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# -*- coding: binary -*-
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require 'postgres_msf'
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require 'postgres/binary_writer'
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require 'postgres/binary_reader'
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# Namespace for Metasploit branch.
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module Msf
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module Db
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# Fixed size buffer.
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class Buffer
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  class Error < RuntimeError; end
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  class EOF < Error; end
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  def self.from_string(str)
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    new(str)
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  end
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  def self.of_size(size)
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    raise ArgumentError if size < 0
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    new('#' * size)
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  end
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  def initialize(content)
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    @size = content.size
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    @content = content
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    @position = 0
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  end
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  def size
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    @size
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  end
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  def position
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    @position
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  end
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  def peek
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    @content[@position]
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  end
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  def position=(new_pos)
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    raise ArgumentError if new_pos < 0 or new_pos > @size
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    @position = new_pos
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  end
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  def at_end?
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    @position == @size
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  end
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  def content
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    @content
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  end
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  def read(n)
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    raise EOF, 'cannot read beyond the end of buffer' if @position + n > @size
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    str = @content[@position, n]
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    @position += n
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    str
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  end
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  def write(str)
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    sz = str.size
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    raise EOF, 'cannot write beyond the end of buffer' if @position + sz > @size
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    @content[@position, sz] = str
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    @position += sz
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    self
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  end
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  def copy_from_stream(stream, n)
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    raise ArgumentError if n < 0
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    while n > 0
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      str = stream.read(n)
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      write(str)
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      n -= str.size
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    end
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    raise if n < 0
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  end
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  NUL = "\000"
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  def write_cstring(cstr)
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    raise ArgumentError, "Invalid Ruby/cstring" if cstr.include?(NUL)
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    write(cstr)
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    write(NUL)
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  end
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  # returns a Ruby string without the trailing NUL character
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  def read_cstring
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    nul_pos = @content.index(NUL, @position)
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    raise Error, "no cstring found!" unless nul_pos
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    sz = nul_pos - @position
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    str = @content[@position, sz]
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    @position += sz + 1
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    return str
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  end
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  # read till the end of the buffer
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  def read_rest
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    read(self.size-@position)
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  end
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  include BinaryWriterMixin
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  include BinaryReaderMixin
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end
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end
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end
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