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 import portage
  16 from portage import os
  17 from portage.const import PORTAGE_BIN_PATH
  18 from portage.exception import DirectoryNotFound, FileNotFound, \
  19         InvalidData, TryAgain, OperationNotPermitted, PermissionDenied
  20 from portage.data import portage_gid
  21 from portage.util import writemsg
  22 from portage.localization import _
  23
  24 if sys.hexversion >= 0x3000000:
  25         basestring = str
  26
  27 HARDLINK_FD = -2
  28
  29 # Used by emerge in order to disable the "waiting for lock" message
  30 # so that it doesn't interfere with the status display.
  31 _quiet = False
  32
  33 def lockdir(mydir):
  34         return lockfile(mydir,wantnewlockfile=1)
  35 def unlockdir(mylock):
  36         return unlockfile(mylock)
  37
  38 def lockfile(mypath, wantnewlockfile=0, unlinkfile=0,
  39         waiting_msg=None, flags=0):
  40         """
  41         If wantnewlockfile is True then this creates a lockfile in the parent
  42         directory as the file: '.' + basename + '.portage_lockfile'.
  43         """
  44
  45         if not mypath:
  46                 raise InvalidData(_("Empty path given"))
  47
  48         if isinstance(mypath, basestring) and mypath[-1] == '/':
  49                 mypath = mypath[:-1]
  50
  51         if hasattr(mypath, 'fileno'):
  52                 mypath = mypath.fileno()
  53         if isinstance(mypath, int):
  54                 lockfilename    = mypath
  55                 wantnewlockfile = 0
  56                 unlinkfile      = 0
  57         elif wantnewlockfile:
  58                 base, tail = os.path.split(mypath)
  59                 lockfilename = os.path.join(base, "." + tail + ".portage_lockfile")
  60                 del base, tail
  61                 unlinkfile   = 1
  62         else:
  63                 lockfilename = mypath
  64
  65         if isinstance(mypath, basestring):
  66                 if not os.path.exists(os.path.dirname(mypath)):
  67                         raise DirectoryNotFound(os.path.dirname(mypath))
  68                 preexisting = os.path.exists(lockfilename)
  69                 old_mask = os.umask(000)
  70                 try:
  71                         try:
  72                                 myfd = os.open(lockfilename, os.O_CREAT|os.O_RDWR, 0o660)
  73                         except OSError as e:
  74                                 func_call = "open('%s')" % lockfilename
  75                                 if e.errno == OperationNotPermitted.errno:
  76                                         raise OperationNotPermitted(func_call)
  77                                 elif e.errno == PermissionDenied.errno:
  78                                         raise PermissionDenied(func_call)
  79                                 else:
  80                                         raise
  81
  82                         if not preexisting:
  83                                 try:
  84                                         if os.stat(lockfilename).st_gid != portage_gid:
  85                                                 os.chown(lockfilename, -1, portage_gid)
  86                                 except OSError as e:
  87                                         if e.errno in (errno.ENOENT, errno.ESTALE):
  88                                                 return lockfile(mypath,
  89                                                         wantnewlockfile=wantnewlockfile,
  90                                                         unlinkfile=unlinkfile, waiting_msg=waiting_msg,
  91                                                         flags=flags)
  92                                         else:
  93                                                 writemsg("%s: chown('%s', -1, %d)\n" % \
  94                                                         (e, lockfilename, portage_gid), noiselevel=-1)
  95                                                 writemsg(_("Cannot chown a lockfile: '%s'\n") % \
  96                                                         lockfilename, noiselevel=-1)
  97                                                 writemsg(_("Group IDs of current user: %s\n") % \
  98                                                         " ".join(str(n) for n in os.getgroups()),
  99                                                         noiselevel=-1)
 100                 finally:
 101                         os.umask(old_mask)
 102
 103         elif isinstance(mypath, int):
 104                 myfd = mypath
 105
 106         else:
 107                 raise ValueError(_("Unknown type passed in '%s': '%s'") % \
 108                         (type(mypath), mypath))
 109
 110         # try for a non-blocking lock, if it's held, throw a message
 111         # we're waiting on lockfile and use a blocking attempt.
 112         locking_method = fcntl.lockf
 113         try:
 114                 fcntl.lockf(myfd,fcntl.LOCK_EX|fcntl.LOCK_NB)
 115         except IOError as e:
 116                 if "errno" not in dir(e):
 117                         raise
 118                 if e.errno in (errno.EACCES, errno.EAGAIN):
 119                         # resource temp unavailable; eg, someone beat us to the lock.
 120                         if flags & os.O_NONBLOCK:
 121                                 raise TryAgain(mypath)
 122
 123                         global _quiet
 124                         if _quiet:
 125                                 out = None
 126                         else:
 127                                 out = portage.output.EOutput()
 128                         if waiting_msg is None:
 129                                 if isinstance(mypath, int):
 130                                         waiting_msg = _("waiting for lock on fd %i") % myfd
 131                                 else:
 132                                         waiting_msg = _("waiting for lock on %s\n") % lockfilename
 133                         if out is not None:
 134                                 out.ebegin(waiting_msg)
 135                         # try for the exclusive lock now.
