zeroinstall/injector/distro.py

   1 """
   2 Integration with native distribution package managers.
   3 @since: 0.28
   4 """
   5
   6 # Copyright (C) 2009, Thomas Leonard
   7 # See the README file for details, or visit http://0install.net.
   8
   9 import os, re
  10 from logging import warn, info
  11 from zeroinstall.injector import namespaces, model
  12 from zeroinstall.support import basedir
  13
  14 _dotted_ints = '[0-9]+(\.[0-9]+)*'
  15 _version_regexp = '(%s)(-(pre|rc|post|)%s)*' % (_dotted_ints, _dotted_ints)
  16
  17 def try_cleanup_distro_version(version):
  18         """Try to turn a distribution version string into one readable by Zero Install.
  19         We do this by stripping off anything we can't parse.
  20         @return: the part we understood, or None if we couldn't parse anything
  21         @rtype: str"""
  22         match = re.match(_version_regexp, version)
  23         if match:
  24                 return match.group(0)
  25         return None
  26
  27 class Distribution(object):
  28         """Represents a distribution with which we can integrate.
  29         Sub-classes should specialise this to integrate with the package managers of
  30         particular distributions. This base class ignores the native package manager.
  31         @since: 0.28
  32         """
  33
  34         def get_package_info(self, package, factory):
  35                 """Get information about the given package.
  36                 Add zero or more implementations using the factory (typically at most two
  37                 will be added; the currently installed version and the latest available).
  38                 @param package: package name (e.g. "gimp")
  39                 @type package: str
  40                 @param factory: function for creating new DistributionImplementation objects from IDs
  41                 @type factory: str -> L{model.DistributionImplementation}
  42                 """
  43                 return
  44
  45 class CachedDistribution(Distribution):
  46         """For distributions where querying the package database is slow (e.g. requires running
  47         an external command), we cache the results.
  48         @since: 0.39
  49         """
  50
  51         def __init__(self, db_status_file):
  52                 """@param db_status_file: update the cache when the timestamp of this file changes"""
  53                 self._status_details = os.stat(db_status_file)
  54
  55                 self.versions = {}
  56                 self.cache_dir = basedir.save_cache_path(namespaces.config_site,
  57                                                          namespaces.config_prog)
  58
  59                 try:
  60                         self._load_cache()
  61                 except Exception, ex:
  62                         info("Failed to load distribution database cache (%s). Regenerating...", ex)
  63                         try:
  64                                 self.generate_cache()
  65                                 self._load_cache()
  66                         except Exception, ex:
  67                                 warn("Failed to regenerate distribution database cache: %s", ex)
  68
  69         def _load_cache(self):
  70                 """Load {cache_leaf} cache file into self.versions if it is available and up-to-date.
  71                 Throws an exception if the cache should be (re)created."""
  72                 stream = file(os.path.join(self.cache_dir, self.cache_leaf))
  73
  74                 cache_version = None
  75                 for line in stream:
  76                         if line == '\n':
  77                                 break
  78                         name, value = line.split(': ')
  79                         if name == 'mtime' and int(value) != int(self._status_details.st_mtime):
  80                                 raise Exception("Modification time of package database file has changed")
  81                         if name == 'size' and int(value) != self._status_details.st_size:
  82                                 raise Exception("Size of package database file has changed")
  83                         if name == 'version':
  84                                 cache_version = int(value)
  85                 else:
  86                         raise Exception('Invalid cache format (bad header)')
  87
  88                 if cache_version is None:
  89                         raise Exception('Old cache format')
  90
  91                 versions = self.versions
  92                 for line in stream:
  93                         package, version, zi_arch = line[:-1].split('\t')
  94                         versions[package] = (version, intern(zi_arch))
  95
  96         def _write_cache(self, cache):
  97                 #cache.sort()   # Might be useful later; currently we don't care
  98                 import tempfile
  99                 fd, tmpname = tempfile.mkstemp(prefix = 'zeroinstall-cache-tmp',
 100                                                dir = self.cache_dir)
 101                 try:
 102                         stream = os.fdopen(fd, 'wb')
 103                         stream.write('version: 2\n')
 104                         stream.write('mtime: %d\n' % int(self._status_details.st_mtime))
 105                         stream.write('size: %d\n' % self._status_details.st_size)
 106                         stream.write('\n')
 107                         for line in cache:
 108                                 stream.write(line + '\n')
 109                         stream.close()
 110
 111                         os.rename(tmpname,
 112                                   os.path.join(self.cache_dir,
 113                                                self.cache_leaf))
 114                 except:
 115                         os.unlink(tmpname)
 116                         raise
 117
 118 class DebianDistribution(CachedDistribution):
 119         """A dpkg-based distribution."""
