Bug #18805: IO::Buffer is inconsistent when returning a string from an empty buffer

• Status: Closed
• Assignee: ioquatix (Samuel Williams)
• Target version: -

[procmarco (Marco Concetto Rudilosso)]

I’ve been using IO::Buffer and I found it to be slightly inconsistent when it comes to returning empty string for empty buffers.
for example, a slice of an allocated buffer with size = 0, returns "" with get_string, as an example:

buffer = IO::Buffer.new(5)
empty_buffer = buffer.slice(0,0)
puts empty_buffer.size # this prints 0
empty_buffer.get_string # this returns ""

but, if you create a buffer with IO::Buffer.new(0) then it stops working

empty_buffer = IO::Buffer.new(0)
puts empty_buffer.size # this prints 0
empty_buffer.get_string # this raises The buffer is not allocated! (IO::Buffer::AllocationError)

Is this working as intended? It would be good I think to have a consistent experience where the base case (buffer with size 0) always returns an empty string.
I have a prototype of a possible patch I could send upstream to fix it, which would check the size of the buffer and if 0 it would always return an empty string.

[jeremyevans0 (Jeremy Evans)]

• Assignee set to ioquatix (Samuel Williams)

@ioquatix (Samuel Williams) Is this expected behavior or a bug?

[ioquatix (Samuel Williams)]

This is currently working as intended but we could consider changing the behaviour. I understand the use case.

[ioquatix (Samuel Williams)]

• Related to Bug #19542: Operations on zero-sized IO::Buffer are raising added

[ioquatix (Samuel Williams)]

As a 2nd issue was created about the similar issue, I think it's worth improving.

See https://github.com/ruby/ruby/pull/9532 for the proposed changes.

[ioquatix (Samuel Williams)]

• Status changed from Open to Closed

Fixed in https://github.com/ruby/ruby/commit/c5cf4d4e129f64cb69aaf0a829aed068ef1943c4

[ioquatix (Samuel Williams)]

• Backport deleted (2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN)