shelve: remove useless and incorrect code paths for file access

This patch removes code paths in "shelvedfile.opener()", because:

    - explicit "vfs.mkdir()" invocation is useless

      "vfs.__call__()" for modes other than "read" creates parent
      directory of target file automatically by "util.ensuredirs()".

    - mode checking in "except IOError" code path is useless

      ENOENT occurs only for "read" mode, because target file is
      created forcibly for other modes.

    - there is no explicit "return" statement in the code path for
      "except IOError" if "mode[0] in 'wa'"

      this is incorrect, because None may be returnd unexpectedly,
      even though it seems the EEXIST case in the directory creation
      race for ".hg/shelved" and is very rare.

      this directory creation race is also treated in
      "util.ensuredirs()".

hgext/shelve.py

@@ -1,709 +1,700
 # shelve.py - save/restore working directory state
 #
 # Copyright 2013 Facebook, Inc.
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 """save and restore changes to the working directory
 
 The "hg shelve" command saves changes made to the working directory
 and reverts those changes, resetting the working directory to a clean
 state.
 
 Later on, the "hg unshelve" command restores the changes saved by "hg
 shelve". Changes can be restored even after updating to a different
 parent, in which case Mercurial's merge machinery will resolve any
 conflicts if necessary.
 
 You can have more than one shelved change outstanding at a time; each
 shelved change has a distinct name. For details, see the help for "hg
 shelve".
 """
 
 from mercurial.i18n import _
 from mercurial.node import nullid, bin, hex
 from mercurial import changegroup, cmdutil, scmutil, phases
 from mercurial import error, hg, mdiff, merge, patch, repair, util
 from mercurial import templatefilters
 from mercurial import lock as lockmod
 from hgext import rebase
 import errno
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
 testedwith = 'internal'
 
 class shelvedfile(object):
     """Helper for the file storing a single shelve
 
     Handles common functions on shelve files (.hg/.files/.patch) using
     the vfs layer"""
     def __init__(self, repo, name, filetype=None):
         self.repo = repo
         self.name = name
         self.vfs = scmutil.vfs(repo.join('shelved'))
         if filetype:
             self.fname = name + '.' + filetype
         else:
             self.fname = name
 
     def exists(self):
         return self.vfs.exists(self.fname)
 
     def filename(self):
         return self.vfs.join(self.fname)
 
     def unlink(self):
         util.unlink(self.filename())
 
     def stat(self):
         return self.vfs.stat(self.fname)
 
     def opener(self, mode='rb'):
         try:
             return self.vfs(self.fname, mode)
         except IOError, err:
             if err.errno != errno.ENOENT:
                 raise
-            if mode[0] in 'wa':
-                try:
-                    self.vfs.mkdir()
-                    return self.vfs(self.fname, mode)
-                except IOError, err:
-                    if err.errno != errno.EEXIST:
-                        raise
-            elif mode[0] == 'r':
-                raise util.Abort(_("shelved change '%s' not found") %
-                                 self.name)
+            raise util.Abort(_("shelved change '%s' not found") % self.name)
 
 class shelvedstate(object):
     """Handle persistence during unshelving operations.
 
     Handles saving and restoring a shelved state. Ensures that different
     versions of a shelved state are possible and handles them appropriately.
     """
     _version = 1
     _filename = 'shelvedstate'
 
     @classmethod
     def load(cls, repo):
         fp = repo.opener(cls._filename)
         try:
             version = int(fp.readline().strip())
 
             if version != cls._version:
                 raise util.Abort(_('this version of shelve is incompatible '
                                    'with the version used in this repo'))
             name = fp.readline().strip()
             wctx = fp.readline().strip()
             pendingctx = fp.readline().strip()
             parents = [bin(h) for h in fp.readline().split()]
             stripnodes = [bin(h) for h in fp.readline().split()]
             unknownfiles = fp.readline()[:-1].split('\0')
         finally:
             fp.close()
 
         obj = cls()
         obj.name = name
         obj.wctx = repo[bin(wctx)]
         obj.pendingctx = repo[bin(pendingctx)]
         obj.parents = parents
         obj.stripnodes = stripnodes
         obj.unknownfiles = unknownfiles
 
