partgrator-pre

#!/bin/sh

# partgrator-pre version 1.0.0
#
# partgrator-pre truncates logfiles, cleans mountpoints, and wraps disk-check tools
#
# For more information, issues, or assistance visit: https://github.com/caribpa/partgrator
#
# Author: caribpa (https://github.com/caribpa)
#
# Copyright 2020 caribpa
#
# partgrator-pre is free to use under the Artistic License 2.0
#
# Find the Artistic License 2.0 here: https://spdx.org/licenses/Artistic-2.0.html


########### USER VARIABLES ###########

partgrator_dir="/jffs/addons/partgrator"    # Partgrator installation directory path

  logfile_truncate_lines=500  # Lines to remain on ${logfile} after being truncated
logfile_truncate_minutes=30   # Minutes for truncating ${logfile} since last modification

 process_tools="e2fsck"       # disk-check tools whose return code will be processed by
                              # partgrator and a migration will be scheduled if needed
                              # Note that the tool name can only contain characters
                              # considered valid as function names

  mount_folder="/tmp/mnt"     # Absolute path to the folder where the partitions are
                              # automatically mounted


######################################
###                               ####
###  USERS DO NOT NEED TO MODIFY  ####
###       BELOW THIS POINT        ####
###                               ####
######################################


######### GENERAL VARIABLES ##########

tools_needed="[
              awk
              blkid
              date
              echo
              expr
              false
              grep
              rm
              sed
              rmdir
              tail
              type
              wc
              ${process_tools}"


########### SOURCE INCLUDE ###########

log_tag="partgrator-pre"            # Tag used as prefix when logging messages

helpers_tools_check="no"
. "${partgrator_dir}/helpers"

logfile_last_modified="$(LC_ALL=C                             ; \
                           PATH=/sbin:/bin:/usr/sbin:/usr/bin ; \
                         date -r "${logfile}" +%s 2> /dev/null  )"

helpers_tools_check="yes"
check_helpers_tools || exit $?


########### PREREQUISITES ############

log_msg "Initializing partgrator-pre script"

check_tools "${tools_needed}" \
                              \
                              \
&& ( # Beginning of main subshell - Beginning of check_tools conditional execution

########### SHELL VARIABLES ##########

    LC_ALL=C
      PATH=/sbin:/bin:/usr/sbin:/usr/bin


########## GLOBAL VARIABLES ##########

 partition="$1"
filesystem="$2"


############## HELPERS ###############

truncate_logfile() {
    local          current_time="$(awk 'BEGIN{srand(); print srand()}')"   || return $?
    local logfile_current_lines="$(wc -l "${logfile}")"                    || return $?
    local    seconds_difference=$(expr ${current_time} - ${logfile_last_modified:-0})
    local              ret_code=0

    if    [                           -n "${logfile_last_modified}"           ] \
       && [                           -n "${logfile_truncate_minutes}"        ] \
       && [ ${seconds_difference#-}   -gt $((logfile_truncate_minutes \* 60)) ] \
       && [ ${logfile_truncate_lines} -le ${logfile_current_lines%% *}        ]
    then
        log_msg "Truncating logfile ${logfile} to the last" \
                "${logfile_truncate_lines} lines"

        echo "$(tail -n -${logfile_truncate_lines} "${logfile}")" > "${logfile}"
        ret_code=$?

        if [ ${ret_code} -ne 0 ]; then
            log_msg -p error "echo failed with error code ${ret_code} when" \
                             "truncating ${logfile}"
        else
            log_msg "${logfile} truncated successfully"
        fi
    fi
    return ${ret_code}
}

# Automatically remove previously existing mountpoint folders
clean_partition_mountpoint() {
    local   partition="$1"

    local       label=''
    local  mountpoint=''
    local mountpoints=''

    local    ret_code=0

    label="$(get_partition_label "${partition}")" || return $?

    log_msg "Starting partition mountpoint cleaner"

     mountpoint="${mount_folder}/${label//[ \"\']/_}"   # Replace problematic symbols
    mountpoints="${mountpoint}*"                        # Shell expansion for-loop

    log_msg "Checking if ${partition} mountpoint (${mountpoint})" \
            "needs to be cleaned before being mounted"

    if grep -q "^${partition} " "${mtab}"; then
        log_msg -p warning "${partition} seems to be mounted"
        log_msg -p warning "Not cleaning ${mountpoint} folder"
        return 0
    fi

