Initial commitHEADmaster

10 files changed, 1803 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..225fc6f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/__pycache__
diff --git a/check_reverts.py b/check_reverts.py
new file mode 100644
index 0000000..f8598d3
--- /dev/null
+++ b/check_reverts.py
@@ -0,0 +1,58 @@
+import patchstate as ps
+import io, os, sys, subprocess, tempfile
+
+def main(args):
+    args = iter(args)
+    arg0 = next(args)
+
+    @ps.argparse_all(args)
+    def path(arg):
+        raise RuntimeError(f'Invalid argument: {arg!r}')
+
+    [repo_path] = path
+
+    repo = ps.Repository(repo_path)
+
+    with io.open(os.path.join(repo.path, 'series'), 'r') as f:
+        pcur = ps.Series.parse(f.read())
+
+    ok = True
+    reverted = {}
+    for pi in pcur.info:
+        mode = pi.mode
+        p = pi.get_patch(repo)
+        if mode == 'reverted':
+            pid = p.id
+            if pid in reverted:
+                raise RuntimeError(f'reverted twice: {pid!r}')
+            reverted[pid] = p
+            continue
+        if not mode.startswith('reverts '):
+            continue
+        pid = mode[8:]
+        revp = reverted.pop(pid)
+
+        d1 = ps.fmt_diff(revp.files, munge=True)
+        d2 = ps.fmt_diff(p.revert().files, munge=True)
+        if d1 != d2:
+            ok = False
+            print(f'Bad diff for {pid} {revp.title}:')
+            if 0:
+                with tempfile.NamedTemporaryFile('w+b') as t1, tempfile.NamedTemporaryFile('w+b') as t2:
+                    t1.write(d1)
+                    t1.flush()
+                    t2.write(d2)
+                    t2.flush()
+                    diff = subprocess.run(['diff', t1.name, t2.name], capture_output=True, check=False)
+                diff = diff.stdout.decode('utf-8')
+                for line in diff.splitlines():
+                    print(f'\t{line}')
+
+    for p in reverted.values():
+        print(f'Not reverted: {pid} {revp.title}')
+        ok = False
+
+    return 0 if ok else 1
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv))
diff --git a/export_series.py b/export_series.py
new file mode 100644
index 0000000..a4ebc8f
--- /dev/null
+++ b/export_series.py
@@ -0,0 +1,154 @@
+import patchstate as ps
+import patchtheory as pt
+import os, sys
+
+class PatchSeq:
+    __slots__ = ('upstreamed', 'diff', 'reverted', 'late')
+
+    def __init__(self, *, rebase=pt.Diff()):
+        self.upstreamed = -rebase
+        self.diff = pt.Diff()
+        self.reverted = []
+
+    def flush(self):
+        # We move all late patches back through the reverted
+        try:
+            late_kind,late = self.late
+        except AttributeError:
+            return
+        del self.late
+
+        print('Flushing', file=sys.stderr)
+
+        late = sum(late, pt.Diff())
+
+        for rev in reversed(self.reverted):
+            (late, rev[1]) = pt.Diff.commute(rev[1], late)
+
+        if late_kind == 'apply':
+            self.diff += late
+            return
+
+        (late, self.diff) = pt.Diff.commute(self.diff, late)
+
+        if late_kind == 'upstreamed':
+            self.upstreamed += late
+            return
+
+        raise AssertionError
+
+    def _push_late(self, kind, diff):
+        try:
+            lkind,late = self.late
+        except AttributeError:
+            self.late = (kind, (late := []))
+        else:
+            if lkind != kind:
+                self.flush()
+                self.late = (kind, (late := []))
+        late.append(diff)
+
+    def _push_reverted(self, by_pid, diff):
+        self.flush()
+        self.reverted.append([by_pid, diff])
+
+    def _push_revert(self, pid, diff):
+        self.flush()
+
+        for i,rev in enumerate(reverted := self.reverted):
+            if rev[0] == pid:
+                break
+        else:
+            raise KeyError(f'patch {pid} not marked as reverted')
+
+        if reverted.pop(i) is not rev:
+            raise AssertionError
+
+        rdiff = rev[1]
+        for rev in reverted[i:]:
+            rev[1],rdiff = pt.Diff.commute(rdiff, rev[1])
+
+        if rdiff + diff:
+            raise KeyError(f'revert of {pid} not exact')
+
+    def push(self, patch_info, patch):
+        diff = patch.diff
+        mode = patch_info.mode.split(' ', 1)
+        kind = mode[0]
+
+        if kind in {'apply', 'upstreamed'}:
+            self._push_late(kind, diff)
+            return
+
+        if kind == 'subst':
+            with open(mode[1], 'rb') as diff2:
+                diff2 = diff2.read()
+            diff2 = pt.Diff.parse(diff2)
+            self._push_late('apply', diff2)
+            self._push_reverted(None, (-diff2) + diff)
+            return
+
+        if kind == 'reverted':
+            self._push_reverted(patch_info.patch_id, diff)
+            return
+
+        if kind in {'skip', 'replaced'}:
+            self._push_reverted(None, diff)
+            return
+
+        if kind == 'reverts':
+            self._push_revert(mode[1], diff)
+            return
+
+        raise TypeError(f'bad patch kind: {kind!r}')
+
+    def finish(self, prb):
+        self.flush()
+
+        for pid,_ in self.reverted:
+            if pid is not None:
+                raise RuntimeError(f'missing revert for {pid!r}')
+
+        return prb + pt.Diff.commute(-prb + self.upstreamed, self.diff)[0]
+
+def main(args):
+    args = iter(args)
+    arg0 = next(args)
+
+    @ps.argparse_all(args)
+    def path(arg):
+        raise RuntimeError(f'Invalid argument: {arg!r}')
+
+    repo_path = path.pop(0)
+
+    if path:
+        with open(path.pop(0), 'rb') as rebase_patch:
+            rebase_patch = rebase_patch.read()
+        rebase_patch = pt.Diff.parse(rebase_patch)
+    else:
+        rebase_patch = pt.Diff()
+
+    if path:
+        with open(path.pop(0), 'rb') as prb_patch:
+            prb_patch = prb_patch.read()
+        prb_patch = pt.Diff.parse(prb_patch)
+    else:
+        prb_patch = pt.Diff()
+
+    assert not path
+
+    repo = ps.Repository(repo_path)
+
+    with open(os.path.join(repo.path, 'series'), 'r') as f:
+        pcur = ps.Series.parse(f.read())
+
+    seq = PatchSeq(rebase=rebase_patch)
+    for pi in pcur.info:
+        p = pi.get_patch(repo)
+        print('Applying', p.title, file=sys.stderr)
+        seq.push(pi, p)
+    seq.finish(prb_patch).write(sys.stdout.buffer.write)
+    return 0
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv))
diff --git a/import_series.py b/import_series.py
new file mode 100644
index 0000000..800f0c9
--- /dev/null
+++ b/import_series.py
@@ -0,0 +1,86 @@
+import patchstate as ps
+import io, os, sys
+
+def lcs(a, b, *, key):
