Library/Homebrew: move stdin ruby scripts to files under utils.

This avoids can avoid UID/EUID related issues with Ruby scripts passed
over `stdin` clashing with Ruby security features.

It's also just a bit nicer to have Ruby scripts in files instead.

While we're here:
- refactor some shared logic into a new `setup-gem-home-bundle-gemfile`
  function in `ruby.sh`
- do some general cleanup of `lock.sh`
- prioritise `flock` over `python` in `lock.sh`

Library/Homebrew/brew.sh

@@ -897,9 +897,6 @@ then
   unset HOMEBREW_AUTO_UPDATE_CASK_TAP
 fi
 
-# Disable Ruby options we don't need.
-export HOMEBREW_RUBY_DISABLE_OPTIONS="--disable=gems,rubyopt"
-
 if [[ -z "${HOMEBREW_RUBY_WARNINGS}" ]]
 then
   export HOMEBREW_RUBY_WARNINGS="-W1"

Library/Homebrew/cmd/setup-ruby.sh

@@ -5,9 +5,7 @@
 #:  command.
 #:
 
-# HOMEBREW_LIBRARY is from the user environment.
-# HOMEBREW_RUBY_PATH is set by utils/ruby.sh
-# RUBY_DISABLE_OPTIONS is set by brew.sh
+# HOMEBREW_LIBRARY is set by brew.sh
 # HOMEBREW_BREW_FILE is set by extend/ENV/super.rb
 # shellcheck disable=SC2154
 homebrew-setup-ruby() {
@@ -37,13 +35,7 @@ homebrew-setup-ruby() {
     fi
   fi
 
-  GEM_VERSION="$("${HOMEBREW_RUBY_PATH}" "${HOMEBREW_RUBY_DISABLE_OPTIONS}" /dev/stdin <<<'require "rbconfig"; puts RbConfig::CONFIG["ruby_version"]')"
-  echo "${GEM_VERSION}"
-  GEM_HOME="${HOMEBREW_LIBRARY}/Homebrew/vendor/bundle/ruby/${GEM_VERSION}"
-  BUNDLE_GEMFILE="${HOMEBREW_LIBRARY}/Homebrew/Gemfile"
-
-  export GEM_HOME
-  export BUNDLE_GEMFILE
+  setup-gem-home-bundle-gemfile
 
   if ! bundle check &>/dev/null
   then

Library/Homebrew/dev-cmd/rubocop.sh

@@ -4,25 +4,19 @@
 
 # HOMEBREW_LIBRARY is from the user environment.
 # HOMEBREW_RUBY_PATH is set by utils/ruby.sh
-# RUBY_DISABLE_OPTIONS is set by brew.sh
 # HOMEBREW_BREW_FILE is set by extend/ENV/super.rb
 # shellcheck disable=SC2154
 homebrew-rubocop() {
   source "${HOMEBREW_LIBRARY}/Homebrew/utils/ruby.sh"
   setup-ruby-path
+  setup-gem-home-bundle-gemfile
 
-  GEM_VERSION="$("${HOMEBREW_RUBY_PATH}" "${HOMEBREW_RUBY_DISABLE_OPTIONS}" /dev/stdin <<<'require "rbconfig"; puts RbConfig::CONFIG["ruby_version"]')"
-  GEM_HOME="${HOMEBREW_LIBRARY}/Homebrew/vendor/bundle/ruby/${GEM_VERSION}"
-  BUNDLE_GEMFILE="${HOMEBREW_LIBRARY}/Homebrew/Gemfile"
   BUNDLE_WITH="style"
-
-  export GEM_HOME
-  export BUNDLE_GEMFILE
   export BUNDLE_WITH
 
   if ! bundle check &>/dev/null
   then
-    "${HOMEBREW_BREW_FILE}" install-bundler-gems --add-groups=style
+    "${HOMEBREW_BREW_FILE}" install-bundler-gems --add-groups="${BUNDLE_WITH}"
   fi
 
   export PATH="${GEM_HOME}/bin:${PATH}"

Library/Homebrew/utils/lock.sh

@@ -1,6 +1,7 @@
 # create a lock using `flock(2)`. A name is required as first argument.
 # the lock will be automatically unlocked when the shell process quits.
 # Noted due to the fixed FD, a shell process can only create one lock.
+# HOMEBREW_LIBRARY is by brew.sh
 # HOMEBREW_PREFIX is set by extend/ENV/super.rb
 # shellcheck disable=SC2154
 lock() {
@@ -16,7 +17,7 @@ Fix permissions by running:
   sudo chown -R ${USER-\$(whoami)} ${HOMEBREW_PREFIX}/var/homebrew
 EOS
   fi
-  # 200 is the file descriptor used in the lock.
+  # 200 is the file descriptor (FD) used in the lock.
   # This FD should be used exclusively for lock purpose.
   # Any value except 0(stdin), 1(stdout) and 2(stderr) can do the job.
   # Noted, FD is unique per process but it will be shared to subprocess.
@@ -37,26 +38,25 @@ EOS
 }
 
