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