+    a = [*a]
+    b = [*b]
+    if not a or not b:
+        return []
+
+    kas = [*map(key, a)]
+
+    m = [(0,)]
+    for v in a:
+        m.append((m[-1][0] + 1, v, None, m[-1]))
+    for v in b:
+        kb = key(v)
+
+        mi = iter(m)
+        mv = next(mi)
+        m2 = [(mv[0] + 1, None, v, mv)]
+        for ia,mv in enumerate(mi):
+            if kas[ia] == kb:
+                mv = m[ia]
+                m2.append((mv[0], a[ia], v, mv))
+                continue
+            mv1 = m2[-1]
+            if mv[0] <= mv1[0]:
+                m2.append((mv[0] + 1, None, v, mv))
+            else:
+                m2.append((mv1[0] + 1, a[ia], None, mv1))
+            del mv1
+            del ia
+        del mi, mv
+        m = m2
+
+    m = m[-1]
+    del v, a, b, kas
+    m2 = []
+    while len(m) == 4:
+        _,a,b,m = m
+        m2.append((a,b))
+    assert m == (0,)
+    m2.reverse()
+    return m2
+
+def main(args):
+    args = iter(args)
+    arg0 = next(args)
+
+    @ps.argparse_all(args)
+    def path(arg):
+        raise RuntimeError(f'Invalid argument: {arg!r}')
+
+    [repo_path, import_path] = path
+
+    repo = ps.Repository(repo_path)
+
+    pnew = repo.import_dir(import_path)
+
+    with io.open(os.path.join(repo.path, 'series'), 'r') as f:
+        pcur = ps.Series.parse(f.read())
+
+    r = []
+    for p1,p2 in lcs(pcur.info, pnew.info, key=lambda p: p.patch_id):
+        if p1 is None:
+            r.append(p2)
+            continue
+
+        if p2 is None:
+            r.append(p1.update(new_mode='gone'))
+            continue
+
+        r.append(p2.update(mode=p1.mode, info=p1.info))
+
+    pnew.info = r
+
+    pnew_data = pnew.fmt()
+    with io.open(os.path.join(repo.path, 'series'), 'w') as f:
+        f.write(pnew_data)
+
+    repo.gc({p.patch_hash for p in pnew.info})
+
+    return 0
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv))
diff --git a/linux.sh b/linux.sh
new file mode 100755
index 0000000..11b9fe7
--- /dev/null
+++ b/linux.sh
@@ -0,0 +1,23 @@
+#!/bin/bash
+
+set -e
+
+ver=5.13
+
+DIR="$(realpath $(dirname "$BASH_SOURCE"))"
+cd "$DIR"
+
+rm -rf "incoming-$ver"
+mkdir "incoming-$ver"
+
+(
+	cd "$HOME/sw/linux"
+	base="$(git merge-base "linux-stable/linux-$ver.y" "raspberrypi/rpi-$ver.y")"
+	git format-patch -o "$DIR/incoming-$ver" "$base".."raspberrypi/rpi-$ver.y"
+	git diff "$base".."linux-stable/linux-$ver.y" > "$DIR/stable-$ver.patch"
+)
+
+python3 import_series.py "rpi-$ver" "incoming-$ver"
+
+python3 export_series.py "rpi-$ver" "stable-$ver.patch" "prb-$ver.patch" > "rpi-$ver.patch"
+cp "rpi-$ver.patch" ~/sw/fedora/hvenev-kernel/patches/9000-rpi.patch
diff --git a/migrate_series.py b/migrate_series.py
new file mode 100644
index 0000000..c09dea1
--- /dev/null
+++ b/migrate_series.py
@@ -0,0 +1,47 @@
+import patchstate as ps
+import io, os, sys
+
+def main(args):
+    args = iter(args)
+    arg0 = next(args)
+
+    @ps.argparse_all(args)
+    def path(arg):
+        raise RuntimeError(f'Invalid argument: {arg!r}')
+
+    [repo_path] = path
+
+    repo = ps.Repository(repo_path)
+
+    with io.open(os.path.join(repo.path, 'series'), 'r') as f:
+        pcur = ps.Series.parse(f.read())
+
+    idmap = {}
+    for i,pi in enumerate(pcur.info):
+        h = pi.patch_hash
+        try:
+            h = repo.aliases[h]
+        except KeyError:
+            pass
+        p = repo.patches[h]
+        if pi.patch_id in idmap:
+            raise RuntimeError(f'duplicate patch id: {pi.patch_id!r}')
+        idmap[pi.patch_id] = p.id
+        pcur.info[i] = pi.update(patch=p)
+
+    print(idmap)
+
+    for i,pi in enumerate(pcur.info):
+        m = pi.mode
+        if m.startswith('reverts '):
+            m = f'reverts {idmap[m[8:]]}'
+            pcur.info[i] = pi.update(mode=m)
+
+    pcur = pcur.fmt()
+    with io.open(os.path.join(repo.path, 'series'), 'w') as f:
+        f.write(pcur)
+
+    return 0
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv))
diff --git a/patchstate.py b/patchstate.py
new file mode 100644
index 0000000..79600e0
--- /dev/null
+++ b/patchstate.py
@@ -0,0 +1,383 @@
+import io, sys, os, operator, re, base64, hashlib
+import patchtheory
+
+def strip_subject(s):
+    if not s.startswith(b'[PATCH'):
+        raise ValueError(f'Invalid subject: {s!r}')
+    i = s.find(b'] ')
+    if i == -1:
+        raise ValueError(f'Invalid subject: {s!r}')
+    return s[i+2:]
+
+rem_patch = re.compile('patch ([0-9a-z]{16})').fullmatch
+rem_author = re.compile('[^\0-\x1f]+ <[^\0-\x1f]+@[^\0-\x1f]+>').fullmatch
+rem_date = re.compile('[^\0-\x1f]+').fullmatch
+rem_title = re.compile('[^\0-\x1f]+').fullmatch
+
+class Patch:
+    __slots__ = ('author', 'date', 'title', 'body', 'diff', 'data', 'hash', 'id')
+
+    def __init__(self, /, *, author, date, title, body, diff):
+        assert type(author) is str and rem_author(author) is not None
+        assert type(date) is str and rem_date(date) is not None
+        assert type(title) is str and rem_title(title) is not None
+        assert type(body) is str
+        assert type(diff) is patchtheory.Diff
+
+        self.author = author
+        self.date = date
+        self.title = title
+        self.body = body
+        self.diff = diff
+
+        self._set_data()
+        self._set_id()
+
+    @classmethod
+    def parse(tp, body):
+        lines = iter(body.split(b'\n'))
+        line = lines.__next__
+
+        l = line()
+        if l.startswith(b'From '):
+            l = line()
+
+        headers = {}
+        hdr = None
+        while True:
+            if not l:
+                break
+            if hdr is not None and l.startswith(b' '):
+                headers[hdr] += l
+            else:
+                hdr,sep,val = l.partition(b':')
+                if not sep:
+                    raise ValueError(f'Expected header line: {l!r}')
+                headers[hdr] = val.lstrip()
+            l = line()
+
+        author = headers.pop(b'From').decode('utf-8')
+        date = headers.pop(b'Date').decode('utf-8')
+        title = strip_subject(headers.pop(b'Subject')).decode('utf-8')
+
+        headers.pop(b'MIME-Version', None)
+        headers.pop(b'Content-Type', None)
+        headers.pop(b'Content-Transfer-Encoding', None)
+
+        body = []
+        for l in lines:
+            if l.startswith(b'diff --git'):
+                break
+            body.append(l)
+        else:
+            raise RuntimeError('unexpected EOF')
+        while not body[-1]:
+            del body[-1]
+        while body[-1].startswith(b' '):
+            del body[-1]
+        if body[-1] != b'---':
+            raise RuntimeError
+        del body[-1]
