def hardlink_lockfile(lockfilename, max_wait=DeprecationWarning,
waiting_msg=None, flags=0):
"""Does the NFS, hardlink shuffle to ensure locking on the disk.
We create a PRIVATE hardlink to the real lockfile, that is just a
placeholder on the disk.
If our file can 2 references, then we have the lock. :)
Otherwise we lather, rise, and repeat.
"""
if max_wait is not DeprecationWarning:
warnings.warn("The 'max_wait' parameter of "
"portage.locks.hardlink_lockfile() is now unused. Use "
"flags=os.O_NONBLOCK instead.",
DeprecationWarning, stacklevel=2)
global _quiet
out = None
displayed_waiting_msg = False
preexisting = os.path.exists(lockfilename)
myhardlock = hardlock_name(lockfilename)
# Since Python 3.4, chown requires int type (no proxies).
portage_gid = int(portage.data.portage_gid)
# myhardlock must not exist prior to our link() call, and we can
# safely unlink it since its file name is unique to our PID
try:
os.unlink(myhardlock)
except OSError as e:
if e.errno in (errno.ENOENT, errno.ESTALE):
pass
else:
func_call = "unlink('%s')" % myhardlock
if e.errno == OperationNotPermitted.errno:
raise OperationNotPermitted(func_call)
elif e.errno == PermissionDenied.errno:
raise PermissionDenied(func_call)
else:
raise
while True:
# create lockfilename if it doesn't exist yet
try:
myfd = os.open(lockfilename, os.O_CREAT|os.O_RDWR, 0o660)
except OSError as e:
func_call = "open('%s')" % lockfilename
if e.errno == OperationNotPermitted.errno:
raise OperationNotPermitted(func_call)
elif e.errno == PermissionDenied.errno:
raise PermissionDenied(func_call)
elif e.errno == ReadOnlyFileSystem.errno:
raise ReadOnlyFileSystem(func_call)
else:
raise
else:
myfd_st = None
try:
myfd_st = os.fstat(myfd)
if not preexisting:
# Don't chown the file if it is preexisting, since we
# want to preserve existing permissions in that case.
if myfd_st.st_gid != portage_gid:
os.fchown(myfd, -1, portage_gid)
except OSError as e:
if e.errno not in (errno.ENOENT, errno.ESTALE):
writemsg("%s: fchown('%s', -1, %d)\n" % \
(e, lockfilename, portage_gid), noiselevel=-1)
writemsg(_("Cannot chown a lockfile: '%s'\n") % \
lockfilename, noiselevel=-1)
writemsg(_("Group IDs of current user: %s\n") % \
" ".join(str(n) for n in os.getgroups()),
noiselevel=-1)
else:
# another process has removed the file, so we'll have
# to create it again
continue
finally:
os.close(myfd)
# If fstat shows more than one hardlink, then it's extremely
# unlikely that the following link call will result in a lock,
# so optimize away the wasteful link call and sleep or raise
# TryAgain.
if myfd_st is not None and myfd_st.st_nlink < 2:
try:
os.link(lockfilename, myhardlock)
except OSError as e:
func_call = "link('%s', '%s')" % (lockfilename, myhardlock)
if e.errno == OperationNotPermitted.errno:
raise OperationNotPermitted(func_call)
elif e.errno == PermissionDenied.errno:
raise PermissionDenied(func_call)
elif e.errno in (errno.ESTALE, errno.ENOENT):
# another process has removed the file, so we'll have
# to create it again
continue
else:
raise
else:
if hardlink_is_mine(myhardlock, lockfilename):
if out is not None:
out.eend(os.EX_OK)
break
try:
os.unlink(myhardlock)
except OSError as e:
# This should not happen, since the file name of
# myhardlock is unique to our host and PID,
# and the above link() call succeeded.
if e.errno not in (errno.ENOENT, errno.ESTALE):
raise
raise FileNotFound(myhardlock)
if flags & os.O_NONBLOCK:
raise TryAgain(lockfilename)
if out is None and not _quiet:
out = portage.output.EOutput()
if out is not None and not displayed_waiting_msg:
displayed_waiting_msg = True
if waiting_msg is None:
waiting_msg = _("waiting for lock on %s\n") % lockfilename
out.ebegin(waiting_msg)
time.sleep(_HARDLINK_POLL_LATENCY)
return True
def hardlink_lockfile(lockfilename,
max_wait=DeprecationWarning,
waiting_msg=None,
flags=0):
"""Does the NFS, hardlink shuffle to ensure locking on the disk.
