bpf_postprocess.rb

#!/usr/bin/env ruby

require 'open3'

@allocated_addrs = {}
@allocation_time = {}
@symbol_cache = {}
@app_pid = ARGV[0]

def resolve_symbol(addr)
  return @symbol_cache[addr] if @symbol_cache[addr]
  output, err, st = Open3.capture3('gdb', '-p', @app_pid, '-ex', "info line * #{addr}", stdin_data: "")
  raise "fail: #{st}" unless st.success?
  output.each_line do |l|
    if l =~ /Line ([0-9]+) of "([^"]+)"/
      ln = "#{$2}:#{$1}"
      @symbol_cache[addr] = ln
      return ln
    end
  end
  ln = "Unknown <#{addr}>"
  @symbol_cache[addr] = ln
  return ln
end

cur_ptr = nil
STDIN.each_line do |ln|
  if ln =~ /@allocated_addrs\[([0-9]+)\]:/
    cur_ptr = $1.to_i
  elsif ln =~ /@allocation_time\[([0-9]+)\]: ([0-9]+)/
    @allocation_time[$1.to_i] = $2.to_i
  elsif ln =~ /^\s*(0x[0-9a-f]*)$/
    @allocated_addrs[cur_ptr] ||= []
    @allocated_addrs[cur_ptr] << $1
  end
end


@allocation_time.sort_by { |k, v| v}.each do |ptr, t|
  stack = @allocated_addrs[ptr]
  puts "Pointer at #{ptr}:"
  stack&.each do |s|
    puts "    #{resolve_symbol s}"
  end
end