pym/portage/locks.py

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