eol: document why os.utime doesn't work here

I wanted to use

  os.utime(self.join("eol.cache"), None)

as a cleaner way of touching the cache file -- but this fails when the
cache doesn't exist.

hgext/eol.py

@@ -1,347 +1,347 b''
 """automatically manage newlines in repository files
 
 This extension allows you to manage the type of line endings (CRLF or
 LF) that are used in the repository and in the local working
 directory. That way you can get CRLF line endings on Windows and LF on
 Unix/Mac, thereby letting everybody use their OS native line endings.
 
 The extension reads its configuration from a versioned ``.hgeol``
 configuration file found in the root of the working copy. The
 ``.hgeol`` file use the same syntax as all other Mercurial
 configuration files. It uses two sections, ``[patterns]`` and
 ``[repository]``.
 
 The ``[patterns]`` section specifies how line endings should be
 converted between the working copy and the repository. The format is
 specified by a file pattern. The first match is used, so put more
 specific patterns first. The available line endings are ``LF``,
 ``CRLF``, and ``BIN``.
 
 Files with the declared format of ``CRLF`` or ``LF`` are always
 checked out and stored in the repository in that format and files
 declared to be binary (``BIN``) are left unchanged. Additionally,
 ``native`` is an alias for checking out in the platform's default line
 ending: ``LF`` on Unix (including Mac OS X) and ``CRLF`` on
 Windows. Note that ``BIN`` (do nothing to line endings) is Mercurial's
 default behaviour; it is only needed if you need to override a later,
 more general pattern.
 
 The optional ``[repository]`` section specifies the line endings to
 use for files stored in the repository. It has a single setting,
 ``native``, which determines the storage line endings for files
 declared as ``native`` in the ``[patterns]`` section. It can be set to
 ``LF`` or ``CRLF``. The default is ``LF``. For example, this means
 that on Windows, files configured as ``native`` (``CRLF`` by default)
 will be converted to ``LF`` when stored in the repository. Files
 declared as ``LF``, ``CRLF``, or ``BIN`` in the ``[patterns]`` section
 are always stored as-is in the repository.
 
 Example versioned ``.hgeol`` file::
 
   [patterns]
   **.py = native
   **.vcproj = CRLF
   **.txt = native
   Makefile = LF
   **.jpg = BIN
 
   [repository]
   native = LF
 
 .. note::
    The rules will first apply when files are touched in the working
    copy, e.g. by updating to null and back to tip to touch all files.
 
 The extension uses an optional ``[eol]`` section read from both the
 normal Mercurial configuration files and the ``.hgeol`` file, with the
 latter overriding the former. You can use that section to control the
 overall behavior. There are three settings:
 
 - ``eol.native`` (default ``os.linesep``) can be set to ``LF`` or
   ``CRLF`` to override the default interpretation of ``native`` for
   checkout. This can be used with :hg:`archive` on Unix, say, to
   generate an archive where files have line endings for Windows.
 
 - ``eol.only-consistent`` (default True) can be set to False to make
   the extension convert files with inconsistent EOLs. Inconsistent
   means that there is both ``CRLF`` and ``LF`` present in the file.
   Such files are normally not touched under the assumption that they
   have mixed EOLs on purpose.
 
 - ``eol.fix-trailing-newline`` (default False) can be set to True to
   ensure that converted files end with a EOL character (either ``\\n``
   or ``\\r\\n`` as per the configured patterns).
 
 The extension provides ``cleverencode:`` and ``cleverdecode:`` filters
 like the deprecated win32text extension does. This means that you can
 disable win32text and enable eol and your filters will still work. You
 only need to these filters until you have prepared a ``.hgeol`` file.
 
 The ``win32text.forbid*`` hooks provided by the win32text extension
 have been unified into a single hook named ``eol.checkheadshook``. The
 hook will lookup the expected line endings from the ``.hgeol`` file,
 which means you must migrate to a ``.hgeol`` file first before using
 the hook. ``eol.checkheadshook`` only checks heads, intermediate
 invalid revisions will be pushed. To forbid them completely, use the
 ``eol.checkallhook`` hook. These hooks are best used as
 ``pretxnchangegroup`` hooks.
 
