Class: Backdat::Daemon

Inherits:
Object
  • Object
show all
Defined in:
lib/backdat/daemon.rb

Overview

Daemon helper routines.

Class Attribute Summary collapse

Class Method Summary collapse

Class Attribute Details

.name ⇒ Object

Returns the value of attribute name.



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# File 'lib/backdat/daemon.rb', line 6

def name
  @name
end

Class Method Details

._change_privilege(user, group = user) ⇒ Object

Note:

The group parameter defaults to user unless specified.

Change privileges of the process to be the specified user and group

Parameters:

  • user (String) —

    The user to change the process to.

  • group (String) (defaults to: user) —

    The group to change the process to.



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# File 'lib/backdat/daemon.rb', line 122

def _change_privilege(user, group=user)
  uid, gid = Process.euid, Process.egid

  begin
    target_uid = Etc.getpwnam(user).uid
  rescue ArgumentError => e
    msg =  "Failed to get UID for user #{user}, does it exist? "
    msg << e.message
    Backdat::Application.fatal!(msg)
    return false
  end
 
  begin
    target_gid = Etc.getgrnam(group).gid
  rescue ArgumentError => e
    msg =  "Failed to get GID for group #{group}, does it exist? "
    msg << e.message
    Backdat::Application.fatal!(msg)
    return false
  end

  if (uid != target_uid) or (gid != target_gid)
    Process.initgroups(user, target_gid)
    Process::GID.change_privilege(target_gid)
    Process::UID.change_privilege(target_uid)
  end
  true
rescue Errno::EPERM => e
  msg =  "Permission denied when trying to change #{uid}:#{gid} "
  msg << "to #{target_uid}:#{target_gid}. #{e.message}"
  Backdat::Application.fatal!(msg)
end

.change_privilege ⇒ Object

Change process user/group to those specified in Backdat::Config



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# File 'lib/backdat/daemon.rb', line 100

def change_privilege
  Dir.chdir("/")

  msg =  "About to change privilege to "
  if Backdat::Config[:user] and Backdat::Config[:group]
    msg << "#{Backdat::Config[:user]}:#{Backdat::Config[:group]}"
    Backdat::Log.info(msg)
    _change_privilege(Backdat::Config[:user], Backdat::Config[:group])
  elsif Backdat::Config[:user]
    msg << "#{Backdat::Config[:user]}"
    Backdat::Log.info(msg)
    _change_privilege(Backdat::Config[:user])
  end
end

.daemonize(name) ⇒ Object

Daemonize the current process, managing pidfiles and process uid/gid.

Parameters:

  • name (String) —

    The name to be used for the pid file



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# File 'lib/backdat/daemon.rb', line 11

def daemonize(name)
  @name = name
  pid = pid_from_file
  unless running?
    remove_pid_file()
    Backdat::Log.info("Daemonizing...")
    begin
      exit if fork; Process.setsid; exit if fork
      msg =  "Forked, in #{Process.pid}. "
      msg << "Privileges: #{Process.euid} #{Process.egid}"
      Backdat::Log.info(msg)
      File.umask Backdat::Config[:umask]
      $stdin.reopen("/dev/null")
      $stdout.reopen("/dev/null", "a")
      $stderr.reopen($stdout)
      save_pid_file;
      at_exit { remove_pid_file }
    rescue NotImplementedError => e
      Backdat::Application.fatal!("There is no fork: #{e.message}")
    end
  else
    Backdat::Application.fatal!("Backdat is already running pid #{pid}")
  end
end

.pid_file ⇒ String

Gets the pid file for @name.

Returns:

  • (String) —

    Location of the pid file for @name.



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# File 'lib/backdat/daemon.rb', line 57

def pid_file
   Backdat::Config[:pid_file] or "/tmp/#{@name}.pid"
end

.pid_from_file ⇒ Fixnum, NilClass

Sucks the pid out of pid_file.

Returns:

  • (Fixnum, NilClass) —

    The PID from pid_file or nil if it doesn’t exist.



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# File 'lib/backdat/daemon.rb', line 64

def pid_from_file
  File.read(pid_file).chomp.to_i
rescue Errno::ENOENT, Errno::EACCES
  nil
end

.remove_pid_file ⇒ Object

Delete the PID from the filesystem



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# File 'lib/backdat/daemon.rb', line 95

def remove_pid_file
  FileUtils.rm(pid_file) if File.exists?(pid_file)
end

.running? ⇒ true, false

Checks if Backdat is running based on the pid_file.

Returns:

  • (true, false) —

    Whether or not Backdat is running.



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# File 'lib/backdat/daemon.rb', line 39

def running?
  if pid_from_file.nil?
    false
  else
    Process.kill(0, pid_from_file)
    true
  end
rescue Errno::ESRCH, Errno::ENOENT
  false
rescue Errno::EACCES => e
  msg =  "You don't have access to the PID "
  msg << "file at #{pid_file}: #{e.message}"
  Backdat::Application.fatal!(msg)
end

.save_pid_file ⇒ Object

Note:

This uses the Backdat::Config option or “/tmp/name.pid” by default.

Store the PID on the filesystem.



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# File 'lib/backdat/daemon.rb', line 75

def save_pid_file
  file = pid_file
  begin
    FileUtils.mkdir_p(File.dirname(file))
  rescue Errno::EACCES => e
    msg =  "Failed store pid in #{File.dirname(file)}, "
    msg << "permission denied: #{e.message}"
    Backdat::Application.fatal!(msg)
  end

  begin
    File.open(file, "w") { |f| f.write(Process.pid.to_s) }
  rescue Errno::EACCES => e
    msg =  "Couldn't write to pidfile #{file}, "
    msg << "permission denied: #{e.message}"
    Backdat::Application.fatal!(msg)
  end
end