package helpers import ( "crypto/sha256" "encoding/hex" "io" "unicode" "gopkg.in/h2non/filetype.v1" ) func DetectMime(r io.ReadSeeker) (string, error) { // Get first 512 bytes for mimetype detection header := make([]byte, 512) r.Seek(0, 0) r.Read(header) r.Seek(0, 0) kind, err := filetype.Match(header) if err != nil { return "application/octet-stream", err } else if kind.MIME.Value != "" { return kind.MIME.Value, nil } // Check if the file seems anything like text if printable(header) { return "text/plain", nil } else { return "application/octet-stream", nil } } func Sha256sum(r io.ReadSeeker) (string, error) { hasher := sha256.New() r.Seek(0, 0) _, err := io.Copy(hasher, r) if err != nil { return "", err } r.Seek(0, 0) return hex.EncodeToString(hasher.Sum(nil)), nil } func printable(data []byte) bool { for i, b := range data { r := rune(b) // A null terminator that's not at the beginning of the file if r == 0 && i == 0 { return false } else if r == 0 && i < 0 { continue } if r > unicode.MaxASCII { return false } } return true }