    # The shell expansion is needed to catch folders with numbers prefixed due to
    # bad unmounting or missed cleanup
    for mountpoint in ${mountpoints}; do
        if      [ -d "${mountpoint}" ]              \
           && ! grep -q " ${mountpoint} " "${mtab}"
        then
            log_msg "Cleaning ${mountpoint}"

            rm -f -- "${mountpoint}/.autocreated-dir"
            rmdir -- "${mountpoint}"
            ret_code=$?
            if [ ${ret_code} -eq 0 ]; then
                log_msg "${mountpoint} was successfully cleaned"
            else
                log_msg -p error   "rmdir failed with error code ${ret_code}" \
                                   "when trying to remove ${mountpoint}"
                log_msg -p warning "Continuing without cleaning the" \
                                   "previous mountpoint folder"
            fi
        fi
    done

    log_msg "Finishing partition mountpoint cleaner"

    return ${ret_code}
}


############### MAIN #################

log_msg "Starting with ${partition} and ${filesystem} as parameters"

truncate_logfile

clean_partition_mountpoint "${partition}"

# End of main subshell - Comment redirection for debugging
) > /dev/null 2> /dev/null \
                           \
&& {              # All the following will only be executed if the subshell succeeded


########## EXPORTED HELPERS ##########

override_tool() {
    local tool_name="$1"
    local tool_path="$(LC_ALL=C type "${tool_name}" 2>&1)"
    local  ret_code=0

    log_msg "Overriding tool ${tool_name}"

    if [ ! -e "${tool_path##* }" ]; then
        log_msg -p error "Unable to override ${tool_name} as it${tool_path#${tool_name}}"
        return 1
    fi

    tool_path="${tool_path##* }"

    eval "${tool_name}"'() {
              local       params="$@"

              local    partition="${params##* }"

              local file_content=""
              local    blkid_out=""
              local        label=""

              local     ret_code=0

              # Return early if the partition is already mounted
              grep -q "^${partition} " "'"${mtab}"'" && return 0

              blkid_out="$(blkid "${partition}" 2> /dev/null)" || return $?

              if expr "${blkid_out}" : "${partition}: LABEL=" > /dev/null; then
                  # Partition has a label
                  # Trim everything around the first and last double-quotes of the label
                  label="${blkid_out#*=\"}"
                  label="${label%\" *}"
              else
                  # Partition has no label so assign as label the partition device
                  # (device name + partition number)
                  label="${partition##*\/}"
              fi

              # The tool should only be run for non-${partgrator_label} partitions
                 ! case "${label}" in '"${partgrator_label}"'*) false;; esac \
              || '"${tool_path}"' ${params}
              ret_code=$?

              # Write the status only if a migration is not in progress
              if [ ! -f "'"${migrating_file}"'" ]; then
                  # Delete the previous entry
                     [ -f "'"${partitions_status}"'" ]                  \
                  && file_content="$(sed "/^"${partition//\//\\\/}" /d" \
                                         "'"${partitions_status}"'"     )"

                  # The newline can be used without a variable because of eval
                  echo "${file_content}${file_content:+'$'\n''}${partition}" \
                                                              "${ret_code}"  \
                                                             ":${label}"     \
                       > "'"${partitions_status}"'"
              fi

              # Prematurely exit pre-mount for ${partgrator_label} partitions
                 [ "'"${partgrator_pre_mount}"'" = "0" ]                     \
              && ! case "${label}" in '"${partgrator_label}"'*) false;; esac \
              && exit ${ret_code}

              return ${ret_code}
          }                                                                              '
    ret_code=$?

    if [ ${ret_code} -ne 0 ]; then
        log_msg -p error "eval failed with error code ${ret_code} when" \
                         "trying to override tool ${tool_name}"
    else
        log_msg "Tool ${tool_name} was overridden successfully"
    fi

    return ${ret_code}
}


########### EXPORTED MAIN ############

log_msg "Starting overriding tools for processing" \
        "their exit code when executed"

for tool in ${process_tools}; do
    override_tool "${tool}"
done

log_msg "Finished overriding tools"


####### UNSET EXPORTED HELPERS #######

unset -f override_tool


}  # End of the check_tools conditional execution

log_msg "Exiting"


####### UNSET GENERAL HELPERS ########

unset_helpers  # log_tag and helpers_tools_check are unset here


###### UNSET GENERAL VARIABLES #######

unset -v tools_needed          \
         logfile_last_modified


######## UNSET USER VARIABLES ########

unset -v partgrator_dir           \
         logfile_truncate_lines   \
         logfile_truncate_minutes \
         process_tools            \
         mount_folder


# EOF