1 files changed, 41 insertions, 0 deletions
diff --git a/tools/updater/manifest.go b/tools/updater/manifest.go
new file mode 100644
index 0000000..942a5e7
--- /dev/null
+++ b/tools/updater/manifest.go
@@ -0,0 +1,41 @@
+package main
+
+import (
+    "crypto/sha512"
+    "os"
+    "io"
+    "fmt"
+)
+
+func checkFile(filepath string, checksum string) (bool, error) {
+    if _, err := os.Stat(filepath); os.IsNotExist(err) {
+        return false, nil
+    }
+
+    // file exists, check checksum
+    lsum, err := hash(filepath)
+    if err != nil {
+        return false, err
+    }
+
+    if checksum != fmt.Sprintf("%x", lsum) {
+        return false, nil
+    }
+
+    return true, nil
+}
+
+func hash(filepath string) ([]byte, error) {
+    file, err := os.Open(filepath)
+    if err != nil {
+        return nil, err
+    }
+    defer file.Close()
+
+    hasher := sha512.New()
+    if _, err := io.Copy(hasher, file); err != nil {
+        return nil, err
+    }
+
+    return hasher.Sum(nil), nil
+}