[ruby-core:112487] [Ruby master Bug#19441] Closing an Tempfile#dup behaviour

Issue #19441 has been updated by stac47 (Laurent Stacul).


Thanks nobu for your answer it makes perfect sense.

My case which led to the current question comes from a Rails application which has a controller receiving a file. My input `params[:file]` hold an `ActionDispatch::Http::UploadedFile` which itself has an attribute `tempfile`.

In the controller, `params[:file]` is passed to some functions (I don't have the control of) that can read and close the underlying `tempfile`. As a matter a fact, the code calls `ActionDispatch::Http::UploadedFile#open` (shortcut to `tempfile#open`) after the calls that close the file.

I was wondering whether I could avoid calling `#open` by providing the methods which can close the file with a `dup`ed file descriptor so that the original `ActionDispatch::Http::UploadedFile` is left untouched until I really use it in my own code.

The scenario in itself is not really interesting, it is just I was surprised by the behaviour when I used `Tempfile#dup` but your explanation is acceptable. Thanks for this.

----------------------------------------
Bug #19441: Closing an Tempfile#dup behaviour
https://bugs.ruby-lang.org/issues/19441#change-101930

* Author: stac47 (Laurent Stacul)
* Status: Open
* Priority: Normal
* ruby -v: ruby 3.2.1 (2023-02-08 revision 31819e82c8) [x86_64-darwin20]
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
Hello amazing ruby folks!

I classified that ticket as a "Bug" although it is perhaps something I did not understand.

Here is a ruby session:

``` ruby
irb(main):001:0> file = Tempfile.new
=> #<File:/var/folders/m2/bljzrgq160vbf0vk466k_7gw0000gn/T/20230216-39664-davfmj>
irb(main):002:0> file.fileno
=> 9
irb(main):003:0> dup = file.dup
=> #<File:/var/folders/m2/bljzrgq160vbf0vk466k_7gw0000gn/T/20230216-39664-davfmj>
irb(main):004:0> dup.fileno
=> 10
irb(main):005:0> dup.close
=> nil
irb(main):006:0> dup.closed?
=> false
irb(main):007:0> file.closed?
=> true
```

The two last lines are unexpected to me. I would have expected the converse:

```ruby
irb(main):006:0> dup.closed?
=> true
irb(main):007:0> file.closed?
=> false
```

I tried this scenario in latest ruby but also in ruby 2.7.

Thanks in advance for helping me to understand this behaviour.



-- 
https://bugs.ruby-lang.org/
 ______________________________________________
 ruby-core mailing list -- [e-mail]
 To unsubscribe send an email to [e-mail]
 ruby-core info -- https://ml.ruby-lang.org/mailman3/postorius/lists/ruby-core.ml.ruby-lang.org/