 See :hg:`help patterns` for more information about the glob patterns
 used.
 """
 
 from mercurial.i18n import _
 from mercurial import util, config, extensions, match, error
 import re, os
 
 # Matches a lone LF, i.e., one that is not part of CRLF.
 singlelf = re.compile('(^|[^\r])\n')
 # Matches a single EOL which can either be a CRLF where repeated CR
 # are removed or a LF. We do not care about old Machintosh files, so a
 # stray CR is an error.
 eolre = re.compile('\r*\n')
 
 
 def inconsistenteol(data):
     return '\r\n' in data and singlelf.search(data)
 
 def tolf(s, params, ui, **kwargs):
     """Filter to convert to LF EOLs."""
     if util.binary(s):
         return s
     if ui.configbool('eol', 'only-consistent', True) and inconsistenteol(s):
         return s
     if ui.configbool('eol', 'fix-trailing-newline', False) and s and s[-1] != '\n':
         s = s + '\n'
     return eolre.sub('\n', s)
 
 def tocrlf(s, params, ui, **kwargs):
     """Filter to convert to CRLF EOLs."""
     if util.binary(s):
         return s
     if ui.configbool('eol', 'only-consistent', True) and inconsistenteol(s):
         return s
     if ui.configbool('eol', 'fix-trailing-newline', False) and s and s[-1] != '\n':
         s = s + '\n'
     return eolre.sub('\r\n', s)
 
 def isbinary(s, params):
     """Filter to do nothing with the file."""
     return s
 
 filters = {
     'to-lf': tolf,
     'to-crlf': tocrlf,
     'is-binary': isbinary,
     # The following provide backwards compatibility with win32text
     'cleverencode:': tolf,
     'cleverdecode:': tocrlf
 }
 
 class eolfile(object):
     def __init__(self, ui, root, data):
         self._decode = {'LF': 'to-lf', 'CRLF': 'to-crlf', 'BIN': 'is-binary'}
         self._encode = {'LF': 'to-lf', 'CRLF': 'to-crlf', 'BIN': 'is-binary'}
 
         self.cfg = config.config()
         # Our files should not be touched. The pattern must be
         # inserted first override a '** = native' pattern.
         self.cfg.set('patterns', '.hg*', 'BIN')
         # We can then parse the user's patterns.
         self.cfg.parse('.hgeol', data)
 
         isrepolf = self.cfg.get('repository', 'native') != 'CRLF'
         self._encode['NATIVE'] = isrepolf and 'to-lf' or 'to-crlf'
         iswdlf = ui.config('eol', 'native', os.linesep) in ('LF', '\n')
         self._decode['NATIVE'] = iswdlf and 'to-lf' or 'to-crlf'
 
         include = []
         exclude = []
         for pattern, style in self.cfg.items('patterns'):
             key = style.upper()
             if key == 'BIN':
                 exclude.append(pattern)
             else:
                 include.append(pattern)
         # This will match the files for which we need to care
         # about inconsistent newlines.
         self.match = match.match(root, '', [], include, exclude)
 
     def copytoui(self, ui):
         for pattern, style in self.cfg.items('patterns'):
             key = style.upper()
             try:
                 ui.setconfig('decode', pattern, self._decode[key])
                 ui.setconfig('encode', pattern, self._encode[key])
             except KeyError:
                 ui.warn(_("ignoring unknown EOL style '%s' from %s\n")
                         % (style, self.cfg.source('patterns', pattern)))
         # eol.only-consistent can be specified in ~/.hgrc or .hgeol
         for k, v in self.cfg.items('eol'):
             ui.setconfig('eol', k, v)
 
     def checkrev(self, repo, ctx, files):
         failed = []
         for f in (files or ctx.files()):
             if f not in ctx:
                 continue
             for pattern, style in self.cfg.items('patterns'):
                 if not match.match(repo.root, '', [pattern])(f):
                     continue
                 target = self._encode[style.upper()]
                 data = ctx[f].data()
                 if (target == "to-lf" and "\r\n" in data
                     or target == "to-crlf" and singlelf.search(data)):
                     failed.append((str(ctx), target, f))
                 break
         return failed
 
 def parseeol(ui, repo, nodes):
     try:
         for node in nodes:
             try:
                 if node is None:
                     # Cannot use workingctx.data() since it would load
                     # and cache the filters before we configure them.
                     data = repo.wfile('.hgeol').read()
                 else:
                     data = repo[node]['.hgeol'].data()
                 return eolfile(ui, repo.root, data)
             except (IOError, LookupError):
                 pass
     except error.ParseError, inst:
         ui.warn(_("warning: ignoring .hgeol file due to parse error "
                   "at %s: %s\n") % (inst.args[1], inst.args[0]))
     return None
 