+        while body and not body[-1]:
+            del body[-1]
+
+        body = b'\n'.join(body).decode('utf-8')
+
+        return Patch(
+            author = author,
+            date = date,
+            title = title,
+            body = body,
+            diff = patchtheory.Diff.parse_l(l, line),
+        )
+
+    def _set_id(self):
+        out = io.BytesIO()
+        w = out.write
+        w(self.author.encode('utf-8'))
+        w(b'\n')
+        w(self.date.encode('utf-8'))
+        w(b'\n')
+        w(self.title.encode('utf-8'))
+        w(b'\n')
+        self.diff.write_munged(w)
+
+        out = out.getvalue()
+        dgst = hashlib.blake2b(out).digest()
+        self.id = base64.b32encode(dgst[:10]).lower().decode('ascii')
+
+    def as_filename(self):
+        return '-'.join(re.findall('[0-9A-Za-z]+', self.title))[:72]
+
+    def _set_data(self):
+        out = io.BytesIO()
+        w = out.write
+
+        w(b'From: ')
+        w(self.author.encode('utf-8'))
+        w(b'\nDate: ')
+        w(self.date.encode('utf-8'))
+        w(b'\nSubject: [PATCH] ')
+        w(self.title.encode('utf-8'))
+        w(b'\n\n')
+        w(self.body.encode('utf-8'))
+        w(b'\n---\n\n')
+        self.diff.write(w)
+        w(b'-- \n0.0.0 patchstate\n\n')
+
+        self.data = data = out.getvalue()
+
+        self.hash = base64.b32encode(hashlib.blake2b(data).digest()[:20]).lower().decode('ascii')
+
+    def revert(self):
+        r = Patch(
+            author = self.author,
+            date = self.date,
+            title = f'Revert "{self.title}"',
+            body = self.body,
+            diff = -self.diff,
+        )
+
+        r._set_data()
+        r._set_id()
+        return r
+
+class PatchInfo:
+    __slots__ = ('patch_id', '_body')
+
+    def __init__(self, patch_id, info):
+        self.patch_id = patch_id
+        self._body = info
+
+    def get_patch(self, repo):
+        p = repo.patches[self.patch_hash]
+        if p.id != self.patch_id:
+            raise KeyError(f'patch id mismatch: {self.patch_id!r} -> {p.id!r}')
+        if p.title != self.patch_title:
+            raise KeyError(f'patch title mismatch: {self.patch_title!r} -> {p.title!r}')
+        return p
+
+    @property
+    def patch_hash(self):
+        return self._body[0]
+
+    @property
+    def patch_title(self):
+        return self._body[1]
+
+    @property
+    def mode(self):
+        return self._body[2]
+
+    @property
+    def info(self):
+        return self._body[3:]
+
+    def update(self, *, patch=None, patch_id=None, patch_hash=None, patch_title=None, mode=None, new_mode=None, info=None):
+        if patch_title is None:
+            patch_title = self.patch_title
+
+        if patch is not None:
+            assert patch_id is None
+            assert patch_hash is None
+            if patch_title != patch.title:
+                raise ValueError('patch title change: {patch_title!r} -> {patch.title!r}')
+            patch_id = patch.id
+            patch_hash = patch.hash
+
+        else:
+            if patch_id is None:
+                patch_id = self.patch_id
+
+            if patch_hash is None:
+                patch_hash = self.patch_hash
+
+        if info is None:
+            info = self.info
+
+        if mode is None:
+            mode = self.mode
+
+        if new_mode is not None and new_mode != mode:
+            info.insert(0, f'(was {mode})')
+            mode = new_mode
+
+        return PatchInfo(patch_id, [patch_hash, patch_title, mode, *info])
+
+class Series:
+    __slots__ = ('info',)
+
+    def __init__(self, /, info=None):
+        if info is None:
+            info = []
+        self.info = info
+
+    @classmethod
+    def parse(tp, data):
+        inf = []
+
+        lines = iter(data.split('\n'))
+        l = next(lines)
+        while True:
+            if not l:
+                try:
+                    l = next(lines)
+                except StopIteration:
+                    break
+                continue
+            m = rem_patch(l)
+            if m is None:
+                raise ValueError(f'Invalid header: {l!r}')
+            pid = m.group(1)
+            ldata = []
+            while True:
+                l = next(lines)
+                if not l.startswith('\t'):
+                    break
+                ldata.append(l[1:])
+            if len(ldata) < 3:
+                raise ValueError(f'Expected data after {f"patch {pid}"!r}')
+
+            while ldata and not ldata[-1]:
+                del ldata[-1]
+
+            inf.append(PatchInfo(pid, ldata))
+
+        return tp(info=inf)
+
+    def fmt(self):
+        out = io.StringIO()
+        w = out.write
+
+        for pi in self.info:
+            w(f'patch {pi.patch_id}')
+            for line in pi._body:
+                w('\n\t')
+                w(line)
+            w('\n')
+
+        return out.getvalue()
+
+class Repository:
+    __slots__ = ('path', 'patches', 'aliases', 'by_id')
+
+    def __init__(self, path):
+        self.path = path
+        self.patches = {}
+        self.by_id = {}
+
+        aliases = {}
+        for fn in os.listdir(path):
+            if not fn.endswith('.patch'):
+                continue
+            fp = os.path.join(path, fn)
+            with io.open(fp, 'rb') as f:
+                data = f.read()
+
+            try:
+                p = Patch.parse(data)
+            except ValueError as exc:
+                print(f'Failed to parse {fn!r}: {exc}', file=sys.stderr)
+                os.unlink(fp)
+                continue
+
+            h = p.hash
+            if fn != f'{h}.patch':
+                aliases[fn[:-6]] = (h,p)
+            else:
+                self.patches[h] = p
+            self.by_id.setdefault(p.id, []).append(p)
+
+        for h,(h2,p) in aliases.items():
+            assert h != h2
+            assert h not in self.patches
+            if h2 in self.patches:
+                continue
+            print(f'Migrating patch: {h!r} -> {h2!r}', file=sys.stderr)
+            self.patches[h2] = p
+            with io.open(os.path.join(self.path, f'{h2}.patch'), 'xb') as f:
+                f.write(p.data)
+
+        self.aliases = {h: h2 for h,(h2,p) in aliases.items()}
+
+    def hash_data(self, data):
+        data = hashlib.blake2b(data).digest()
+        return base64.b32encode(data[:20]).lower().decode()
+
+    def insert_patch(self, patch):
+        p = self.patches.setdefault(patch.hash, patch)
+        if p is patch:
+            pid = p.id
+            try:
+                pd = self.by_id[pid]
+            except KeyError:
+                self.by_id[pid] = [p]
+            else:
