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https://issues.apache.org/jira/browse/THRIFT-6138?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dmytro Shteflyuk resolved THRIFT-6138.
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Fix Version/s: 0.25.0
Resolution: Fixed
> Ruby MemoryBufferTransport should privately own initial buffers
> ---------------------------------------------------------------
>
> Key: THRIFT-6138
> URL: https://issues.apache.org/jira/browse/THRIFT-6138
> Project: Thrift
> Issue Type: Bug
> Components: Ruby - Library
> Reporter: Dmytro Shteflyuk
> Assignee: Dmytro Shteflyuk
> Priority: Major
> Fix For: 0.25.0
>
> Time Spent: 50m
> Remaining Estimate: 0h
>
> h3. Problem
> {{MemoryBufferTransport}} stores a caller-supplied String as its internal
> buffer. The transport and caller therefore continue to share the same mutable
> object.
> A caller can change unread transport data by modifying the original String,
> while writes through the transport modify the caller's String. An
> already-binary frozen String is accepted during construction but later raises
> {{FrozenError}} when the transport writes to or resets its buffer.
> Construction can also change a mutable caller String's encoding to
> {{ASCII-8BIT}}.
> h3. Client impact
> Ruby clients that construct a memory transport from a String must currently
> duplicate that String themselves to avoid shared mutation. Reusing or
> freezing the input can otherwise change the bytes observed by the transport
> or cause an exception during a later operation. The behavior is the same with
> and without the native extension.
> Changing the transport to own its initial buffer deliberately removes the
> historical shared-buffer behavior. Callers that intentionally used the
> original String as a live view of the transport would no longer observe
> transport writes through that object.
> h3. Reproduction
> {code:ruby}
> require "thrift"
> source = +"abc"
> transport = Thrift::MemoryBufferTransport.new(source)
> source.replace("xyz")
> puts "caller mutation: #{transport.read(3).inspect}"
> source = +"abc"
> transport = Thrift::MemoryBufferTransport.new(source)
> transport.write("d")
> puts "transport write: #{source.inspect}"
> frozen = "abc".b.freeze
> transport = Thrift::MemoryBufferTransport.new(frozen)
> begin
> transport.write("d")
> rescue => e
> puts "frozen write: #{e.class}: #{e.message}"
> end
> utf8 = +"é"
> Thrift::MemoryBufferTransport.new(utf8)
> puts "caller encoding: #{utf8.encoding}"
> {code}
> Testing on master commit {{e4473c9e296b79003ca04128612e7b6a846a6552}}
> produces:
> {noformat}
> caller mutation: "xyz"
> transport write: "abcd"
> frozen write: FrozenError: can't modify frozen String: "abc"
> caller encoding: ASCII-8BIT
> {noformat}
> h3. Expected behavior
> {{MemoryBufferTransport}} should create a private mutable binary buffer from
> constructor input. Mutating either the caller's String or the transport
> should not affect the other object. Frozen input should remain usable for
> subsequent writes and resets, and construction should not change the caller's
> encoding.
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