executable-wrapper-template.sh

#!/usr/bin/env bash

# Recursively unwrap itself from the path, eventually calling the target binary's
# `run-<target>.sh` script, which will inject a feed authentication token.

TARGET_BIN_NAME=SUBST_TARGET_BIN_NAME
TARGET_WRAPPER_PATH=SUBST_TARGET_WRAPPER_PATH

log() {
    # Print to stderr to avoid interfering with scripts that capture stdout.
    # Prefix error messages so the user can quickly determine that it's from our
    # artifacts-helper wrapper, not an error originating from the wrapped binary.
    printf >&2 "[codespace-features/artifacts-helper] %s" "$1"
}

log_line() {
    log "$1
"
}

log_debug_line() {
    if [ "$ARTIFACTS_HELPER_DEBUG" == "1" ]; then
        log_line "$1"
    fi
}

call_wrapped_bin() {
    CURRENT_SCRIPT_PATH=$(realpath "${BASH_SOURCE[0]}")
    if [ -z "$CURRENT_SCRIPT_PATH" ]; then
        log_line "Error: Current script path could not be determined! This will result in infinite recursion. Bailing early."
        exit 1
    fi

    # Find the next executable from the PATH order, which would be shadowed by this wrapper
    if [ -z "$ARTIFACTS_HELPER_TARGET_BIN_PATHS" ]; then
        ARTIFACTS_HELPER_TARGET_BIN_PATHS=$(which -a "$TARGET_BIN_NAME")
    fi

    ARTIFACTS_HELPER_TARGET_BIN_PATHS=$(sed '/^[[:space:]]*$/d' <<<"$ARTIFACTS_HELPER_TARGET_BIN_PATHS")
    ARTIFACTS_HELPER_TARGET_BIN_PATHS=$(grep --color=never -Fve "$CURRENT_SCRIPT_PATH" <<<"$ARTIFACTS_HELPER_TARGET_BIN_PATHS")
    NEXT_SHADOWED_BIN=$(head -n 1 <<<"$ARTIFACTS_HELPER_TARGET_BIN_PATHS")

    log_debug_line "CURRENT_SCRIPT_PATH=$CURRENT_SCRIPT_PATH"
    log_debug_line "TARGET_BIN_NAME=$TARGET_BIN_NAME"
    log_debug_line "TARGET_WRAPPER_PATH=$TARGET_WRAPPER_PATH"
    log_debug_line "ARTIFACTS_HELPER_TARGET_BIN_PATHS=$ARTIFACTS_HELPER_TARGET_BIN_PATHS"
    log_debug_line "NEXT_SHADOWED_BIN=$NEXT_SHADOWED_BIN"

    if [ -z "$NEXT_SHADOWED_BIN" ]; then
        log_line "Error: The real $TARGET_BIN_NAME could not be found on PATH."
        log_line "which -a $TARGET_BIN_NAME:\n%s\n" "$(which -a $TARGET_BIN_NAME)"
        log_line "CC_SHADOWED_BINS:\n%s\n" "$ARTIFACTS_HELPER_TARGET_BIN_PATHS"
        log_line "CURRENT_SCRIPT_PATH: %s\n" "$CURRENT_SCRIPT_PATH"
        exit 1
    fi

    # Recursively removing the wrapper script(s) from the shadowed bin paths will
    # allow us to account for circumstances where the wrapper script appears multiple
    # times on the PATH. We will eventually descend to the real target binary.
    export ARTIFACTS_HELPER_TARGET_BIN_PATHS

    log_debug_line "Running: SUBST_EXE_ENV_VAR=$NEXT_SHADOWED_BIN $TARGET_WRAPPER_PATH"
    SUBST_EXE_ENV_VAR="$NEXT_SHADOWED_BIN" "$TARGET_WRAPPER_PATH" "$@"
    return "$?"
}

call_wrapped_bin "$@"
EXIT_CODE=$?
exit $EXIT_CODE