From 8c6f250dcf4624892347e7d15c9739c043528abf Mon Sep 17 00:00:00 2001
From: Takashi Kokubun <takashikkbn@gmail.com>
Date: Fri, 18 Apr 2025 06:56:41 +0900
Subject: [PATCH] Copy over bin/auto-style.rb

from ruby/git.ruby-lang.org as of:
https://github.com/ruby/git.ruby-lang.org/commit/a8635a4cd93c8adc2e1b48b6ae8fa3fcd3bb4b34
---
 tool/auto-style.rb | 239 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 239 insertions(+)
 create mode 100644 tool/auto-style.rb

diff --git a/tool/auto-style.rb b/tool/auto-style.rb
new file mode 100644
index 0000000000..8dc7e1bdee
--- /dev/null
+++ b/tool/auto-style.rb
@@ -0,0 +1,239 @@
+#!/usr/bin/env ruby
+# Usage:
+#   auto-style.rb [repo_path] [args...]
+
+require 'shellwords'
+require 'tmpdir'
+ENV['LC_ALL'] = 'C'
+
+class Git
+  attr_reader :depth
+
+  def initialize(oldrev, newrev, branch)
+    @oldrev = oldrev
+    @newrev = newrev
+    @branch = branch
+    with_clean_env do
+      @revs = {}
+      IO.popen(['git', 'log', '--format=%H %s', "#{@oldrev}..#{@newrev}"]) do |f|
+        f.each do |line|
+          line.chomp!
+          rev, subj = line.split(' ', 2)
+          @revs[rev] = subj
+        end
+      end
+      @depth = @revs.size
+    end
+  end
+
+  # ["foo/bar.c", "baz.h", ...]
+  def updated_paths
+    with_clean_env do
+      IO.popen(['git', 'diff', '--name-only', @oldrev, @newrev], &:readlines).each(&:chomp!)
+    end
+  end
+
+  # [0, 1, 4, ...]
+  def updated_lines(file)
+    lines = []
+    revs = @revs.map {|rev, subj| rev unless subj.start_with?("Revert ")}.compact
+    revs_pattern = /\A(?:#{revs.join('|')}) /
+    with_clean_env { IO.popen(['git', 'blame', '-l', '--', file], &:readlines) }.each_with_index do |line, index|
+      if revs_pattern =~ line
+        lines << index
+      end
+    end
+    lines
+  end
+
+  def commit(log, *files)
+    git('add', *files)
+    git('commit', '-m', log)
+    git('push', 'origin', @branch)
+  end
+
+  private
+
+  def git(*args)
+    cmd = ['git', *args].shelljoin
+    unless with_clean_env { system(cmd) }
+      abort "Failed to run: #{cmd}"
+    end
+  end
+
+  def with_clean_env
+    git_dir = ENV.delete('GIT_DIR') # this overcomes '-C' or pwd
+    yield
+  ensure
+    ENV['GIT_DIR'] = git_dir if git_dir
+  end
+end
+
+DEFAULT_GEM_LIBS = %w[
+  bundler
+  cmath
+  csv
+  e2mmap
+  fileutils
+  forwardable
+  ipaddr
+  irb
+  logger
+  matrix
+  mutex_m
+  ostruct
+  prime
+  rdoc
+  rexml
+  rss
+  scanf
+  shell
+  sync
+  thwait
+  tracer
+  webrick
+]
+
+DEFAULT_GEM_EXTS = %w[
+  bigdecimal
+  date
+  dbm
+  digest
+  etc
+  fcntl
+  fiddle
+  gdbm
+  io/console
+  io/nonblock
+  json
+  openssl
+  psych
+  racc
+  sdbm
+  stringio
+  strscan
+  zlib
+]
+
+IGNORED_FILES = [
+  # default gems whose master is GitHub
+  %r{\Abin/(?!erb)\w+\z},
+  *(DEFAULT_GEM_LIBS + DEFAULT_GEM_EXTS).flat_map { |lib|
+    [
+      %r{\Alib/#{lib}/},
+      %r{\Alib/#{lib}\.gemspec\z},
+      %r{\Alib/#{lib}\.rb\z},
+      %r{\Atest/#{lib}/},
+    ]
+  },
+  *DEFAULT_GEM_EXTS.flat_map { |ext|
+    [
+      %r{\Aext/#{ext}/},
+      %r{\Atest/#{ext}/},
+    ]
+  },
+
+  # vendoring (ccan)
+  %r{\Accan/},
+
+  # vendoring (io/)
+  %r{\Aext/io/},
+
+  # vendoring (nkf)
+  %r{\Aext/nkf/nkf-utf8/},
+
+  # vendoring (onigmo)
+  %r{\Aenc/},
