Fix restarting with locked version when $PROGRAM_NAME has been changed

[CamJN]

What was the end-user or developer problem that led to this PR?

If a ruby process has changed it's name for ease of understanding in ps or top output, and then loads bundler, but the correct bundler is not installed, then the error message the user sees is very confusing.

Links:
phusion/passenger#2567
phusion/passenger#2577

What is your fix for the problem, implemented in this PR?

Use Process.argv0 instead of $PROGRAM_NAME because $PROGRAM_NAME is liable to be changed but Process.argv0 is not.

Links:

• Ruby docs mentioning that $0/$PROCESS_NAME may be reassigned: https://docs.ruby-lang.org/en/3.3/globals_rdoc.html#label-240
• Process.argv0 docs indicating that it is not reassigned with $0/$PROCESS_NAME : https://docs.ruby-lang.org/en/master/Process.html#method-c-argv0

Make sure the following tasks are checked

• Describe the problem / feature
• Write tests for features and bug fixes
• Write code to solve the problem
• Make sure you follow the current code style and write meaningful commit messages without tags

Sorry I didn't write any tests, I have no idea how to setup the required failing environment in your test environment. I've created a minimal reproduction environment below, which I used to verify the fix.

If you create all of these files, then run the following commands, you can trigger the bad error message, and then if you patch the /usr/local/lib/ruby/site_ruby/3.2.0/bundler/self_manager.rb file in the container and run ruby test.rb again, you will get a good error message.

docker build -t bundler_bug .
docker run -it bundler_bug
docker run -it bundler_bug bash
# edit /usr/local/lib/ruby/site_ruby/3.2.0/bundler/self_manager.rb
ruby test.rb

Dockerfile:

FROM ruby:3.2.6

WORKDIR /root
COPY test.rb /root/test.rb
COPY Gemfile /root/Gemfile
COPY Gemfile.lock /root/Gemfile.lock

RUN gem update --system
RUN bundle config set --local deployment "true"
RUN bundle config set --local path vendor/ruby
RUN bundle install
RUN rm -rf /root/vendor/ruby/ruby/3.2.0/gems/bundler-2.5.12

CMD ["ruby", "test.rb"]

Gemfile:

# frozen_string_literal: true

source "https://rubygems.org"

ruby '3.2.6'

Gemfile.lock:

GEM
  remote: https://rubygems.org/
  specs:

PLATFORMS
  arm64-darwin-23
  ruby

DEPENDENCIES

RUBY VERSION
   ruby 3.2.6p234

BUNDLED WITH
   2.5.12

test.rb

#!/usr/bin/env ruby
$0 = "this is the program name"
require 'bundler/setup'

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[deivid-rodriguez]

Thanks a lot, this must have been really hard to debug, so good to save that for others from now on :)

I tried adding a spec to cover the fix.

[CamJN]

Thanks for the spec, I appreciate it!

[deivid-rodriguez]

Thanks so much!

[CamJN]

No, thank you! This will save me a lot of headaches in the future, I'm sure.