Initial Commit

utils/utils.go

@@ -0,0 +1,49 @@
+package utils
+
+import (
+	"bytes"
+	"crypto/md5"
+	// "encoding/hex"
+	"fmt"
+	"io"
+	"os"
+)
+
+func CalculatePartialMD5(filePath string) string {
+	file, err := os.Open(filePath)
+	if err != nil {
+		panic(err)
+	}
+
+	defer file.Close()
+
+	var step int64 = 1024
+	var size int64 = 1024
+	var buf bytes.Buffer
+
+	for i := -1; i <= 10; i++ {
+		byteStep := make([]byte, size)
+
+		var newShift int64 = int64(i * 2)
+		var newOffset int64
+		if i == -1 {
+			newOffset = 0
+		} else {
+			newOffset = step << newShift
+		}
+
+		_, err := file.ReadAt(byteStep, newOffset)
+		if err == io.EOF {
+			break
+		}
+		buf.Write(byteStep)
+	}
+
+	allBytes := buf.Bytes()
+	return fmt.Sprintf("%x", md5.Sum(allBytes))
+}
+
+func main() {
+	fileHash := CalculatePartialMD5("test.epub")
+	fmt.Println("MD5: ", fileHash)
+}