pym/portage/locks.py

   1 # portage: Lock management code
   2 # Copyright 2004-2010 Gentoo Foundation
   3 # Distributed under the terms of the GNU General Public License v2
   4
   5 __all__ = ["lockdir", "unlockdir", "lockfile", "unlockfile", \
   6         "hardlock_name", "hardlink_is_mine", "hardlink_lockfile", \
   7         "unhardlink_lockfile", "hardlock_cleanup"]
   8
   9 import errno
  10 import fcntl
  11 import stat
  12 import sys
  13 import time
  14
  15 from portage import os
  16 from portage.const import PORTAGE_BIN_PATH
  17 from portage.exception import DirectoryNotFound, FileNotFound, \
  18         InvalidData, TryAgain, OperationNotPermitted, PermissionDenied
  19 from portage.data import portage_gid
  20 from portage.util import writemsg
  21 from portage.localization import _
  22
  23 if sys.hexversion >= 0x3000000:
  24         basestring = str
  25
  26 HARDLINK_FD = -2
  27
  28 # Used by emerge in order to disable the "waiting for lock" message
  29 # so that it doesn't interfere with the status display.
  30 _quiet = False
  31
  32 def lockdir(mydir):
  33         return lockfile(mydir,wantnewlockfile=1)
  34 def unlockdir(mylock):
  35         return unlockfile(mylock)
  36
  37 def lockfile(mypath, wantnewlockfile=0, unlinkfile=0,
  38         waiting_msg=None, flags=0):
  39         """
  40         If wantnewlockfile is True then this creates a lockfile in the parent
  41         directory as the file: '.' + basename + '.portage_lockfile'.
  42         """
  43
  44         if not mypath:
  45                 raise InvalidData(_("Empty path given"))
  46
  47         if isinstance(mypath, basestring) and mypath[-1] == '/':
  48                 mypath = mypath[:-1]
  49
  50         if hasattr(mypath, 'fileno'):
  51                 mypath = mypath.fileno()
  52         if isinstance(mypath, int):
  53                 lockfilename    = mypath
  54                 wantnewlockfile = 0
  55                 unlinkfile      = 0
  56         elif wantnewlockfile:
  57                 base, tail = os.path.split(mypath)
  58                 lockfilename = os.path.join(base, "." + tail + ".portage_lockfile")
  59                 del base, tail
  60                 unlinkfile   = 1
  61         else:
  62                 lockfilename = mypath
  63
  64         if isinstance(mypath, basestring):
  65                 if not os.path.exists(os.path.dirname(mypath)):
  66                         raise DirectoryNotFound(os.path.dirname(mypath))
  67                 preexisting = os.path.exists(lockfilename)
  68                 old_mask = os.umask(000)
  69                 try:
  70                         try:
  71                                 myfd = os.open(lockfilename, os.O_CREAT|os.O_RDWR, 0o660)
  72                         except OSError as e:
  73                                 func_call = "open('%s')" % lockfilename
  74                                 if e.errno == OperationNotPermitted.errno:
  75                                         raise OperationNotPermitted(func_call)
  76                                 elif e.errno == PermissionDenied.errno:
  77                                         raise PermissionDenied(func_call)
  78                                 else:
  79                                         raise
  80
  81                         if not preexisting:
  82                                 try:
  83                                         if os.stat(lockfilename).st_gid != portage_gid:
  84                                                 os.chown(lockfilename, -1, portage_gid)
  85                                 except OSError as e:
  86                                         if e.errno in (errno.ENOENT, errno.ESTALE):
  87                                                 return lockfile(mypath,
  88                                                         wantnewlockfile=wantnewlockfile,
  89                                                         unlinkfile=unlinkfile, waiting_msg=waiting_msg,
  90                                                         flags=flags)
  91                                         else:
  92                                                 writemsg("%s: chown('%s', -1, %d)\n" % \
  93                                                         (e, lockfilename, portage_gid), noiselevel=-1)
  94                                                 writemsg(_("Cannot chown a lockfile: '%s'\n") % \
  95                                                         lockfilename, noiselevel=-1)
  96                                                 writemsg(_("Group IDs of current user: %s\n") % \
  97                                                         " ".join(str(n) for n in os.getgroups()),
  98                                                         noiselevel=-1)
  99                 finally:
 100                         os.umask(old_mask)
 101
 102         elif isinstance(mypath, int):
 103                 myfd = mypath
 104
 105         else:
 106                 raise ValueError(_("Unknown type passed in '%s': '%s'") % \
 107                         (type(mypath), mypath))
 108
 109         # try for a non-blocking lock, if it's held, throw a message
 110         # we're waiting on lockfile and use a blocking attempt.
