#! /bin/bash

error_exit()
{
    echo "======================="
    echo $1
    echo "======================="
    cat_stack
    exit 1
}

cat_stack()
{
    P=">"
    while read LINE
    do
        printf "%s\n" "${P}${LINE}"
        P="-"${P}
    done < ${STACK}
}

add_trace()
{
    sed "s/^$1/$1: $2 - /" ${STACK} > ${SWP}
    mv ${SWP} ${STACK}
    exit 1
}

f1()
{
    push "${FUNCNAME} called from line $(caller 0 | cut -d" " -f1,2)"
    R=$(f2) || error_exit "Exception raised below call to f2() in (${FUNCNAME})"
    pop
}

f2()
{
    push "${FUNCNAME} called from line $(caller 0 | cut -d" " -f1,2)"
    echo "In f2"
    R=$(f3) || add_trace ${FUNCNAME} "Call to f3() failed"
    pop
}

f4()
{
    push "${FUNCNAME} called from line $(caller 0 | cut -d" " -f1,2)"
    echo "In f4"
    slurp 1 2>/dev/null || add_trace ${FUNCNAME} "Sleep failed"
    pop
}

f3()
{
    push "${FUNCNAME} called from line $(caller 0 | cut -d" " -f1,2)"
    echo "In f3"
    R=$(f5) || add_trace ${FUNCNAME} "Call to f5() failed"
    R=$(f4) || add_trace ${FUNCNAME} "Call to f4() failed"
    pop
}

f5()
{
    push "${FUNCNAME} called from line $(caller 0 | cut -d" " -f1,2)"
    echo "In f5"
    pop
}
push()
{
    echo $1 >> ${STACK}
    printf "%s%s\n" "$(seq -s " " ${SSO} | sed 's/[0-9]//g')" "${1}" >> ${TRACE}
    SSO=$(($SSO + 2))
}

pop()
{
    SSO=$((${SSO} - 2))
    TMP="Returned from $(tail -n 1 ${STACK} | cut -d" " -f1)"
    printf "%s%s\n" "$(seq -s " " ${SSO} | sed 's/[0-9]//g')"  "${TMP}" >> ${TRACE}
    head -n -1 ${STACK} > ${SWP}
    mv ${SWP} ${STACK}
}

STACK=stack
:>${STACK}
TRACE=trace
:>${TRACE}

SWP=/tmp/swpx
SSO=1

f1

=======================
Exception raised below call to f2() in (f1)
=======================
>f1 called from line 91 main
->f2: Call to f3() failed -  called from line 32 f1
-->f3: Call to f4() failed -  called from line 40 f2
--->f4: Sleep failed -  called from line 57 f3