filelog: raise CensoredNodeError when hash checks fail with censor metadata
With this change, when a revlog revision hash does not match its content, and
the content is empty with a special metadata key, the integrity failure is
assumed to be intentionally caused to remove sensitive content from repository
history.
To allow different Mercurial functionality to handle this scenario differently
a more specific exception is raised than "ordinary" hash failures.
Alternatives to this approach include, but are not limited to:
- Calling a hook when hashes mismatch to allow arbitrary tombstone validation.
Cons: Irresponsibly easy to disable integrity checking altogether.
- Returning empty revision data eagerly instead of raising, masking the error.
Cons: Push/pull won't roundtrip the tombstone, so client repos are unusable.
- Doing nothing differently at this layer. Callers must do their own detection
of tombstoned data if they want to handle some hash checks and not others.
- Impacts dozens of callsites, many of which don't have the revision data
- Would probably be missing one or two callsites at any given time
- Currently we throw a RevlogError, as do 12 other places in revlog.py.
Callers would need to parse the exception message and/or ensure
RevlogError is not thrown from any other part of their call tree.
# hook.py - hook support for mercurial
#
# Copyright 2007 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from i18n import _
import os, sys, time
import extensions, util, demandimport
def _pythonhook(ui, repo, name, hname, funcname, args, throw):
'''call python hook. hook is callable object, looked up as
name in python module. if callable returns "true", hook
fails, else passes. if hook raises exception, treated as
hook failure. exception propagates if throw is "true".
reason for "true" meaning "hook failed" is so that
unmodified commands (e.g. mercurial.commands.update) can
be run as hooks without wrappers to convert return values.'''
if callable(funcname):
obj = funcname
funcname = obj.__module__ + "." + obj.__name__
else:
d = funcname.rfind('.')
if d == -1:
raise util.Abort(_('%s hook is invalid ("%s" not in '
'a module)') % (hname, funcname))
modname = funcname[:d]
oldpaths = sys.path
if util.mainfrozen():
# binary installs require sys.path manipulation
modpath, modfile = os.path.split(modname)
if modpath and modfile:
sys.path = sys.path[:] + [modpath]
modname = modfile
demandimportenabled = demandimport.isenabled()
if demandimportenabled:
demandimport.disable()
try:
try:
obj = __import__(modname)
except ImportError:
e1 = sys.exc_type, sys.exc_value, sys.exc_traceback
try:
# extensions are loaded with hgext_ prefix
obj = __import__("hgext_%s" % modname)
except ImportError:
e2 = sys.exc_type, sys.exc_value, sys.exc_traceback
if ui.tracebackflag:
ui.warn(_('exception from first failed import '
'attempt:\n'))
ui.traceback(e1)
if ui.tracebackflag:
ui.warn(_('exception from second failed import '
'attempt:\n'))
ui.traceback(e2)
raise util.Abort(_('%s hook is invalid '
'(import of "%s" failed)') %
(hname, modname))
finally:
if demandimportenabled:
demandimport.enable()
sys.path = oldpaths
try:
for p in funcname.split('.')[1:]:
obj = getattr(obj, p)
except AttributeError:
raise util.Abort(_('%s hook is invalid '
'("%s" is not defined)') %
(hname, funcname))
if not callable(obj):
raise util.Abort(_('%s hook is invalid '
'("%s" is not callable)') %
(hname, funcname))
ui.note(_("calling hook %s: %s\n") % (hname, funcname))
starttime = time.time()
try:
try:
# redirect IO descriptors to the ui descriptors so hooks
# that write directly to these don't mess up the command
# protocol when running through the command server
old = sys.stdout, sys.stderr, sys.stdin
sys.stdout, sys.stderr, sys.stdin = ui.fout, ui.ferr, ui.fin
r = obj(ui=ui, repo=repo, hooktype=name, **args)
except KeyboardInterrupt:
raise
except Exception, exc:
if isinstance(exc, util.Abort):
ui.warn(_('error: %s hook failed: %s\n') %
(hname, exc.args[0]))
else:
ui.warn(_('error: %s hook raised an exception: '
'%s\n') % (hname, exc))
if throw:
raise
ui.traceback()
return True
finally:
sys.stdout, sys.stderr, sys.stdin = old
duration = time.time() - starttime
ui.log('pythonhook', 'pythonhook-%s: %s finished in %0.2f seconds\n',
name, funcname, duration)
if r:
if throw:
raise util.Abort(_('%s hook failed') % hname)
ui.warn(_('warning: %s hook failed\n') % hname)
return r
def _exthook(ui, repo, name, cmd, args, throw):
ui.note(_("running hook %s: %s\n") % (name, cmd))
starttime = time.time()
env = {}
for k, v in args.iteritems():
if callable(v):
v = v()
if isinstance(v, dict):
# make the dictionary element order stable across Python
# implementations
v = ('{' +
', '.join('%r: %r' % i for i in sorted(v.iteritems())) +
'}')
env['HG_' + k.upper()] = v
if repo:
cwd = repo.root
else:
cwd = os.getcwd()
if 'HG_URL' in env and env['HG_URL'].startswith('remote:http'):
r = util.system(cmd, environ=env, cwd=cwd, out=ui)
else:
r = util.system(cmd, environ=env, cwd=cwd, out=ui.fout)
duration = time.time() - starttime
ui.log('exthook', 'exthook-%s: %s finished in %0.2f seconds\n',
name, cmd, duration)
if r:
desc, r = util.explainexit(r)
if throw:
raise util.Abort(_('%s hook %s') % (name, desc))
ui.warn(_('warning: %s hook %s\n') % (name, desc))
return r
def _allhooks(ui):
hooks = []
for name, cmd in ui.configitems('hooks'):
if not name.startswith('priority'):
priority = ui.configint('hooks', 'priority.%s' % name, 0)
hooks.append((-priority, len(hooks), name, cmd))
return [(k, v) for p, o, k, v in sorted(hooks)]
_redirect = False
def redirect(state):
global _redirect
_redirect = state
def hook(ui, repo, name, throw=False, **args):
if not ui.callhooks:
return False
r = False
oldstdout = -1
try:
for hname, cmd in _allhooks(ui):
if hname.split('.')[0] != name or not cmd:
continue
if oldstdout == -1 and _redirect:
try:
stdoutno = sys.__stdout__.fileno()
stderrno = sys.__stderr__.fileno()
# temporarily redirect stdout to stderr, if possible
if stdoutno >= 0 and stderrno >= 0:
sys.__stdout__.flush()
oldstdout = os.dup(stdoutno)
os.dup2(stderrno, stdoutno)
except (OSError, AttributeError):
# files seem to be bogus, give up on redirecting (WSGI, etc)
pass
if callable(cmd):
r = _pythonhook(ui, repo, name, hname, cmd, args, throw) or r
elif cmd.startswith('python:'):
if cmd.count(':') >= 2:
path, cmd = cmd[7:].rsplit(':', 1)
path = util.expandpath(path)
if repo:
path = os.path.join(repo.root, path)
try:
mod = extensions.loadpath(path, 'hghook.%s' % hname)
except Exception:
ui.write(_("loading %s hook failed:\n") % hname)
raise
hookfn = getattr(mod, cmd)
else:
hookfn = cmd[7:].strip()
r = _pythonhook(ui, repo, name, hname, hookfn, args, throw) or r
else:
r = _exthook(ui, repo, hname, cmd, args, throw) or r
finally:
if _redirect and oldstdout >= 0:
os.dup2(oldstdout, stdoutno)
os.close(oldstdout)
return r