+                print(f'Duplicate patch ID: {pid!r} {p.title}', file=sys.stderr)
+                pd.append(p)
+
+            with io.open(os.path.join(self.path, f'{p.hash}.patch'), 'xb') as f:
+                f.write(p.data)
+
+        return p
+
+    def import_dir(self, path):
+        r = Series()
+        r.info = inf = []
+
+        for fn in sorted(os.listdir(path)):
+            if not fn.endswith('.patch'):
+                print(f'Skipping {fn!r}', file=sys.stderr)
+                continue
+            with io.open(os.path.join(path, fn), 'rb') as f:
+                patch = Patch.parse(f.read())
+
+            patch = self.insert_patch(patch)
+            inf.append(PatchInfo(patch.id, [patch.hash, patch.title, 'new']))
+
+        return r
+
+    def gc(self, keep):
+        for h in self.patches.keys() - keep:
+            del self.patches[h]
+            print(f'Removing patch: {h!r}', file=sys.stderr)
+            os.unlink(os.path.join(self.path, f'{h}.patch'))
+
+def argparse_next(args, func=...):
+    def do_argparse(func):
+        while True:
+            try:
+                arg = next(args)
+            except StopIteration:
+                return None
+            if arg == '--':
+                return next(args, None)
+            if not arg.startswith('-'):
+                return arg
+            arg = func(arg)
+            if arg is not None:
+                return arg
+    if func is not ...:
+        return do_argparse(func)
+    return do_argparse
+
+def argparse_all(args, func=...):
+    def do_argparse(func):
+        r = []
+        while True:
+            try:
+                arg = next(args)
+            except StopIteration:
+                return r
+            if arg == '--':
+                r.extend(args)
+                return r
+            if not arg.startswith('-'):
+                r.append(arg)
+                continue
+            arg = func(arg)
+            if arg is not None:
+                r.extend(arg)
+    if func is not ...:
+        return do_argparse(func)
+    return do_argparse
diff --git a/patchtheory.py b/patchtheory.py
new file mode 100644
index 0000000..21b3e29
--- /dev/null
+++ b/patchtheory.py
@@ -0,0 +1,960 @@
+import re, operator, io, sys
+
+rem_range = re.compile(b'@@ -([0-9]+)(?:,([0-9]+))? \\+([0-9]+)(?:,([0-9]+))? @@(?: .*)?').fullmatch
+rem_diffgit = re.compile('diff --git a/([^ ]*) b/([^ ]*)').fullmatch
+
+INFINITY = 2**64
+
+class PatchError(Exception):
+    __slots__ = ('a', 'b')
+    def __init__(self, a, b, /, fn=None):
+        super().__init__(fn)
+        self.a = a
+        self.b = b
+
+    def __str__(self, /):
+        fn = self.args[0]
+        r = [f' in {fn!r}:' if fn is not None else ':']
+
+        def tabmangle(p):
+            o = io.BytesIO()
+            p.write(o.write)
+            p = o.getvalue().decode('utf-8', 'replace').splitlines()
+            return ['    ' + l for l in p]
+
+        r.append('')
+        r += tabmangle(self.a)
+
+        r.append('')
+        r += tabmangle(self.b)
+
+        return '\n'.join(r)
+
+class ConflictError(PatchError):
+    __slots__ = ()
+    
+    def __str__(self, /):
+        return 'Conflict' + PatchError.__str__(self)
+
+class MismatchError(PatchError):
+    __slots__ = ()
+    
+    def __str__(self, /):
+        return 'Mismatch' + PatchError.__str__(self)
+
+class Hunk:
+    __slots__ = ('lhs_line', 'rhs_line', 'pre_context', 'lhs', 'rhs', 'post_context')
+
+    def __init__(self, /, *, lhs_line, rhs_line, pre_context, lhs, rhs, post_context):
+        assert lhs_line > 0
+        assert rhs_line > 0
+
+        self.lhs_line = lhs_line
+        self.rhs_line = rhs_line
+        self.pre_context = pre_context
+        self.lhs = lhs
+        self.rhs = rhs
+        self.post_context = post_context
+
+    @property
+    def lhs_size(self, /):
+        return len(self.pre_context) + len(self.lhs) + len(self.post_context)
+
+    @property
+    def rhs_size(self, /):
+        return len(self.pre_context) + len(self.rhs) + len(self.post_context)
+
+    def write(self, w, /, munge=False, *, lhs_line=None, rhs_line=None, lhs_nl=True, rhs_nl=True):
+        if lhs_line is None:
+            lhs_line = self.lhs_line
+        if rhs_line is None:
+            rhs_line = self.rhs_line
+        pre_context = self.pre_context
+        lhs = self.lhs
+        rhs = self.rhs
+        post_context = self.post_context
+        clen = len(pre_context) + len(post_context)
+        llen = len(lhs) + clen
+        rlen = len(rhs) + clen
+
+        if munge:
+            w(f'@@ -xxx,{llen} +yyy,{rlen} @@'.encode('utf-8'))
+        else:
+            w(f'@@ -{lhs_line},{llen} +{rhs_line},{rlen} @@'.encode('utf-8'))
+
+        for l in pre_context:
+            w(b'\n ')
+            w(l)
+
+        for l in lhs:
+            w(b'\n-')
+            w(l)
+
+        for l in rhs:
+            w(b'\n+')
+            w(l)
+
+        for l in post_context:
+            w(b'\n ')
+            w(l)
+
+        w(b'\n')
+
+    @classmethod
+    def parse_l(tp, l, line, /):
+        m = rem_range(l)
+        if m is None:
+            raise ValueError(f'Invalid patch: bad range info {l!r}')
+        lhs_line,n2,rhs_line,n4 = m.groups()
+        lhs_line = 1 if lhs_line == b'0' else int(lhs_line)
+        rhs_line = 1 if rhs_line == b'0' else int(rhs_line)
+        n2 = int(n2) if n2 else 1
+        n4 = int(n4) if n4 else 1
+
+        hunk = []
+        prev = -1
+        lhs_nl = True
+        rhs_nl = True
+        post_nl = True
+        while True:
+            l = line()
+            if l.startswith(b'\\ '):
+                if prev == 0:
+                    lhs_nl = False
+                elif prev == 1:
+                    rhs_nl = False
+                elif prev == -1:
+                    post_nl = False
+                else:
+                    raise ValueError('Invalid patch: bad "No newline at end of file" flag')
+                prev = -2
+                continue
+            if not n2 and not n4:
+                break
+            k = l[0]
+            if k == b' '[0]:
+                if not post_nl or not lhs_nl or not rhs_nl:
+                    raise ValueError('Invalid patch: bad "No newline at end of file" flag')
+                if not n2 or not n4:
+                    raise ValueError('Invalid patch: bad line count')
+                n2 -= 1
+                n4 -= 1
+                prev = -1
+            elif k == b'-'[0]:
+                if not post_nl or not lhs_nl:
+                    raise ValueError('Invalid patch: bad "No newline at end of file" flag')
+                if not n2:
+                    raise ValueError('Invalid patch: bad line count')
