-#!/bin/bash
-# Bash Error Handler
-# Copyright (C) 2020 Ian Kelling <ian@iankelling.org>
-# SPDX-License-Identifier: GPL-3.0-or-later
-#
-# This program 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 3 of the License, or
-# (at your option) any later version.
-#
-# This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
-
-
-# This is a single file library, just source this file. When an error
-# happens, we print a stack trace then exit. In an interactive shell, we
-# return from functions instead of exiting. If err-cleanup is a command,
-# it runs before the stack trace. Functions are documented inline below
-# for additional use cases.
-#
-# Note: occasionally the line numbers are off a bit (at least in Bash
-# 5.0). This appears to be a bash bug. I plan to report it next time it
-# happens to me.
-#
-# Please email me if you use this or have anything to contribute. I'm
-# not aware of any users yet Ian Kelling <ian@iankelling.org>.
-#
-# Tested on bash 4.4.20(1)-release (x86_64-pc-linux-gnu) and
-# 5.0.17(1)-release (x86_64-pc-linux-gnu).
-#
-# Related: see my bash script template repo at https://iankelling.org/git.
-
-
-# TODO: investigate to see if we can format output betting in case of
-# subshell failure. Right now, we get independent trace from inside and
-# outside of the subshell. Note, errexit + inherit_errexit doesn't have
-# any smarts around this either.
-
-if ! test "$BASH_VERSION"; then echo "error: shell is not bash" >&2; exit 1; fi
-
-#######################################
-# err-catch: Setup trap on ERR to print stack trace and exit (or return
-# if the shell is interactive). This is the most common use case so we
-# run it after defining it, you can call err-allow to undo that.
-#
-# This also sets pipefail because it's a good practice to catch more
-# errors.
-#
-# Note: In interactive shell, stack calling line number is not
-# available, so we print function definition lines.
-#
-# Note: This works like set -e, which has one unintuitive feature: If
-# you use a function as part of a conditional, eg: func && come_cmd, a
-# failed command within func won't trigger an error.
-#
-# Globals
-#
-# err_catch_ignore Array containing glob patterns to test against
-# filenames to ignore errors from in interactive
-# shell. Initialized to ignore bash-completion
-# scripts on debian based systems.
-#
-# err-cleanup If set, this command will run just before exiting.
-#
-# _err_func_last Used internally in err-bash-trace-interactive
-#
-#######################################
-err-catch() {
- set -E;
- if [[ $- == *i* ]]; then
- if ! test ${err_catch_ignore+defined}; then
- err_catch_ignore=(
- '/etc/bash_completion.d/*'
- '*/bash-completion/*'
- )
- fi
- declare -i _err_func_last=0
- if [[ $- != *c* ]]; then
- shopt -s extdebug
- fi
- # shellcheck disable=SC2154
- trap '_err-bash-trace-interactive $? "${PIPESTATUS[*]}" "$BASH_COMMAND" ${BASH_ARGC[0]} "${BASH_ARGV[@]}" || return $?' ERR
- else
- # Man bash on exdebug: "If set at shell invocation, arrange to
- # execute the debugger". We want to avoid that, but I want this file
- # to be sourceable from bash startup files. noninteractive ssh and
- # sources .bashrc on invocation. login_shell sources things on
- # invocation.
- #
- # extdebug allows us to print function arguments in our stack trace.
- if ! shopt login_shell >/dev/null && [[ ! $SSH_CONNECTION ]]; then
- shopt -s extdebug
- fi
- trap err-exit ERR
- fi
- set -o pipefail
-}
-# This is the most common use case so run it now.
-err-catch
-
-#######################################
-# Undo err-catch/err-catch-interactive
-#######################################
-err-allow() {
- shopt -u extdebug
- set +E +o pipefail
- trap ERR
-}
-
-#######################################
-# err-exit: Print stack trace and exit
-#
-# Use this instead of the exit command to be more informative.
-#
-# usage: err-exit [-EXIT_CODE] [MESSAGE]
-#
-# EXIT_CODE Default: $? if it is nonzero, otherwise 1.
-# MESSAGE Print MESSAGE to stderr. Default:
-# ${BASH_SOURCE[1]}:${BASH_LINENO[0]}: `$BASH_COMMAND' returned $?
-#
-# Globals
-#
-# err-cleanup If set, this command will run just before exiting.
-#
-#######################################
-err-exit() {
- # vars have _ prefix so that we can inspect existing set vars without
- # too much overwriting of them.
- local _err=$? _pipestatus="${_pipestatus[*]}"
-
- # This has to come before most things or vars get changed
- local _msg="${BASH_SOURCE[1]}:${BASH_LINENO[0]}: \`$BASH_COMMAND' returned $_err"
- local _cmdr="$BASH_COMMAND" # command right. we chop of the left, keep the right.
