3 # Tool to manipulate QED image files
5 # Copyright (C) 2010 IBM, Corp.
8 # Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
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.
18 # This can be used as a module
19 __all__ = ['QED_F_NEED_CHECK', 'QED']
21 QED_F_NEED_CHECK = 0x02
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']
30 table_elem_size = struct.calcsize(table_elem_fmt)
33 sys.stderr.write(msg + '\n')
37 fields = struct.unpack(header_fmt, s)
38 return dict((field_names[idx], val) for idx, val in enumerate(fields))
40 def pack_header(header):
41 fields = tuple(header[x] for x in field_names)
42 return struct.pack(header_fmt, *fields)
44 def unpack_table_elem(s):
45 return struct.unpack(table_elem_fmt, s)[0]
47 def pack_table_elem(elem):
48 return struct.pack(table_elem_fmt, elem)
51 def __init__(self, f):
55 self.filesize = f.tell()
60 def raw_pread(self, offset, size):
62 return self.f.read(size)
64 def raw_pwrite(self, offset, data):
66 return self.f.write(data)
68 def load_header(self):
69 self.header = unpack_header(self.raw_pread(0, header_size))
71 def store_header(self):
72 self.raw_pwrite(0, pack_header(self.header))
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)]
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
84 def write_table(self, offset, table):
85 s = ''.join(pack_table_elem(x) for x in table)
86 self.raw_pwrite(offset, s)
88 def random_table_item(table):
89 vals = [(index, offset) for index, offset in enumerate(table) if offset != 0]
91 err('cannot pick random item because table is empty')
92 return random.choice(vals)
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
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)
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':
112 elif args[0] == 'l1':
114 elif len(args) == 2 and args[0] == 'l2':
115 offset = int(args[1])
116 print(qed.read_table(offset))
118 err('unrecognized sub-command')
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']
125 elif table_level == 'l2':
126 _, offset = random_table_item(qed.l1_table)
127 table = qed.read_table(offset)
129 err('unrecognized sub-command')
130 corrupt_table_duplicate(table)
131 qed.write_table(offset, table)
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']
138 elif table_level == 'l2':
139 _, offset = random_table_item(qed.l1_table)
140 table = qed.read_table(offset)
142 err('unrecognized sub-command')
143 corrupt_table_invalidate(qed, table)
144 qed.write_table(offset, table)
146 def cmd_need_check(qed, *args):
147 '''need-check [on|off] - Test, set, or clear the QED_F_NEED_CHECK header bit'''
149 print(bool(qed.header['features'] & QED_F_NEED_CHECK))
153 qed.header['features'] |= QED_F_NEED_CHECK
154 elif args[0] == 'off':
155 qed.header['features'] &= ~QED_F_NEED_CHECK
157 err('unrecognized sub-command')
160 def cmd_zero_cluster(qed, pos, *args):
161 '''zero-cluster <pos> [<n>] - Zero data clusters'''
165 err('expected one argument')
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')
173 l2_offset = qed.l1_table[l1_index]
174 l2_table = qed.read_table(l2_offset)
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']
181 def cmd_copy_metadata(qed, outfile):
182 '''copy-metadata <outfile> - Copy metadata only (for scrubbing corrupted images)'''
183 out = open(outfile, 'wb')
186 out.seek(qed.filesize - 1)
189 # Copy header clusters
191 header_size_bytes = qed.header['header_size'] * qed.header['cluster_size']
192 out.write(qed.raw_pread(0, header_size_bytes))
195 out.seek(qed.header['l1_table_offset'])
196 s = ''.join(pack_table_elem(x) for x in qed.l1_table)
200 for l2_offset in qed.l1_table:
203 l2_table = qed.read_table(l2_offset)
205 s = ''.join(pack_table_elem(x) for x in l2_table)
211 print('Usage: %s <file> <cmd> [<arg>, ...]' % sys.argv[0])
213 print('Supported commands:')
214 for cmd in sorted(x for x in globals() if x.startswith('cmd_')):
215 print(globals()[cmd].__doc__)
219 if len(sys.argv) < 3:
221 filename, cmd = sys.argv[1:3]
223 cmd = 'cmd_' + cmd.replace('-', '_')
224 if cmd not in globals():
227 qed = QED(open(filename, 'r+b'))
229 globals()[cmd](qed, *sys.argv[3:])
230 except TypeError as e:
231 sys.stderr.write(globals()[cmd].__doc__ + '\n')
234 if __name__ == '__main__':