 _create_lock() {
-  local lock_fd="$1"
+  local lock_file_descriptor="$1"
   local name="$2"
   local ruby="/usr/bin/ruby"
   local python="/usr/bin/python"
   [[ -x "${ruby}" ]] || ruby="$(type -P ruby)"
   [[ -x "${python}" ]] || python="$(type -P python)"
 
-  # Use /dev/stdin, otherwise Ruby can error if uid != euid.
-  # Can't use "-" as that's also blocked:
-  # https://github.com/ruby/ruby/blob/e51435177e88fc845528dff7cf2bc2b75dd36144/ruby.c#L2333-L2335
-  if [[ -x "${ruby}" ]] && "${ruby}" /dev/stdin <<<"exit(RUBY_VERSION >= '1.8.7')"
+  local utils_lock_sh="${HOMEBREW_LIBRARY}/Homebrew/utils/lock_sh"
+  local oldest_ruby_with_flock="1.8.7"
+  if [[ -x "${ruby}" ]] && "${ruby}" "${utils_lock_sh}/ruby_check_version.rb" "${oldest_ruby_with_flock}"
   then
-    "${ruby}" /dev/stdin <<<"File.new(${lock_fd}).flock(File::LOCK_EX | File::LOCK_NB) || exit(1)"
+    "${ruby}" "${utils_lock_sh}/ruby_lock_file_descriptor.rb" "${lock_file_descriptor}"
+  elif [[ -x "$(type -P flock)" ]]
+  then
+    flock -n "${lock_file_descriptor}"
   elif [[ -x "${python}" ]]
   then
     "${python}" -c "import fcntl; fcntl.flock(${lock_fd}, fcntl.LOCK_EX | fcntl.LOCK_NB)"
-  elif [[ -x "$(type -P flock)" ]]
-  then
-    flock -n "${lock_fd}"
   else
-    onoe "Cannot create ${name} lock, please avoid running Homebrew in parallel."
+    onoe "Cannot create ${name} lock due to missing/too old ruby/flock/python, please avoid running Homebrew in parallel."
   fi
 }

Library/Homebrew/utils/lock_sh/ruby_check_version.rb

@@ -0,0 +1,5 @@
+# typed: strict
+# frozen_string_literal: true
+
+ruby_version_to_check = ARGV.first
+exit(ruby_version_to_check < RUBY_VERSION)

Library/Homebrew/utils/lock_sh/ruby_lock_file_descriptor.rb

@@ -0,0 +1,6 @@
+# typed: strict
+# frozen_string_literal: true
+
+file_descriptor = ARGV.first.to_i
+file = File.new(file_descriptor)
+file.flock(File::LOCK_EX | File::LOCK_NB) || exit(1)

Library/Homebrew/utils/ruby.sh

@@ -2,6 +2,9 @@
 # When bumping to a new major/minor version, also update the bounds in the Gemfile
 export HOMEBREW_REQUIRED_RUBY_VERSION=3.1
 
+# Disable Ruby options we don't need.
+export HOMEBREW_RUBY_DISABLE_OPTIONS="--disable=gems,rubyopt"
+
 # HOMEBREW_LIBRARY is from the user environment
 # shellcheck disable=SC2154
 test_ruby() {
@@ -145,3 +148,12 @@ If there's no Homebrew Portable Ruby available for your processor:
   export HOMEBREW_RUBY_PATH
   [[ -n "${HOMEBREW_LINUX}" && -n "${TERMINFO_DIRS}" ]] && export TERMINFO_DIRS
 }
+
+setup-gem-home-bundle-gemfile() {
+  GEM_VERSION="$("${HOMEBREW_RUBY_PATH}" "${HOMEBREW_RUBY_DISABLE_OPTIONS}" "${HOMEBREW_LIBRARY}/Homebrew/utils/ruby_sh/ruby_gem_version.rb")"
+  GEM_HOME="${HOMEBREW_LIBRARY}/Homebrew/vendor/bundle/ruby/${GEM_VERSION}"
+  BUNDLE_GEMFILE="${HOMEBREW_LIBRARY}/Homebrew/Gemfile"
+
+  export GEM_HOME
+  export BUNDLE_GEMFILE
+}

Library/Homebrew/utils/ruby_sh/ruby_gem_version.rb

@@ -0,0 +1,5 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "rbconfig"
+puts RbConfig::CONFIG["ruby_version"]