commit fcdb66acd3afd4068a3b200ffc71daeab72e0fcc Author: Nick Mathewson nickm@torproject.org Date: Wed Oct 23 13:26:08 2019 -0400
Add a script to rename C identifiers, and optionally add a commit message
This script should "pay for itself" if it prevents one bug caused by careless search-replace-commit loops. --- changes/ticket32237 | 5 + scripts/maint/rename_c_identifier.py | 261 +++++++++++++++++++++++++++++++++++ 2 files changed, 266 insertions(+)
diff --git a/changes/ticket32237 b/changes/ticket32237 new file mode 100644 index 000000000..dfa0b7840 --- /dev/null +++ b/changes/ticket32237 @@ -0,0 +1,5 @@ + o Minor features (developer tools): + - Add a rename_c_identifiers.py tool to rename a bunch of C + identifiers at once, and generate a well-formed commit message + describing the change. This should help with refactoring. Closes + ticket 32237. diff --git a/scripts/maint/rename_c_identifier.py b/scripts/maint/rename_c_identifier.py new file mode 100755 index 000000000..0e56dc48d --- /dev/null +++ b/scripts/maint/rename_c_identifier.py @@ -0,0 +1,261 @@ +#!/usr/bin/python3 +# +# Copyright (c) 2001 Matej Pfajfar. +# Copyright (c) 2001-2004, Roger Dingledine. +# Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. +# Copyright (c) 2007-2019, The Tor Project, Inc. +# See LICENSE for licensing information + +""" +Helpful script to replace one or more C identifiers, and optionally +generate a commit message explaining what happened. +""" + +import argparse +import fileinput +import os +import re +import shlex +import subprocess +import sys +import tempfile + +TOPDIR = "src" + + +def is_c_file(fn): + """ + Return true iff fn is the name of a C file. + + >>> is_c_file("a/b/module.c") + True + >>> is_c_file("a/b/module.h") + True + >>> is_c_file("a/b/module.c~") + False + >>> is_c_file("a/b/.module.c") + False + >>> is_c_file("a/b/module.cpp") + False + """ + fn = os.path.split(fn)[1] + if fn.startswith("."): + return False + ext = os.path.splitext(fn)[1] + return ext in {".c", ".h", ".i", ".inc"} + + +def list_c_files(topdir=TOPDIR): + """ + Use git to list all the C files under version control. + + >>> lst = list(list_c_files()) + >>> "src/core/mainloop/mainloop.c" in lst + True + >>> "src/core/mainloop/twiddledeedoo.c" in lst + False + >>> "micro-revision.i" in lst + False + """ + proc = subprocess.Popen( + ["git", "ls-tree", "--name-only", "-r", "HEAD", topdir], + stdout=subprocess.PIPE, + encoding="utf-8") + for line in proc.stdout.readlines(): + line = line.strip() + if is_c_file(line): + yield line + + +class Rewriter: + """ + A rewriter applies a series of word-by-word replacements, in + sequence. Replacements only happen at "word boundaries", + as determined by the \b regular expression marker. + + ("A word is defined as a sequence of alphanumeric or underscore + characters", according to the documentation.) + + >>> R = Rewriter([("magic", "secret"), ("words", "codes")]) + >>> R.apply("The magic words are rambunctious bluejay") + 'The secret codes are rambunctious bluejay' + >>> R.apply("The magical words are rambunctious bluejay") + 'The magical codes are rambunctious bluejay' + >>> R.get_count() + 3 + + """ + + def __init__(self, replacements): + """Make a new Rewriter. Takes a sequence of pairs of + (from_id, to_id), where from_id is an identifier to replace, + and to_id is its replacement. + """ + self._patterns = [] + for id1, id2 in replacements: + pat = re.compile(r"\b{}\b".format(re.escape(id1))) + self._patterns.append((pat, id2)) + + self._count = 0 + + def apply(self, line): + """Return `line` as transformed by this rewriter.""" + for pat, ident in self._patterns: + line, count = pat.subn(ident, line) + self._count += count + return line + + def get_count(self): + """Return the number of identifiers that this rewriter has + rewritten.""" + return self._count + + +def rewrite_files(files, rewriter): + """ + Apply `rewriter` to every file in `files`, replacing those files + with their rewritten contents. + """ + for line in fileinput.input(files, inplace=True): + sys.stdout.write(rewriter.apply(line)) + + +def