 def _checkhook(ui, repo, node, headsonly):
     # Get revisions to check and touched files at the same time
     files = set()
     revs = set()
     for rev in xrange(repo[node].rev(), len(repo)):
         revs.add(rev)
         if headsonly:
             ctx = repo[rev]
             files.update(ctx.files())
             for pctx in ctx.parents():
                 revs.discard(pctx.rev())
     failed = []
     for rev in revs:
         ctx = repo[rev]
         eol = parseeol(ui, repo, [ctx.node()])
         if eol:
             failed.extend(eol.checkrev(repo, ctx, files))
 
     if failed:
         eols = {'to-lf': 'CRLF', 'to-crlf': 'LF'}
         msgs = []
         for node, target, f in failed:
             msgs.append(_("  %s in %s should not have %s line endings") %
                         (f, node, eols[target]))
         raise util.Abort(_("end-of-line check failed:\n") + "\n".join(msgs))
 
 def checkallhook(ui, repo, node, hooktype, **kwargs):
     """verify that files have expected EOLs"""
     _checkhook(ui, repo, node, False)
 
 def checkheadshook(ui, repo, node, hooktype, **kwargs):
     """verify that files have expected EOLs"""
     _checkhook(ui, repo, node, True)
 
 # "checkheadshook" used to be called "hook"
 hook = checkheadshook
 
 def preupdate(ui, repo, hooktype, parent1, parent2):
     #print "preupdate for %s: %s -> %s" % (repo.root, parent1, parent2)
     repo.loadeol([parent1])
     return False
 
 def uisetup(ui):
     ui.setconfig('hooks', 'preupdate.eol', preupdate)
 
 def extsetup(ui):
     try:
         extensions.find('win32text')
         ui.warn(_("the eol extension is incompatible with the "
                   "win32text extension\n"))
     except KeyError:
         pass
 
 
 def reposetup(ui, repo):
     uisetup(repo.ui)
     #print "reposetup for", repo.root
 
     if not repo.local():
         return
     for name, fn in filters.iteritems():
         repo.adddatafilter(name, fn)
 
     ui.setconfig('patch', 'eol', 'auto')
 
     class eolrepo(repo.__class__):
 
         def loadeol(self, nodes):
             eol = parseeol(self.ui, self, nodes)
             if eol is None:
                 return None
             eol.copytoui(self.ui)
             return eol.match
 
         def _hgcleardirstate(self):
             self._eolfile = self.loadeol([None, 'tip'])
             if not self._eolfile:
                 self._eolfile = util.never
                 return
 
             try:
                 cachemtime = os.path.getmtime(self.join("eol.cache"))
             except OSError:
                 cachemtime = 0
 
             try:
                 eolmtime = os.path.getmtime(self.wjoin(".hgeol"))
             except OSError:
                 eolmtime = 0
 
             if eolmtime > cachemtime:
                 ui.debug("eol: detected change in .hgeol\n")
                 wlock = None
                 try:
                     wlock = self.wlock()
                     for f in self.dirstate:
                         if self.dirstate[f] == 'n':
                             # all normal files need to be looked at
                             # again since the new .hgeol file might no
                             # longer match a file it matched before
                             self.dirstate.normallookup(f)
-                    # Touch the cache to update mtime.
+                    # Create or touch the cache to update mtime
                     self.opener("eol.cache", "w").close()
                     wlock.release()
                 except error.LockUnavailable:
                     # If we cannot lock the repository and clear the
                     # dirstate, then a commit might not see all files
                     # as modified. But if we cannot lock the
                     # repository, then we can also not make a commit,
                     # so ignore the error.
                     pass
 
         def commitctx(self, ctx, error=False):
             for f in sorted(ctx.added() + ctx.modified()):
                 if not self._eolfile(f):
                     continue
                 try:
                     data = ctx[f].data()
                 except IOError:
                     continue
                 if util.binary(data):
                     # We should not abort here, since the user should
                     # be able to say "** = native" to automatically
                     # have all non-binary files taken care of.
                     continue
                 if inconsistenteol(data):
                     raise util.Abort(_("inconsistent newline style "
                                        "in %s\n" % f))
             return super(eolrepo, self).commitctx(ctx, error)
     repo.__class__ = eolrepo
     repo._hgcleardirstate()