err

   1 #!/bin/bash
   2 # Copyright (C) 2019 Ian Kelling
   3 # SPDX-License-Identifier: GPL-3.0-or-later
   4
   5 # Commentary: Bash stack trace and error handling functions. This file
   6 # is meant to be sourced. It loads some functions which you may want to
   7 # call manually (see the comments at the start of each one), and then
   8 # runs err-catch. See the README file for a slightly longer explanation.
   9
  10
  11 #######################################
  12 # Print stack trace
  13 #
  14 # usage: err-bash-trace [MESSAGE]
  15 #
  16 # This function is called by the other functions which print stack
  17 # traces.
  18 #
  19 # It does not show function args unless you first run:
  20 # shopt -s extdebug
  21 # which err-catch & err-print do for you.
  22 #
  23 # MESSAGE       Message to print just before the stack trace.
  24 #
  25 # _frame_start  Optional variable to set before calling. The frame to
  26 #               start printing on. default=1. Useful when printing from
  27 #               an ERR trap function to avoid printing that function.
  28 #######################################
  29 err-bash-trace() {
  30   local -i argc_index=0 frame i start=${_frame_start:-1}
  31   local source
  32   if [[ $1 ]]; then
  33     printf "%s\n" "$1"
  34   fi
  35   for ((frame=0; frame < ${#FUNCNAME[@]}; frame++)); do
  36     argc=${BASH_ARGC[frame]}
  37     argc_index+=$argc
  38     ((frame < start)) && continue
  39     if (( ${#BASH_SOURCE[@]} > 1 )); then
  40       source="${BASH_SOURCE[frame]}:${BASH_LINENO[frame-1]}:"
  41     fi
  42     printf "  from %sin \`%s" "$source" "${FUNCNAME[frame]}"
  43     if shopt extdebug >/dev/null; then
  44       for ((i=argc_index-1; i >= argc_index-argc; i--)); do
  45         printf " %s" "${BASH_ARGV[i]}"
  46       done
  47     fi
  48     echo \'
  49   done
  50   return 0
  51 }
  52
  53 #######################################
  54 # On error print stack trace and exit
  55 #
  56 # Globals:
  57 #   errcatch-cleanup  If set, this command will run just before exiting.
  58 #######################################
  59 err-catch() {
  60   set -E;
  61   # This condition avoids starting the bash debugger in the case that
  62   # this is sourced from a startup file, and you use a login shell to
  63   # run a command. Avoid doing that if you want function arguments in
  64   # your trace.
  65   if [[ $- != *c* ]] && ! shopt login_shell >/dev/null; then
  66     shopt -s extdebug
  67   fi
  68   _err-trap() {
  69     err=$?
  70     exec >&2
  71     set +x
  72     local msg="${BASH_SOURCE[1]}:${BASH_LINENO[0]}: \`$BASH_COMMAND' returned $err"
  73     if (( ${#FUNCNAME[@]} > 2 )); then
  74       local _frame_start=2
  75       err-bash-trace "$msg"
  76     else
  77       echo "$msg"
  78     fi
  79     set -e # err trap does not work within an error trap
  80     if type -t errcatch-cleanup >/dev/null; then
  81       errcatch-cleanup
  82     fi
  83     echo "$0: exiting with status $err"
  84     exit $err
  85   }
  86   trap _err-trap ERR
  87   set -o pipefail
  88 }
  89
  90
  91 #######################################
  92 # For interactive shells: on error, print stack trace and return
  93 #
  94 # Globals:
  95 #   err_catch_ignore  Array containing glob patterns to test against filenames to ignore
  96 #                     errors from. Initialized to ignore bash-completion scripts on debian
  97 #                     based systems.
  98 #   _err_func_last  Used internally.
  99 #   _err_catch_err  Used internally.
 100 #   _err_catch_i    Used internally.
 101 #   _err_catch_ignore Used internally.
