#!/usr/bin/ruby

require 'flexnbd'

binary      = ARGV.shift
test_size   = ARGV.shift.to_i
repetitions = ARGV.shift.to_i
repetitions = 50 if repetitions == 0
seed        = ARGV.shift.to_i

max_length  = test_size > 10000000 ? 10000000 : test_size
CHEAT_AND_ROUND_DOWN = false # set to 'false' to expose bugs

srand(seed)

if test_size < 32768 || repetitions < 1 || !File.executable?(binary)
  STDERR.print "Syntax: #{$0} <flexnbd bin> <test size> [repetitions] [seed]\n"
  STDERR.print "test_size must be >= 32768 and repeitions must be >= 1"
  exit 1
end

testname_local = "#{$0}.test.#{$$}.local"
testname_serve = "#{$0}.test.#{$$}.serve"
[testname_local, testname_serve].each do |name|
  File.open(name, "w+") { |fh| fh.seek(test_size-1, IO::SEEK_SET); fh.write("0") }
end

@local = File.open(testname_local, "r+")

@serve = FlexNBD.new(binary, "127.0.0.1", 41234)
@serve.serve(testname_serve)

repetitions.times do |n|

  begin
  
    if File.size(testname_local) != File.size(testname_serve)
      STDERR.print "Before pass #{n}: File sizes are different: local=#{File.size(testname_local)} serve=#{File.size(testname_serve)}\n"
      exit 1;
    end

    md5_local = `md5sum < #{testname_local}`.split(" ").first
    md5_serve = `md5sum < #{testname_serve}`.split(" ").first
  
    if md5_local != md5_serve
      STDERR.print "Before pass #{n}: MD5 error: local=#{md5_local} serve=#{md5_serve}\n"
      STDERR.print "**** Local contents:\n"
      system("hexdump #{testname_local}")
      STDERR.print "**** Serve contents:\n"
      system("hexdump #{testname_serve}")
      exit 1
    end

    length = rand(max_length)
    length &= 0xfffff000 if CHEAT_AND_ROUND_DOWN
    offset = rand(test_size - length)
    offset &= 0xfffff000 if CHEAT_AND_ROUND_DOWN
    content = (n%2 == 1) ? ("x" * length) : ("\0" * length)
  
    @local.seek(offset, IO::SEEK_SET)
    @local.write(content)
  
    @serve.write(offset, content)
  
    if @serve.read(offset, length) != content
      STDERR.print "After pass #{n}: Didn't read back what we wrote!"
      exit 1
    end
    
  rescue StandardError => ex
    STDERR.print "During pass #{n}: Exception: #{ex}"
    STDERR.print ex.backtrace.join("\n") + "\n"
    exit 2
  end
  
end

File.unlink(testname_local)
File.unlink(testname_serve)