new file mode 100644
--- /dev/null
+++ b/mercurial/patch.py
@@ -0,0 +1,365 @@
+# patch.py - patch file parsing routines
+#
+# Copyright 2006 Brendan Cully <brendan@kublai.com>
+#
+# This software may be used and distributed according to the terms
+# of the GNU General Public License, incorporated herein by reference.
+
+from demandload import demandload
+from i18n import gettext as _
+from node import *
+demandload(globals(), "cmdutil mdiff util")
+demandload(globals(), "cStringIO email.Parser os re shutil sys tempfile")
+
+def extract(ui, fileobj):
+    '''extract patch from data read from fileobj.
+
+    patch can be normal patch or contained in email message.
+
+    return tuple (filename, message, user, date). any item in returned
+    tuple can be None.  if filename is None, fileobj did not contain
+    patch. caller must unlink filename when done.'''
+
+    # attempt to detect the start of a patch
+    # (this heuristic is borrowed from quilt)
+    diffre = re.compile(r'^(?:Index:[ \t]|diff[ \t]|RCS file: |' +
+                        'retrieving revision [0-9]+(\.[0-9]+)*$|' +
+                        '(---|\*\*\*)[ \t])', re.MULTILINE)
+
+    fd, tmpname = tempfile.mkstemp(prefix='hg-patch-')
+    tmpfp = os.fdopen(fd, 'w')
+    try:
+        hgpatch = False
+
+        msg = email.Parser.Parser().parse(fileobj)
+
+        message = msg['Subject']
+        user = msg['From']
+        # should try to parse msg['Date']
+        date = None
+
+        if message:
+            message = message.replace('\n\t', ' ')
+            ui.debug('Subject: %s\n' % message)
+        if user:
+            ui.debug('From: %s\n' % user)
+        diffs_seen = 0
+        ok_types = ('text/plain', 'text/x-diff', 'text/x-patch')
+
+        for part in msg.walk():
+            content_type = part.get_content_type()
+            ui.debug('Content-Type: %s\n' % content_type)
+            if content_type not in ok_types:
+                continue
+            payload = part.get_payload(decode=True)
+            m = diffre.search(payload)
+            if m:
+                ui.debug(_('found patch at byte %d\n') % m.start(0))
+                diffs_seen += 1
+                cfp = cStringIO.StringIO()
+                if message:
+                    cfp.write(message)
+                    cfp.write('\n')
+                for line in payload[:m.start(0)].splitlines():
+                    if line.startswith('# HG changeset patch'):
+                        ui.debug(_('patch generated by hg export\n'))
+                        hgpatch = True
+                        # drop earlier commit message content
+                        cfp.seek(0)
+                        cfp.truncate()
+                    elif hgpatch:
+                        if line.startswith('# User '):
+                            user = line[7:]
+                            ui.debug('From: %s\n' % user)
+                        elif line.startswith("# Date "):
+                            date = line[7:]
+                    if not line.startswith('# '):
+                        cfp.write(line)
+                        cfp.write('\n')
+                message = cfp.getvalue()
+                if tmpfp:
+                    tmpfp.write(payload)
+                    if not payload.endswith('\n'):
+                        tmpfp.write('\n')
+            elif not diffs_seen and message and content_type == 'text/plain':
+                message += '\n' + payload
+    except:
+        tmpfp.close()
+        os.unlink(tmpname)
+        raise
+
+    tmpfp.close()
+    if not diffs_seen:
+        os.unlink(tmpname)
+        return None, message, user, date
+    return tmpname, message, user, date
+
+def readgitpatch(patchname):
+    """extract git-style metadata about patches from <patchname>"""
+    class gitpatch:
+        "op is one of ADD, DELETE, RENAME, MODIFY or COPY"
+        def __init__(self, path):
+            self.path = path
+            self.oldpath = None
+            self.mode = None
+            self.op = 'MODIFY'
+            self.copymod = False
+            self.lineno = 0
+    
+    # Filter patch for git information
+    gitre = re.compile('diff --git a/(.*) b/(.*)')
+    pf = file(patchname)
+    gp = None
+    gitpatches = []
+    # Can have a git patch with only metadata, causing patch to complain
+    dopatch = False
+
+    lineno = 0
+    for line in pf:
+        lineno += 1
+        if line.startswith('diff --git'):
+            m = gitre.match(line)
+            if m:
+                if gp:
