dbg-sig.inc

bash debugger. You can use this tool to debug bash shell script

# dbg-sig.inc - Bourne Again Shell Debugger Signal handling routines
#
#   Copyright (C) 2002, 2003, 2004, 2006, 2007 Rocky Bernstein 
#   [e-mail]
#
#   Bash is free software; you can redistribute it and/or modify it under
#   the terms of the GNU General Public License as published by the Free
#   Software Foundation; either version 2, or (at your option) any later
#   version.
#
#   Bash is distributed in the hope that it will be useful, but WITHOUT ANY
#   WARRANTY; without even the implied warranty of MERCHANTABILITY or
#   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
#   for more details.
#
#   You should have received a copy of the GNU General Public License along
#   with Bash; see the file COPYING.  If not, write to the Free Software
#   Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA.

# ==================== VARIABLES =======================================

# The "set" options in effect ($-) before debugger was invoked.
typeset _Dbg_old_setopts

# Place to save debugged program's exit handler, if any.
typeset _Dbg_old_EXIT_handler=''  

typeset BASHDB_RESTART_COMMAND=''
typeset -i BASHDB_QUIT_ON_QUIT=0

# Return code that debugged program reports
typeset -i _Dbg_program_exit_code=0

# This is set to 1 if you want to debug debugger routines, i.e. routines
# which start _Dbg_. But you better should know what you are doing
# if you do this or else you may get into a recursive loop.
typeset -i _Dbg_debug_debugger=0

############################################################
## Signal arrays: These are indexed by the signal number. ##
############################################################

# Should we print that a signal was intercepted? 
# Each entry is "print" or "noprint" or null.
typeset -a _Dbg_sig_print=()

# Should we reentry the debugger command loop on receiving the signal? 
# Each entry is "stop" or "nostop" or null.
typeset -a _Dbg_sig_stop=()

# Should we show a traceback on receiving the signal? 
# Each entry is "stack" or "nostack" or null.
typeset -a _Dbg_sig_show_stack=()

# Should pass the signal to the user program?? 
# Each entry is the trap handler with some variables substituted.
typeset -a _Dbg_sig_passthrough=()

# Should pass the signal to the user program?? 
# Each entry is the trap handler with some variables substituted.
typeset -i _Dbg_return_level=0

# Place to save values of $1, $2, etc.
typeset -a _Dbg_arg=()

# ===================== FUNCTIONS =======================================

# We come here after before statement is run. This is the function named
# in trap SIGDEBUG.

# Note: We have to be careful here in naming "local" variables. In contrast
# to other places in the debugger, because of the read/eval loop, they are
# in fact seen by those using the debugger. So in contrast to other "local"s
# in the debugger, we prefer to preface these with _Dbg_.

_Dbg_debug_trap_handler() {

  ### The below is also copied below in _Dbg_sig_handler...
  ### Should put common stuff into a function.

  # Consider putting the following line(s) in a routine.
  # Ditto for the restore environment
  local -i _Dbg_debugged_exit_code=$?
  _Dbg_old_set_opts=$-
  shopt -s extdebug

  # Turn off line and variable trace listing if were not in our own debug
  # mode, and set our own PS4 for debugging inside the debugger
  (( !_Dbg_debug_debugger )) && set +x +v +u

  # If we are in our own routines -- these start with _bashdb -- then
  # return.
  if [[ ${FUNCNAME[1]} == _Dbg_* ]] && ((  !_Dbg_debug_debugger )); then
    _Dbg_set_to_return_from_debugger 0
    return 0
  fi

  _Dbg_set_debugger_entry

  local -i _Dbg_rc=0

  # Shift off "RETURN";  we do not need that any more.
  shift 

  _Dbg_bash_command=$1
  shift

  # Save values of $1 $2 $3 when debugged program was stopped
  # We use the loop below rather than _Dbg_set_args="(@)" because
  # we want to preserve embedded blanks in the arguments.
  local -i _Dbg_n=${#@}
  local -i _Dbg_i
  local -i _Dbg_arg_max=${#_Dbg_arg[@]}

  # If there has been a shift since the last time we entered,
  # it is possible that _Dbg_arg will contain too many values.
  # So remove those that have disappeared.
  for (( _Dbg_i=_Dbg_arg_max; _Dbg_i > _Dbg_n ; _Dbg_i-- )) ; do
      unset _Dbg_arg[$_Dbg_i]
  done
 
  # Populate _Dbg_args with $1, $2, etc.
  for (( _Dbg_i=1 ; _Dbg_n > 0; _Dbg_n-- )) ; do
    _Dbg_arg[$_Dbg_i]=$1
    ((_Dbg_i++))
    shift
  done
  unset _Dbg_arg[0]       # Get rid of line number; makes array count
                          # correct; also listing all _Dbg_arg works
                          # like $*.

