Add missing .binmode for Gem::AtomicFileWriter

[kou]

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

I can't reproduce this again but I got the following error when I install many gems at once:

Fetching pg-1.6.3.gem
#<Thread:0x00007ff77fe16210 /var/tmp/local/lib/ruby/4.1.0+1/rubygems/request_set.rb:168 run> terminated with exception (report_on_exception is true):
/var/tmp/local/lib/ruby/4.1.0+1/rubygems.rb:841:in 'IO#write': "\x8B" from ASCII-8BIT to UTF-8 (Encoding::UndefinedConversionError)
	from /var/tmp/local/lib/ruby/4.1.0+1/rubygems.rb:841:in 'block in Gem.write_binary'
	from /var/tmp/local/lib/ruby/4.1.0+1/rubygems/util/atomic_file_writer.rb:44:in 'block in Gem::AtomicFileWriter.open'
	from /var/tmp/local/lib/ruby/4.1.0+1/rubygems/util/atomic_file_writer.rb:32:in 'IO.open'
	from /var/tmp/local/lib/ruby/4.1.0+1/rubygems/util/atomic_file_writer.rb:32:in 'Gem::AtomicFileWriter.open'
	from /var/tmp/local/lib/ruby/4.1.0+1/rubygems.rb:840:in 'Gem.write_binary'
	from /var/tmp/local/lib/ruby/4.1.0+1/rubygems/remote_fetcher.rb:304:in 'Gem::RemoteFetcher#cache_update_path'
	from /var/tmp/local/lib/ruby/4.1.0+1/rubygems/remote_fetcher.rb:151:in 'Gem::RemoteFetcher#download'
	from /var/tmp/local/lib/ruby/4.1.0+1/rubygems/source.rb:195:in 'Gem::Source#download'
	from /var/tmp/local/lib/ruby/4.1.0+1/rubygems/resolver/specification.rb:113:in 'Gem::Resolver::Specification#download'
	from /var/tmp/local/lib/ruby/4.1.0+1/rubygems/request_set.rb:174:in 'block (2 levels) in Gem::RequestSet#install'
ERROR:  While executing gem ... (Encoding::UndefinedConversionError)
    "\x8B" from ASCII-8BIT to UTF-8
	/var/tmp/local/lib/ruby/4.1.0+1/rubygems.rb:841:in 'IO#write'
	/var/tmp/local/lib/ruby/4.1.0+1/rubygems.rb:841:in 'block in Gem.write_binary'
	/var/tmp/local/lib/ruby/4.1.0+1/rubygems/util/atomic_file_writer.rb:44:in 'block in Gem::AtomicFileWriter.open'
	/var/tmp/local/lib/ruby/4.1.0+1/rubygems/util/atomic_file_writer.rb:32:in 'IO.open'
	/var/tmp/local/lib/ruby/4.1.0+1/rubygems/util/atomic_file_writer.rb:32:in 'Gem::AtomicFileWriter.open'
	/var/tmp/local/lib/ruby/4.1.0+1/rubygems.rb:840:in 'Gem.write_binary'
	/var/tmp/local/lib/ruby/4.1.0+1/rubygems/remote_fetcher.rb:304:in 'Gem::RemoteFetcher#cache_update_path'
	/var/tmp/local/lib/ruby/4.1.0+1/rubygems/remote_fetcher.rb:151:in 'Gem::RemoteFetcher#download'
	/var/tmp/local/lib/ruby/4.1.0+1/rubygems/source.rb:195:in 'Gem::Source#download'
	/var/tmp/local/lib/ruby/4.1.0+1/rubygems/resolver/specification.rb:113:in 'Gem::Resolver::Specification#download'
	/var/tmp/local/lib/ruby/4.1.0+1/rubygems/request_set.rb:174:in 'block (2 levels) in Gem::RequestSet#install'

I think that it's not related to pg gem. We can reproduce similar error by the following script:

require "fileutils"
path = "/tmp/abc.txt"
FileUtils.rm_f(path)
flags = File::RDWR|File::CREAT|File::EXCL|File::BINARY
Encoding.default_internal = Encoding::UTF_8 # This is the important part. This change file.external_encoding to Encoding::UTF_8
File.open(path, flags) do |file|
  file.write("\x8b".b)
end

/var/tmp/xxx.rb:7:in 'IO#write': "\x8B" from ASCII-8BIT to UTF-8 (Encoding::UndefinedConversionError)
	from /var/tmp/xxx.rb:7:in 'block in <main>'
	from /var/tmp/xxx.rb:6:in 'IO.open'
	from /var/tmp/xxx.rb:6:in '<main>'

We can solve this by adding file.binmode:

require "fileutils"
path = "/tmp/abc.txt"
FileUtils.rm_f(path)
flags = File::RDWR|File::CREAT|File::EXCL|File::BINARY
Encoding.default_internal = Encoding::UTF_8
File.open(path, flags) do |file|
  file.binmode
  file.write("\x8b".b)
end

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

Add missing .binmode that is included in the original change in GH-9202. I commented that temp_file.binmode is redundant. But I was wrong. We need temp_file.binmode even when we specify File::BINARY. Sorry.

See also: https://docs.ruby-lang.org/en/master/File.html#class-file-data-mode-specified-as-an-integer

Note that although there is a constant File::BINARY, setting its value in an integer stream mode has no effect; this is because, as documented in File::Constants, the File::BINARY value disables line code conversion, but does not change the external encoding.

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

[hsbt]

👍