Coverage for diffoscope/comparators/fsimage.py: 81%

2# diffoscope: in-depth comparison of files, archives, and directories

7# diffoscope is free software: you can redistribute it and/or modify

8# it under the terms of the GNU General Public License as published by

9# the Free Software Foundation, either version 3 of the License, or

10# (at your option) any later version.

11#

12# diffoscope is distributed in the hope that it will be useful,

13# but WITHOUT ANY WARRANTY; without even the implied warranty of

14# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

15# GNU General Public License for more details.

16#

17# You should have received a copy of the GNU General Public License

18# along with diffoscope. If not, see <https://www.gnu.org/licenses/>.

20import re

21import logging

22import os.path

24from diffoscope.difference import Difference

25from diffoscope.tools import python_module_missing

26from diffoscope.profiling import profile

27from diffoscope.tools import get_comment_for_missing_python_module

29from .utils.file import File

30from .utils.archive import Archive

32try:

33 import guestfs

34except ImportError:

35 python_module_missing("guestfs")

36 guestfs = None

38logger = logging.getLogger(__name__)

41class FsImageContainer(Archive):

42 def open_archive(self):

43 if not guestfs:

44 return None

46 self.g = guestfs.GuestFS(python_return_dict=True)

47 try:

48 # force a check that LIBGUESTFS_CACHEDIR exists. otherwise guestfs

49 # will fall back to /var/tmp, which we don't want

50 self.g.set_cachedir(os.environ["LIBGUESTFS_CACHEDIR"])

51 except KeyError:

52 pass

53 self.g.add_drive_opts(self.source.path, format="raw", readonly=1)

54 try:

55 logger.debug("Launching guestfs; this may take some time")

56 with profile("command", "guestfs"):

57 self.g.launch()

58 logger.debug("guestfs successfully launched")

59 except RuntimeError:

60 logger.exception("guestfs failed to launch")

61 logger.error(

62 "If memory is too tight for 512 MiB, try running "

63 "with LIBGUESTFS_MEMSIZE=256 or lower."

64 )

65 return None

66 devices = self.g.list_devices()

67 try:

68 self.g.mount_options("ro", devices[0], "/")

69 except RuntimeError:

70 logger.exception("guestfs count not mount image; invalid file?")

71 return None

72 self.fs = self.g.list_filesystems()[devices[0]]

73 return self

75 def close_archive(self):

76 if not guestfs:

77 return None

79 try:

80 self.g.umount_all()

81 self.g.close()

82 except Exception: # noqa

83 pass

85 def get_member_names(self):

86 if not guestfs:

87 return []

88 return [os.path.basename(self.source.path) + ".tar"]

90 def extract(self, member_name, dest_dir):

91 dest_path = os.path.join(dest_dir, member_name)

92 logger.debug("filesystem image extracting to %s", dest_path)

93 self.g.tar_out("/", dest_path)

94 return dest_path

97class FsImageFile(File):

98 DESCRIPTION = "ext2/ext3/ext4/btrfs/fat filesystems"

99 CONTAINER_CLASSES = [FsImageContainer]

100 FILE_TYPE_RE = re.compile(

101 r"^(Linux.*filesystem data|BTRFS Filesystem|F2FS filesystem).*"

102 )

103

104 @classmethod

105 def recognizes(cls, file):

106 # Avoid DOS / MBR file type as it generate a lot of false positives,

107 # manually check "System identifier string" instead

108 with open(file.path, "rb") as f:

109 f.seek(54)

110 if f.read(8) in (b"FAT12 ", b"FAT16 "):

111 return True

112 f.seek(82)

113 if f.read(8) == b"FAT32 ":

114 return True

115 return super().recognizes(file)

116

117 def compare_details(self, other, source=None):

118 differences = []

119 my_fs = ""

120 other_fs = ""

121 if hasattr(self.as_container, "fs"):

122 my_fs = self.as_container.fs

123 if hasattr(other.as_container, "fs"):

124 other_fs = other.as_container.fs

125 if my_fs != other_fs:

126 differences.append(

127 Difference.from_text(

128 my_fs, other_fs, None, None, source="filesystem"

129 )

130 )

131 if not guestfs:

132 self.add_comment(get_comment_for_missing_python_module("guestfs"))

133 return differences