mklog: Add --append option to auto add generate ChangeLog to patch file

This tiny patch add --append option to mklog.py that support add generated
change-log to the corresponding patch file. With this option there is no need
to manually copy the generated change-log to the patch file. e.g.:

Run `mklog.py --append /path/to/this/patch` will add the generated change-log
to the right place of the /path/to/this/patch file.

contrib/ChangeLog:

	* mklog.py: Add --append option.

Signed-off-by: Lehua Ding <lehua.ding@rivai.ai>

1 files changed, 26 insertions, 1 deletions

diff --git a/contrib/mklog.py b/contrib/mklog.py
index 777212c..26230b9 100755
--- a/contrib/mklog.py
+++ b/contrib/mklog.py
@@ -358,6 +358,8 @@ if __name__ == '__main__':
                              'file')
     parser.add_argument('--update-copyright', action='store_true',
                         help='Update copyright in ChangeLog files')
+    parser.add_argument('-a', '--append', action='store_true',
+                        help='Append the generate ChangeLog to the patch file')
     args = parser.parse_args()
     if args.input == '-':
         args.input = None
@@ -370,7 +372,30 @@ if __name__ == '__main__':
     else:
         output = generate_changelog(data, args.no_functions,
                                     args.fill_up_bug_titles, args.pr_numbers)
-        if args.changelog:
+        if args.append:
+            if (not args.input):
+                raise Exception("`-a or --append` option not support standard input")
+            lines = []
+            with open(args.input, 'r', newline='\n') as f:
+                # 1 -> not find the possible start of diff log
+                # 2 -> find the possible start of diff log
+                # 3 -> finish add ChangeLog to the patch file
+                maybe_diff_log = 1
+                for line in f:
+                    if maybe_diff_log == 1 and line == "---\n":
+                        maybe_diff_log = 2
+                    elif maybe_diff_log == 2 and \
+                         re.match("\s[^\s]+\s+\|\s\d+\s[+\-]+\n", line):
+                        lines += [output, "---\n", line]
+                        maybe_diff_log = 3
+                    else:
+                        # the possible start is not the true start.
+                        if maybe_diff_log == 2:
+                            maybe_diff_log = 1
+                        lines.append(line)
+            with open(args.input, "w") as f:
+                f.writelines(lines)
+        elif args.changelog:
             lines = open(args.changelog).read().split('\n')
             start = list(takewhile(skip_line_in_changelog, lines))
             end = lines[len(start):]