+                n2 -= 1
+                prev = 0
+            elif k == b'+'[0]:
+                if not post_nl or not rhs_nl:
+                    raise ValueError('Invalid patch: bad "No newline at end of file" flag')
+                if not n4:
+                    raise ValueError('Invalid patch: bad line count')
+                n4 -= 1
+                prev = 1
+            else:
+                raise ValueError(f'Invalid patch: bad prefix character {chr(k)!r}')
+                assert False
+            hunk.append(l)
+        lret = l
+
+        strip1 = operator.itemgetter(slice(1,None))
+
+        for i,l in enumerate(hunk):
+            if l[0] != b' '[0]:
+                break
+        else:
+            raise ValueError('Invalid patch: no changed lines in hunk')
+        pre_context = (*map(strip1, hunk[:i]),)
+        del hunk[:i]
+
+        j = -1
+        while True:
+            l = hunk[j]
+            if l[0] != b' '[0]:
+                break
+            j -= 1
+        j += len(hunk) + 1
+        if not post_nl:
+            hunk[j] += b'\n\\ No newline at end of file'
+        post_context = (*map(strip1, hunk[j:]),)
+        del hunk[j:]
+
+        lhs = []
+        rhs = []
+        for l in hunk:
+            l0 = l[0]
+            if l0 != b'+'[0]:
+                lhs.append(l)
+            if l0 != b'-'[0]:
+                rhs.append(l)
+        if not lhs_nl:
+            lhs[-1] += b'\n\\ No newline at end of file'
+        if not rhs_nl:
+            rhs[-1] += b'\n\\ No newline at end of file'
+
+        return lret, tp(
+            lhs_line = lhs_line,
+            rhs_line = rhs_line,
+            pre_context = pre_context,
+            lhs = (*map(strip1, lhs),),
+            rhs = (*map(strip1, rhs),),
+            post_context = post_context,
+        )
+
+    def reduce_context(self, n=3):
+        pre = self.pre_context
+        lhs = self.lhs
+        rhs = self.rhs
+        post = self.post_context
+
+        i = 0
+        j = -1
+        m = min(len(lhs), len(rhs))
+        while i - j <= m:
+            if lhs[i] == rhs[i]:
+                i += 1
+                if i - j > m:
+                    break
+                if lhs[j] == rhs[j]:
+                    j -= 1
+            else:
+                if lhs[j] != rhs[j]:
+                    break
+                j -= 1
+        j += 1
+        jl = len(lhs) + j
+        jr = len(rhs) + j
+
+        assert lhs[:i] == rhs[:i]
+        assert lhs[jl:] == rhs[jr:]
+        pre = pre + lhs[:i]
+        post = lhs[jl:] + post
+        lhs = lhs[i:jl]
+        rhs = rhs[i:jr]
+
+        if not lhs and not rhs:
+            return None
+
+        assert lhs != rhs
+        assert not lhs or not rhs or lhs[0] != rhs[0] and lhs[-1] != rhs[-1]
+
+        lhs_line = self.lhs_line
+        rhs_line = self.rhs_line
+
+        if n is None:
+            pass
+        elif not n:
+            d = len(pre)
+            lhs_line += d
+            rhs_line += d
+            pre = ()
+            post = ()
+        else:
+            if len(pre) > n:
+                d = len(pre) - n
+                lhs_line += d
+                rhs_line += d
+                pre = pre[d:]
+
+            if len(post) > n:
+                post = post[:n]
+
+        return Hunk(
+            lhs_line = lhs_line,
+            rhs_line = rhs_line,
+            pre_context = pre,
+            lhs = lhs,
+            rhs = rhs,
+            post_context = post,
+        )
+
+def join_hunks(hs_a, hs_b):
+    hs_a = iter(hs_a)
+    hs_b = iter(hs_b)
+
+    need_a = True
+    need_b = True
+    have_cur = False
+
+    def make_cur(n):
+        if not have_cur:
+            return None
+        return Hunk(
+            lhs_line = cur_lhs_line,
+            rhs_line = cur_rhs_line,
+            pre_context = (),
+            lhs = tuple(cur_lhs),
+            rhs = tuple(cur_rhs),
+            post_context = (),
+        ).reduce_context(n)
+
+    delta = 0
+    r = []
+
+    while True:
+        if need_a:
+            need_a = False
+            a = next(hs_a, None)
+
+        if need_b:
+            need_b = False
+            b = next(hs_b, None)
+
+        if not have_cur:
+            if a is not None and (b is None or a.rhs_line <= b.lhs_line):
+                cur_lhs_line = a.lhs_line
+                cur_rhs_line = a.lhs_line + delta
+                cur_lhs = [*a.pre_context, *a.lhs, *a.post_context]
+                cur_rhs = [*a.pre_context, *a.rhs, *a.post_context]
+                need_a = True
+            elif b is not None:
+                cur_lhs_line = b.rhs_line - delta
+                cur_rhs_line = b.rhs_line
+                cur_lhs = [*b.pre_context, *b.lhs, *b.post_context]
+                cur_rhs = [*b.pre_context, *b.rhs, *b.post_context]
+                need_b = True
+            else:
+                return (*r,)
+            have_cur = True
+            continue
+
+        cur_lhs_end = cur_lhs_line + len(cur_lhs)
+        cur_rhs_end = cur_rhs_line + len(cur_rhs)
+
+        if a is not None and a.lhs_line <= cur_lhs_end:
+            lhs = [*a.pre_context, *a.lhs, *a.post_context]
+            rhs = [*a.pre_context, *a.rhs, *a.post_context]
+
+            i = a.lhs_line - cur_lhs_line
+            k = i + len(rhs)
+
+            if len(cur_lhs) >= k:
+                if cur_lhs[i:k] != rhs:
+                    raise MismatchError(make_cur(None), a)
+                cur_lhs[i:k] = lhs
+            else:
+                j = len(cur_lhs) - i
+                if cur_lhs[i:] != rhs[:j]:
+                    raise MismatchError(make_cur(None), a)
+                cur_lhs[i:] = lhs
+                cur_rhs.extend(rhs[j:])
+            need_a = True
+            continue
+
+        if b is not None and b.rhs_line <= cur_rhs_end:
+            lhs = [*b.pre_context, *b.lhs, *b.post_context]
+            rhs = [*b.pre_context, *b.rhs, *b.post_context]
+            i = b.rhs_line - cur_rhs_line
+            k = i + len(lhs)
+
+            if len(cur_rhs) >= k:
+                if cur_rhs[i:k] != lhs:
+                    raise MismatchError(make_cur(None), b)
+                cur_rhs[i:k] = rhs
+            else:
+                j = len(cur_rhs) - i
+                if cur_rhs[i:] != lhs[:j]:
+                    raise MismatchError(make_cur(None), b)
+                cur_rhs[i:] = rhs
+                cur_lhs.extend(lhs[j:])
+            need_b = True
+            continue
+
+        cur = make_cur(3)
+        have_cur = False
+        if cur is None:
+            continue
+        r.append(cur)
+        delta += len(cur.rhs) - len(cur.lhs)
