# frozen_string_literal: false require 'fcntl' module Terrapin module MultiPipeExtensions def initialize @stdout_in, @stdout_out = IO.pipe @stderr_in, @stderr_out = IO.pipe clear_nonblocking_flags! end def pipe_options # Add some flags to explicitly close the other end of the pipes { out: @stdout_out, err: @stderr_out, @stdout_in => :close, @stderr_in => :close } end def read # While we are patching Terrapin, fix child process potentially getting stuck on writing # to stderr. @stdout_output = +'' @stderr_output = +'' fds_to_read = [@stdout_in, @stderr_in] until fds_to_read.empty? rs, = IO.select(fds_to_read) read_nonblocking!(@stdout_in, @stdout_output, fds_to_read) if rs.include?(@stdout_in) read_nonblocking!(@stderr_in, @stderr_output, fds_to_read) if rs.include?(@stderr_in) end end private # @param [IO] io IO Stream to read until there is nothing to read # @param [String] result Mutable string to which read values will be appended to # @param [Array<IO>] fds_to_read Mutable array from which `io` should be removed on EOF def read_nonblocking!(io, result, fds_to_read) while (partial_result = io.read_nonblock(8192)) result << partial_result end rescue IO::WaitReadable # Do nothing rescue EOFError fds_to_read.delete(io) end def clear_nonblocking_flags! # Ruby 3.0 sets pipes to non-blocking mode, and resets the flags as # needed when calling fork/exec-related syscalls, but posix-spawn does # not currently do that, so we need to do it manually for the time being # so that the child process do not error out when the buffers are full. stdout_flags = @stdout_out.fcntl(Fcntl::F_GETFL) @stdout_out.fcntl(Fcntl::F_SETFL, stdout_flags & ~Fcntl::O_NONBLOCK) if stdout_flags & Fcntl::O_NONBLOCK stderr_flags = @stderr_out.fcntl(Fcntl::F_GETFL) @stderr_out.fcntl(Fcntl::F_SETFL, stderr_flags & ~Fcntl::O_NONBLOCK) if stderr_flags & Fcntl::O_NONBLOCK rescue NameError, NotImplementedError, Errno::EINVAL # Probably on windows, where pipes are blocking by default end end end Terrapin::CommandLine::MultiPipe.prepend(Terrapin::MultiPipeExtensions)