locate-exit.sh

locate-exit.sh

# -*- mode: sh; sh-shell: bash; -*-
# shellcheck shell=bash

# MIT license (c) 2021 https://github.com/slowpeek
# Homepage: https://gist.github.com/slowpeek/7e2731b620d558f44841da6772743d38

# This script can help you find out which line and why (end of code,
# literal exit, 'set -e' violation, bash error) your bash script
# finished execution.
#
# Source it in the head of your code (after 'set -e' if you're using
# it). You can deactivate it with LOCATE_EXIT=n env var. The report is
# printed to stderr.
#
# Your code should NOT:
# - trap EXIT and ERR
# - override 'exit' builtin
#
# SAMPLE REPORT
#
# --- locate-exit report ---
# Code: 4
# Reason: 'set -e' violation
#
# Context:
# ./2.sh:8 helper_1
# ./2.sh:14 do_something
# ./2.sh:18
# ---
#
# KNOWN PROBLEMS
#
# If you dont use 'set -e' and the last command in your script returns
# a non-zero status, it would be reported as 'bash error' even though
# it was end of code actually.

[[ ! ${LOCATE_EXIT-} == n ]] || return 0

if [[ $- == *e* ]]; then
    set -E
    trap 'locate_exit_trap err' ERR
fi

trap 'locate_exit_trap exit' EXIT

# This override is a trick to catch lineno on literal exit.
exit () {
    builtin exit "$@"
}

locate_exit_trap () {
    local st=$?

    [[ $$ == "$BASHPID" ]] || return 0 # Ignore subshells.

    trap EXIT

    {
        echo -ne "\n--- locate-exit report ---\nCode: $st\nReason: "

        local context=y skip=1 lineno=("${BASH_LINENO[@]}")
        if [[ $1 == exit ]]; then
            if [[ ${FUNCNAME[1]} == exit ]]; then
                skip=2
                echo 'literal exit'
            else
                if [[ $st == 0 ]]; then
                    echo 'end of code'
                    context=n
                else
                    echo 'bash error'

                    # On bash error it always reports line#1 no matter
                    # where it actually happened.
                    lineno[0]=\?
                fi
            fi
        else
            echo "'set -e' violation"
        fi

        if [[ $context == y ]]; then
            echo -e '\nContext:'

            local n=${#FUNCNAME[@]} i=$skip s
            for ((; i<n; i++)); do
                s="${BASH_SOURCE[i]}:${lineno[i-1]}"
                ((i >= n-1)) || [[ ${FUNCNAME[i]} == source ]] ||
                    s+=" ${FUNCNAME[i]}"

                printf '%s\n' "$s"
            done
        fi

        echo '---'
    } >&2
}