+
+def commute_hunks(hs_a, hs_b):
+    hs_a = iter(hs_a)
+    hs_b = iter(hs_b)
+
+    need_a = True
+    need_b = True
+
+    delta_a = 0
+    delta_b = 0
+    ra = []
+    rb = []
+    wa = ra.append
+    wb = rb.append
+
+    while True:
+        if need_a:
+            need_a = False
+            try:
+                a = next(hs_a)
+            except StopIteration:
+                if b is None and not need_b:
+                    break
+                a = None
+                a_begin = INFINITY
+                a_pre = ()
+                a_post = ()
+                a_end = INFINITY
+            else:
+                a_pre = a.pre_context
+                a_post = a.post_context
+                a_begin = a.rhs_line + len(a_pre)
+                a_end = a_begin + len(a.rhs)
+
+        if need_b:
+            need_b = False
+            try:
+                b = next(hs_b)
+            except StopIteration:
+                if a is None:
+                    break
+                b = None
+                b_begin = INFINITY
+                b_pre = ()
+                b_post = ()
+                b_end = INFINITY
+            else:
+                b_pre = b.pre_context
+                b_post = b.post_context
+                b_begin = b.lhs_line + len(b_pre)
+                b_end = b_begin + len(b.lhs)
+
+        if a_end <= b_begin:
+            gap = b_begin - a_end
+
+            if (n := len(a_post) + len(b_pre) - gap) > 0:
+                assert (a_pre + a.rhs + a_post)[-n:] == (b_pre + b.lhs + b_post)[:n]
+                if (n := len(a_post) - gap) > 0:
+                    a_post = a_post[:gap] + (b.rhs + b_post)[:n]
+                if (n := len(b_pre) - gap) > 0:
+                    b_pre = (a_pre + a.lhs)[-n:] + b_pre[n:]
+
+            wa(Hunk(
+                lhs_line = a.lhs_line + delta_b,
+                rhs_line = a.rhs_line + delta_b,
+                pre_context = a_pre,
+                lhs = a.lhs,
+                rhs = a.rhs,
+                post_context = a_post,
+            ))
+            delta_a += len(a.rhs) - len(a.lhs)
+            need_a = True
+            continue
+
+        if b_end <= a_begin:
+            gap = a_begin - b_end
+
+            if (n := len(b_post) + len(a_pre) - gap) > 0:
+                assert (b_pre + b.lhs + b_post)[-n:] == (a_pre + a.rhs + a_post)[:n]
+                if (n := len(b_post) - gap) > 0:
+                    b_post = b_post[:gap] + (a.lhs + a_post)[:n]
+                if (n := len(a_pre) - gap) > 0:
+                    a_pre = (b_pre + b.rhs)[-n:] + a_pre[n:]
+
+            wb(Hunk(
+                lhs_line = b.lhs_line - delta_a,
+                rhs_line = b.rhs_line - delta_a,
+                pre_context = b_pre,
+                lhs = b.lhs,
+                rhs = b.rhs,
+                post_context = b_post,
+            ))
+            delta_b += len(b.rhs) - len(b.lhs)
+            need_b = True
+            continue
+
+        raise ConflictError(a, b)
+
+    return (*rb,), (*ra,)
+
+class FileDiff:
+    __slots__ = ('src_name', 'dst_name', 'src_mode', 'dst_mode', 'hunks',)
+
+    def __init__(self, /, *, src_name, dst_name, src_mode, dst_mode, hunks):
+        assert (src_mode is ...) == (dst_mode is ...)
+        assert (src_name is None) == (src_mode is None)
+        assert (dst_name is None) == (dst_mode is None)
+
+        self.src_name = src_name
+        self.dst_name = dst_name
+        if src_mode == dst_mode:
+            self.src_mode = ...
+            self.dst_mode = ...
+        else:
+            self.src_mode = src_mode
+            self.dst_mode = dst_mode
+        self.hunks = hunks
+
+    @property
+    def op_kind_name(self):
+        if self.src_name is None:
+            return 'create'
+        if self.dst_name is None:
+            return 'delete'
+        is_chmod = self.dst_mode != self.dst_mode
+        if self.dst_name != self.dst_name:
+            return 'chmod+rename' if is_chmod else 'rename'
+        if self.hunks:
+            return 'chmod+modify' if is_chmod else 'modify'
+        return 'chmod' if is_chmod else 'noop'
+
+    def write(self, w):
+        src_name = self.src_name
+        dst_name = self.dst_name
+
+        if src_name is None:
+            assert dst_name is not None
+            w(f'diff --git a/{dst_name} b/{dst_name}\n'.encode('utf-8'))
+        elif dst_name is None:
+            w(f'diff --git a/{src_name} b/{src_name}\n'.encode('utf-8'))
+        else:
+            w(f'diff --git a/{src_name} b/{dst_name}\n'.encode('utf-8'))
+
+        if src_name is not None and dst_name is not None and src_name != dst_name:
+            w(f'rename from {src_name}\nrename to {dst_name}\n'.encode('utf-8'))
+
+        m = self.src_mode
+        if dst_name is None:
+            assert m is not None
+            w(f'deleted file mode {m}\n'.encode('utf-8'))
+        elif m not in (None, ...):
+            w(f'old mode {m}\n'.encode('utf-8'))
+
+        m = self.dst_mode
+        if src_name is None:
+            assert m is not None
+            w(f'new file mode {m}\n'.encode('utf-8'))
+        elif m not in (None, ...):
+            w(f'new mode {m}\n'.encode('utf-8'))
+
+        h = self.hunks
+        if h:
+            if src_name is None:
+                src_name = '/dev/null'
+                lhs_line = 0
+            else:
+                src_name = f'a/{src_name}'
+                lhs_line = None
+            if dst_name is None:
+                dst_name = '/dev/null'
+                rhs_line = 0
+            else:
+                dst_name = f'b/{dst_name}'
+                rhs_line = None
+
+            w(f'--- {src_name}\n+++ {dst_name}\n'.encode('utf-8'))
+
+            for h in h:
+                h.write(w, lhs_line=lhs_line, rhs_line=rhs_line)
+
+    def __neg__(self, /):
+        tp = type(self)
+
+class Diff:
+    __slots__ = ('files',)
+
+    def __init__(self):
+        self.files = ()
+
+    def __bool__(self):
+        return not not self.files
+
+    @classmethod
+    def _sort_files(tp, files):
+        r = object.__new__(tp)
+        r.files = (*sorted(files, key=lambda f: (f.src_name or '', f.dst_name or '')),)
+        return r
+
+    @classmethod
+    def parse_l(tp, l, line):
+        files = []
+
+        while True:
+            l = l.decode('utf-8').rstrip()
+            if l == '--' or not l:
+                break
+            m = rem_diffgit(l)
+            if m is None:
+                raise ValueError(f'Invalid patch: expected \'diff --git ...\' header, got {l!r}')
+
+            header = l
+
+            src_name,dst_name = m.groups()
+            src_exists = ...
