1 files changed, 37 insertions, 0 deletions
diff --git a/python/mozversioncontrol/mozversioncontrol/repoupdate.py b/python/mozversioncontrol/mozversioncontrol/repoupdate.py
new file mode 100644
index 0000000000..5336263794
--- /dev/null
+++ b/python/mozversioncontrol/mozversioncontrol/repoupdate.py
@@ -0,0 +1,37 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this,
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import subprocess
+from pathlib import Path
+from typing import Union
+
+# The logic here is far from robust. Improvements are welcome.
+
+
+def update_mercurial_repo(
+    hg: str,
+    repo,
+    path: Union[str, Path],
+    revision="default",
+    hostfingerprints=None,
+    global_args=None,
+):
+    """Ensure a HG repository exists at a path and is up to date."""
+    hostfingerprints = hostfingerprints or {}
+
+    path = Path(path)
+
+    args = [hg]
+    if global_args:
+        args.extend(global_args)
+
+    for host, fingerprint in sorted(hostfingerprints.items()):
+        args.extend(["--config", "hostfingerprints.%s=%s" % (host, fingerprint)])
+
+    if path.exists():
+        subprocess.check_call(args + ["pull", repo], cwd=str(path))
+    else:
+        subprocess.check_call(args + ["clone", repo, str(path)])
+
+    subprocess.check_call([hg, "update", "-r", revision], cwd=str(path))