         return obj
 
     @classmethod
     def save(cls, repo, name, originalwctx, pendingctx, stripnodes,
              unknownfiles):
         fp = repo.opener(cls._filename, 'wb')
         fp.write('%i\n' % cls._version)
         fp.write('%s\n' % name)
         fp.write('%s\n' % hex(originalwctx.node()))
         fp.write('%s\n' % hex(pendingctx.node()))
         fp.write('%s\n' % ' '.join([hex(p) for p in repo.dirstate.parents()]))
         fp.write('%s\n' % ' '.join([hex(n) for n in stripnodes]))
         fp.write('%s\n' % '\0'.join(unknownfiles))
         fp.close()
 
     @classmethod
     def clear(cls, repo):
         util.unlinkpath(repo.join(cls._filename), ignoremissing=True)
 
 def createcmd(ui, repo, pats, opts):
     """subcommand that creates a new shelve"""
 
     def publicancestors(ctx):
         """Compute the heads of the public ancestors of a commit.
 
         Much faster than the revset heads(ancestors(ctx) - draft())"""
         seen = set()
         visit = util.deque()
         visit.append(ctx)
         while visit:
             ctx = visit.popleft()
             for parent in ctx.parents():
                 rev = parent.rev()
                 if rev not in seen:
                     seen.add(rev)
                     if parent.mutable():
                         visit.append(parent)
                     else:
                         yield parent.node()
 
     wctx = repo[None]
     parents = wctx.parents()
     if len(parents) > 1:
         raise util.Abort(_('cannot shelve while merging'))
     parent = parents[0]
 
     # we never need the user, so we use a generic user for all shelve operations
     user = 'shelve@localhost'
     label = repo._bookmarkcurrent or parent.branch() or 'default'
 
     # slashes aren't allowed in filenames, therefore we rename it
     origlabel, label = label, label.replace('/', '_')
 
     def gennames():
         yield label
         for i in xrange(1, 100):
             yield '%s-%02d' % (label, i)
 
     shelvedfiles = []
 
     def commitfunc(ui, repo, message, match, opts):
         # check modified, added, removed, deleted only
         for flist in repo.status(match=match)[:4]:
             shelvedfiles.extend(flist)
         hasmq = util.safehasattr(repo, 'mq')
         if hasmq:
             saved, repo.mq.checkapplied = repo.mq.checkapplied, False
         try:
             return repo.commit(message, user, opts.get('date'), match)
         finally:
             if hasmq:
                 repo.mq.checkapplied = saved
 
     if parent.node() != nullid:
         desc = parent.description().split('\n', 1)[0]
     else:
         desc = '(empty repository)'
 
     if not opts['message']:
         opts['message'] = desc
 
     name = opts['name']
 
     wlock = lock = tr = bms = None
     try:
         wlock = repo.wlock()
         lock = repo.lock()
 
         bms = repo._bookmarks.copy()
         # use an uncommitted transaction to generate the bundle to avoid
         # pull races. ensure we don't print the abort message to stderr.
         tr = repo.transaction('commit', report=lambda x: None)
 
         if name:
             if shelvedfile(repo, name, 'hg').exists():
                 raise util.Abort(_("a shelved change named '%s' already exists")
                                  % name)
         else:
             for n in gennames():
                 if not shelvedfile(repo, n, 'hg').exists():
                     name = n
                     break
             else:
                 raise util.Abort(_("too many shelved changes named '%s'") %
                                  label)
 
         # ensure we are not creating a subdirectory or a hidden file
         if '/' in name or '\\' in name:
             raise util.Abort(_('shelved change names may not contain slashes'))
         if name.startswith('.'):
             raise util.Abort(_("shelved change names may not start with '.'"))
 
