d',   'refcount_order' ],
  49         [ uint32_t, '%d',   'header_length' ],
  50     ];
  51
  52     fmt = '>' + ''.join(field[0] for field in fields)
  53
  54     def __init__(self, fd):
  55
  56         buf_size = struct.calcsize(QcowHeader.fmt)
  57
  58         fd.seek(0)
  59         buf = fd.read(buf_size)
  60
  61         header = struct.unpack(QcowHeader.fmt, buf)
  62         self.__dict__ = dict((field[2], header[i])
  63             for i, field in enumerate(QcowHeader.fields))
  64
  65         self.set_defaults()
  66         self.cluster_size = 1 << self.cluster_bits
  67
  68         fd.seek(self.header_length)
  69         self.load_extensions(fd)
  70
  71         if self.backing_file_offset:
  72             fd.seek(self.backing_file_offset)
  73             self.backing_file = fd.read(self.backing_file_size)
  74         else:
  75             self.backing_file = None
  76
  77     def set_defaults(self):
  78         if self.version == 2:
  79             self.incompatible_features = 0
  80             self.compatible_features = 0
  81             self.autoclear_features = 0
  82             self.refcount_order = 4
  83             self.header_length = 72
  84
  85     def load_extensions(self, fd):
  86         self.extensions = []
  87
  88         if self.backing_file_offset != 0:
  89             end = min(self.cluster_size, self.backing_file_offset)
  90         else:
  91             end = self.cluster_size
  92
  93         while fd.tell() < end:
  94             (magic, length) = struct.unpack('>II', fd.read(8))
  95             if magic == 0:
  96                 break
  97             else:
  98                 padded = (length + 7) & ~7
  99                 data = fd.read(padded)
 100                 self.extensions.append(QcowHeaderExtension(magic, length, data))
 101
 102     def update_extensions(self, fd):
 103
 104         fd.seek(self.header_length)
 105         extensions = self.extensions
 106         extensions.append(QcowHeaderExtension(0, 0, b""))
 107         for ex in extensions:
 108             buf = struct.pack('>II', ex.magic, ex.length)
 109             fd.write(buf)
 110             fd.write(ex.data)
 111
 112         if self.backing_file != None:
 113             self.backing_file_offset = fd.tell()
 114             fd.write(self.backing_file)
 115
 116         if fd.tell() > self.cluster_size:
 117             raise Exception("I think I just broke the image...")
 118
 119
 120     def update(self, fd):
 121         header_bytes = self.header_length
 122
 123         self.update_extensions(fd)
 124
 125         fd.seek(0)
 126         header = tuple(self.__dict__[f] for t, p, f in QcowHeader.fields)
 127         buf = struct.pack(QcowHeader.fmt, *header)
 128         buf = buf[0:header_bytes-1]
 129         fd.write(buf)
 130
 131     def dump(self):
 132         for f in QcowHeader.fields:
 133             value = self.__dict__[f[2]]
 134             if f[1] == 'mask':
 135                 bits = []
 136                 for bit in range(64):
 137                     if value & (1 << bit):
 138                         bits.append(bit)
 139                 value_str = str(bits)
 140             else:
 141                 value_str = f[1] % value
 142
 143             print("%-25s" % f[2], value_str)
 144         print("")
 145
 146     def dump_extensions(self):
 147         for ex in self.extensions:
 148
 149             data = ex.data[:ex.length]
 150             if all(c in string.printable.encode('ascii') for c in data):
 151                 data = "'%s'" % data.decode('ascii')
 152             else:
 153                 data = "<binary>"
 154
 155             print("Header extension:")
 156             print("%-25s %#x" % ("magic", ex.magic))
 157             print("%-25s %d" % ("length", ex.length))
 158             print("%-25s %s" % ("data", data))
 159             print("")
 160
 161
 162 def cmd_dump_header(fd):
 163     h = QcowHeader(fd)
