zeroinstall/zerostore/__init__.py

   1 """
   2 Code for managing the implementation cache.
   3 """
   4
   5 # Copyright (C) 2009, Thomas Leonard
   6 # See the README file for details, or visit http://0install.net.
   7
   8 from zeroinstall import _
   9 import os
  10 from logging import debug, info, warn
  11
  12 from zeroinstall.support import basedir
  13 from zeroinstall import SafeException, support
  14
  15 class BadDigest(SafeException):
  16         """Thrown if a digest is invalid (either syntactically or cryptographically)."""
  17         detail = None
  18
  19 class NotStored(SafeException):
  20         """Throws if a requested implementation isn't in the cache."""
  21
  22 class NonwritableStore(SafeException):
  23         """Attempt to add to a non-writable store directory."""
  24
  25 def _copytree2(src, dst):
  26         import shutil
  27         names = os.listdir(src)
  28         assert os.path.isdir(dst)
  29         errors = []
  30         for name in names:
  31                 srcname = os.path.join(src, name)
  32                 dstname = os.path.join(dst, name)
  33                 if os.path.islink(srcname):
  34                         linkto = os.readlink(srcname)
  35                         os.symlink(linkto, dstname)
  36                 elif os.path.isdir(srcname):
  37                         os.mkdir(dstname)
  38                         mtime = int(os.lstat(srcname).st_mtime)
  39                         _copytree2(srcname, dstname)
  40                         os.utime(dstname, (mtime, mtime))
  41                 else:
  42                         shutil.copy2(srcname, dstname)
  43
  44 class Store:
  45         """A directory for storing implementations."""
  46
  47         def __init__(self, dir, public = False):
  48                 """Create a new Store.
  49                 @param dir: directory to contain the implementations
  50                 @type dir: str
  51                 @param public: deprecated
  52                 @type public: bool"""
  53                 self.dir = dir
  54
  55         def __str__(self):
  56                 return _("Store '%s'") % self.dir
  57
  58         def lookup(self, digest):
  59                 try:
  60                         alg, value = digest.split('=', 1)
  61                 except ValueError:
  62                         raise BadDigest(_("Digest must be in the form ALG=VALUE, not '%s'") % digest)
  63                 try:
  64                         assert '/' not in value
  65                         int(value, 16)          # Check valid format
  66                 except ValueError, ex:
  67                         raise BadDigest(_("Bad value for digest: %s") % str(ex))
  68                 dir = os.path.join(self.dir, digest)
  69                 if os.path.isdir(dir):
  70                         return dir
  71                 return None
  72
  73         def get_tmp_dir_for(self, required_digest):
  74                 """Create a temporary directory in the directory where we would store an implementation
  75                 with the given digest. This is used to setup a new implementation before being renamed if
  76                 it turns out OK.
  77                 @raise NonwritableStore: if we can't create it"""
  78                 try:
  79                         if not os.path.isdir(self.dir):
  80                                 os.makedirs(self.dir)
  81                         from tempfile import mkdtemp
  82                         tmp = mkdtemp(dir = self.dir, prefix = 'tmp-')
  83                         os.chmod(tmp, 0755)     # r-x for all; needed by 0store-helper
  84                         return tmp
  85                 except OSError, ex:
  86                         raise NonwritableStore(str(ex))
  87
  88         def add_archive_to_cache(self, required_digest, data, url, extract = None, type = None, start_offset = 0, try_helper = False):
  89                 import unpack
  90                 info(_("Caching new implementation (digest %s)"), required_digest)
  91
  92                 if self.lookup(required_digest):
  93                         info(_("Not adding %s as it already exists!"), required_digest)
  94                         return
  95
  96                 tmp = self.get_tmp_dir_for(required_digest)
  97                 try:
  98                         unpack.unpack_archive(url, data, tmp, extract, type = type, start_offset = start_offset)
  99                 except:
 100                         import shutil
 101                         shutil.rmtree(tmp)
 102                         raise
 103
 104                 try:
 105                         self.check_manifest_and_rename(required_digest, tmp, extract, try_helper = try_helper)
 106                 except Exception, ex:
 107                         warn(_("Leaving extracted directory as %s"), tmp)
 108                         raise
 109
 110         def add_dir_to_cache(self, required_digest, path, try_helper = False):
 111                 """Copy the contents of path to the cache.
