[ruby-core:61184] [ruby-trunk - Bug #9583] Open3 cannot talk correctly with Ruby when there is a large DATA segment passed through stdin. Broken pipe (Errno::EPIPE)

Issue #9583 has been updated by Charlie Somerville.


As surprising as this behaviour seems, it's actually legit.

What's breaking is not `ruby -c` - this is behaving correctly. As akr noted, Ruby does not read input files past the `__END__` marker. The `DATA` constant is set to an IO which can be used to read further into the file.

When `ruby -c` finished reading the file, it checks the syntax and then exits. Any attempts to write more data will raise `EPIPE`. The bug here is actually in the invoking program, not `ruby -c` itself. This behaviour can be reproduced by piping data into any child process that terminates before seeing EOF on standard input.

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Bug #9583: Open3 cannot talk correctly with Ruby when there is a large DATA segment passed through stdin. Broken pipe (Errno::EPIPE)
https://bugs.ruby-lang.org/issues/9583#change-45543

* Author: Josh Cheek
* Status: Rejected
* Priority: Normal
* Assignee: 
* Category: 
* Target version: 
* ruby -v: ruby 2.2.0dev (2014-03-01 trunk 45219) [x86_64-darwin12.0]
* Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN, 2.1: UNKNOWN
----------------------------------------
$ # Tested against 
$ ruby -v
ruby 2.2.0dev (2014-03-01 trunk 45219) [x86_64-darwin12.0]


Example
$ ruby -e 'puts "__END__"; puts "."*24_568' > f.rb; ruby -r open3 -e 'Open3.popen3("ruby") { |i, o, e| i.write File.read "f.rb"; i.close; puts o.read; puts e.read }'
-e:1:in `write': Broken pipe (Errno::EPIPE)
	from -e:1:in `block in <main>'
	from /Users/josh/.rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/open3.rb:217:in `popen_run'
	from /Users/josh/.rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/open3.rb:99:in `popen3'
	from -e:1:in `<main>'

If we reduce the size of the data segment by 1 character, it works:
$ ruby -e 'puts "__END__"; puts "."*24_567' > f.rb; ruby -r open3 -e 'Open3.popen3("ruby") { |i, o, e| i.write File.read "f.rb"; i.close; puts o.read; puts e.read }'

If we take it out of the data segment, it is fine
$ ruby -e 'puts "#" + "."*100_000' > f.rb; ruby -r open3 -e 'Open3.popen3("ruby") { |i, o, e| i.write File.read "f.rb"; i.close; puts o.read; puts e.read }'



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