+            dst_exists = ...
+
+            if not src_exists and not dst_exists:
+                raise RuntimeError('wtf')
+            if (not src_exists or not dst_exists) and src_name != dst_name:
+                raise RuntimeError('wtf')
+
+            has_diff = False
+            has_chmod = False
+            has_rename = False
+            dst_mode = ...
+            src_mode = ...
+
+            while True:
+                l = line()
+                if l.startswith(b'--- a/'):
+                    if src_exists is False: raise RuntimeError('wtf')
+                    src_exists = True
+                    if l[6:].decode('utf-8') != src_name:
+                        raise RuntimeError('wtf')
+                    has_diff = True
+                    continue
+                if l == b'--- /dev/null':
+                    if src_exists is True: raise RuntimeError('wtf')
+                    src_exists = False
+                    has_diff = True
+                    continue
+                if l.startswith(b'+++ b/'):
+                    if dst_exists is False: raise RuntimeError('wtf')
+                    dst_exists = True
+                    if l[6:].decode('utf-8') != dst_name:
+                        raise RuntimeError('wtf')
+                    has_diff = True
+                    continue
+                if l == b'+++ /dev/null':
+                    if dst_exists is True: raise RuntimeError('wtf')
+                    dst_exists = False
+                    has_diff = True
+                    continue
+                if l.startswith(b'index '):
+                    continue
+                if l.startswith(b'new file mode '):
+                    if src_exists is True: raise RuntimeError('wtf')
+                    if dst_exists is False: raise RuntimeError('wtf')
+                    src_exists = False
+                    dst_exists=True
+                    dst_mode = l[14:].decode('ascii')
+                    src_mode = None
+                    continue
+                if l.startswith(b'new mode '):
+                    dst_mode = l[9:].decode('ascii')
+                    has_chmod = True
+                    continue
+                if l.startswith(b'deleted file mode '):
+                    if src_exists is False: raise RuntimeError('wtf')
+                    if dst_exists is True: raise RuntimeError('wtf')
+                    src_exists = True
+                    dst_exists = False
+                    src_mode = l[18:].decode('ascii')
+                    dst_mode = None
+                    continue
+                if l.startswith(b'old mode '):
+                    if dst_exists is False:
+                        raise RuntimeError('File deleted')
+                    src_mode = l[9:].decode('ascii')
+                    has_chmod = True
+                    dst_exists = True
+                    continue
+                if l.startswith(b'similarity index '):
+                    has_rename = True
+                    continue
+                if l.startswith(b'rename from '):
+                    has_rename = True
+                    rename_from = l[12:].decode('utf-8')
+                    continue
+                if l.startswith(b'rename to '):
+                    rename_to = l[10:].decode('utf-8')
+                    has_rename = True
+                    continue
+                break
+
+            if has_chmod or has_rename:
+                if src_exists is False: raise RuntimeError('wtf')
+                if dst_exists is False: raise RuntimeError('wtf')
+                src_exists = True
+                dst_exists = True
+
+            if has_chmod:
+                assert src_mode is not ...
+                assert dst_mode is not ...
+
+            assert src_exists is not ...
+            if not src_exists:
+                assert dst_mode is not ...
+
+            assert dst_exists is not ...
+            if not dst_exists:
+                assert src_mode is not ...
+
+            if has_rename:
+                if src_name == dst_name or not src_exists or not dst_exists:
+                    raise RuntimeError(f'Bad rename: {src_name!r} -> {dst_name!r}')
+                assert rename_from == src_name
+                assert rename_to == dst_name
+
+            if not src_exists: src_name = None
+            if not dst_exists: dst_name = None
+
+            assert (src_mode is ...) == (dst_mode is ...)
+            assert has_diff or has_chmod or has_rename or not dst_exists
+
+            #want_header = fmt_diff_git(src_name, dst_name)
+            #if header != want_header:
+            #    raise ValueError(f'Invalid patch: expected {want_header!r} header, got {header!r}')
+
+            if has_diff:
+                hunks = []
+
+                while True:
+                    l,hunk = Hunk.parse_l(l, line)
+                    hunk = hunk.reduce_context()
+                    if hunk is not None:
+                        hunks.append(hunk)
+                    if not l.startswith(b'@@ '):
+                        break
+
+                if src_name is None:
+                    assert len(hunks) == 1
+                    assert len(hunks[0].pre_context) == 0
+                    assert len(hunks[0].post_context) == 0
+                    assert len(hunks[0].lhs) == 0
+                    assert hunks[0].lhs_line == 1
+                    hunks[0].lhs_line = 1
+
+                if dst_name is None:
+                    assert len(hunks) == 1
+                    assert len(hunks[0].pre_context) == 0
+                    assert len(hunks[0].post_context) == 0
+                    assert len(hunks[0].rhs) == 0
+                    assert hunks[0].rhs_line == 1
+
+                hunks = (*hunks,)
+
+            else:
+                hunks = ()
+
+            files.append(FileDiff(
+                src_name = src_name,
+                dst_name = dst_name,
+                src_mode = src_mode,
+                dst_mode = dst_mode,
+                hunks = hunks,
+            ))
+
+        try:
+            l = line().rstrip()
+        except StopIteration:
+            pass
+        else:
+            if l[0] not in b'0123456789':
+                l = l.decode('utf-8')
+                raise ValueError('Invalid patch: expected git version, got {l!r}')
+
+
+            while True:
+                try:
+                    l = line()
+                except StopIteration:
+                    break
+                if l.strip():
+                    l = l.decode('utf-8')
+                    raise ValueError('Invalid patch: got trailing garbage {l!r}')
+
+        return tp._sort_files(files)
+
+    @classmethod
+    def parse(tp, body):
+        line = iter(body.split(b'\n')).__next__
+        return tp.parse_l(line(), line)
+
+    def write(self, w, /):
+        for f in self.files:
+            f.write(w)
+
+    def write_munged(self, w, /):
+        for f in self.files:
+            w((f.src_name or '').encode('utf-8'))
+            w(b'\n')
+            w((f.dst_name or '').encode('utf-8'))
+            w(b'\n')
+            for h in f.hunks:
+                h.write(w, True)
+            w(b'\n')
+
+    def __neg__(self):
+        return Diff._sort_files((*(FileDiff(
+            src_name = f.dst_name,
+            dst_name = f.src_name,
+            src_mode = f.dst_mode,
+            dst_mode = f.src_mode,
+            hunks = (*(Hunk(
+                lhs_line = h.rhs_line,
+                rhs_line = h.lhs_line,
+                pre_context = h.pre_context,
+                lhs = h.rhs,
+                rhs = h.lhs,
+                post_context = h.post_context,
+            ) for h in f.hunks),),
+        ) for f in self.files),))
+
+    def __add__(a, b):
+        tp = type(a)
+        if type(b) is not tp:
+            raise TypeError
+
+        r = []
+        w = r.append
+
+        fdiff = FileDiff
+        def join(fa, fb):
+            src_name = fa.src_name
+            dst_name = fb.dst_name
+            src_mode = fa.src_mode
+            dst_mode = fb.dst_mode
+            if src_mode is ...:
+                if dst_mode is not ...:
+                    src_mode = fb.src_mode
+            elif dst_mode is ...:
+                dst_mode = fa.dst_mode
+            elif fa.dst_mode != fb.src_mode:
+                raise ValueError('mismatch')
+
+            hunks = (*join_hunks(fa.hunks, fb.hunks),)
+
+            if src_name is None and dst_name is None:
+                if hunks:
+                    raise ValueError('mismatch')
+                return
+
+            if src_name == dst_name and src_mode == dst_mode and not hunks:
+                return
+
+            w(fdiff(
+                src_name = src_name,
+                dst_name = dst_name,
+                src_mode = src_mode,
+                dst_mode = dst_mode,
+                hunks = hunks,
+            ))
+
+        _pair_diffs(a, b, on_lhs=w, on_rhs=w, on_pair=join, on_re=join)
+        return tp._sort_files(r)
+
+    @classmethod
+    def commute(tp, a, b):
+        if type(a) is not tp or type(b) is not tp:
+            raise TypeError
+
+        ra = []
+        rb = []
+        wa = ra.append
+        wb = rb.append
+        fdiff = FileDiff
+
+        def join(fa, fb):
+            name1 = fa.src_name
+            name2 = fa.dst_name
+            name3 = fb.dst_name
+            if name1 == name2:
+                name2 = name3
+            elif name2 == name3:
+                name2 = name1
+            else:
+                raise ValueError('cannot commute {name2!r}: {fa.op_kind_name} / {fb.op_kind_name}')
+
+            mode1 = fa.src_mode
+            mode3 = fb.dst_mode
+            if mode1 is ...:
+                if mode3 is ...:
+                    mode2 = ...