 111         locking_method = fcntl.lockf
 112         try:
 113                 fcntl.lockf(myfd,fcntl.LOCK_EX|fcntl.LOCK_NB)
 114         except IOError as e:
 115                 if "errno" not in dir(e):
 116                         raise
 117                 if e.errno in (errno.EACCES, errno.EAGAIN):
 118                         # resource temp unavailable; eg, someone beat us to the lock.
 119                         if flags & os.O_NONBLOCK:
 120                                 raise TryAgain(mypath)
 121
 122                         global _quiet
 123                         if _quiet:
 124                                 out = None
 125                         else:
 126                                 out = portage.output.EOutput()
 127                         if waiting_msg is None:
 128                                 if isinstance(mypath, int):
 129                                         waiting_msg = _("waiting for lock on fd %i") % myfd
 130                                 else:
 131                                         waiting_msg = _("waiting for lock on %s\n") % lockfilename
 132                         if out is not None:
 133                                 out.ebegin(waiting_msg)
 134                         # try for the exclusive lock now.
 135                         try:
 136                                 fcntl.lockf(myfd, fcntl.LOCK_EX)
 137                         except EnvironmentError as e:
 138                                 if out is not None:
 139                                         out.eend(1, str(e))
 140                                 raise
 141                         if out is not None:
 142                                 out.eend(os.EX_OK)
 143                 elif e.errno == errno.ENOLCK:
 144                         # We're not allowed to lock on this FS.
 145                         os.close(myfd)
 146                         link_success = False
 147                         if lockfilename == str(lockfilename):
 148                                 if wantnewlockfile:
 149                                         try:
 150                                                 if os.stat(lockfilename)[stat.ST_NLINK] == 1:
 151                                                         os.unlink(lockfilename)
 152                                         except OSError:
 153                                                 pass
 154                                         link_success = hardlink_lockfile(lockfilename)
 155                         if not link_success:
 156                                 raise
 157                         locking_method = None
 158                         myfd = HARDLINK_FD
 159                 else:
 160                         raise
 161
 162
 163         if isinstance(lockfilename, basestring) and \
 164                 myfd != HARDLINK_FD and _fstat_nlink(myfd) == 0:
 165                 # The file was deleted on us... Keep trying to make one...
 166                 os.close(myfd)
 167                 writemsg(_("lockfile recurse\n"), 1)
 168                 lockfilename, myfd, unlinkfile, locking_method = lockfile(
 169                         mypath, wantnewlockfile=wantnewlockfile, unlinkfile=unlinkfile,
 170                         waiting_msg=waiting_msg, flags=flags)
 171
 172         writemsg(str((lockfilename,myfd,unlinkfile))+"\n",1)
 173         return (lockfilename,myfd,unlinkfile,locking_method)
 174
 175 def _fstat_nlink(fd):
 176         """
 177         @param fd: an open file descriptor
 178         @type fd: Integer
 179         @rtype: Integer
 180         @return: the current number of hardlinks to the file
 181         """
 182         try:
 183                 return os.fstat(fd).st_nlink
 184         except EnvironmentError as e:
 185                 if e.errno in (errno.ENOENT, errno.ESTALE):
 186                         # Some filesystems such as CIFS return
 187                         # ENOENT which means st_nlink == 0.