We create a PRIVATE hardlink to the real lockfile, that is just a
placeholder on the disk.
If our file can 2 references, then we have the lock. :)
Otherwise we lather, rise, and repeat.
"""
if max_wait is not DeprecationWarning:
warnings.warn(
"The 'max_wait' parameter of "
"portage.locks.hardlink_lockfile() is now unused. Use "
"flags=os.O_NONBLOCK instead.",
DeprecationWarning,
stacklevel=2)
global _quiet
out = None
displayed_waiting_msg = False
preexisting = os.path.exists(lockfilename)
myhardlock = hardlock_name(lockfilename)
# Since Python 3.4, chown requires int type (no proxies).
portage_gid = int(portage.data.portage_gid)
# myhardlock must not exist prior to our link() call, and we can
# safely unlink it since its file name is unique to our PID
try:
os.unlink(myhardlock)
except OSError as e:
if e.errno in (errno.ENOENT, errno.ESTALE):
pass
else:
func_call = "unlink('%s')" % myhardlock
if e.errno == OperationNotPermitted.errno:
raise OperationNotPermitted(func_call)
elif e.errno == PermissionDenied.errno:
raise PermissionDenied(func_call)
else:
raise
while True:
# create lockfilename if it doesn't exist yet
try:
myfd = os.open(lockfilename, os.O_CREAT | os.O_RDWR, 0o660)
except OSError as e:
func_call = "open('%s')" % lockfilename
if e.errno == OperationNotPermitted.errno:
raise OperationNotPermitted(func_call)
elif e.errno == PermissionDenied.errno:
raise PermissionDenied(func_call)
elif e.errno == ReadOnlyFileSystem.errno:
raise ReadOnlyFileSystem(func_call)
else:
raise
else:
myfd_st = None
try:
myfd_st = os.fstat(myfd)
if not preexisting:
# Don't chown the file if it is preexisting, since we
# want to preserve existing permissions in that case.
if portage.data.secpass >= 1 and myfd_st.st_gid != portage_gid:
os.fchown(myfd, -1, portage_gid)
except OSError as e:
if e.errno not in (errno.ENOENT, errno.ESTALE):
writemsg("%s: fchown('%s', -1, %d)\n" % \
(e, lockfilename, portage_gid), noiselevel=-1)
writemsg(_("Cannot chown a lockfile: '%s'\n") % \
lockfilename, noiselevel=-1)
writemsg(_("Group IDs of current user: %s\n") % \
" ".join(str(n) for n in os.getgroups()),
noiselevel=-1)
else:
# another process has removed the file, so we'll have
# to create it again
continue
finally:
os.close(myfd)
# If fstat shows more than one hardlink, then it's extremely
# unlikely that the following link call will result in a lock,
# so optimize away the wasteful link call and sleep or raise
# TryAgain.
if myfd_st is not None and myfd_st.st_nlink < 2:
try:
os.link(lockfilename, myhardlock)
except OSError as e:
func_call = "link('%s', '%s')" % (lockfilename, myhardlock)
if e.errno == OperationNotPermitted.errno:
raise OperationNotPermitted(func_call)
elif e.errno == PermissionDenied.errno:
raise PermissionDenied(func_call)
elif e.errno in (errno.ESTALE, errno.ENOENT):
# another process has removed the file, so we'll have
# to create it again
continue
else:
raise
else:
if hardlink_is_mine(myhardlock, lockfilename):
if out is not None:
out.eend(os.EX_OK)
break
try:
os.unlink(myhardlock)
except OSError as e:
# This should not happen, since the file name of
# myhardlock is unique to our host and PID,
# and the above link() call succeeded.
if e.errno not in (errno.ENOENT, errno.ESTALE):
raise
raise FileNotFound(myhardlock)
if flags & os.O_NONBLOCK:
raise TryAgain(lockfilename)
if out is None and not _quiet:
out = portage.output.EOutput()
if out is not None and not displayed_waiting_msg:
displayed_waiting_msg = True
if waiting_msg is None:
waiting_msg = _("waiting for lock on %s\n") % lockfilename
out.ebegin(waiting_msg)
time.sleep(_HARDLINK_POLL_LATENCY)
return True
