#!/custom/ree/bin/ruby

# USAGE:
#
# echo "|/path/to/core_helper.rb %p %s %u %g" > /proc/sys/kernel/core_pattern 
#

require 'etc'
require 'net/smtp'

CORE_DIR = "/cores"
TO_EMAIL = "dev@blah.com"
FROM_EMAIL = "core_watcher@blah.com"
MAIL_SERVER = "blah"

class CoreHelper
  def self.start!

    time = Time.now.strftime("%Y-%m-%d-%H:%M")
    corefile = "#{CORE_DIR}/core-#{time}.core"
    cmdline = File.read("/proc/#{ARGV[0]}/cmdline")

    f = File.new("#{CORE_DIR}/core-#{time}-metadata", "w")
    f.puts "PID: #{ARGV[0]}"
    f.puts "Signal: #{ARGV[1]}"
    f.puts "UID: #{Etc.getpwuid(ARGV[2].to_i)[:name]}/#{ARGV[2]}, GID: #{Etc.getgrgid(ARGV[3].to_i)[:name]}/#{ARGV[3]}"
    f.puts "Command line: #{cmdline}"
    f.puts
    f.puts
    f.flush

    core = File.new(corefile, "w")
    begin
      while (chunk = STDIN.read)
        core.write chunk
        break if chunk == nil || chunk.length == 0
      end
    rescue EOFError
      core.close
    end
    core.close

    r,w = IO.pipe
    child = fork{ $stdin.reopen(r); $stdout.reopen(f); $stderr.reopen(f); exec "/usr/bin/gdb -q -c #{corefile}" }
    w.puts "set height 0"
    w.puts "backtrace"
    w.puts "info registers"
    w.puts "x/5i $rip"
    w.puts "quit"
    Process.wait

    msg = <<MESSAGE
From: #{FROM_EMAIL}
To: #{TO_EMAIL}
Subject:  Core dump on #{`hostname`}

#{File.read("#{CORE_DIR}/core-#{time}-metadata")}
MESSAGE

    Net::SMTP.start(MAIL_SERVER) do |smtp|
      smtp.send_message msg, FROM_EMAIL, TO_EMAIL
    end

    f.close

    exit 0
  end
end

CoreHelper.start!