  # Read in the journal to pick up variable settings that might have
  # been left from a subshell.
  _Dbg_source_journal

  if (( $BASHDB_QUIT_LEVELS > 0 )) ; then
    _Dbg_do_quit $_Dbg_debugged_exit_code
  fi

  # if in step mode, decrement counter
  if ((_Dbg_steps >= 0)) ; then 
    ((_Dbg_steps--))
    _Dbg_write_journal "_Dbg_steps=$_Dbg_steps"
  fi

  # look for watchpoints.
  local -i _Dbg_i
  for (( _Dbg_i=0; _Dbg_i < _Dbg_watch_max ; _Dbg_i++ )) ; do
    if [ -n "${_Dbg_watch_exp[$_Dbg_i]}" ] \
      && [[ ${_Dbg_watch_enable[_Dbg_i]} != 0 ]] ; then
      local new_val=`_Dbg_get_watch_exp_eval $_Dbg_i`
      local old_val=${_Dbg_watch_val[$_Dbg_i]}
      if [[ $old_val != $new_val ]] ; then
	((_Dbg_watch_count[_Dbg_i]++))
	_Dbg_msg "Watchpoint $i: ${_Dbg_watch_exp[$_Dbg_i]} changed:"
	_Dbg_msg "  old value: '$old_val'"
	_Dbg_msg "  new value: '$new_val'"
	_Dbg_print_source_line
	_Dbg_watch_val[$_Dbg_i]=$new_val
	_Dbg_cmdloop
	_Dbg_set_to_return_from_debugger 1
	return $_Dbg_rc
      fi
    fi
  done

  # Run applicable action statement
  local entries=`_Dbg_get_assoc_array_entry "_Dbg_action_$_cur_filevar" $_curline`
  if [[ $entries != "" ]]  ; then
    local -i _Dbg_i
    for _Dbg_i in $entries ; do
      if [[ ${_Dbg_action_enable[_Dbg_i]} != 0 ]] ; then
	. ${_Dbg_libdir}/dbg-set-d-vars.inc
	eval "${_Dbg_action_stmt[$_Dbg_i]}"
      fi
    done
  fi

  # check if breakpoint reached
  local -r entries=`_Dbg_get_assoc_array_entry "_Dbg_brkpt_$_cur_filevar" $_curline`
  if [[ $entries != "" ]]  ; then
    local -i _Dbg_i
    for _Dbg_i in $entries ; do
      if [[ ${_Dbg_brkpt_enable[_Dbg_i]:0} != 0 ]] ; then
	local -i cond
	. ${_Dbg_libdir}/dbg-set-d-vars.inc
	eval let cond=${_Dbg_brkpt_cond[$_Dbg_i]:0}
	if [[ $cond != 0 ]] ; then
	  ((_Dbg_brkpt_count[_Dbg_i]++))
	  if [[ ${_Dbg_brkpt_onetime[_Dbg_i]:0} == 1 ]] ; then
	    _Dbg_stop_reason='at a breakpoint that has since been deleted'
	    _Dbg_delete_brkpt_entry $_Dbg_i
	  else
	    _Dbg_stop_reason='at breakpoint'
	    _Dbg_currentbp=$_Dbg_i
	    _Dbg_msg \
              "Breakpoint $_Dbg_i hit (${_Dbg_brkpt_count[$_Dbg_i]} times)."
	  fi
	  # We're sneaky and check commands_end because start could 
	  # legitimately be 0.
	  if (( ${_Dbg_brkpt_commands_end[$_Dbg_i]} )) ; then
	      # Run any commands associated with this breakpoint
	      _Dbg_bp_commands $_Dbg_i
	  fi
	  _Dbg_print_source_line
	  _Dbg_cmdloop		# enter debugger
	  _Dbg_set_to_return_from_debugger 1
	  return $_Dbg_rc
	fi
      fi

