[#99868] [Ruby master Bug#17144] Tempfile.open { ... } does not unlink the file — eregontp@...
Issue #17144 has been reported by Eregon (Benoit Daloze).
15 messages
2020/09/03
[ruby-core:99881] [Ruby master Bug#17144] Tempfile.open { ... } does not unlink the file
Issue #17144 has been updated by Dan0042 (Daniel DeLorme).
-1 for breaking compatibility with no deprecation, just for the sake of perceived consistency.
But then again it's important to note that `Tempfile.open{ }` returns nil, so the only way to cause an incompatibility is if the blocks "leaks" the Tempfile reference, like `Tempfile.open{ @f = _1 }` or `Tempfile.open{ return _1 }`
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Bug #17144: Tempfile.open { ... } does not unlink the file
https://bugs.ruby-lang.org/issues/17144#change-87410
* Author: Eregon (Benoit Daloze)
* Status: Open
* Priority: Normal
* Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN
----------------------------------------
```
ruby -rtempfile -e 'Tempfile.open("txt") { |f| $path = f.path }; p File.exist?($path)'
true
```
but it should be `false`.
This means even after the block finishes to execute the file still exists on a disk
And this might or not be addressed by finalization much later on.
This is inconsistent with the resource block pattern and basically all usages of `SomeClass.open { ... }`.
There are more than 10 SomeClass.open in core+stdlib, and AFAIK all these methods release all resources at the end of the block, except Tempfile.open.
Since the block creates the file, it should also delete it, so there are no leftovers after the block.
The (English) docs don't mention the file is kept on disk after the block:
https://docs.ruby-lang.org/en/2.7.0/Tempfile.html#method-c-open
I made a PR to do unlink in https://github.com/ruby/tempfile/pull/3 and some commits in ruby/ruby (notably https://github.com/ruby/ruby/commit/fa21985a7a2f8f52a8bd82bd12a724e9dca74934).
However it can cause some incompatibility, if an existing usage relied on the block only closing the file descriptor but not unlink the path.
See https://github.com/ruby/tempfile/issues/2#issuecomment-686323507
When integrating this change in ruby/ruby, I found that many usages expected that the file be unlinked automatically, but had to add an extra `ensure tempfile.close!` on top of the block:
https://github.com/ruby/ruby/commit/e8c3872555fc85640505974e6b1c39d315572689 (later partially reverted because such libraries probably want to keep compat with older Rubies)
In all of ruby/ruby I found only [2 usages](https://github.com/ruby/ruby/commit/3beecafc2cae86290a191c1e841be13f5b08795d) depending on the file to still be on disk after the block.
@shugo brought to my attention that `Tempfile.create { ... }` unlinks the file (Tempfile.create seems to exist since 2.1 yet very few seem to know about it).
I think the semantics of `Tempfile.create { ... }` is what the vast majority of usages want for `Tempfile.open { ... }`.
`open` is the name everyone expects, so I think it's best if `Tempfile.open { ... }` also links.
`create` doesn't sound like it will cleanup to me.
As an optimization we can use `Tempfile.create(&block)` to implement `Tempfile.open { ... }` to avoid creating needlessly a finalizer.
Found by https://github.com/ruby/spec/commit/d347e89ef6c817e469a1c25985dbd729c52b80fd and the leak detector.
From https://github.com/ruby/tempfile/issues/2
So, OK to keep this change and make `Tempfile.open { ... }` do what most usages expect,
even if we have to update a few usages that relied on the file to still exist after the block?
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