From: shugo@...
Date: 2017-10-25T04:41:32+00:00
Subject: [ruby-core:83556] [Ruby trunk Bug#14051] net/imap issue on idle method with an empty block

Issue #14051 has been updated by shugo (Shugo Maeda).


simayosi (SHIMAYOSHI Takao) wrote:
> Description
> If Net::IMAP#idle method is called with empty block,  all response handlers that have added beforehand are unintentionally removed before returning from the call.
> 
> Sample Code
>   imap.add_response_handler do |resp|
>     if resp.kind_of?(Net::IMAP::UntaggedResponse) and resp.name == "EXISTS"
>       imap.idle_done
>     end
>   end
>   imap.idle {}
>   # the response handler firstly added is unregistered here

I couldn't reproduce the problem with the following code:

```ruby
imap.add_response_handler do |resp|
  if resp.kind_of?(Net::IMAP::UntaggedResponse) and resp.name == "EXISTS"
    imap.idle_done
  end
end
p imap.response_handlers #=> [#<Proc:0x0000560887b7b958@t.rb:8>]
imap.idle {}
p imap.response_handlers #=> [#<Proc:0x0000560887b7b958@t.rb:8>]
```

> Cause
> @response_handlers.delete(nil) is executed in Net::IMAP#remove_response_handler called from the idle method.

Even if the body of a block is empty, a block parameter cannot be nil.

```ruby
def foo(&b)
  p b
end
foo {} #=> #<Proc:0x00005595c4e7f298@(irb):2>
```

And even if no block is given, a LocalJumpError will be raised.

```ruby
    def idle(timeout = nil, &response_handler)
      raise LocalJumpError, "no block given" unless response_handler
```


----------------------------------------
Bug #14051: net/imap issue on idle method with an empty block
https://bugs.ruby-lang.org/issues/14051#change-67583

* Author: simayosi (SHIMAYOSHI Takao)
* Status: Assigned
* Priority: Normal
* Assignee: shugo (Shugo Maeda)
* Target version: 
* ruby -v: 
* Backport: 2.3: UNKNOWN, 2.4: UNKNOWN
----------------------------------------
Description
If Net::IMAP#idle method is called with empty block,  all response handlers that have added beforehand are unintentionally removed before returning from the call.

Sample Code
  imap.add_response_handler do |resp|
    if resp.kind_of?(Net::IMAP::UntaggedResponse) and resp.name == "EXISTS"
      imap.idle_done
    end
  end
  imap.idle {}
  # the response handler firstly added is unregistered here

Cause
@response_handlers.delete(nil) is executed in Net::IMAP#remove_response_handler called from the idle method.




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