1 files changed, 54 insertions, 0 deletions
diff --git a/third_party/python/taskcluster_taskgraph/taskgraph/util/hash.py b/third_party/python/taskcluster_taskgraph/taskgraph/util/hash.py
new file mode 100644
index 0000000000..bf786e92e4
--- /dev/null
+++ b/third_party/python/taskcluster_taskgraph/taskgraph/util/hash.py
@@ -0,0 +1,54 @@
+# 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 hashlib
+from pathlib import Path
+
+from taskgraph.util import path as mozpath
+from taskgraph.util.memoize import memoize
+
+
+@memoize
+def hash_path(path):
+    """Hash a single file.
+
+    Returns the SHA-256 hash in hex form.
+    """
+    with open(path, "rb") as fh:
+        return hashlib.sha256(fh.read()).hexdigest()
+
+
+def _find_files(base_path):
+    for path in Path(base_path).rglob("*"):
+        if path.is_file():
+            yield str(path)
+
+
+def hash_paths(base_path, patterns):
+    """
+    Give a list of path patterns, return a digest of the contents of all
+    the corresponding files, similarly to git tree objects or mercurial
+    manifests.
+
+    Each file is hashed. The list of all hashes and file paths is then
+    itself hashed to produce the result.
+    """
+    h = hashlib.sha256()
+
+    found = set()
+    for pattern in patterns:
+        files = _find_files(base_path)
+        matches = [path for path in files if mozpath.match(path, pattern)]
+        if matches:
+            found.update(matches)
+        else:
+            raise Exception("%s did not match anything" % pattern)
+    for path in sorted(found):
+        h.update(
+            "{} {}\n".format(
+                hash_path(mozpath.abspath(mozpath.join(base_path, path))),
+                mozpath.normsep(path),
+            ).encode("utf-8")
+        )
+    return h.hexdigest()