--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hgext3rd/hggit_serve.py	Wed Feb 18 14:45:19 2026 -0500
@@ -0,0 +1,367 @@
+from __future__ import annotations
+
+import binascii
+import email.parser
+import email.policy
+import re
+import shutil
+import subprocess
+import typing as t
+
+import dulwich.refs
+import mercurial.error as hgerr
+from hggit import git_handler
+from mercurial import extensions
+from mercurial import registrar
+from mercurial import wireprotoserver
+from mercurial.thirdparty import attr
+
+if t.TYPE_CHECKING:
+    import mercurial.hgweb.hgweb_mod_inner as web_inner
+    import mercurial.hgweb.request as hgreq
+    import mercurial.interfaces.repository as hgrepo
+    import mercurial.ui as hgui
+
+    class GittyRepo(hgrepo.IRepo, t.Protocol):
+        githandler: git_handler.GitHandler
+
+    PermissionCheck = t.Callable[
+        [web_inner.requestcontext, hgreq.parsedrequest, bytes],
+        None,
+    ]
+
+
+def _is_gitty(repo: hgrepo.IRepo) -> t.TypeGuard[GittyRepo]:
+    """Ensures that we have hg-git installed and active."""
+    return hasattr(repo, 'githandler')
+
+
+_CGI_VAR = re.compile(rb'[A-Z0-9_]+$')
+"""Environment variables that we need to pass to git-as-cgi."""
+
+
+def _build_git_environ(
+    req_ctx: web_inner.requestcontext,
+    request: hgreq.parsedrequest,
+) -> dict[bytes, bytes]:
+    """Builds the environment to be sent to Git to serve HTTP."""
+    fixed = {
+        k: v
+        for (k, v) in request.rawenv.items()
+        if isinstance(v, bytes) and _CGI_VAR.match(k)
+    }
+    fixed.update(
+        {
+            b'GIT_HTTP_EXPORT_ALL': b'yes',
+            b'GIT_PROJECT_ROOT': req_ctx.repo.path,
+            b'PATH_INFO': b'/git/' + request.dispatchpath,
+            # Since Mercurial is taking care of authorization checking,
+            # we tell Git to always allow push.
+            b'GIT_CONFIG_COUNT': b'1',
+            b'GIT_CONFIG_KEY_0': b'http.receivepack',
+            b'GIT_CONFIG_VALUE_0': b'true',
+        }
+    )
+    return fixed
+
+
+def _parse_cgi_response(
+    output: t.IO[bytes],
+) -> tuple[bytes, dict[bytes, bytes], t.IO[bytes]]:
+    """Parses a CGI response into a status, headers, and everyhting else."""
+    parser = email.parser.BytesFeedParser(policy=email.policy.HTTP)
+    while line := output.readline():
+        if not line.rstrip(b'\r\n'):
+            # We've reached the end of the headers.
+            # Leave the rest in the output for later.
+            break
+        parser.feed(line)
+    msg = parser.close()
+    status = msg.get('Status', '200 OK I guess').encode('utf-8')
+    del msg['Status']  # this won't raise an exception
+    byte_headers = {
+        k.encode('utf-8'): v.encode('utf-8') for (k, v) in msg.items()
+    }
+    return status, byte_headers, output
+
+
+_PULL = b'pull'
+_PUSH = b'push'
+
+_SERVICE_PERMISSIONS = {
+    b'git-upload-pack': _PULL,
+    b'git-receive-pack': _PUSH,
+}
+"""The Mercurial permission corresponding to each Git action.
+
+These seem backwards because the direction of up/download is relative to
+the server, so when the client pulls, the server is *uploading*,
+and when the client pushes, the server is *downloading*.
+"""
+
+
+def _git_service_permission(request: hgreq.parsedrequest) -> bytes | None:
+    """Figures out what Mercurial permission corresponds to a request from Git.
+
+    If the request is a supported Git action, returns the permission it needs.
+    If the request is not a Git action, returns None.
+    """
+    if perm := _SERVICE_PERMISSIONS.get(request.dispatchpath):
+        return perm
+    if request.dispatchpath != b'info/refs':
+        return None
+    qs = request.querystring
+    service = qs.removeprefix(b'service=')
+    if qs == service:
+        # Nothing was stripped.