 112                 @param required_digest: the expected digest
 113                 @type required_digest: str
 114                 @param path: the root of the tree to copy
 115                 @type path: str
 116                 @param try_helper: attempt to use privileged helper before user cache (since 0.26)
 117                 @type try_helper: bool
 118                 @raise BadDigest: if the contents don't match the given digest."""
 119                 if self.lookup(required_digest):
 120                         info(_("Not adding %s as it already exists!"), required_digest)
 121                         return
 122
 123                 tmp = self.get_tmp_dir_for(required_digest)
 124                 try:
 125                         _copytree2(path, tmp)
 126                         self.check_manifest_and_rename(required_digest, tmp, try_helper = try_helper)
 127                 except:
 128                         warn(_("Error importing directory."))
 129                         warn(_("Deleting %s"), tmp)
 130                         support.ro_rmtree(tmp)
 131                         raise
 132
 133         def _add_with_helper(self, required_digest, path):
 134                 """Use 0store-secure-add to copy 'path' to the system store.
 135                 @param required_digest: the digest for path
 136                 @type required_digest: str
 137                 @param path: root of implementation directory structure
 138                 @type path: str
 139                 @return: True iff the directory was copied into the system cache successfully
 140                 """
 141                 if required_digest.startswith('sha1='):
 142                         return False            # Old digest alg not supported
 143                 helper = support.find_in_path('0store-secure-add-helper')
 144                 if not helper:
 145                         info(_("'0store-secure-add-helper' command not found. Not adding to system cache."))
 146                         return False
 147                 import subprocess
 148                 env = os.environ.copy()
 149                 env['ENV_NOT_CLEARED'] = 'Unclean'      # (warn about insecure configurations)
 150                 env['HOME'] = 'Unclean'                 # (warn about insecure configurations)
 151                 dev_null = os.open('/dev/null', os.O_RDONLY)
 152                 try:
 153                         info(_("Trying to add to system cache using %s"), helper)
 154                         child = subprocess.Popen([helper, required_digest],
 155                                                  stdin = dev_null,
 156                                                  cwd = path,
 157                                                  env = env)
 158                         exit_code = child.wait()
 159                 finally:
 160                         os.close(dev_null)
 161
 162                 if exit_code:
 163                         warn(_("0store-secure-add-helper failed."))
 164                         return False
 165
 166                 info(_("Added succcessfully."))
 167                 return True
 168
 169         def check_manifest_and_rename(self, required_digest, tmp, extract = None, try_helper = False):
 170                 """Check that tmp[/extract] has the required_digest.
 171                 On success, rename the checked directory to the digest, and
 172                 make the whole tree read-only.
 173                 @param try_helper: attempt to use privileged helper to import to system cache first (since 0.26)
 174                 @type try_helper: bool
 175                 @raise BadDigest: if the input directory doesn't match the given digest"""
 176                 if extract:
 177                         extracted = os.path.join(tmp, extract)
 178                         if not os.path.isdir(extracted):
 179                                 raise Exception(_('Directory %s not found in archive') % extract)
 180                 else:
 181                         extracted = tmp
 182
 183                 import manifest
 184
 185                 manifest.fixup_permissions(extracted)
 186
 187                 alg, required_value = manifest.splitID(required_digest)
 188                 actual_digest = alg.getID(manifest.add_manifest_file(extracted, alg))
 189                 if actual_digest != required_digest:
 190                         raise BadDigest(_('Incorrect manifest -- archive is corrupted.\n'
 191                                         'Required digest: %(required_digest)s\n'
 192                                         'Actual digest: %(actual_digest)s\n') %
 193                                         {'request_digest': required_digest, 'actual_digest': actual_digest})
 194
 195                 if try_helper:
 196                         if self._add_with_helper(required_digest, extracted):
 197                                 support.ro_rmtree(tmp)
 198                                 return
 199                         info(_("Can't add to system store. Trying user store instead."))
