1 files changed, 107 insertions, 0 deletions
diff --git a/dom/media/webrtc/third_party_build/restore_patch_stack.py b/dom/media/webrtc/third_party_build/restore_patch_stack.py
new file mode 100644
index 0000000000..6db3a64192
--- /dev/null
+++ b/dom/media/webrtc/third_party_build/restore_patch_stack.py
@@ -0,0 +1,107 @@
+# 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 argparse
+import os
+import re
+import shutil
+
+from fetch_github_repo import fetch_repo
+from run_operations import run_git, run_shell
+
+# This script restores the mozilla patch stack and no-op commit tracking
+# files.  In the case of repo corruption or a mistake made during
+# various rebase conflict resolution operations, the patch-stack can be
+# restored rather than requiring the user to restart the fast-forward
+# process from the beginning.
+
+
+def get_last_line(file_path):
+    # technique from https://stackoverflow.com/questions/46258499/how-to-read-the-last-line-of-a-file-in-python
+    with open(file_path, "rb") as f:
+        try:  # catch OSError in case of a one line file
+            f.seek(-2, os.SEEK_END)
+            while f.read(1) != b"\n":
+                f.seek(-2, os.SEEK_CUR)
+        except OSError:
+            f.seek(0)
+        return f.readline().decode().strip()
+
+
+def restore_patch_stack(
+    github_path, github_branch, patch_directory, state_directory, tar_name
+):
+    # first, refetch the repo (hopefully utilizing the tarfile for speed) so
+    # the patches apply cleanly
+    fetch_repo(github_path, True, os.path.join(state_directory, tar_name))
+
+    # remove any stale no-op-cherry-pick-msg files in state_directory
+    run_shell("rm {}/*.no-op-cherry-pick-msg || true".format(state_directory))
+
+    # lookup latest vendored commit from third_party/libwebrtc/README.moz-ff-commit
+    file = os.path.abspath("third_party/libwebrtc/README.moz-ff-commit")
+    last_vendored_commit = get_last_line(file)
+
+    # checkout the previous vendored commit with proper branch name
+    cmd = "git checkout -b {} {}".format(github_branch, last_vendored_commit)
+    run_git(cmd, github_path)
+
+    # restore the patches to moz-libwebrtc repo, use run_shell instead of
+    # run_hg to allow filepath wildcard
+    print("Restoring patch stack")
+    run_shell("cd {} && git am {}/*.patch".format(github_path, patch_directory))
+
+    # it is also helpful to restore the no-op-cherry-pick-msg files to
+    # the state directory so that if we're restoring a patch-stack we
+    # also restore the possibly consumed no-op tracking files.
+    no_op_files = [
+        path
+        for path in os.listdir(patch_directory)
+        if re.findall(".*no-op-cherry-pick-msg$", path)
+    ]
+    for file in no_op_files:
+        shutil.copy(os.path.join(patch_directory, file), state_directory)
+
+
+if __name__ == "__main__":
+    default_patch_dir = "third_party/libwebrtc/moz-patch-stack"
+    default_state_dir = ".moz-fast-forward"
+    default_tar_name = "moz-libwebrtc.tar.gz"
+
+    parser = argparse.ArgumentParser(
+        description="Restore moz-libwebrtc github patch stack"
+    )
+    parser.add_argument(
+        "--repo-path",
+        required=True,
+        help="path to libwebrtc repo",
+    )
+    parser.add_argument(
+        "--branch",
+        default="mozpatches",
+        help="moz-libwebrtc branch (defaults to mozpatches)",
+    )
+    parser.add_argument(
+        "--patch-path",
+        default=default_patch_dir,
+        help="path to save patches (defaults to {})".format(default_patch_dir),
+    )
+    parser.add_argument(
+        "--tar-name",
+        default=default_tar_name,
+        help="name of tar file (defaults to {})".format(default_tar_name),
+    )
+    parser.add_argument(
+        "--state-path",
+        default=default_state_dir,
+        help="path to state directory (defaults to {})".format(default_state_dir),
+    )
+    args = parser.parse_args()
+
+    restore_patch_stack(
+        args.repo_path,
+        args.branch,
+        os.path.abspath(args.patch_path),
+        args.state_path,
+        args.tar_name,
+    )