+  %r{\Ainclude/ruby/onigmo\.h\z},
+  %r{\Areg.+\.(c|h)\z},
+
+  # explicit or implicit `c-file-style: "linux"`
+  %r{\Aaddr2line\.c\z},
+  %r{\Amissing/},
+  %r{\Astrftime\.c\z},
+  %r{\Avsnprintf\.c\z},
+
+  # to respect the original statements of licenses
+  %r{\ALEGAL\z},
+
+  # trailing spaces could be intentional in TRICK code
+  %r{\Asample/trick[^/]*/},
+]
+
+repo_path, *rest = ARGV
+rest.each_slice(3).map do |oldrev, newrev, refname|
+  branch = IO.popen({ 'GIT_DIR' => repo_path }, ['git', 'rev-parse', '--symbolic', '--abbrev-ref', refname], &:read).strip
+  next if branch != 'master' # Stable branches are on svn, and for consistency we should not make a git-specific commit.
+  vcs = Git.new(oldrev, newrev, branch)
+
+  Dir.mktmpdir do |workdir|
+    depth = vcs.depth + 1
+    system "git clone --depth=#{depth} --branch=#{branch} file:///#{repo_path} #{workdir}"
+    Dir.chdir(workdir)
+
+    paths = vcs.updated_paths
+    paths.select! {|l|
+      /^\d/ !~ l and /\.bat\z/ !~ l and
+      (/\A(?:config|[Mm]akefile|GNUmakefile|README)/ =~ File.basename(l) or
+       /\A\z|\.(?:[chsy]|\d+|e?rb|tmpl|bas[eh]|z?sh|in|ma?k|def|src|trans|rdoc|ja|en|el|sed|awk|p[ly]|scm|mspec|html|)\z/ =~ File.extname(l))
+    }
+    files = paths.select {|n| File.file?(n) }
+    files.reject! do |f|
+      IGNORED_FILES.any? { |re| f.match(re) }
+    end
+    next if files.empty?
+
+    trailing = eofnewline = expandtab = false
+
+    edited_files = files.select do |f|
+      src = File.binread(f) rescue next
+      eofnewline = eofnewline0 = true if src.sub!(/(?<!\A|\n)\z/, "\n")
+
+      trailing0 = false
+      expandtab0 = false
+      updated_lines = vcs.updated_lines(f)
+      if !updated_lines.empty?
+        src.gsub!(/^.*$/).with_index do |line, lineno|
+          if updated_lines.include?(lineno)
+            trailing = trailing0 = true if line.sub!(/[ \t]+$/, '')
+          end
+          line
+        end
+      end
+
+      if !updated_lines.empty? && (f.end_with?('.c') || f.end_with?('.h') || f == 'insns.def')
+        # If and only if unedited lines did not have tab indentation, prevent introducing tab indentation to the file.
+        expandtab_allowed = src.each_line.with_index.all? do |line, lineno|
+          updated_lines.include?(lineno) || !line.start_with?("\t")
+        end
+
+        if expandtab_allowed
+          src.gsub!(/^.*$/).with_index do |line, lineno|
+            if updated_lines.include?(lineno) && line.start_with?("\t") # last-committed line with hard tabs
+              expandtab = expandtab0 = true
+              line.sub(/\A\t+/) { |tabs| ' ' * (8 * tabs.length) }
+            else
+              line
+            end
+          end
+        end
+      end
+
+      if trailing0 or eofnewline0 or expandtab0
+        File.binwrite(f, src)
+        true
+      end
+    end
+    unless edited_files.empty?
+      msg = [('remove trailing spaces' if trailing),
+             ('append newline at EOF' if eofnewline),
+             ('expand tabs' if expandtab),
+            ].compact
+      message = "* #{msg.join(', ')}. [ci skip]"
+      if expandtab
+        message += "\nPlease consider using misc/expand_tabs.rb as a pre-commit hook."
+      end
+      vcs.commit(message, *edited_files)
+    end
+  end
+end