 188                         return 0
 189                 raise
 190
 191 def unlockfile(mytuple):
 192
 193         #XXX: Compatability hack.
 194         if len(mytuple) == 3:
 195                 lockfilename,myfd,unlinkfile = mytuple
 196                 locking_method = fcntl.flock
 197         elif len(mytuple) == 4:
 198                 lockfilename,myfd,unlinkfile,locking_method = mytuple
 199         else:
 200                 raise InvalidData
 201
 202         if(myfd == HARDLINK_FD):
 203                 unhardlink_lockfile(lockfilename)
 204                 return True
 205
 206         # myfd may be None here due to myfd = mypath in lockfile()
 207         if isinstance(lockfilename, basestring) and \
 208                 not os.path.exists(lockfilename):
 209                 writemsg(_("lockfile does not exist '%s'\n") % lockfilename,1)
 210                 if myfd is not None:
 211                         os.close(myfd)
 212                 return False
 213
 214         try:
 215                 if myfd is None:
 216                         myfd = os.open(lockfilename, os.O_WRONLY,0o660)
 217                         unlinkfile = 1
 218                 locking_method(myfd,fcntl.LOCK_UN)
 219         except OSError:
 220                 if isinstance(lockfilename, basestring):
 221                         os.close(myfd)
 222                 raise IOError(_("Failed to unlock file '%s'\n") % lockfilename)
 223
 224         try:
 225                 # This sleep call was added to allow other processes that are
 226                 # waiting for a lock to be able to grab it before it is deleted.
 227                 # lockfile() already accounts for this situation, however, and
 228                 # the sleep here adds more time than is saved overall, so am
 229                 # commenting until it is proved necessary.
 230                 #time.sleep(0.0001)
 231                 if unlinkfile:
 232                         locking_method(myfd,fcntl.LOCK_EX|fcntl.LOCK_NB)
 233                         # We won the lock, so there isn't competition for it.
 234                         # We can safely delete the file.
 235                         writemsg(_("Got the lockfile...\n"), 1)
 236                         if _fstat_nlink(myfd) == 1:
 237                                 os.unlink(lockfilename)
 238                                 writemsg(_("Unlinked lockfile...\n"), 1)
 239                                 locking_method(myfd,fcntl.LOCK_UN)
 240                         else:
 241                                 writemsg(_("lockfile does not exist '%s'\n") % lockfilename, 1)
 242                                 os.close(myfd)
 243                                 return False
 244         except SystemExit:
 245                 raise
 246         except Exception as e:
 247                 writemsg(_("Failed to get lock... someone took it.\n"), 1)
 248                 writemsg(str(e)+"\n",1)
 249
 250         # why test lockfilename?  because we may have been handed an
 251         # fd originally, and the caller might not like having their
 252         # open fd closed automatically on them.
 253         if isinstance(lockfilename, basestring):
 254                 os.close(myfd)
 255
 256         return True
 257
 258
 259
 260
 261 def hardlock_name(path):
 262         return path+".hardlock-"+os.uname()[1]+"-"+str(os.getpid())
 263
 264 def hardlink_is_mine(link,lock):
 265         try:
 266                 return os.stat(link).st_nlink == 2
 267         except OSError:
 268                 return False
 269
 270 def hardlink_lockfile(lockfilename, max_wait=14400):
 271         """Does the NFS, hardlink shuffle to ensure locking on the disk.
 272         We create a PRIVATE lockfile, that is just a placeholder on the disk.
 273         Then we HARDLINK the real lockfile to that private file.
 274         If our file can 2 references, then we have the lock. :)
 275         Otherwise we lather, rise, and repeat.
 276         We default to a 4 hour timeout.
 277         """
 278
 279         start_time = time.time()
 280         myhardlock = hardlock_name(lockfilename)
 281         reported_waiting = False
 282
 283         while(time.time() < (start_time + max_wait)):
 284                 # We only need it to exist.