    done
  fi

  # next, check if step mode and no. of steps is up
  if ((_Dbg_steps == 0)); then
    _Dbg_stop_reason='after being stepped'
    _Dbg_print_source_line
    # _Dbg_msg "Stopped at line $_curline"
    _Dbg_cmdloop		# enter debugger
    _Dbg_set_to_return_from_debugger 1
    return $_Dbg_rc
  elif (( ${#FUNCNAME[@]} == _Dbg_return_level )) ; then
    # here because a trap RETURN
    _Dbg_stop_reason='on a return'
    _Dbg_return_level=0
    _Dbg_print_source_line
    _Dbg_cmdloop		# enter debugger
    _Dbg_set_to_return_from_debugger 1
    return $_Dbg_rc
  elif (( -1 == _Dbg_return_level )) ; then
    # here because we are fielding a signal.
    _Dbg_stop_reason='on fielding signal'
    _Dbg_print_source_line
    _Dbg_cmdloop		# enter debugger
    _Dbg_set_to_return_from_debugger 1
    return $_Dbg_rc
  else
    if ((_Dbg_linetrace==1)) ; then 
      if ((_Dbg_linetrace_delay)) ; then
	  sleep $_Dbg_linetrace_delay
      fi
      _Dbg_print_linetrace
    fi
  fi
  _Dbg_set_to_return_from_debugger 1
  return $_Dbg_inside_skip
}

# Cleanup routine: erase temp files before exiting.
_Dbg_cleanup() {
  rm $_Dbg_evalfile 2>/dev/null
  _Dbg_erase_journals
  _Dbg_restore_user_vars
}

# Somehow we can't put this in _Dbg_cleanup and have it work.
# I am not sure why.
_Dbg_cleanup2() {
  _Dbg_erase_journals
  trap - EXIT
}

# The real way to leave this program.
_Dbg_do_quit() {
  local -i return_code=${1:-$_Dbg_program_exit_code}

  local -i desired_quit_levels=${2:-0}

  if (( desired_quit_levels == 0 \
    || desired_quit_levels > BASH_SUBSHELL+1)) ; then
    ((desired_quit_levels=BASH_SUBSHELL+1))
  fi

  ((BASHDB_QUIT_LEVELS+=desired_quit_levels))

  # Reduce the number of recorded levels that we need to leave by
  # if BASHDB_QUIT_LEVELS is greater than 0.
  ((BASHDB_QUIT_LEVELS--))

  ## write this to the next level up can read it.
  _Dbg_write_journal "BASHDB_QUIT_LEVELS=$BASHDB_QUIT_LEVELS"

  # Reset signal handlers to their default but only if 
  # we are not in a subshell.
  if (( BASH_SUBSHELL == 0 )) ; then

    # If we were told to restart from deep down, restart instead of quit.
    if [ -n "$BASHDB_RESTART_COMMAND" ] ; then 
      _Dbg_erase_journals
      _Dbg_save_state
      exec $BASHDB_RESTART_COMMAND
    fi

    _Dbg_cleanup
    trap - DEBUG
    # This is a hack we need. I am not sure why.
    trap "_Dbg_cleanup2" EXIT
  fi

  # And just when you thought we'd never get around to it...
  exit $return_code
}

# Save value of handler variable _Dbg_old_$sig
_Dbg_save_handler() {
  local -r sig=$1
  local old_handler='#unset#';
  if [[ `trap -p $sig` ]] ; then 
    old_handler=`trap -p $sig`
  fi
  if [[ $old_handler != '#unset#' ]] ; then
    local -a old_hand_a
    old_hand_a=($old_handler)
    old_handler=`_Dbg_subst_handler_var ${old_hand_a[2]}`
    local -r decl_cmd="typeset -r _Dbg_old_${sig}_handler='$old_handler'"
    eval $decl_cmd
  fi
  
}

# Adjust handler variables to take into account the fact that when we
# call the handler we will have added another call before the user's
# handler.