setup

Signed-off-by: Simon de Vlieger <supakeen@redhat.com>

README.md

@@ -1,5 +1,7 @@
 # zerkalo
 
+A tool to efficiently mirror Linux distribution repositories (and perhaps some other forms of repositories). Uses a [git](https://git-scm.com/)-alike blob storage for data allowing for cheap snapshotting of repositories.
+
 ## Name
 
 The name zerkalo comes from the Russian [зеркало](https://en.wiktionary.org/wiki/%D0%B7%D0%B5%D1%80%D0%BA%D0%B0%D0%BB%D0%BE) which is a mirror.

cmd/root.go

@@ -6,14 +6,14 @@ import (
 
 var (
 	// Used for flags.
-	userLicense string
+	storagePath string
 
 	rootCmd = &cobra.Command{
 		Use:   "zerkalo",
-		Short: "",
-		//Long: `Cobra is a CLI library for Go that empowers applications.
-		//This application is a tool to generate the needed files
-		//to quickly create a Cobra application.`,
+		Short: "Efficiently mirror Linux distribution repositories",
+		Long: `zerkalo is a CLI program that allows its users to mirror.
+Linux distribution repositories such as apt, or yum. It lets users easily
+snapshot repositories per day and deduplicates as much content as it can.`,
 	}
 )
 
@@ -23,5 +23,5 @@ func Execute() error {
 }
 
 func init() {
-	// rootCmd.PersistentFlags().StringVarP(&userLicense, "license", "l", "", "name of license for the project")
+	rootCmd.PersistentFlags().StringVarP(&storagePath, "storage-path", "p", "", "zerkalo storage path")
 }

cmd/storage.go

@@ -0,0 +1,20 @@
+package cmd
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	rootCmd.AddCommand(storageCmd)
+}
+
+var storageCmd = &cobra.Command{
+	Use:   "storage",
+	Short: "Interact with the storage used by zerkalo",
+	//Long:  `All software has versions. This is Hugo's`,
+	Run: func(cmd *cobra.Command, args []string) {
+		fmt.Println("Hugo Static Site Generator v0.9 -- HEAD")
+	},
+}

internal/format/yum/yum.go

@@ -0,0 +1 @@
+package yum

internal/storage/storage.go

@@ -0,0 +1,61 @@
+package storage
+
+import (
+	"crypto/sha256"
+)
+
+type Storage struct {
+	Path string
+}
+
+func NewStorage(path string) (*Storage, error) {
+	s := Storage{
+		Path: path,
+	}
+
+	return &s, nil
+}
+
+type Object interface {
+	GetHash() [32]byte
+}
+
+type Blob struct {
+	Data []byte
+}
+
+// The `GetHash()` for a `Blob` is a straightforward SHA256 hash of the
+// contents of that blob.
+func (b *Blob) GetHash() [32]byte {
+	return sha256.Sum256(b.Data)
+}
+
+func NewBlob(data []byte) (*Blob, error) {
+	b := Blob{
+		Data: data,
+	}
+
+	return &b, nil
+}
+
+type Tree struct {
+	Items map[string]Object
+}
+
+func NewTree() (*Tree, error) {
+	return nil, nil
+}
+
+// For a `Tree` the `GetHash()` is a bit more intertwined. It's basically the
+// hash of all its items. Yes, this recurses trees which is bad but the naive
+// approach suffices for now. I also don't like the `[32]` vs `[]` dance here.
+func (t *Tree) GetHash() [32]byte {
+	h := sha256.New()
+
+	for _, v := range t.Items {
+		s := v.GetHash()
+		h.Write(s[:])
+	}
+
+	return [32]byte(h.Sum(nil))
+}