+        return None
+    return _SERVICE_PERMISSIONS.get(service)
+
+
+def _handle_git_protocol(
+    original: t.Callable[..., bool],
+    req_ctx: web_inner.requestcontext,
+    request: hgreq.parsedrequest,
+    response: hgreq.wsgiresponse,
+    check_permission: PermissionCheck,
+) -> bool:
+    """Intercepts requests from Git, if needed."""
+    perm = _git_service_permission(request)
+    repo: hgrepo.IRepo = req_ctx.repo
+    if not perm or not _is_gitty(repo):
+        # We only handle Git requests to Gitty repos.
+        return original(req_ctx, request, response, check_permission)
+
+    # Permission workaround: Mercurial requires POSTs for push,
+    # but the advertisement request from Git will be a GET.
+    # We just lie to Mercurial about what we're doing.
+    check_permission(
+        req_ctx,
+        (
+            attr.evolve(req_ctx.req, method=b'POST')
+            if perm == _PUSH
+            else req_ctx.req
+        ),
+        perm,
+    )
+    cgi_env = _build_git_environ(req_ctx, request)
+    http_backend = repo.ui.configlist(
+        b'hggit-serve', b'http-backend', default=(b'git', b'http-backend')
+    )
+    call = subprocess.Popen(
+        http_backend,
+        close_fds=True,
+        stdin=subprocess.PIPE,
+        stdout=subprocess.PIPE,
+        stderr=subprocess.DEVNULL,
+        env=cgi_env,
+        text=False,
+    )
+    assert call.stdout
+    assert call.stdin
+    # Git will not start writing output until stdin is fully closed.
+    with call.stdin:
+        # This is how we know if there's anything to read from bodyfh.
+        # If we try to read from bodyfh on a request with no content,
+        # it hangs forever.
+        if b'CONTENT_LENGTH' in request.rawenv:
+            shutil.copyfileobj(request.bodyfh, call.stdin)
+
+    status, headers, rest = _parse_cgi_response(call.stdout)
+    response.status = status
+    for k, v in headers.items():
+        response.headers[k] = v
+
+    def write_the_rest() -> t.Iterator[bytes]:
+        with call, rest:
+            # if it's good enough for shutil it's good enough for me
+            # technically not in the docs but everybody it
+            bs = shutil.COPY_BUFSIZE  # type: ignore[attr-defined]
+            while more := rest.read(bs):
+                yield more
+        if perm == _PUSH:
+            _importing_enter(repo)
+            try:
+                gh = repo.githandler
+                gh.import_git_objects(
+                    b'git-push', remote_names=(), refs=gh.git.refs.as_dict()
+                )
+            finally:
+                _importing_exit(repo)
+
+    response.setbodygen(write_the_rest())
+    response.sendresponse()
+    return True
+
+
+#
+# Stuff so that we don't try to export revisions while we're importing.
+#
+
+_ILEVEL_ATTR = '@hggit_import_level'
+"""An attribute that tracks how many "levels deep" we are into importing.
+
+We set this on the repository object when we're importing and remove it
+when we're done. It's not just a bool in case somebody sets up some crazy
+recursive hook situation where we start importing inside another import.
+"""
+
+
+def _importing_enter(repo: hgrepo.IRepo) -> None:
+    """Call this before you start importing from Git."""
+    level = getattr(repo, _ILEVEL_ATTR, 0) + 1
+    setattr(repo, _ILEVEL_ATTR, level)
+
+
+def _is_importing(repo: hgrepo.IRepo) -> bool:
+    """Call this to check if you're currently importing."""
+    return hasattr(repo, _ILEVEL_ATTR)
+
+
+def _importing_exit(repo: hgrepo.IRepo) -> None:
+    """Call this after you finish importing from Git."""
+    level = getattr(repo, _ILEVEL_ATTR) - 1
+    if level:
+        setattr(repo, _ILEVEL_ATTR, level)
+    else:
+        delattr(repo, _ILEVEL_ATTR)
+
+
+#
+# Export handling.
+#
+
+
+def _clean_all_refs(refs: dulwich.refs.RefsContainer) -> None:
+    """Removes all refs from the Git repository."""
+
+
+def _set_head(ui: hgui.ui, repo: GittyRepo, at_name: bytes) -> None:
+    """Creates a HEAD reference in Git referring to the current HEAD."""
+    # By default, we use '@', since that's what will be auto checked out.
+    current = b'@'
+    if current not in repo._bookmarks:
+        current = repo._bookmarks.active or current
+
+    # We'll be moving this (possibly fake) bookmark into Git.