-
- if [[ $_pipestatus != "$_err" ]]; then
- _msg+=", PIPESTATUS: $_pipestatus"
- fi
- set +x
- if [[ $1 == -* ]]; then
- _err=${1#-}
- shift
- elif (( ! _err )); then
- _err=1
- fi
- if [[ $1 ]]; then
- _msg="$1"
- fi
-
- ## Begin printing vars from within BASH_COMMAND ##
- local _var _chars _l
- local -A _vars
- while [[ $_cmdr ]]; do
- _chars="${#_cmdr}"
- _cmdr="${_cmdr#*$}"
- _cmdr="${_cmdr#{}"
- if (( _chars == ${#_cmdr} )); then
- break
- fi
- _var="${_cmdr%%[^a-zA-Z0-9_]*}"
- if [[ ! $_var || $_var == [0-9]* ]]; then
- continue
- fi
- _vars[${_var}]=t
- done
- #echo "iank ${_vars[*]}"
- #set |& grep ^password
- # in my small test, this took 50% longer than piping to grep.
- # That seems a small enough penalty to stay in bash here.
- if (( ${#_vars[@]} )); then
- set |& while read -r _l; do
- for _var in "${!_vars[@]}"; do
- case $_l in
- ${_var}=*) printf "%s\n" "$_l" >&2 ;;
- esac
- done
- done
- fi
- ## End printing vars from within BASH_COMMAND ##
-
- printf "%s\n" "$_msg" >&2
- err-bash-trace 2
- set -e # err trap does not work within an error trap
- if type -t err-cleanup >/dev/null; then
- err-cleanup
- fi
- printf "%s: exiting with status %s\n" "$0" "$_err" >&2
- exit $_err
-}
-
-#######################################
-# Print stack trace
-#
-# usage: err-bash-trace [FRAME_START]
-#
-# This function is called by the other functions which print stack
-# traces.
-#
-# It does not show function args unless you first run:
-# shopt -s extdebug
-# which err-catch does for you.
-#
-# FRAME_START Optional variable to set before calling. The frame to
-# start printing on. default=1. If ${#FUNCNAME[@]} <=
-# FRAME_START + 1, don't print anything because we are at
-# the top level of the script and better off printing a
-# general message, for example see what our callers print.
-#
-#######################################
-err-bash-trace() {
- local -i argc_index=0 frame i frame_start=${1:-1}
- local source_loc
- if (( ${#FUNCNAME[@]} <= frame_start + 1 )); then
- return 0
- fi
- for ((frame=0; frame < ${#FUNCNAME[@]}; frame++)); do
- argc=${BASH_ARGC[frame]}
- argc_index+=$argc
- if ((frame < frame_start)); then continue; fi
- if (( ${#BASH_SOURCE[@]} > 1 )); then
- source_loc="${BASH_SOURCE[frame]}:${BASH_LINENO[frame-1]}:"
- fi
- printf " from %sin \`%s" "$source_loc" "${FUNCNAME[frame]}" >&2
- if shopt extdebug >/dev/null; then
- for ((i=argc_index-1; i >= argc_index-argc; i--)); do
- printf " %s" "${BASH_ARGV[i]}" >&2
- done
- fi
- echo \' >&2
- done
- return 0
-}
-
-#######################################
-# Internal function for err-catch. Prints stack trace from interactive
-# shell trap.
-#
-# Usage: see err-catch-interactive
-#######################################
-_err-bash-trace-interactive() {
- if (( ${#FUNCNAME[@]} <= 1 )); then
- return 0
- fi
-
- for pattern in "${err_catch_ignore[@]}"; do
- # shellcheck disable=SC2053
- if [[ ${BASH_SOURCE[1]} == $pattern ]]; then
- return 0
- fi
- done
-
- local ret bash_command argc pattern i last
- last=$_err_func_last
- _err_func_last=${#FUNCNAME[@]}
- # We have these passed to us because they are lost inside the
- # function.
- ret=$1
- pipestatus="$2"
- bash_command="$3"
- argc=$(( $4 - 1 ))
- shift 4
- argv=("$@")
- # The trap returns a nonzero, then gets called again. This condition
- # tells us if is that has happened by checking if we've gone down a
- # stack level.
- if (( _err_func_last >= last )); then
- printf "ERR: \`%s\' returned %s" "$bash_command" $ret >&2
- if [[ $pipestatus != "$ret" ]]; then
- printf ", PIPESTATUS: %s" "$pipestatus" >&2
- fi
- echo >&2
- fi
- printf " from \`%s" "${FUNCNAME[1]}" >&2
- if shopt extdebug >/dev/null; then
- for ((i=argc; i >= 0; i--)); do
- printf " %s" "${argv[i]}" >&2
- done
- fi
- printf "\' defined at %s:%s\n" "${BASH_SOURCE[1]}" "$(declare -F "${FUNCNAME[1]}"|awk "{print \$2}")" >&2
- if [[ -t 1 ]]; then
- return $ret
- else
- # Part of an outgoing pipe, avoid getting get us stuck in a weird
- # subshell if we returned nonzero, which would happen in a situation
- # like this:
- #
- # tf() { while read -r line; do :; done < <(asdf); };
- # tf
- #
- # Note: exit $ret also avoids the stuck subshell problem, and I
- # can't notice any difference, but this seems more proper.
- return 0
- fi
-}
iankelling.org / git / automated-distro-installer / commitdiff