 136                         try:
 137                                 fcntl.lockf(myfd, fcntl.LOCK_EX)
 138                         except EnvironmentError as e:
 139                                 if out is not None:
 140                                         out.eend(1, str(e))
 141                                 raise
 142                         if out is not None:
 143                                 out.eend(os.EX_OK)
 144                 elif e.errno == errno.ENOLCK:
 145                         # We're not allowed to lock on this FS.
 146                         os.close(myfd)
 147                         link_success = False
 148                         if lockfilename == str(lockfilename):
 149                                 if wantnewlockfile:
 150                                         try:
 151                                                 if os.stat(lockfilename)[stat.ST_NLINK] == 1:
 152                                                         os.unlink(lockfilename)
 153                                         except OSError:
 154                                                 pass
 155                                         link_success = hardlink_lockfile(lockfilename)
 156                         if not link_success:
 157                                 raise
 158                         locking_method = None
 159                         myfd = HARDLINK_FD
 160                 else:
 161                         raise
 162
 163
 164         if isinstance(lockfilename, basestring) and \
 165                 myfd != HARDLINK_FD and _fstat_nlink(myfd) == 0:
 166                 # The file was deleted on us... Keep trying to make one...
 167                 os.close(myfd)
 168                 writemsg(_("lockfile recurse\n"), 1)
 169                 lockfilename, myfd, unlinkfile, locking_method = lockfile(
 170                         mypath, wantnewlockfile=wantnewlockfile, unlinkfile=unlinkfile,
 171                         waiting_msg=waiting_msg, flags=flags)
 172
 173         writemsg(str((lockfilename,myfd,unlinkfile))+"\n",1)
 174         return (lockfilename,myfd,unlinkfile,locking_method)
 175
 176 def _fstat_nlink(fd):
 177         """
 178         @param fd: an open file descriptor
 179         @type fd: Integer
 180         @rtype: Integer
 181         @return: the current number of hardlinks to the file
 182         """
 183         try:
 184                 return os.fstat(fd).st_nlink
 185         except EnvironmentError as e:
 186                 if e.errno in (errno.ENOENT, errno.ESTALE):
 187                         # Some filesystems such as CIFS return
 188                         # ENOENT which means st_nlink == 0.
 189                         return 0
 190                 raise
 191
 192 def unlockfile(mytuple):
 193
 194         #XXX: Compatability hack.
 195         if len(mytuple) == 3:
 196                 lockfilename,myfd,unlinkfile = mytuple
 197                 locking_method = fcntl.flock
 198         elif len(mytuple) == 4:
 199                 lockfilename,myfd,unlinkfile,locking_method = mytuple
 200         else:
 201                 raise InvalidData
 202
 203         if(myfd == HARDLINK_FD):
 204                 unhardlink_lockfile(lockfilename)
 205                 return True
 206
 207         # myfd may be None here due to myfd = mypath in lockfile()
 208         if isinstance(lockfilename, basestring) and \
 209                 not os.path.exists(lockfilename):
 210                 writemsg(_("lockfile does not exist '%s'\n") % lockfilename,1)
 211                 if myfd is not None:
 212                         os.close(myfd)
 213                 return False
 214
 215         try:
 216                 if myfd is None:
 217                         myfd = os.open(lockfilename, os.O_WRONLY,0o660)
 218                         unlinkfile = 1
 219                 locking_method(myfd,fcntl.LOCK_UN)
 220         except OSError:
 221                 if isinstance(lockfilename, basestring):
 222                         os.close(myfd)
 223                 raise IOError(_("Failed to unlock file '%s'\n") % lockfilename)
 224
 225         try:
 226                 # This sleep call was added to allow other processes that are
 227                 # waiting for a lock to be able to grab it before it is deleted.
 228                 # lockfile() already accounts for this situation, however, and
 229                 # the sleep here adds more time than is saved overall, so am
 230                 # commenting until it is proved necessary.
 231                 #time.sleep(0.0001)
 232                 if unlinkfile:
 233                         locking_method(myfd,fcntl.LOCK_EX|fcntl.LOCK_NB)
 234                         # We won the lock, so there isn't competition for it.
 235                         # We can safely delete the file.
 236                         writemsg(_("Got the lockfile...\n"), 1)
 237                         if _fstat_nlink(myfd) == 1:
 238                                 os.unlink(lockfilename)
 239                                 writemsg(_("Unlinked lockfile...\n"), 1)
 240                                 locking_method(myfd,fcntl.LOCK_UN)
 241                         else:
 242                                 writemsg(_("lockfile does not exist '%s'\n") % lockfilename, 1)
 243                                 os.close(myfd)
 244                                 return False
 245         except SystemExit:
 246                 raise
 247         except Exception as e:
 248                 writemsg(_("Failed to get lock... someone took it.\n"), 1)
 249                 writemsg(str(e)+"\n",1)
 250
 251         # why test lockfilename?  because we may have been handed an
 252         # fd originally, and the caller might not like having their
 253         # open fd closed automatically on them.