         node = cmdutil.commit(ui, repo, commitfunc, pats, opts)
 
         if not node:
             stat = repo.status(match=scmutil.match(repo[None], pats, opts))
             if stat[3]:
                 ui.status(_("nothing changed (%d missing files, see "
                             "'hg status')\n") % len(stat[3]))
             else:
                 ui.status(_("nothing changed\n"))
             return 1
 
         phases.retractboundary(repo, phases.secret, [node])
 
         fp = shelvedfile(repo, name, 'files').opener('wb')
         fp.write('\0'.join(shelvedfiles))
 
         bases = list(publicancestors(repo[node]))
         cg = repo.changegroupsubset(bases, [node], 'shelve')
         changegroup.writebundle(cg, shelvedfile(repo, name, 'hg').filename(),
                                 'HG10UN')
         cmdutil.export(repo, [node],
                        fp=shelvedfile(repo, name, 'patch').opener('wb'),
                        opts=mdiff.diffopts(git=True))
 
 
         if ui.formatted():
             desc = util.ellipsis(desc, ui.termwidth())
         ui.status(_('shelved as %s\n') % name)
         hg.update(repo, parent.node())
     finally:
         if bms:
             # restore old bookmarks
             repo._bookmarks.update(bms)
             repo._bookmarks.write()
         if tr:
             tr.abort()
         lockmod.release(lock, wlock)
 
 def cleanupcmd(ui, repo):
     """subcommand that deletes all shelves"""
 
     wlock = None
     try:
         wlock = repo.wlock()
         for (name, _) in repo.vfs.readdir('shelved'):
             suffix = name.rsplit('.', 1)[-1]
             if suffix in ('hg', 'files', 'patch'):
                 shelvedfile(repo, name).unlink()
     finally:
         lockmod.release(wlock)
 
 def deletecmd(ui, repo, pats):
     """subcommand that deletes a specific shelve"""
     if not pats:
         raise util.Abort(_('no shelved changes specified!'))
     wlock = None
     try:
         wlock = repo.wlock()
         try:
             for name in pats:
                 for suffix in 'hg files patch'.split():
                     shelvedfile(repo, name, suffix).unlink()
         except OSError, err:
             if err.errno != errno.ENOENT:
                 raise
             raise util.Abort(_("shelved change '%s' not found") % name)
     finally:
         lockmod.release(wlock)
 
 def listshelves(repo):
     """return all shelves in repo as list of (time, filename)"""
     try:
         names = repo.vfs.readdir('shelved')
     except OSError, err:
         if err.errno != errno.ENOENT:
             raise
         return []
     info = []
     for (name, _) in names:
         pfx, sfx = name.rsplit('.', 1)
         if not pfx or sfx != 'patch':
             continue
         st = shelvedfile(repo, name).stat()
         info.append((st.st_mtime, shelvedfile(repo, pfx).filename()))
     return sorted(info, reverse=True)
 
 def listcmd(ui, repo, pats, opts):
     """subcommand that displays the list of shelves"""
     pats = set(pats)
     width = 80
     if not ui.plain():
         width = ui.termwidth()
     namelabel = 'shelve.newest'
     for mtime, name in listshelves(repo):
         sname = util.split(name)[1]
         if pats and sname not in pats:
             continue
         ui.write(sname, label=namelabel)
         namelabel = 'shelve.name'
         if ui.quiet:
             ui.write('\n')
             continue
         ui.write(' ' * (16 - len(sname)))
         used = 16
         age = '(%s)' % templatefilters.age(util.makedate(mtime), abbrev=True)
         ui.write(age, label='shelve.age')
         ui.write(' ' * (12 - len(age)))
         used += 12
         fp = open(name + '.patch', 'rb')
         try:
             while True:
                 line = fp.readline()
                 if not line:
                     break
                 if not line.startswith('#'):
                     desc = line.rstrip()
                     if ui.formatted():
                         desc = util.ellipsis(desc, width - used)
                     ui.write(desc)
                     break
             ui.write('\n')
             if not (opts['patch'] or opts['stat']):
                 continue
             difflines = fp.readlines()
             if opts['patch']:
                 for chunk, label in patch.difflabel(iter, difflines):
                     ui.write(chunk, label=label)
             if opts['stat']:
                 for chunk, label in patch.diffstatui(difflines, width=width,
                                                      git=True):
                     ui.write(chunk, label=label)
         finally:
             fp.close()
 
 def readshelvedfiles(repo, basename):
     """return the list of files touched in a shelve"""
     fp = shelvedfile(repo, basename, 'files').opener()
     return fp.read().split('\0')
 