 200
 201                 final_name = os.path.join(self.dir, required_digest)
 202                 if os.path.isdir(final_name):
 203                         raise Exception(_("Item %s already stored.") % final_name) # XXX: not really an error
 204
 205                 # If we just want a subdirectory then the rename will change
 206                 # extracted/.. and so we'll need write permission on 'extracted'
 207
 208                 os.chmod(extracted, 0755)
 209                 os.rename(extracted, final_name)
 210                 os.chmod(final_name, 0555)
 211
 212                 if extract:
 213                         os.rmdir(tmp)
 214
 215         def __repr__(self):
 216                 return "<store: %s>" % self.dir
 217
 218 class Stores(object):
 219         """A list of L{Store}s. All stores are searched when looking for an implementation.
 220         When storing, we use the first of the system caches (if writable), or the user's
 221         cache otherwise."""
 222         __slots__ = ['stores']
 223
 224         def __init__(self):
 225                 user_store = os.path.join(basedir.xdg_cache_home, '0install.net', 'implementations')
 226                 self.stores = [Store(user_store)]
 227
 228                 impl_dirs = basedir.load_first_config('0install.net', 'injector',
 229                                                           'implementation-dirs')
 230                 debug(_("Location of 'implementation-dirs' config file being used: '%s'"), impl_dirs)
 231                 if impl_dirs:
 232                         dirs = file(impl_dirs)
 233                 else:
 234                         dirs = ['/var/cache/0install.net/implementations']
 235                 for directory in dirs:
 236                         directory = directory.strip()
 237                         if directory and not directory.startswith('#'):
 238                                 debug(_("Added system store '%s'"), directory)
 239                                 self.stores.append(Store(directory))
 240
 241         def lookup(self, digest):
 242                 """Search for digest in all stores."""
 243                 assert digest
 244                 if '/' in digest or '=' not in digest:
 245                         raise BadDigest(_('Syntax error in digest (use ALG=VALUE, not %s)') % digest)
 246                 for store in self.stores:
 247                         path = store.lookup(digest)
 248                         if path:
 249                                 return path
 250                 raise NotStored(_("Item with digest '%(digest)s' not found in stores. Searched:\n- %(stores)s") %
 251                         {'digest': digest, 'stores': '\n- '.join([s.dir for s in self.stores])})
 252
 253         def add_dir_to_cache(self, required_digest, dir):
 254                 """Add to the best writable cache.
 255                 @see: L{Store.add_dir_to_cache}"""
 256                 self._write_store(lambda store, **kwargs: store.add_dir_to_cache(required_digest, dir, **kwargs))
 257
 258         def add_archive_to_cache(self, required_digest, data, url, extract = None, type = None, start_offset = 0):
 259                 """Add to the best writable cache.
 260                 @see: L{Store.add_archive_to_cache}"""
 261                 self._write_store(lambda store, **kwargs: store.add_archive_to_cache(required_digest,
 262                                                 data, url, extract, type = type, start_offset = start_offset, **kwargs))
 263
 264         def _write_store(self, fn):
 265                 """Call fn(first_system_store). If it's read-only, try again with the user store."""
 266                 if len(self.stores) > 1:
 267                         try:
 268                                 fn(self.get_first_system_store())
 269                                 return
 270                         except NonwritableStore:
 271                                 debug(_("%s not-writable. Trying helper instead."), self.get_first_system_store())
 272                                 pass
 273                 fn(self.stores[0], try_helper = True)
 274
 275         def get_first_system_store(self):
 276                 """The first system store is the one we try writing to first.
 277                 @since: 0.30"""
 278                 try:
 279                         return self.stores[1]
 280                 except IndexError:
 281                         raise SafeException(_("No system stores have been configured"))