SIGINT is not cleaned up in "${FUNCNAME[@]}"

Question

Take the following script, interrupted by keyboard input Ctrl+C as shown:

$ function a() { echo "Performing"; sleep 10; echo "Performed"; }
$ a
Performing
^C
$ echo "${FUNCNAME[@]}"
a source

If we repeat the SIGINT during function a many times, we eventually end up with this scenario:

...

$ a
Performing
^C
$ a
Performing
^C
$ echo "${FUNCNAME[@]}"
a a a a a a a a a source

To demonstrate the issue, let's have another function, b, that gives an message_error function, also defined below:

$ function message_error() {
>   local MESSAGE="$1"
>
>   # FUNCNAME[1], as [0] is `message_error`, gets the calling function
>   echo "[[ ERROR ]] ${FUNCNAME[1]}: $MESSAGE"
>   echo "Rest of the stack: ${FUNCNAME[@]}"
>}
$ function b() { message_error "Oh no"; }
$ b
[[ ERROR ]] b: Oh no
Rest of the stack: message_error b a a a a a a a a a source

Even though the function is called in the source, a shows up as the calling function. As you can see, all these a functions were exited. However they remain in the FUNCNAME array.

Why is this? How can I remove it after SIGINT fails to remove it? Please note all functions are sourced from a large collection of commonly used functions, ~/.bash_functions, if sourcing the functions affects how they interpret SIGINT.

Answer 1

Since FUNCNAME is a read-only array, there's probably no way to remove items in it. It seems unset FUNCNAME sort of works, yet that also breaks bash's special FUNCNAME behavior.

Prevention of FUNCNAME garbage can be done by using trap:

$ trap : SIGINT
$ function a() {  echo "Performing"; sleep 10; echo "Performed"; } 
$ a
Performing
^C
$ echo %"${FUNCNAME[@]}"%
%%

To disable the above prevention, do trap - SIGINT.