 def checkparents(repo, state):
     """check parent while resuming an unshelve"""
     if state.parents != repo.dirstate.parents():
         raise util.Abort(_('working directory parents do not match unshelve '
                            'state'))
 
 def pathtofiles(repo, files):
     cwd = repo.getcwd()
     return [repo.pathto(f, cwd) for f in files]
 
 def unshelveabort(ui, repo, state, opts):
     """subcommand that abort an in-progress unshelve"""
     wlock = repo.wlock()
     lock = None
     try:
         checkparents(repo, state)
 
         util.rename(repo.join('unshelverebasestate'),
                     repo.join('rebasestate'))
         try:
             rebase.rebase(ui, repo, **{
                 'abort' : True
             })
         except Exception:
             util.rename(repo.join('rebasestate'),
                         repo.join('unshelverebasestate'))
             raise
 
         lock = repo.lock()
 
         mergefiles(ui, repo, state.wctx, state.pendingctx, state.unknownfiles)
 
         repair.strip(ui, repo, state.stripnodes, backup='none', topic='shelve')
         shelvedstate.clear(repo)
         ui.warn(_("unshelve of '%s' aborted\n") % state.name)
     finally:
         lockmod.release(lock, wlock)
 
 def mergefiles(ui, repo, wctx, shelvectx, unknownfiles):
     """updates to wctx and merges the changes from shelvectx into the
     dirstate. drops any files in unknownfiles from the dirstate."""
     oldquiet = ui.quiet
     try:
         ui.quiet = True
         hg.update(repo, wctx.node())
         files = []
         files.extend(shelvectx.files())
         files.extend(shelvectx.parents()[0].files())
         cmdutil.revert(ui, repo, shelvectx, repo.dirstate.parents(),
                        *pathtofiles(repo, files),
                        **{'no_backup': True})
     finally:
         ui.quiet = oldquiet
 
     # Send untracked files back to being untracked
     dirstate = repo.dirstate
     for f in unknownfiles:
         dirstate.drop(f)
 
 def unshelvecleanup(ui, repo, name, opts):
     """remove related files after an unshelve"""
     if not opts['keep']:
         for filetype in 'hg files patch'.split():
             shelvedfile(repo, name, filetype).unlink()
 
 def unshelvecontinue(ui, repo, state, opts):
     """subcommand to continue an in-progress unshelve"""
     # We're finishing off a merge. First parent is our original
     # parent, second is the temporary "fake" commit we're unshelving.
     wlock = repo.wlock()
     lock = None
     try:
         checkparents(repo, state)
         ms = merge.mergestate(repo)
         if [f for f in ms if ms[f] == 'u']:
             raise util.Abort(
                 _("unresolved conflicts, can't continue"),
                 hint=_("see 'hg resolve', then 'hg unshelve --continue'"))
 
         lock = repo.lock()
 
         util.rename(repo.join('unshelverebasestate'),
                     repo.join('rebasestate'))
         try:
             rebase.rebase(ui, repo, **{
                 'continue' : True
             })
         except Exception:
             util.rename(repo.join('rebasestate'),
                         repo.join('unshelverebasestate'))
             raise
 
         shelvectx = repo['tip']
         if not shelvectx in state.pendingctx.children():
             # rebase was a no-op, so it produced no child commit
             shelvectx = state.pendingctx
 
         mergefiles(ui, repo, state.wctx, shelvectx, state.unknownfiles)
 
         state.stripnodes.append(shelvectx.node())
         repair.strip(ui, repo, state.stripnodes, backup='none', topic='shelve')
         shelvedstate.clear(repo)
         unshelvecleanup(ui, repo, state.name, opts)
         ui.status(_("unshelve of '%s' complete\n") % state.name)
     finally:
         lockmod.release(lock, wlock)
 
 @command('unshelve',
          [('a', 'abort', None,
            _('abort an incomplete unshelve operation')),
           ('c', 'continue', None,
            _('continue an incomplete unshelve operation')),
           ('', 'keep', None,
            _('keep shelve after unshelving'))],
          _('hg unshelve [SHELVED]'))
 def unshelve(ui, repo, *shelved, **opts):
     """restore a shelved change to the working directory
 
     This command accepts an optional name of a shelved change to
     restore. If none is given, the most recent shelved change is used.
 
