commit 767c889afc955db7780dc52eccac503951b780c5
Author: Mark Sanborn <marcrosoft@gmail.com>
Date:   Tue Nov 12 22:16:08 2013 -0800

    Initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..492a759
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,14 @@
+# Use glob syntax.
+syntax: glob
+
+*.DS_Store
+*.swp
+*.swo
+*.pyc
+*.php~
+*.orig
+*~
+*.db
+*.log
+public/*
+go-selfupdate
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..be11f09
--- /dev/null
+++ b/main.go
@@ -0,0 +1,131 @@
+package main
+
+import (
+    "fmt"
+    "os"
+    "encoding/json"
+    "io/ioutil"
+    "io"
+    "path/filepath"
+    "compress/gzip"
+    "bytes"
+    "crypto/sha256"
+    "github.com/kr/binarydist"
+    "runtime"
+    //"encoding/base64"
+)
+
+const (
+    plat = runtime.GOOS + "-" + runtime.GOARCH
+)
+
+type current struct {
+    Version string
+    Sha256 []byte
+}
+
+func generateSha256(path string) []byte {
+    h := sha256.New()
+    b, err := ioutil.ReadFile(path)
+    if err != nil {
+        fmt.Println(err)
+    }
+    h.Write(b)
+    sum := h.Sum(nil)
+    return sum
+    //return base64.URLEncoding.EncodeToString(sum)
+}
+
+type gzReader struct {
+        z, r io.ReadCloser
+}
+
+func (g *gzReader) Read(p []byte) (int, error) {
+        return g.z.Read(p)
+}
+
+func (g *gzReader) Close() error {
+        g.z.Close()
+        return g.r.Close()
+}
+
+func newGzReader(r io.ReadCloser) io.ReadCloser {
+        var err error
+        g := new(gzReader)
+        g.r = r
+        g.z, err = gzip.NewReader(r)
+        if err != nil {
+            panic(err)
+        }
+        return g
+}
+
+func main() {
+    appPath := os.Args[1]
+    version := os.Args[2]
+    genDir := "public"
+    os.MkdirAll(genDir, 0755)
+
+    c := current{Version: version, Sha256: generateSha256(appPath)}
+
+    b, err := json.MarshalIndent(c, "", "    ")
+    if err != nil {
+        fmt.Println("error:", err)
+    }
+    err = ioutil.WriteFile(filepath.Join(genDir, plat + ".json"), b, 0755)
+    if err != nil {
+        panic(err)
+    }
+
+    os.MkdirAll(filepath.Join(genDir, version), 0755)
+
+    var buf bytes.Buffer
+    w := gzip.NewWriter(&buf)
+    f, err := ioutil.ReadFile(appPath)
+    if err != nil {
+        panic(err)
+    }
+    w.Write(f)
+    w.Close() // You must close this first to flush the bytes to the buffer.
+    err = ioutil.WriteFile(filepath.Join(genDir, version, plat + ".gz"), buf.Bytes(), 0755)
+
+    files, err := ioutil.ReadDir(genDir)
+    if err != nil {
+        fmt.Println(err)
+    }
+
+    for _, file := range files {
+        if file.IsDir() == false {
+            continue
+        }
+        if file.Name() == version {
+            continue
+        }
+        os.Mkdir(filepath.Join(genDir, file.Name(), version), 0755)
+
+        fName := filepath.Join(genDir, file.Name(), plat + ".gz")
+        old, err := os.Open(fName)
+        if err != nil {
+            fmt.Fprintf(os.Stderr, "Can't open %s: error: %s\n", fName, err)
+            os.Exit(1)
+        }
+
+        fName = filepath.Join(genDir, version, plat + ".gz")
+        newF, err := os.Open(fName)
+        if err != nil {
+            fmt.Fprintf(os.Stderr, "Can't open %s: error: %s\n", fName, err)
+            os.Exit(1)
+        }
+
+        ar := newGzReader(old)
+        defer ar.Close()
+        br := newGzReader(newF)
+        defer br.Close()
+        patch := new(bytes.Buffer)
+        if err := binarydist.Diff(ar, br, patch); err != nil {
+            panic(err)
+        }
+        ioutil.WriteFile(filepath.Join(genDir, file.Name(), version, plat), patch.Bytes(), 0755)
+    }
+
+}