+                    gitpatches.append(gp)
+                src, dst = m.group(1,2)
+                gp = gitpatch(dst)
+                gp.lineno = lineno
+        elif gp:
+            if line.startswith('--- '):
+                if gp.op in ('COPY', 'RENAME'):
+                    gp.copymod = True
+                    dopatch = 'filter'
+                gitpatches.append(gp)
+                gp = None
+                if not dopatch:
+                    dopatch = True
+                continue
+            if line.startswith('rename from '):
+                gp.op = 'RENAME'
+                gp.oldpath = line[12:].rstrip()
+            elif line.startswith('rename to '):
+                gp.path = line[10:].rstrip()
+            elif line.startswith('copy from '):
+                gp.op = 'COPY'
+                gp.oldpath = line[10:].rstrip()
+            elif line.startswith('copy to '):
+                gp.path = line[8:].rstrip()
+            elif line.startswith('deleted file'):
+                gp.op = 'DELETE'
+            elif line.startswith('new file mode '):
+                gp.op = 'ADD'
+                gp.mode = int(line.rstrip()[-3:], 8)
+            elif line.startswith('new mode '):
+                gp.mode = int(line.rstrip()[-3:], 8)
+    if gp:
+        gitpatches.append(gp)
+
+    if not gitpatches:
+        dopatch = True
+
+    return (dopatch, gitpatches)
+
+def dogitpatch(patchname, gitpatches):
+    """Preprocess git patch so that vanilla patch can handle it"""
+    pf = file(patchname)
+    pfline = 1
+
+    fd, patchname = tempfile.mkstemp(prefix='hg-patch-')
+    tmpfp = os.fdopen(fd, 'w')
+
+    try:
+        for i in range(len(gitpatches)):
+            p = gitpatches[i]
+            if not p.copymod:
+                continue
+
+            if os.path.exists(p.path):
+                raise util.Abort(_("cannot create %s: destination already exists") %
+                            p.path)
+
+            (src, dst) = [os.path.join(os.getcwd(), n)
+                          for n in (p.oldpath, p.path)]
+
+            targetdir = os.path.dirname(dst)
+            if not os.path.isdir(targetdir):
+                os.makedirs(targetdir)
+            try:
+                shutil.copyfile(src, dst)
+                shutil.copymode(src, dst)
+            except shutil.Error, inst:
+                raise util.Abort(str(inst))
+
+            # rewrite patch hunk
+            while pfline < p.lineno:
+                tmpfp.write(pf.readline())
+                pfline += 1
+            tmpfp.write('diff --git a/%s b/%s\n' % (p.path, p.path))
+            line = pf.readline()
+            pfline += 1
+            while not line.startswith('--- a/'):
+                tmpfp.write(line)
+                line = pf.readline()
+                pfline += 1
+            tmpfp.write('--- a/%s\n' % p.path)
+
+        line = pf.readline()
+        while line:
+            tmpfp.write(line)
+            line = pf.readline()
+    except:
+        tmpfp.close()
+        os.unlink(patchname)
+        raise
+
+    tmpfp.close()
+    return patchname
+
+def patch(strip, patchname, ui, cwd=None):
+    """apply the patch <patchname> to the working directory.
+    a list of patched files is returned"""
+
+    (dopatch, gitpatches) = readgitpatch(patchname)
+
+    files = {}
+    if dopatch:
+        if dopatch == 'filter':
+            patchname = dogitpatch(patchname, gitpatches)
+        patcher = util.find_in_path('gpatch', os.environ.get('PATH', ''), 'patch')
+        args = []
+        if cwd:
+            args.append('-d %s' % util.shellquote(cwd))
+        fp = os.popen('%s %s -p%d < %s' % (patcher, ' '.join(args), strip,
+                                           util.shellquote(patchname)))
+
+        if dopatch == 'filter':
+            False and os.unlink(patchname)
+
+        for line in fp:
+            line = line.rstrip()
+            ui.status("%s\n" % line)
+            if line.startswith('patching file '):
+                pf = util.parse_patch_output(line)
+                files.setdefault(pf, (None, None))
+        code = fp.close()
+        if code:
+            raise util.Abort(_("patch command failed: %s") %
+                             util.explain_exit(code)[0])
+
+    for gp in gitpatches:
+        files[gp.path] = (gp.op, gp)
+
+    return files
+
+def diff(repo, node1=None, node2=None, files=None, match=util.always,
+         fp=None, changes=None, opts=None):
+    '''print diff of changes to files between two nodes, or node and
+    working directory.