 120
 121         cache_leaf = 'dpkg-status.cache'
 122
 123         def generate_cache(self):
 124                 cache = []
 125
 126                 for line in os.popen("dpkg-query -W --showformat='${Package}\t${Version}\t${Architecture}\n'"):
 127                         package, version, debarch = line.split('\t', 2)
 128                         if ':' in version:
 129                                 # Debian's 'epoch' system
 130                                 version = version.split(':', 1)[1]
 131                         if debarch == 'amd64\n':
 132                                 zi_arch = 'x86_64'
 133                         else:
 134                                 zi_arch = '*'
 135                         clean_version = try_cleanup_distro_version(version)
 136                         if clean_version:
 137                                 cache.append('%s\t%s\t%s' % (package, clean_version, zi_arch))
 138                         else:
 139                                 warn("Can't parse distribution version '%s' for package '%s'", version, package)
 140
 141                 self._write_cache(cache)
 142
 143         def get_package_info(self, package, factory):
 144                 try:
 145                         version, machine = self.versions[package]
 146                 except KeyError:
 147                         return
 148
 149                 impl = factory('package:deb:%s:%s' % (package, version))
 150                 impl.version = model.parse_version(version)
 151                 if machine != '*':
 152                         impl.machine = machine
 153
 154 class RPMDistribution(CachedDistribution):
 155         """An RPM-based distribution."""
 156
 157         cache_leaf = 'rpm-status.cache'
 158
 159         def generate_cache(self):
 160                 cache = []
 161
 162                 for line in os.popen("rpm -qa --qf='%{NAME}\t%{VERSION}-%{RELEASE}\t%{ARCH}\n'"):
 163                         package, version, rpmarch = line.split('\t', 2)
 164                         if package == 'gpg-pubkey':
 165                                 continue
 166                         if rpmarch == 'amd64\n':
 167                                 zi_arch = 'x86_64'
 168                         elif rpmarch == 'noarch\n' or rpmarch == "(none)\n":
 169                                 zi_arch = '*'
 170                         else:
 171                                 zi_arch = rpmarch.strip()
 172                         clean_version = try_cleanup_distro_version(version)
 173                         if clean_version:
 174                                 cache.append('%s\t%s\t%s' % (package, clean_version, zi_arch))
 175                         else:
 176                                 warn("Can't parse distribution version '%s' for package '%s'", version, package)
 177
 178                 self._write_cache(cache)
 179
 180         def get_package_info(self, package, factory):
 181                 try:
 182                         version, machine = self.versions[package]
 183                 except KeyError:
 184                         return
 185
 186                 impl = factory('package:rpm:%s:%s' % (package, version))
 187                 impl.version = model.parse_version(version)
 188                 if machine != '*':
 189                         impl.machine = machine
 190
 191 _host_distribution = None
 192 def get_host_distribution():
 193         """Get a Distribution suitable for the host operating system.
 194         Calling this twice will return the same object.
 195         @rtype: L{Distribution}"""
 196         global _host_distribution
 197         if not _host_distribution:
 198                 _dpkg_db_status = '/var/lib/dpkg/status'
 199                 _rpm_db = '/var/lib/rpm/Packages'
 200
 201                 if os.access(_dpkg_db_status, os.R_OK):
 202                         _host_distribution = DebianDistribution(_dpkg_db_status)
 203                 elif os.path.isfile(_rpm_db):
 204                         _host_distribution = RPMDistribution(_rpm_db)
 205                 else:
 206                         _host_distribution = Distribution()
 207
 208         return _host_distribution