sgit/sgit-mkblob

#! /bin/bash

source_file="$1"
objdir="$PWD/.git/objects"
[[ ! -f "$source_file" ]] && echo "Usage: sgit-mkblob FILE

Creates a git blob object from FILE.
Assumes $objdir exists." && exit 1
[[ ! -d "$objdir" ]] && echo "Please create $objdir, for example by running sgit-init." && exit 1


# Every object header contains the object type
# followed by the payload byte length terminated 
# with a null byte (\0).
function header() {
    printf "blob $(wc -c $PWD/$source_file | awk '{print $1}')\0"
}

# A blob contains header + payload.
function blob() {
    cat <(header) "$source_file"
}


# Determine where to store the object, based on its
# sha1 hash, and create the necessary directory.
sha=$(blob | sha1sum)
dest_dir="$objdir"/$(echo $sha | awk '{print substr($1,1,2)}')
mkdir -p "$dest_dir"
dest_file=$(echo $sha | awk '{print substr($1,3)}')

# Compress the object with zlib.
blob | openssl zlib > "$dest_dir"/"$dest_file"