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✏️ Editing: 040_check_backup_and_output_scheme.sh

#
# Check conditions that depend on BACKUP_URL or OUTPUT_URL
# in particular conditions that depend on their schemes.
#

if test "$BACKUP_URL" ; then
    local backup_scheme=$( url_scheme "$BACKUP_URL" )
    case $backup_scheme in
       (iso)
           case $WORKFLOW in
               (mkrescue|mkbackuponly)
                   # When the backup is configured to be in the ISO (e.g. via BACKUP_URL="iso:///mybackup")
                   # only "rear mkbackup" results an ISO (or ISOs cf. https://github.com/rear/rear/issues/1545)
                   # that is/are usable for "rear recover". When the backup is configured to be in the ISO
                   # the mkrescue workflow results an ISO without backup which lets "rear recover"
                   # fail with "ERROR: Backup archive 'backup.tar.gz' not found."
                   # cf. https://github.com/rear/rear/issues/1547 and https://github.com/rear/rear/issues/1545
                   # and the mkbackuponly workflow exits with exit code 0 but results no ISO at all
                   # cf. https://github.com/rear/rear/issues/1548
                   # so that mkrescue and mkbackuponly usually do not work for the 'iso' backup scheme.
                   # But there are special cases where mkrescue/mkbackuponly with BACKUP_URL=iso is used
                   # so that we cannot error out in any case, cf. https://github.com/rear/rear/issues/1613
                   # Accordingly a UserInput dialog that errors out by default to be on the safe side is used
                   # to provide a ready for use mean of final power to the user to enforce what ReaR must do:
                   prompt="Proceed regardless that '$WORKFLOW' could be destructive with a '$backup_scheme' BACKUP_URL ?"
                   workflow_uppercase="$( tr '[:lower:]' '[:upper:]' <<< $WORKFLOW )"
                   user_input_ID="BACKUP_URL_ISO_PROCEED_$workflow_uppercase"
                   input_value=""
                   wilful_input=""
                   input_value="$( UserInput -I $user_input_ID -p "$prompt" -D 'No' )" && wilful_input="yes" || wilful_input="no"
                   if ! is_true "$input_value" ; then
                       if is_true "$wilful_input" ; then
                           LogPrint "User confirmed to not proceed '$WORKFLOW' with a '$backup_scheme' BACKUP_URL"
                       else
                           LogPrint "Aborting '$WORKFLOW' with a '$backup_scheme' BACKUP_URL by default"
                       fi
                       Error "The $WORKFLOW workflow does not work for the BACKUP_URL scheme '$backup_scheme'"
                   fi
                   LogPrint "User confirmed to proceed regardless that '$WORKFLOW' could be destructive with a '$backup_scheme' BACKUP_URL"
                   ;;
           esac
           ;;
    esac
else
    # A BACKUP_URL is not mandatory in general, see in 'man rear'
    # "An example to use TSM for backup and ISO for output"
    # cf. https://github.com/rear/rear/issues/1532#issuecomment-336810460
    # but for BACKUP=NETFS a BACKUP_URL is required in practice
    # cf. https://github.com/rear/rear/issues/1532#issuecomment-336810460
    # so that we error out to be safe against possible "rear recover" failures:
    test "NETFS" = $BACKUP && Error "BACKUP=NETFS requires a BACKUP_URL backup target location"
fi

if test "$OUTPUT_URL" ; then
    local output_scheme=$( url_scheme "$OUTPUT_URL" )
    case $output_scheme in
        (fish|ftp|ftps|hftp|http|https|sftp)
            local required_prog='lftp'
            has_binary $required_prog || Error "The OUTPUT_URL scheme '$output_scheme' requires the '$required_prog' command which is missing"
            ;;
        (iso)
            Error "The OUTPUT_URL scheme cannot be '$output_scheme'"
            ;;
        (null)
            # OUTPUT_URL=null conflicts with OUTPUT=USB
            # because for OUTPUT=USB output/USB/Linux-i386/850_make_USB_bootable.sh
            # wants to make the USB device bootable which cannot work with OUTPUT_URL=null
            # see https://github.com/rear/rear/issues/1571#issuecomment-343467593
            test "USB" = "$OUTPUT" && Error "'OUTPUT_URL=null' conflicts with 'OUTPUT=USB'"
            ;;
    esac
fi

MR SKB