Repository: spf13/cobra
File: bash_completionsV2.go (Go)

Code before:
        fi

        return 0
    fi

    local longest=0
    local compline
    # Look for the longest completion so that we can format things nicely
    while IFS='' read -r compline; do
        [[ -z $compline ]] && continue
        # Strip any description before checking the length
        comp=${compline%%%%$tab*}
        # Only consider the completions that match
        [[ $comp == "$cur"* ]] || continue
        COMPREPLY+=("$compline")
        if ((${#comp}>longest)); then
            longest=${#comp}
        fi
    done < <(printf "%%s\n" "${completions[@]}")

    # If there is a single completion left, remove the description text and escape the completion
    if ((${#COMPREPLY[*]} == 1)); then
        __%[1]s_debug "COMPREPLY[0]: ${COMPREPLY[0]}"
        comp="${COMPREPLY[0]%%%%$tab*}"
        __%[1]s_debug "Removed description from single completion, which is now: ${comp}"
        COMPREPLY[0]=$(printf %%q "${comp}")
    else # Format the descriptions
        __%[1]s_format_comp_descriptions $longest
    fi
}

__%[1]s_handle_special_char()
{
    local comp="$1"
    local char=$2
    if [[ "$comp" == *${char}* && "$COMP_WORDBREAKS" == *${char}* ]]; then
        local word=${comp%%"${comp##*${char}}"}
        local idx=${#COMPREPLY[*]}
        while ((--idx >= 0)); do
            COMPREPLY[idx]=${COMPREPLY[idx]#"$word"}
        done
    fi
}

__%[1]s_format_comp_descriptions()
{
    local tab=$'\t'
    local comp desc maxdesclength
    local longest=$1

    local i ci

Review comment (security):
It turns out that doing the escaping only when there is a single completion is not sufficient.
```
# Say I have a completion that is "bash1 space"
# The below works
$ testprog prefix special-chars bash1[tab]
$ testprog prefix special-chars bash1\ space

# But this does not
$ testprog prefix special-chars bash1\ s[tab]
```
This is because further above we do `[[ $comp == "$cur"* ]] || continue` but since `$cur == "bash1\ s` (that is what the user has typed), it won't match `$comp` because we haven't escaped `$comp`.
The solution is that we need to escape every completion before we start filtering on `$cur` 

Code after:
        IFS=$'\n' read -ra COMPREPLY -d '' < <(printf "%%q\n" "${COMPREPLY[@]}")
        ;;

    *)
        # Type: complete (normal completion)
        __%[1]s_handle_standard_completion_case
        ;;
    esac
}

__%[1]s_handle_standard_completion_case() {
    local tab=$'\t'

    # If there are no completions, we don't need to do anything
    (( ${#completions[@]} == 0 )) && return 0

    # Short circuit to optimize if we don't have descriptions
    if [[ "${completions[*]}" != *$tab* ]]; then
        # First, escape the completions to handle special characters
        IFS=$'\n' read -ra completions -d '' < <(printf "%%q\n" "${completions[@]}")
        # Only consider the completions that match what the user typed
        IFS=$'\n' read -ra COMPREPLY -d '' < <(IFS=$'\n'; compgen -W "${completions[*]}" -- "${cur}")

        # compgen looses the escaping so, if there is only a single completion, we need to
        # escape it again because it will be inserted on the command-line.  If there are multiple
        # completions, we don't want to escape them because they will be printed in a list
        # and we don't want to show escape characters in that list.
        if (( ${#COMPREPLY[@]} == 1 )); then
            COMPREPLY[0]=$(printf "%%q" "${COMPREPLY[0]}")
        fi
        return 0
    fi

    local longest=0
    local compline
    # Look for the longest completion so that we can format things nicely
    while IFS='' read -r compline; do
        [[ -z $compline ]] && continue

        # Before checking if the completion matches what the user typed,
        # we need to strip any description and escape the completion to handle special
        # characters because those escape characters are part of what the user typed.
        # Don't call "printf" in a sub-shell because it will be much slower
        # since we are in a loop.
        printf -v comp "%%q" "${compline%%%%$tab*}" &>/dev/null || comp=$(printf "%%q" "${compline%%%%$tab*}")

        # Only consider the completions that match
        [[ $comp == "$cur"* ]] || continue

        # The completions matches.  Add it to the list of full completions including
        # its description.  We don't escape the completion because it may get printed