 254         if isinstance(lockfilename, basestring):
 255                 os.close(myfd)
 256
 257         return True
 258
 259
 260
 261
 262 def hardlock_name(path):
 263         return path+".hardlock-"+os.uname()[1]+"-"+str(os.getpid())
 264
 265 def hardlink_is_mine(link,lock):
 266         try:
 267                 return os.stat(link).st_nlink == 2
 268         except OSError:
 269                 return False
 270
 271 def hardlink_lockfile(lockfilename, max_wait=14400):
 272         """Does the NFS, hardlink shuffle to ensure locking on the disk.
 273         We create a PRIVATE lockfile, that is just a placeholder on the disk.
 274         Then we HARDLINK the real lockfile to that private file.
 275         If our file can 2 references, then we have the lock. :)
 276         Otherwise we lather, rise, and repeat.
 277         We default to a 4 hour timeout.
 278         """
 279
 280         start_time = time.time()
 281         myhardlock = hardlock_name(lockfilename)
 282         reported_waiting = False
 283
 284         while(time.time() < (start_time + max_wait)):
 285                 # We only need it to exist.
 286                 myfd = os.open(myhardlock, os.O_CREAT|os.O_RDWR,0o660)
 287                 os.close(myfd)
 288
 289                 if not os.path.exists(myhardlock):
 290                         raise FileNotFound(
 291                                 _("Created lockfile is missing: %(filename)s") % \
 292                                 {"filename" : myhardlock})
 293
 294                 try:
 295                         res = os.link(myhardlock, lockfilename)
 296                 except OSError:
 297                         pass
 298
 299                 if hardlink_is_mine(myhardlock, lockfilename):
 300                         # We have the lock.
 301                         if reported_waiting:
 302                                 writemsg("\n", noiselevel=-1)
 303                         return True
 304
 305                 if reported_waiting:
 306                         writemsg(".", noiselevel=-1)
 307                 else:
 308                         reported_waiting = True
 309                         msg = _("\nWaiting on (hardlink) lockfile: (one '.' per 3 seconds)\n"
 310                                 "%(bin_path)s/clean_locks can fix stuck locks.\n"
 311                                 "Lockfile: %(lockfilename)s\n") % \
 312                                 {"bin_path": PORTAGE_BIN_PATH, "lockfilename": lockfilename}
 313                         writemsg(msg, noiselevel=-1)
 314                 time.sleep(3)
 315
 316         os.unlink(myhardlock)
 317         return False
 318
 319 def unhardlink_lockfile(lockfilename):
 320         myhardlock = hardlock_name(lockfilename)
 321         if hardlink_is_mine(myhardlock, lockfilename):
 322                 # Make sure not to touch lockfilename unless we really have a lock.
 323                 try:
 324                         os.unlink(lockfilename)
 325                 except OSError:
 326                         pass
 327         try:
 328                 os.unlink(myhardlock)
 329         except OSError:
 330                 pass
 331
 332 def hardlock_cleanup(path, remove_all_locks=False):
 333         mypid  = str(os.getpid())
 334         myhost = os.uname()[1]
 335         mydl = os.listdir(path)
 336
 337         results = []
 338         mycount = 0
 339
 340         mylist = {}
 341         for x in mydl:
 342                 if os.path.isfile(path+"/"+x):
 343                         parts = x.split(".hardlock-")
 344                         if len(parts) == 2:
 345                                 filename = parts[0]
 346                                 hostpid  = parts[1].split("-")
 347                                 host  = "-".join(hostpid[:-1])
 348                                 pid   = hostpid[-1]
 349
 350                                 if filename not in mylist:
 351                                         mylist[filename] = {}
 352                                 if host not in mylist[filename]:
 353                                         mylist[filename][host] = []
 354                                 mylist[filename][host].append(pid)
 355
 356                                 mycount += 1
 357
 358
 359         results.append(_("Found %(count)s locks") % {"count":mycount})
 360
 361         for x in mylist:
 362                 if myhost in mylist[x] or remove_all_locks:
 363                         mylockname = hardlock_name(path+"/"+x)
 364                         if hardlink_is_mine(mylockname, path+"/"+x) or \
 365                            not os.path.exists(path+"/"+x) or \
 366                                  remove_all_locks:
 367                                 for y in mylist[x]:
 368                                         for z in mylist[x][y]:
 369                                                 filename = path+"/"+x+".hardlock-"+y+"-"+z
 370                                                 if filename == mylockname:
 371                                                         continue
 372                                                 try:
 373                                                         # We're sweeping through, unlinking everyone's locks.
 374                                                         os.unlink(filename)
 375                                                         results.append(_("Unlinked: ") + filename)
 376                                                 except OSError:
 377                                                         pass
 378                                 try:
 379                                         os.unlink(path+"/"+x)
 380                                         results.append(_("Unlinked: ") + path+"/"+x)
 381                                         os.unlink(mylockname)
 382                                         results.append(_("Unlinked: ") + mylockname)
 383                                 except OSError:
 384                                         pass
 385                         else:
 386                                 try:
 387                                         os.unlink(mylockname)
 388                                         results.append(_("Unlinked: ") + mylockname)
 389                                 except OSError:
 390                                         pass
 391
 392         return results
 393