make_commit_msg(pairs, no_verify): + """Return a commit message to explain what was replaced by the provided + arguments. + """ + script = ["./scripts/maint/rename_c_identifier.py"] + for id1, id2 in pairs: + qid1 = shlex.quote(id1) + qid2 = shlex.quote(id2) + script.append(" {} {}".format(qid1, qid2)) + script = " \\n".join(script) + + if len(pairs) == 1: + line1 = "Rename {} to {}".format(pairs[0]) + else: + line1 = "Replace several C identifiers." + + msg = """\ +{} + +This is an automated commit, generated by this command: + +{} +""".format(line1, script) + + if no_verify: + msg += """ +It was generated with --no-verify, so it probably breaks some commit hooks. +The commiter should be sure to fix them up in a subsequent commit. +""" + + return msg + + +def commit(pairs, no_verify=False): + """Try to commit the current git state, generating the commit message as + appropriate. If `no_verify` is True, pass the --no-verify argument to + git commit. + """ + args = [] + if no_verify: + args.append("--no-verify") + + # We have to use a try block to delete the temporary file here, since we + # are using tempfile with delete=False. We have to use delete=False, + # since otherwise we are not guaranteed to be able to give the file to + # git for it to open. + fname = None + try: + with tempfile.NamedTemporaryFile(mode="w", delete=False) as f: + fname = f.name + f.write(make_commit_msg(pairs, no_verify)) + s = subprocess.run(["git", "commit", "-a", "-F", fname, "--edit"]+args) + if s.returncode != 0 and not no_verify: + print('"git commit" failed. Maybe retry with --no-verify?', + file=sys.stderr) + revert_changes() + return False + finally: + os.unlink(fname) + + return True + + +def any_uncommitted_changes(): + """Return True if git says there are any uncommitted changes in the current + working tree; false otherwise. + """ + s = subprocess.run(["git", "diff-index", "--quiet", "HEAD"]) + return s.returncode != 0 + + +DESC = "Replace one identifier with another throughout our source." +EXAMPLES = """\ +Examples: + + rename_c_identifier.py set_ctrl_id set_controller_id + (Replaces every occurrence of "set_ctrl_id" with "set_controller_id".) + + rename_c_identifier.py --commit set_ctrl_id set_controller_id + (As above, but also generate a git commit with an appropriate message.) + + rename_c_identifier.py a b c d + (Replace "a" with "b", and "c" with "d".)""" + + +def revert_changes(): + """Tell git to revert all the changes in the current working tree. + """ + print('Reverting changes.', file=sys.stderr) + subprocess.run(["git", "checkout", "--quiet", TOPDIR]) + + +def main(argv): + import argparse + parser = argparse.ArgumentParser(description=DESC, epilog=EXAMPLES, + # prevent re-wrapping the examples + formatter_class=argparse.RawDescriptionHelpFormatter) + + parser.add_argument("--commit", action='store_true', + help="Generate a Git commit.") + parser.add_argument("--no-verify", action='store_true', + help="Tell Git not to run its pre-commit hooks.") + parser.add_argument("from_id", type=str, help="Original identifier") + parser.add_argument("to_id", type=str, help="New identifier") + parser.add_argument("more", type=str, nargs=argparse.REMAINDER, + help="Additional identifier pairs") + + args = parser.parse_args(argv[1:]) + + if len(args.more) % 2 != 0: + print("I require an even number of identifiers.", file=sys.stderr) + return 1 + + if any_uncommitted_changes(): + print("Uncommitted changes found. Not running.", file=sys.stderr) + return 1 + + pairs = [] + print("renaming {} to {}".format(args.from_id, args.to_id), file=sys.stderr) + pairs.append((args.from_id, args.to_id)) + for idx in range(0, len(args.more), 2): + id1 = args.more[idx] + id2 = args.more[idx+1] + print("renaming {} to {}".format(id1, id2)) + pairs.append((id1, id2)) + + rewriter = Rewriter(pairs) + + rewrite_files(list_c_files(), rewriter) + + print("Replaced {} identifiers".format(rewriter.get_count()), + file=sys.stderr) + + if args.commit: + commit(pairs, args.no_verify) + + +if __name__ == '__main__': + main(sys.argv)