     If a shelved change is applied successfully, the bundle that
     contains the shelved changes is deleted afterwards.
 
     Since you can restore a shelved change on top of an arbitrary
     commit, it is possible that unshelving will result in a conflict
     between your changes and the commits you are unshelving onto. If
     this occurs, you must resolve the conflict, then use
     ``--continue`` to complete the unshelve operation. (The bundle
     will not be deleted until you successfully complete the unshelve.)
 
     (Alternatively, you can use ``--abort`` to abandon an unshelve
     that causes a conflict. This reverts the unshelved changes, and
     does not delete the bundle.)
     """
     abortf = opts['abort']
     continuef = opts['continue']
     if not abortf and not continuef:
         cmdutil.checkunfinished(repo)
 
     if abortf or continuef:
         if abortf and continuef:
             raise util.Abort(_('cannot use both abort and continue'))
         if shelved:
             raise util.Abort(_('cannot combine abort/continue with '
                                'naming a shelved change'))
 
         try:
             state = shelvedstate.load(repo)
         except IOError, err:
             if err.errno != errno.ENOENT:
                 raise
             raise util.Abort(_('no unshelve operation underway'))
 
         if abortf:
             return unshelveabort(ui, repo, state, opts)
         elif continuef:
             return unshelvecontinue(ui, repo, state, opts)
     elif len(shelved) > 1:
         raise util.Abort(_('can only unshelve one change at a time'))
     elif not shelved:
         shelved = listshelves(repo)
         if not shelved:
             raise util.Abort(_('no shelved changes to apply!'))
         basename = util.split(shelved[0][1])[1]
         ui.status(_("unshelving change '%s'\n") % basename)
     else:
         basename = shelved[0]
 
     shelvedfiles = readshelvedfiles(repo, basename)
 
     wlock = lock = tr = None
     try:
         lock = repo.lock()
         wlock = repo.wlock()
 
         tr = repo.transaction('unshelve', report=lambda x: None)
         oldtiprev = len(repo)
 
         wctx = repo['.']
         tmpwctx = wctx
         # The goal is to have a commit structure like so:
         # ...-> wctx -> tmpwctx -> shelvectx
         # where tmpwctx is an optional commit with the user's pending changes
         # and shelvectx is the unshelved changes. Then we merge it all down
         # to the original wctx.
 
         # Store pending changes in a commit
         m, a, r, d, u = repo.status(unknown=True)[:5]
         if m or a or r or d or u:
             def commitfunc(ui, repo, message, match, opts):
                 hasmq = util.safehasattr(repo, 'mq')
                 if hasmq:
                     saved, repo.mq.checkapplied = repo.mq.checkapplied, False
 
                 try:
                     return repo.commit(message, 'shelve@localhost',
                                        opts.get('date'), match)
                 finally:
                     if hasmq:
                         repo.mq.checkapplied = saved
 
             tempopts = {}
             tempopts['message'] = "pending changes temporary commit"
             tempopts['addremove'] = True
             oldquiet = ui.quiet
             try:
                 ui.quiet = True
                 node = cmdutil.commit(ui, repo, commitfunc, None, tempopts)
             finally:
                 ui.quiet = oldquiet
             tmpwctx = repo[node]
 
         try:
             fp = shelvedfile(repo, basename, 'hg').opener()
             gen = changegroup.readbundle(fp, fp.name)
             repo.addchangegroup(gen, 'unshelve', 'bundle:' + fp.name)
             nodes = [ctx.node() for ctx in repo.set('%d:', oldtiprev)]
             phases.retractboundary(repo, phases.secret, nodes)
         finally:
             fp.close()
 
         shelvectx = repo['tip']
 
