sbxsplit.sh

#!/bin/bash

shopt -s extglob

if (( $# < 4 )); then
    echo "Usage : in_file out_prefix data_chunk parity_chunk [--encode-parts]"
    exit 1
fi

in_file=$1
out_prefix=$2
data_chunk=$3
parity_chunk=$4

encode=false
if (( $# >= 5 )); then
    if [[ $5 == "--encode-parts" ]]; then
        encode=true
    fi
fi

sbx_version=17
sbx_block_size=512

file_size=$(ls -l $in_file | awk '{ print $5 }')

output=$(rsbx calc --json $file_size --sbx-version $sbx_version --rs-data $data_chunk --rs-parity $parity_chunk)

data_block_count=$(echo $output | jq -r ".stats.dataOnlyBlockCount")
block_set_size=$[$data_block_count / $data_chunk]

echo "Encoding file"
output=$(rsbx encode --json $in_file $out_prefix.$in_file.tmp \
              --sbx-version $sbx_version --rs-data $data_chunk --rs-parity $parity_chunk --burst $block_set_size)
error=$(echo $output | jq -r ".error")
if [[ $error != "null" ]]; then
    echo "Error occured during encoding"
    echo $error
    exit 1
fi

# split the file
echo "Splitting container"
for (( i=0; i < $data_chunk; i++ )); do
    out_part=$out_prefix.part$i

    echo "  Creating $out_part"

    dd if=$out_prefix.$in_file.tmp of=$out_part \
       bs=$sbx_block_size skip=$[$i * ($block_set_size + 1)] count=$[$block_set_size + 1] &>/dev/null
done

skip_base=$[$data_chunk * ($block_set_size + 1)]

for (( i=0; i < $parity_chunk; i++ )); do
    chunk_index=$[$i + $data_chunk]
    out_part=$out_prefix.part$chunk_index

    echo "  Creating $out_part"

    dd if=$out_prefix.$in_file.tmp of=$out_part \
       bs=$sbx_block_size skip=$[$i * $block_set_size + $skip_base] count=$block_set_size &>/dev/null
done

echo "Encoding parts"

if $encode; then
    for file in $out_prefix.part+([0-9]); do
        echo "  Encoding $file"

        output=$(rsbx encode --json $file \
                      --sbx-version 17 --rs-data 10 --rs-parity 1 --burst 10)
        error=$(echo $output | jq -r ".error")
        if [[ $error != "null" ]]; then
            echo "  Error occured during encoding"
            echo $error
            exit 1
        fi
        rm $file
    done
else
    echo "  Skipped"
fi

# clean up
echo "Cleaning up"
rm $out_prefix.$in_file.tmp