# frozen_string_literal: true
# Released under the MIT License.
# Copyright, 2019-2022, by Samuel Williams.
module Rackup
# The input stream is an IO-like object which contains the raw HTTP POST data. When applicable, its external encoding must be “ASCII-8BIT” and it must be opened in binary mode, for Ruby 1.9 compatibility. The input stream must respond to gets, each, read and rewind.
class Stream
def initialize(input = nil, output = Buffered.new)
@input = input
@output = output
raise ArgumentError, "Non-writable output!" unless output.respond_to?(:write)
# Will hold remaining data in `#read`.
@buffer = nil
@closed = false
end
attr :input
attr :output
# This provides a read-only interface for data, which is surprisingly tricky to implement correctly.
module Reader
# rack.hijack_io must respond to:
# read, write, read_nonblock, write_nonblock, flush, close, close_read, close_write, closed?
# read behaves like IO#read. Its signature is read([length, [buffer]]). If given, length must be a non-negative Integer (>= 0) or nil, and buffer must be a String and may not be nil. If length is given and not nil, then this method reads at most length bytes from the input stream. If length is not given or nil, then this method reads all data until EOF. When EOF is reached, this method returns nil if length is given and not nil, or “” if length is not given or is nil. If buffer is given, then the read data will be placed into buffer instead of a newly created String object.
# @param length [Integer] the amount of data to read
# @param buffer [String] the buffer which will receive the data
# @return a buffer containing the data
def read(length = nil, buffer = nil)
return '' if length == 0
buffer ||= String.new.force_encoding(Encoding::BINARY)
# Take any previously buffered data and replace it into the given buffer.
if @buffer
buffer.replace(@buffer)
@buffer = nil
else
buffer.clear
end
if length
while buffer.bytesize < length and chunk = read_next
buffer << chunk
end
# This ensures the subsequent `slice!` works correctly.
buffer.force_encoding(Encoding::BINARY)
# This will be at least one copy:
@buffer = buffer.byteslice(length, buffer.bytesize)
# This should be zero-copy:
buffer.slice!(length, buffer.bytesize)
if buffer.empty?
return nil
else
return buffer
end
else
while chunk = read_next
buffer << chunk
end
return buffer
end
end
# Read at most `length` bytes from the stream. Will avoid reading from the underlying stream if possible.
def read_partial(length = nil)
if @buffer
buffer = @buffer
@buffer = nil
else
buffer = read_next
end
if buffer and length
if buffer.bytesize > length
# This ensures the subsequent `slice!` works correctly.
buffer.force_encoding(Encoding::BINARY)
@buffer = buffer.byteslice(length, buffer.bytesize)
buffer.slice!(length, buffer.bytesize)
end
end
return buffer
end
def gets
read_partial
end
def each
while chunk = read_partial
yield chunk
end
end
def read_nonblock(length, buffer = nil)
@buffer ||= read_next
chunk = nil
unless @buffer
buffer&.clear
return
end
if @buffer.bytesize > length
chunk = @buffer.byteslice(0, length)
@buffer = @buffer.byteslice(length, @buffer.bytesize)
else
chunk = @buffer
@buffer = nil
end
if buffer
buffer.replace(chunk)
else
buffer = chunk
end
return buffer
end
end
include Reader
def write(buffer)
if @output
@output.write(buffer)
return buffer.bytesize
else
raise IOError, "Stream is not writable, output has been closed!"
end
end
def write_nonblock(buffer)
write(buffer)
end
def <<(buffer)
write(buffer)
end
def flush
end
def close_read
@input&.close
@input = nil
end
# close must never be called on the input stream. huh?
def close_write
if @output.respond_to?(:close)
@output&.close
end
@output = nil
end
# Close the input and output bodies.
def close(error = nil)
self.close_read
self.close_write
return nil
ensure
@closed = true
end
# Whether the stream has been closed.
def closed?
@closed
end
# Whether there are any output chunks remaining?
def empty?
@output.empty?
end
private
def read_next
if @input
return @input.read
else
@input = nil
raise IOError, "Stream is not readable, input has been closed!"
end
end
end
end
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