+
+    if node1 is None, use first dirstate parent instead.
+    if node2 is None, compare node1 with working directory.'''
+
+    if opts is None:
+        opts = mdiff.defaultopts
+    if fp is None:
+        fp = repo.ui
+
+    if not node1:
+        node1 = repo.dirstate.parents()[0]
+    # reading the data for node1 early allows it to play nicely
+    # with repo.status and the revlog cache.
+    change = repo.changelog.read(node1)
+    mmap = repo.manifest.read(change[0])
+    date1 = util.datestr(change[2])
+
+    if not changes:
+        changes = repo.status(node1, node2, files, match=match)[:5]
+    modified, added, removed, deleted, unknown = changes
+    if files:
+        def filterfiles(filters):
+            l = [x for x in filters if x in files]
+
+            for t in files:
+                if not t.endswith("/"):
+                    t += "/"
+                l += [x for x in filters if x.startswith(t)]
+            return l
+
+        modified, added, removed = map(filterfiles, (modified, added, removed))
+
+    if not modified and not added and not removed:
+        return
+
+    if node2:
+        change = repo.changelog.read(node2)
+        mmap2 = repo.manifest.read(change[0])
+        _date2 = util.datestr(change[2])
+        def date2(f):
+            return _date2
+        def read(f):
+            return repo.file(f).read(mmap2[f])
+    else:
+        tz = util.makedate()[1]
+        _date2 = util.datestr()
+        def date2(f):
+            try:
+                return util.datestr((os.lstat(repo.wjoin(f)).st_mtime, tz))
+            except OSError, err:
+                if err.errno != errno.ENOENT: raise
+                return _date2
+        def read(f):
+            return repo.wread(f)
+
+    if repo.ui.quiet:
+        r = None
+    else:
+        hexfunc = repo.ui.verbose and hex or short
+        r = [hexfunc(node) for node in [node1, node2] if node]
+
+    all = modified + added + removed
+    all.sort()
+    for f in all:
+        to = None
+        tn = None
+        if f in mmap:
+            to = repo.file(f).read(mmap[f])
+        if f not in removed:
+            tn = read(f)
+        fp.write(mdiff.unidiff(to, date1, tn, date2(f), f, r, opts=opts))
+
+def export(repo, revs, template='hg-%h.patch', fp=None, switch_parent=False,
+           opts=None):
+    '''export changesets as hg patches.'''
+
+    total = len(revs)
+    revwidth = max(map(len, revs))
+
+    def single(node, seqno, fp):
+        parents = [p for p in repo.changelog.parents(node) if p != nullid]
+        if switch_parent:
+            parents.reverse()
+        prev = (parents and parents[0]) or nullid
+        change = repo.changelog.read(node)
+
+        if not fp:
+            fp = cmdutil.make_file(repo, template, node, total=total,
+                                   seqno=seqno, revwidth=revwidth)
+        if fp not in (sys.stdout, repo.ui):
+            repo.ui.note("%s\n" % fp.name)
+
+        fp.write("# HG changeset patch\n")
+        fp.write("# User %s\n" % change[1])
+        fp.write("# Date %d %d\n" % change[2])
+        fp.write("# Node ID %s\n" % hex(node))
+        fp.write("# Parent  %s\n" % hex(prev))
+        if len(parents) > 1:
+            fp.write("# Parent  %s\n" % hex(parents[1]))
+        fp.write(change[4].rstrip())
+        fp.write("\n\n")
+
+        diff(repo, prev, node, fp=fp, opts=opts)
+        if fp not in (sys.stdout, repo.ui):
+            fp.close()
+
+    for seqno, cset in enumerate(revs):
+        single(cset, seqno, fp)