/
generate_file.go
84 lines (70 loc) · 1.46 KB
/
generate_file.go
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package main
import (
"context"
"crypto/md5"
"errors"
"fmt"
"io"
"math/rand"
"os"
"time"
sizeFormat "github.com/rdev02/size-format"
)
const defaultBuffer = 20 * sizeFormat.MB
//GenerateLen generates a file of size at path, returns MD5 hash.
func GenerateLen(ctx context.Context, size int64, path string) (string, error) {
if size <= 0 {
return "", errors.New("size must be greater then 0")
}
f, err := os.Create(path)
if err != nil {
return "", err
}
defer f.Close()
hash := md5.New()
hashedWriter := io.MultiWriter(f, hash)
actualBuffer := size
if size > defaultBuffer {
actualBuffer = defaultBuffer
}
tmp := make([]byte, actualBuffer)
rand.Seed(time.Now().UnixNano())
var errorWrite error = nil
t := size / actualBuffer
for i := int64(0); i < t; i++ {
select {
case <-ctx.Done():
break
default:
}
rand.Read(tmp)
_, err := hashedWriter.Write(tmp)
if err != nil {
errorWrite = err
break
}
}
rem := size - t*actualBuffer
if rem > 0 {
tmp = make([]byte, rem)
rand.Read(tmp)
_, err := hashedWriter.Write(tmp)
if err != nil {
errorWrite = err
}
}
return fmt.Sprintf("%x", string(hash.Sum(nil))), errorWrite
}
//GetFileMd5 generates MD5 of the file at path
func GetFileMd5(path string) (string, error) {
f, err := os.Open(path)
if err != nil {
return "", err
}
defer f.Close()
h := md5.New()
if _, err := io.Copy(h, f); err != nil {
return "", err
}
return fmt.Sprintf("%x", string(h.Sum(nil))), nil
}