 102 #
 103 # misc: All shellcheck disables for this function are false positives.
 104 #######################################
 105 # shellcheck disable=SC2120
 106 err-catch-interactive() {
 107   err_catch_ignore=(
 108     '/etc/bash_completion.d/*'
 109   )
 110   # shellcheck disable=SC2034
 111   declare -i _err_func_last=0
 112   set -E; shopt -s extdebug
 113   # shellcheck disable=SC2154
 114   trap '_err_catch_err=$? _trap_bc="$BASH_COMMAND"
 115   _err_catch_ignore=false
 116   for _err_catch_i in "${err_catch_ignore[@]}"; do
 117     if [[ ${BASH_SOURCE[0]} == $_err_catch_i ]]; then
 118       _err_catch_ignore=true
 119       break
 120     fi
 121   done
 122   if ! $_err_catch_ignore; then
 123     if (( ${#FUNCNAME[@]} > _err_func_last )); then
 124       echo ERR: \`$_trap_bc'"\'"' returned $_err_catch_err
 125     fi
 126     _err_func_last=${#FUNCNAME[@]}
 127     if (( _err_func_last )); then
 128       printf "  from %s:%s:in \`%s" "${BASH_SOURCE[0]}" "$(declare -F "${FUNCNAME[0]}"|awk "{print \$2}")" "${FUNCNAME[0]}"
 129       if shopt extdebug >/dev/null; then
 130         for ((_err_catch_i=${BASH_ARGC[0]}-1; _err_catch_i >= 0; _err_catch_i--)); do
 131           printf " %s" "${BASH_ARGV[_err_catch_i]}"
 132         done
 133       fi
 134       echo '"\'"'
 135       return $_err_catch_err
 136     fi
 137   fi' ERR
 138   set -o pipefail
 139 }
 140
 141
 142 #######################################
 143 # Undoes err-catch/err-catch-interactive
 144 #######################################
 145 err-allow() {
 146   shopt -u extdebug
 147   set +E +o pipefail
 148   trap ERR
 149 }
 150
 151 #######################################
 152 # On error, print stack trace
 153 #######################################
 154 err-print() {
 155   # help: on errors: print stack trace
 156   #
 157   # This function depends on err-bash-trace.
 158
 159   set -E; shopt -s extdebug
 160   _err-trap() {
 161     err=$?
 162     exec >&2
 163     set +x
 164     echo "${BASH_SOURCE[1]}:${BASH_LINENO[0]}: \`$BASH_COMMAND' returned $err"
 165     err-bash-trace 2
 166   }
 167   trap _err-trap ERR
 168   set -o pipefail
 169 }
 170
 171
 172 #######################################
 173 # Print stack trace and exit
 174 #
 175 # Use this instead of the exit command to be more informative.
 176 #
 177 # usage: err-exit [EXIT_CODE] [MESSAGE]
 178 #
 179 # EXIT_CODE  Default is 1.
 180 # MESSAGE    Print MESSAGE to stderr. If only one of EXIT_CODE
 181 #            and MESSAGE is given, we consider it to be an
 182 #            exit code if it is a number.
 183 #######################################
 184 err-exit() {
 185   exec >&2
 186   code=1
 187   if [[ "$*" ]]; then
 188     if [[ ${1/[^0-9]/} == "$1" ]]; then
 189       code=$1
 190       if [[ $2 ]]; then
 191         printf '%s\n' "$2" >&2
 192       fi
 193     else
 194       printf '%s\n' "$0: $1" >&2
 195     fi
 196   fi
 197   echo "${BASH_SOURCE[1]}:${BASH_LINENO[0]}"
 198   err-bash-trace 2
 199   echo "$0: exiting with code $code"
 200   exit $err
 201 }
 202
 203 # We want this more often than not, so run it now.
 204 if [[ $- == *i* ]]; then
 205   err-catch-interactive
 206 else
 207   err-catch
 208 fi