A demo script writing Git blob object from ProGit

git_object_storage.rb

require 'digest/sha1'
require 'zlib'
require 'fileutils'

# put_raw_object("what is up, doc?", 'blob')
def put_raw_object(content, type)
  # Generate SHA-1
  header = "#{type} #{content.length}\0"   # => "blob 16\000"
  store = header + content              # => "blob 16\000what is up, doc?"
  sha1 = Digest::SHA1.hexdigest(store)  # => "bd9dbf5aae1a3862dd1526723246b20206e5fc37"
  
  # p sha1
  
  # Compress with Zlib
  zlib_content = Zlib::Deflate.deflate(store)
  
  # Write to disk
  path = '.git/objects/' + sha1[0,2] + '/' + sha1[2,38] # => ".git/objects/bd/9dbf5aae1a3862dd1526723246b20206e5fc37"
  FileUtils.mkdir_p(File.dirname(path))                 # => ".git/objects/bd"
  File.open(path, 'w'){|f| f.write zlib_content }
end