 164     h.dump()
 165     h.dump_extensions()
 166
 167 def cmd_dump_header_exts(fd):
 168     h = QcowHeader(fd)
 169     h.dump_extensions()
 170
 171 def cmd_set_header(fd, name, value):
 172     try:
 173         value = int(value, 0)
 174     except:
 175         print("'%s' is not a valid number" % value)
 176         sys.exit(1)
 177
 178     fields = (field[2] for field in QcowHeader.fields)
 179     if not name in fields:
 180         print("'%s' is not a known header field" % name)
 181         sys.exit(1)
 182
 183     h = QcowHeader(fd)
 184     h.__dict__[name] = value
 185     h.update(fd)
 186
 187 def cmd_add_header_ext(fd, magic, data):
 188     try:
 189         magic = int(magic, 0)
 190     except:
 191         print("'%s' is not a valid magic number" % magic)
 192         sys.exit(1)
 193
 194     h = QcowHeader(fd)
 195     h.extensions.append(QcowHeaderExtension.create(magic, data.encode('ascii')))
 196     h.update(fd)
 197
 198 def cmd_add_header_ext_stdio(fd, magic):
 199     data = sys.stdin.read()
 200     cmd_add_header_ext(fd, magic, data)
 201
 202 def cmd_del_header_ext(fd, magic):
 203     try:
 204         magic = int(magic, 0)
 205     except:
 206         print("'%s' is not a valid magic number" % magic)
 207         sys.exit(1)
 208
 209     h = QcowHeader(fd)
 210     found = False
 211
 212     for ex in h.extensions:
 213         if ex.magic == magic:
 214             found = True
 215             h.extensions.remove(ex)
 216
 217     if not found:
 218         print("No such header extension")
 219         return
 220
 221     h.update(fd)
 222
 223 def cmd_set_feature_bit(fd, group, bit):
 224     try:
 225         bit = int(bit, 0)
 226         if bit < 0 or bit >= 64:
 227             raise ValueError
 228     except:
 229         print("'%s' is not a valid bit number in range [0, 64)" % bit)
 230         sys.exit(1)
 231
 232     h = QcowHeader(fd)
 233     if group == 'incompatible':
 234         h.incompatible_features |= 1 << bit
 235     elif group == 'compatible':
 236         h.compatible_features |= 1 << bit
 237     elif group == 'autoclear':
 238         h.autoclear_features |= 1 << bit
 239     else:
 240         print("'%s' is not a valid group, try 'incompatible', 'compatible', or 'autoclear'" % group)
 241         sys.exit(1)
 242
 243     h.update(fd)
 244
 245 cmds = [
 246     [ 'dump-header',          cmd_dump_header,          0, 'Dump image header and header extensions' ],
 247     [ 'dump-header-exts',     cmd_dump_header_exts,     0, 'Dump image header extensions' ],
 248     [ 'set-header',           cmd_set_header,           2, 'Set a field in the header'],
 249     [ 'add-header-ext',       cmd_add_header_ext,       2, 'Add a header extension' ],
 250     [ 'add-header-ext-stdio', cmd_add_header_ext_stdio, 1, 'Add a header extension, data from stdin' ],
 251     [ 'del-header-ext',       cmd_del_header_ext,       1, 'Delete a header extension' ],
 252     [ 'set-feature-bit',      cmd_set_feature_bit,      2, 'Set a feature bit'],
 253 ]
 254
 255 def main(filename, cmd, args):
 256     fd = open(filename, "r+b")
 257     try:
 258         for name, handler, num_args, desc in cmds:
 259             if name != cmd:
 260                 continue
 261             elif len(args) != num_args:
 262                 usage()
 263                 return
 264             else:
 265                 handler(fd, *args)
 266                 return
 267         print("Unknown command '%s'" % cmd)
 268     finally:
 269         fd.close()
 270
 271 def usage():
 272     print("Usage: %s <file> <cmd> [<arg>, ...]" % sys.argv[0])
 273     print("")
 274     print("Supported commands:")
 275     for name, handler, num_args, desc in cmds:
 276         print("    %-20s - %s" % (name, desc))
 277
 278 if __name__ == '__main__':
 279     if len(sys.argv) < 3:
 280         usage()
 281         sys.exit(1)
 282
 283     main(sys.argv[1], sys.argv[2], sys.argv[3:])