devutils: Add update_platform_patches.py

devutils/update_platform_patches.py

@@ -0,0 +1,178 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+# Copyright (c) 2019 The ungoogled-chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""
+Utility to ease the updating of platform patches against ungoogled-chromium's patches
+"""
+
+import argparse
+import os
+import shutil
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent / 'utils'))
+from _common import ENCODING, get_logger
+from patches import merge_patches
+sys.path.pop(0)
+
+_SERIES = 'series'
+_SERIES_ORIG = 'series.orig'
+_SERIES_PREPEND = 'series.prepend'
+_SERIES_MERGED = 'series.merged'
+
+
+def merge_platform_patches(platform_patches_dir, prepend_patches_dir):
+    '''
+    Prepends prepend_patches_dir into platform_patches_dir
+
+    Returns True if successful, False otherwise
+    '''
+    if not (platform_patches_dir / _SERIES).exists():
+        get_logger().error('Unable to find platform series file: %s',
+                           platform_patches_dir / _SERIES)
+        return False
+
+    # Make series.orig file
+    shutil.copyfile(str(platform_patches_dir / _SERIES), str(platform_patches_dir / _SERIES_ORIG))
+
+    # Make series.prepend
+    shutil.copyfile(str(prepend_patches_dir / _SERIES), str(platform_patches_dir / _SERIES_PREPEND))
+
+    # Merge patches
+    merge_patches([prepend_patches_dir], platform_patches_dir, prepend=True)
+    (platform_patches_dir / _SERIES).replace(platform_patches_dir / _SERIES_MERGED)
+
+    return True
+
+
+def _dir_empty(path):
+    '''
+    Returns True if the directory exists and is empty; False otherwise
+    '''
+    try:
+        next(os.scandir(str(path)))
+    except StopIteration:
+        return True
+    except FileNotFoundError:
+        pass
+    return False
+
+
+def _remove_files_with_dirs(root_dir, sorted_file_iter):
+    '''
+    Deletes a list of sorted files relative to root_dir, removing empty directories along the way
+    '''
+    past_parent = None
+    for partial_path in sorted_file_iter:
+        complete_path = Path(root_dir, partial_path)
+        try:
+            complete_path.unlink()
+        except FileNotFoundError:
+            get_logger().warning('Could not remove prepended patch: %s', complete_path)
+        if past_parent != complete_path.parent:
+            while past_parent and _dir_empty(past_parent):
+                past_parent.rmdir()
+                past_parent = past_parent.parent
+            past_parent = complete_path.parent
+    # Handle last path's directory
+    while _dir_empty(complete_path.parent):
+        complete_path.parent.rmdir()
+        complete_path = complete_path.parent
+
+
+def unmerge_platform_patches(platform_patches_dir):
+    '''
+    Undo merge_platform_patches(), adding any new patches from series.merged as necessary
+
+    Returns True if successful, False otherwise
+    '''
+    if not (platform_patches_dir / _SERIES_PREPEND).exists():
+        get_logger().error('Unable to find series.prepend at: %s',
+                           platform_patches_dir / _SERIES_PREPEND)
+        return False
+    prepend_series = set(
+        filter(len,
+               (platform_patches_dir / _SERIES_PREPEND).read_text(encoding=ENCODING).splitlines()))
+
+    # Remove prepended files with directories
+    _remove_files_with_dirs(platform_patches_dir, sorted(prepend_series))
+
+    # Determine positions of blank spaces in series.orig
+    if not (platform_patches_dir / _SERIES_ORIG).exists():
+        get_logger().error('Unable to find series.orig at: %s', platform_patches_dir / _SERIES_ORIG)
+        return False
+    orig_series = (platform_patches_dir / _SERIES_ORIG).read_text(encoding=ENCODING).splitlines()
+    # patch path -> number of following blank lines
+    path_spaces = dict()
+    previous_path = None
+    for partial_path in orig_series:
+        if partial_path:
+            previous_path = partial_path
+        elif previous_path in path_spaces:
+            path_spaces[previous_path] += 1
+        else:
+            path_spaces[previous_path] = 1
+
+    # Apply changes on series.merged into a modified version of series.orig
+    if not (platform_patches_dir / _SERIES_MERGED).exists():
+        get_logger().error('Unable to find series.merged at: %s',
+                           platform_patches_dir / _SERIES_MERGED)
+        return False
+    new_series = filter(
+        len, (platform_patches_dir / _SERIES_MERGED).read_text(encoding=ENCODING).splitlines())
+    new_series = filter((lambda x: x not in prepend_series), new_series)
+    new_series = list(new_series)
+    series_index = 0
+    while series_index < len(new_series):
+        if new_series[series_index] in path_spaces:
+            new_series.insert(series_index + 1, '\n' * (path_spaces[new_series[series_index]] - 1))
+            series_index += 1
+        series_index += 1
+
+    # Write series file
+    with (platform_patches_dir / _SERIES).open('w', encoding=ENCODING) as series_file:
+        series_file.write('\n'.join(new_series))
+        series_file.write('\n')
+
+    # All other operations are successful; remove merging intermediates
+    (platform_patches_dir / _SERIES_MERGED).unlink()
+    (platform_patches_dir / _SERIES_ORIG).unlink()
+    (platform_patches_dir / _SERIES_PREPEND).unlink()
+
+    return True
+
+
+def main():
+    """CLI Entrypoint"""
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument(
+        'command',
+        choices=('merge', 'unmerge'),
+        help='Merge or unmerge ungoogled-chromium patches with platform patches')
+    parser.add_argument(
+        'platform_patches',
+        type=Path,
+        help='The path to the platform patches in GNU Quilt format to merge into')
+    args = parser.parse_args()
+
+    repo_dir = Path(__file__).resolve().parent.parent
+
+    success = False
+    if args.command == 'merge':
+        success = merge_platform_patches(args.platform_patches, repo_dir / 'patches')
+    elif args.command == 'unmerge':
+        success = unmerge_platform_patches(args.platform_patches)
+    else:
+        raise NotImplementedError(args.command)
+
+    if success:
+        return 0
+    return 1
+
+
+if __name__ == '__main__':
+    exit(main())