carchive

#!/usr/bin/env bash

# uses  cat  for fast appending of files
#       stat for getting file info
#       xxd  for reading byte offsets
#        dd  for extracting files fril

# perhaps stat and dd alone would be more sane

# a cat archive is a carchive? why not?

carchive ()
{
    let offset=0

    STAT="/tmp/stat.tmp"

    [ -f "${STAT}" ] && rm -f "${STAT}"


    CARCHIVE="${1}"

    carext="${CARCHIVE##*.}"

    [ ! "Xcar" == "X${carext}" ] && echo "first paramater should be the archive name: ( <nams>.car )" && exit 1

    shift

    for f in "$@"
    do
    ext="${f##*.}"

    fname="${f%.*}"

    let fsize="$(stat --format='%s' ${f} )"

    let offset="$offset + $fsize"

    cat "$offset" >> "${STAT}"

    stat -t "$f" >> "${STAT}"

    cat "$f" >> /tmp/"$CARCHIVE"
    done

    statfile_size=$(stat --format="%s" "${STAT}")

    cat "${STAT}"

    echo -e "statfile size =\t ${statfile_size} bytes"

    cat "${STAT}"  >> "/tmp/${CARCHIVE}"
    echo ${statfile_size} >> "/tmp/${CARCHIVE}"
    cp "/tmp/${CARCHIVE}" .
}


test_carchive()
{
    # get size of file
    let fsize="$(stat --format="%s" "${1}")"

    #go back 2 bytes
    let offset="fsize - 2"

    # get the byte size put there
    let stat_size="$(xxd -l 2 -ps -c 2 -seek $offset ${1} )"

    # scrape off the stat file
    let startofstat="offset - ${stat_size}"

    dd if="${1}" bs=1 skip=${startofstat} count=${stat_size} iflag=skip_bytes,count_bytes of="/tmp/${1}.stat"


    mapfile -t stat_array < "/tmp/${1}.stat"


    for line in stat_array
    do
    echo "${line}"
    read_stat "${line}"

    done


}

read_stat()
{
    # stat  -t  == --format="%n %s %b %f %u %g %D %i %h %t %T %X %Y %Z %W %o"
    # %n name  %s size  %b blocks  %u uid  %g gid ....

while IFS=$' \n' read -r -a stat_info
do
    offset="${stat_info[0]}"
    >&2 echo "offset = ${offset}"
    name="${stat_info[1]}"
    >&2 echo "name = ${name}"
    size="${stat_info[2]}"
    >&2 echo "size = ${size}"

# the rest
    for s in "${stat_info[@]"
    do
    >&2 echo -e "${s} "
    done
    >&2 echo -e "\n"

# output
echo "${name} ${offset} ${size}"
}



uncarchive()
{
    if [ $# -lt 4 ] ;then
    echo "badly formatted unarchive hint stop stop stop"
    break
    else
    dd if="${1}" bs=1 skip="${2}" count="${3}" iflag=skip_bytes,count_bytes of="${4}"
    echo "unarchived ${4}"
    fi
}