+    git_current = current
+    if current == b'@':
+        # @ is a special keyword in Git, so we can't use it as a bookmark.
+        git_current = at_name
+    git_branch = dulwich.refs.LOCAL_BRANCH_PREFIX + git_current
+    if not dulwich.refs.check_ref_format(git_branch):
+        # We can't export this ref to Git. Give up.
+        ui.warn(f'{git_branch!r} is not a valid branch name for Git.'.encode())
+        return
+    try:
+        # Maybe this is a real bookmark?
+        hgnode = repo._bookmarks[current]
+    except KeyError:
+        # Not a real bookmark. Assume we want the tip of the current branch.
+        branch = repo.dirstate.branch()
+        try:
+            hgnode = repo.branchtip(branch)
+        except hgerr.RepoLookupError:
+            # This branch somehow doesn't exist???
+            ui.warn(f"{branch!r} doesn't seem to exist?".encode())
+            return
+    hgsha = binascii.hexlify(hgnode)
+    gitsha = repo.githandler.map_git_get(hgsha)
+    if not gitsha:
+        # No Git SHA to match this Hg sha. Give up.
+        ui.warn(f'revision {hgsha!r} was not exported to Git'.encode())
+        return
+    refs = repo.githandler.git.refs
+    refs.add_packed_refs({git_branch: gitsha})
+    refs.set_symbolic_ref(b'HEAD', git_branch)
+
+
+def fix_refs_hook(ui: hgui.ui, repo: hgrepo.IRepo, **__: object) -> None:
+    """Exports to Git and sets up for serving.  See ``_fix_refs``."""
+    if not _is_gitty(repo):
+        return
+    _fix_refs(ui, repo)
+
+
+def _fix_refs(ui: hgui.ui, repo: GittyRepo) -> None:
+    """After a git export, fix up the refs.
+
+    This ensures that there are no leftover refs from older, removed bookmarks
+    and that there is a proper HEAD set so that cloning works.
+    """
+    refs = repo.githandler.git.refs
+    # dump to allkeys so we explicitly are iterating over a snapshot
+    # and not over something while we mutate
+    for ref in refs.allkeys():
+        refs.remove_if_equals(ref, None)
+    repo.githandler.export_hg_tags()
+    repo.githandler.update_references()
+    default_branch_name = ui.config(
+        b'hggit-serve', b'default-branch', b'default'
+    )
+    _set_head(ui, repo, default_branch_name)
+
+
+def export_hook(ui: hgui.ui, repo: hgrepo.IRepo, **__: object) -> None:
+    """Maybe exports the repository to get after we get new revs."""
+    if not _is_gitty(repo):
+        return
+    auto_export = ui.config(b'hggit-serve', b'auto-export')
+    if auto_export == b'never':
+        return
+    if auto_export == b'always' or git_handler.has_gitrepo(repo):
+        if _is_importing(repo):
+            ui.note(b'currently importing revs from git; not exporting\n')
+            return
+        repo.githandler.export_commits()
+        _fix_refs(ui, repo)
+
+
+#
+# Interfacing with Mercurial
+#
+
+__version__ = '0.2.0'
+testedwith = b'7.1 7.2'
+minimumhgversion = b'7.1'
+
+cmdtable: dict[bytes, object] = {}
+
+command = registrar.command(cmdtable)
+
+
+def uisetup(_: hgui.ui) -> None:
+    extensions.wrapfunction(
+        wireprotoserver, 'handlewsgirequest', _handle_git_protocol
+    )
+
+
+def uipopulate(ui: hgui.ui) -> None:
+    # Fix up our tags after a Git export.
+    ui.setconfig(
+        b'hooks', b'post-git-export.__gitserve_add_tag__', fix_refs_hook
+    )
+    # Whenever we get new revisions, export them to the Git repository.
+    ui.setconfig(b'hooks', b'txnclose.__gitserve_export__', export_hook)
+    # Don't step on ourselves when importing data from Git.
+    ui.setconfig(
+        b'hooks',
+        b'pre-git-import.__gitserve_suppress_export__',
+        lambda _, repo, **__: _importing_enter(repo),
+    )
+    ui.setconfig(
+        b'hooks',
+        b'post-git-import.__gitserve_suppress_export__',
+        lambda _, repo, **__: _importing_exit(repo),
+    )
+
+
+__all__ = (
+    '__version__',
+    'cmdtable',
+    'command',
+    'minimumhgversion',
+    'testedwith',
+    'uipopulate',
+    'uisetup',
+)