#!/bin/sh
# conf_replace.sh -- Create modified ISO copy with replaced config files
#
# Syntax:  HIPERISO_CONF_REPLACE="org=/iso/path;new=data/path"
#
#   org=   Absolute ISO-internal path (must start with /), e.g. /boot/grub.cfg
#   new=   Relative path on the data partition (no leading /), e.g. overlay/grub.cfg
#
# If set, creates /tmp/modified.iso and prints its path on stdout.
# All diagnostics go to stderr (captured by init's 2> redirect).
# Called by init: _modified=$(sh /conf_replace.sh 2>"$LOG_DIR/conf_replace.log")
# POSIX sh compatible

. /hiperiso-lib.sh

# Redirect stdout → stderr so all hiperiso_log output and xorriso noise
# go to the diagnostic channel.  Preserve the original stdout as fd 3
# for the single path-print at the end.
exec 3>&1 1>&2

if [ -z "${HIPERISO_CONF_REPLACE:-}" ]; then
    exit 0
fi

# Validate the whole config value: semicolon-separated org=/new= entries
# using only safe characters (including / for ISO-internal paths).
if printf '%s' "$HIPERISO_CONF_REPLACE" | grep -qE '[^-a-zA-Z0-9._/;=]|\.\.'; then
    hiperiso_log "conf_replace: config value contains unsafe characters or traversal"
    exit 0
fi

_org=""
_new=""
OLDIFS="$IFS"
IFS=';'
_hiso_glob_state=$-
set -f
for _pair in $HIPERISO_CONF_REPLACE; do
    case "$_pair" in
        org=*) _org="${_pair#org=}" ;;
        new=*) _new="${_pair#new=}" ;;
    esac
done
case "$_hiso_glob_state" in
    *f*) : ;;
    *) set +f ;;
esac
IFS="$OLDIFS"

if [ -z "$_org" ] || [ -z "$_new" ]; then
    hiperiso_log "conf_replace: malformed config, skipping"
    exit 0
fi

# _new: relative path on data partition (no leading /, no traversal)
if ! hiperiso_validate_path "$_new"; then
    hiperiso_log "conf_replace: replacement path is unsafe: $_new"
    exit 0
fi

# _org: absolute ISO-internal path (must start with /, no traversal,
# only path-safe characters including /)
case "$_org" in
    /*) : ;;
    *)
        hiperiso_log "conf_replace: original path must be absolute (start with /): $_org"
        exit 0
        ;;
esac
case "$_org" in
    *..*)
        hiperiso_log "conf_replace: original path contains traversal: $_org"
        exit 0
        ;;
esac
case "$_org" in
    *[!/a-zA-Z0-9._~-]*)
        hiperiso_log "conf_replace: original path has unsafe characters: $_org"
        exit 0
        ;;
esac

_new_abs=$(hiperiso_join_path "${DATA_MOUNT:-}" "$_new") || exit 0
if [ ! -f "$_new_abs" ]; then
    hiperiso_log "conf_replace: replacement file not found: $_new_abs"
    exit 0
fi

XORRISO_BIN=""
for _cand in /usr/bin/xorriso /mnt/runtime/usr/bin/xorriso; do
    if [ -x "$_cand" ]; then XORRISO_BIN="$_cand"; break; fi
done
if [ -z "$XORRISO_BIN" ]; then
    hiperiso_log "conf_replace: xorriso not available — ISO modification skipped"
    exit 0
fi

_modified_iso="/tmp/modified.iso"
hiperiso_log "conf_replace: creating modified ISO copy"
hiperiso_log "conf_replace: org=$_org new=$_new_abs"

if "$XORRISO_BIN" -indev "$ISO_PATH" \
    -outdev "$_modified_iso" \
    -boot_image any keep \
    -map "$_new_abs" "$_org" \
    2>&1; then

    if [ -f "$_modified_iso" ]; then
        hiperiso_log "conf_replace: modified ISO at $_modified_iso"
        printf '%s' "$_modified_iso" >&3
        exit 0
    fi
fi

hiperiso_log "conf_replace: xorriso failed, using original ISO"
rm -f "$_modified_iso" 2>/dev/null || true
exit 0