+                else:
+                    mode1 = fb.src_mode
+                    mode2 = mode3
+
+            elif mode3 is ...:
+                mode3 = fa.dst_mode
+                mode2 = mode1
+
+            else:
+                mode2 = fb.dst_mode
+                if fa.src_mode != mode2:
+                    raise ValueError('mismatch')
+                if mode1 == mode2:
+                    mode2 = mode3
+                elif mode2 == mode3:
+                    mode2 = mode1
+                else:
+                    raise ValueError('cannot commute {name2!r}: chmod/chmod conflict')
+
+            try:
+                hb,ha = commute_hunks(fa.hunks, fb.hunks)
+            except PatchError as err:
+                err.args = (name1, name2, name3)
+                raise
+
+            wa(fdiff(
+                src_name = name1,
+                dst_name = name2,
+                src_mode = mode1,
+                dst_mode = mode2,
+                hunks = ha,
+            ))
+            wb(fdiff(
+                src_name = name2,
+                dst_name = name3,
+                src_mode = mode2,
+                dst_mode = mode3,
+                hunks = hb,
+            ))
+
+        _pair_diffs(a, b, on_lhs=wa, on_rhs=wb, on_re=join, on_pair=join)
+        return tp._sort_files(rb), tp._sort_files(ra)
+
+def _pair_diffs(a, b, *, on_lhs, on_rhs, on_pair, on_re):
+    a_del = {}
+    b_new = {}
+
+    a_dst = {}
+    b_dst = set()
+    for f in a.files:
+        dst = f.dst_name
+        if dst is None:
+            a_del[f.src_name] = f
+            continue
+        a_dst[dst] = f
+
+    a = a_dst.pop
+    for f in b.files:
+        dst = f.dst_name
+        if dst is not None:
+            b_dst.add(dst)
+
+        src = f.src_name
+        if src is None:
+            b_new[dst] = f
+            continue
+
+        try:
+            f2 = a(src)
+        except KeyError:
+            pass
+        else:
+            on_pair(f2, f)
+            continue
+        on_rhs(f)
+
+    for dst in a_dst.keys() & b_dst:
+        raise ValueError(f'mismatch for {dst!r}')
+
+    b = b_new.pop
+    for src,f in a_del.items():
+        try:
+            f2 = b(src)
+        except KeyError:
+            pass
+        else:
+            on_re(f, f2)
+            continue
+        on_lhs(f)
+
+    for f in b_new.values():
+        on_rhs(f)
+
+    for f in a_dst.values():
+        on_lhs(f)
diff --git a/prune_aliases.py b/prune_aliases.py
new file mode 100644
index 0000000..24c5392
--- /dev/null
+++ b/prune_aliases.py
@@ -0,0 +1,21 @@
+import patchstate as ps
+import io, os, sys
+
+def main(args):
+    args = iter(args)
+    arg0 = next(args)
+
+    @ps.argparse_all(args)
+    def path(arg):
+        raise RuntimeError(f'Invalid argument: {arg!r}')
+
+    [repo_path] = path
+
+    repo = ps.Repository(repo_path)
+    for h in repo.aliases:
+        os.unlink(os.path.join(repo.path, f'{h}.patch'))
+
+    return 0
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv))
diff --git a/ungone_series.py b/ungone_series.py
new file mode 100644
index 0000000..065ed01
--- /dev/null
+++ b/ungone_series.py
@@ -0,0 +1,70 @@
+import patchstate as ps
+import io, os, sys
+from import_series import lcs
+
+def parse_prev(info):
+    if not info.startswith('(was ') or not info.endswith(')'):
+        raise ValueError
+    return info[5:-1]
+
+def main(args):
+    args = iter(args)
+    arg0 = next(args)
+
+    @ps.argparse_all(args)
+    def path(arg):
+        raise RuntimeError(f'Invalid argument: {arg!r}')
+
+    [repo_path] = path
+
+    repo = ps.Repository(repo_path)
+
+    with io.open(os.path.join(repo.path, 'series'), 'r') as f:
+        pcur = ps.Series.parse(f.read())
+
+    gone_seq = []
+    new_seq = []
+    updated = {}
+
+    def fix_seq():
+        s = lcs(gone_seq, new_seq, key=lambda p: p.patch_title)
+        del gone_seq[:]
+        del new_seq[:]
+
+        for p_gone, p_new in s:
+            if p_gone is None or p_new is None:
+                continue
+            updated[p_new] = parse_prev(p_gone.info[0])
+            updated[p_gone] = None
+
+    for i,pi in enumerate(pcur.info):
+        m = pi.mode
+        if m == 'gone':
+            gone_seq.append(pi)
+        elif m == 'new':
+            new_seq.append(pi)
+        else:
+            fix_seq()
+    fix_seq()
+
+    inf = []
+    for pi in pcur.info:
+        try:
+            mode = updated[pi]
+        except KeyError:
+            pass
+        else:
+            if mode is None:
+                continue
+            assert pi.mode == 'new'
+            pi = pi.update(mode=mode)
+        inf.append(pi)
+
+    pnew = ps.Series(inf).fmt()
+    with io.open(os.path.join(repo.path, 'series'), 'w') as f:
+        f.write(pnew)
+
+    return 0
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv))