Bug #17675: StringIO#each_byte doesn't check for readabilty while iterating - Ruby master - Ruby Issue Tracking System

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Bug #17675

closed

StringIO#each_byte doesn't check for readabilty while iterating

Added by wyhaines (Kirk Haines) almost 4 years ago. Updated about 3 years ago.

Status:

Closed

Assignee:

Target version:

ruby -v:

Backport:

2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: DONE

[ruby-core:102764]

Description

Bug #17661 is a failure to check readability on each_byte of an IO, causing a segmentation fault.

StringIO has an independent, but related implementation, and it shares the same flaw in its implementation, where it fails to check for the readability of the StringIO object while iterating over the bytes. Unlike IO, this does not result in a segmentation fault. It does, however, allow the continued reading from an object that has been closed.

require "stringio"

strio = StringIO.new
strio.each_byte do |byte|
  puts byte
  strio.close
end

That code should print the first byte, and then throw an IOError, but instead, it iterates through the entire data buffer for the object, calling the block for each byte, without ever raising an exception.

I have a PR for this which I will submit on Github and link to.
The PR simply inserts an appropriate check into the loop for each_byte.