         # If the shelve is not immediately on top of the commit
         # we'll be merging with, rebase it to be on top.
         if tmpwctx.node() != shelvectx.parents()[0].node():
             try:
                 rebase.rebase(ui, repo, **{
                     'rev' : [shelvectx.rev()],
                     'dest' : str(tmpwctx.rev()),
                     'keep' : True,
                 })
             except error.InterventionRequired:
                 tr.close()
 
                 stripnodes = [repo.changelog.node(rev)
                               for rev in xrange(oldtiprev, len(repo))]
                 shelvedstate.save(repo, basename, wctx, tmpwctx, stripnodes, u)
 
                 util.rename(repo.join('rebasestate'),
                             repo.join('unshelverebasestate'))
                 raise error.InterventionRequired(
                     _("unresolved conflicts (see 'hg resolve', then "
                       "'hg unshelve --continue')"))
 
             # refresh ctx after rebase completes
             shelvectx = repo['tip']
 
             if not shelvectx in tmpwctx.children():
                 # rebase was a no-op, so it produced no child commit
                 shelvectx = tmpwctx
 
         mergefiles(ui, repo, wctx, shelvectx, u)
         shelvedstate.clear(repo)
 
         # The transaction aborting will strip all the commits for us,
         # but it doesn't update the inmemory structures, so addchangegroup
         # hooks still fire and try to operate on the missing commits.
         # Clean up manually to prevent this.
         repo.changelog.strip(oldtiprev, tr)
 
         unshelvecleanup(ui, repo, basename, opts)
     finally:
         if tr:
             tr.release()
         lockmod.release(lock, wlock)
 
 @command('shelve',
          [('A', 'addremove', None,
            _('mark new/missing files as added/removed before shelving')),
           ('', 'cleanup', None,
            _('delete all shelved changes')),
           ('', 'date', '',
            _('shelve with the specified commit date'), _('DATE')),
           ('d', 'delete', None,
            _('delete the named shelved change(s)')),
           ('l', 'list', None,
            _('list current shelves')),
           ('m', 'message', '',
            _('use text as shelve message'), _('TEXT')),
           ('n', 'name', '',
            _('use the given name for the shelved commit'), _('NAME')),
           ('p', 'patch', None,
            _('show patch')),
           ('', 'stat', None,
            _('output diffstat-style summary of changes'))],
          _('hg shelve'))
 def shelvecmd(ui, repo, *pats, **opts):
     '''save and set aside changes from the working directory
 
     Shelving takes files that "hg status" reports as not clean, saves
     the modifications to a bundle (a shelved change), and reverts the
     files so that their state in the working directory becomes clean.
 
     To restore these changes to the working directory, using "hg
     unshelve"; this will work even if you switch to a different
     commit.
 
     When no files are specified, "hg shelve" saves all not-clean
     files. If specific files or directories are named, only changes to
     those files are shelved.
 
     Each shelved change has a name that makes it easier to find later.
     The name of a shelved change defaults to being based on the active
     bookmark, or if there is no active bookmark, the current named
     branch.  To specify a different name, use ``--name``.
 
     To see a list of existing shelved changes, use the ``--list``
     option. For each shelved change, this will print its name, age,
     and description; use ``--patch`` or ``--stat`` for more details.
 
     To delete specific shelved changes, use ``--delete``. To delete
     all shelved changes, use ``--cleanup``.
     '''
     cmdutil.checkunfinished(repo)
 
     def checkopt(opt, incompatible):
         if opts[opt]:
             for i in incompatible.split():
                 if opts[i]:
                     raise util.Abort(_("options '--%s' and '--%s' may not be "
                                        "used together") % (opt, i))
             return True
     if checkopt('cleanup', 'addremove delete list message name patch stat'):
         if pats:
             raise util.Abort(_("cannot specify names when using '--cleanup'"))
         return cleanupcmd(ui, repo)
     elif checkopt('delete', 'addremove cleanup list message name patch stat'):
         return deletecmd(ui, repo, pats)
     elif checkopt('list', 'addremove cleanup delete message name'):
         return listcmd(ui, repo, pats, opts)
     else:
         for i in ('patch', 'stat'):
             if opts[i]:
                 raise util.Abort(_("option '--%s' may not be "
                                    "used when shelving a change") % (i,))
         return createcmd(ui, repo, pats, opts)
 
 def extsetup(ui):
     cmdutil.unfinishedstates.append(
         [shelvedstate._filename, False, False,
          _('unshelve already in progress'),
          _("use 'hg unshelve --continue' or 'hg unshelve --abort'")])