 285                 myfd = os.open(myhardlock, os.O_CREAT|os.O_RDWR,0o660)
 286                 os.close(myfd)
 287
 288                 if not os.path.exists(myhardlock):
 289                         raise FileNotFound(
 290                                 _("Created lockfile is missing: %(filename)s") % \
 291                                 {"filename" : myhardlock})
 292
 293                 try:
 294                         res = os.link(myhardlock, lockfilename)
 295                 except OSError:
 296                         pass
 297
 298                 if hardlink_is_mine(myhardlock, lockfilename):
 299                         # We have the lock.
 300                         if reported_waiting:
 301                                 writemsg("\n", noiselevel=-1)
 302                         return True
 303
 304                 if reported_waiting:
 305                         writemsg(".", noiselevel=-1)
 306                 else:
 307                         reported_waiting = True
 308                         msg = _("\nWaiting on (hardlink) lockfile: (one '.' per 3 seconds)\n"
 309                                 "%(bin_path)s/clean_locks can fix stuck locks.\n"
 310                                 "Lockfile: %(lockfilename)s\n") % \
 311                                 {"bin_path": PORTAGE_BIN_PATH, "lockfilename": lockfilename}
 312                         writemsg(msg, noiselevel=-1)
 313                 time.sleep(3)
 314
 315         os.unlink(myhardlock)
 316         return False
 317
 318 def unhardlink_lockfile(lockfilename):
 319         myhardlock = hardlock_name(lockfilename)
 320         if hardlink_is_mine(myhardlock, lockfilename):
 321                 # Make sure not to touch lockfilename unless we really have a lock.
 322                 try:
 323                         os.unlink(lockfilename)
 324                 except OSError:
 325                         pass
 326         try:
 327                 os.unlink(myhardlock)
 328         except OSError:
 329                 pass
 330
 331 def hardlock_cleanup(path, remove_all_locks=False):
 332         mypid  = str(os.getpid())
 333         myhost = os.uname()[1]
 334         mydl = os.listdir(path)
 335
 336         results = []
 337         mycount = 0
 338
 339         mylist = {}
 340         for x in mydl:
 341                 if os.path.isfile(path+"/"+x):
 342                         parts = x.split(".hardlock-")
 343                         if len(parts) == 2:
 344                                 filename = parts[0]
 345                                 hostpid  = parts[1].split("-")
 346                                 host  = "-".join(hostpid[:-1])
 347                                 pid   = hostpid[-1]
 348
 349                                 if filename not in mylist:
 350                                         mylist[filename] = {}
 351                                 if host not in mylist[filename]:
 352                                         mylist[filename][host] = []
 353                                 mylist[filename][host].append(pid)
 354
 355                                 mycount += 1
 356
 357
 358         results.append(_("Found %(count)s locks") % {"count":mycount})
 359
 360         for x in mylist:
 361                 if myhost in mylist[x] or remove_all_locks:
 362                         mylockname = hardlock_name(path+"/"+x)
 363                         if hardlink_is_mine(mylockname, path+"/"+x) or \
 364                            not os.path.exists(path+"/"+x) or \
 365                                  remove_all_locks:
 366                                 for y in mylist[x]:
 367                                         for z in mylist[x][y]:
 368                                                 filename = path+"/"+x+".hardlock-"+y+"-"+z
 369                                                 if filename == mylockname:
 370                                                         continue
 371                                                 try:
 372                                                         # We're sweeping through, unlinking everyone's locks.
 373                                                         os.unlink(filename)
 374                                                         results.append(_("Unlinked: ") + filename)
 375                                                 except OSError:
 376                                                         pass
 377                                 try:
 378                                         os.unlink(path+"/"+x)
 379                                         results.append(_("Unlinked: ") + path+"/"+x)
 380                                         os.unlink(mylockname)
 381                                         results.append(_("Unlinked: ") + mylockname)
 382                                 except OSError:
 383                                         pass
 384                         else:
 385                                 try:
 386                                         os.unlink(mylockname)
 387                                         results.append(_("Unlinked: ") + mylockname)
 388                                 except OSError:
 389                                         pass
 390
 391         return results
 392