file-util.go: new functions CopyFileWithParent(), CopyFile(), CompareFilesBMd5(), CompareLastChangeTime(), and LoadFile()

file-util.go

@@ -5,10 +5,13 @@
 package utils
 
 import (
+	"bytes"
+	"crypto/md5"
 	"errors"
 	"fmt"
 	"io"
 	"os"
+	"path"
 	"strconv"
 	"strings"
 )
@@ -140,3 +143,104 @@ func ParseMemSize(s string) (size int64, err error) {
 	}
 	return
 }
+
+func CopyFileWithParent(src, dst string, perm os.FileMode) (int64, error) {
+	parent := path.Dir(dst)
+	if err := os.MkdirAll(parent, 0775); err != nil {
+		return 0, err
+	}
+	return CopyFile(src, dst, perm)
+}
+
+func CopyFile(src, dst string, perm os.FileMode) (int64, error) {
+	sourceFileStat, err := os.Stat(src)
+	if err != nil {
+		return 0, err
+	}
+
+	if !sourceFileStat.Mode().IsRegular() {
+		return 0, fmt.Errorf("%s is not a regular file", src)
+	}
+
+	source, err := os.Open(src)
+	if err != nil {
+		return 0, err
+	}
+	defer source.Close()
+
+	destination, err := os.Create(dst)
+	if err != nil {
+		return 0, err
+	}
+	defer destination.Close()
+
+	if perm != 0 {
+		os.Chmod(dst, perm)
+	}
+	nBytes, err := io.Copy(destination, source)
+	return nBytes, err
+}
+
+func CompareFilesByMd5(filePath1, filePath2 string) (same bool, err error) {
+	var fh1, fh2 *os.File
+
+	if fh1, err = os.Open(filePath1); err != nil {
+		return
+	}
+	defer fh1.Close()
+
+	if fh2, err = os.Open(filePath2); err != nil {
+		return
+	}
+	defer fh2.Close()
+
+	h1 := md5.New()
+	if _, err = io.Copy(h1, fh1); err != nil {
+		return
+	}
+
+	h2 := md5.New()
+	if _, err = io.Copy(h2, fh2); err != nil {
+		return
+	}
+
+	s1 := h1.Sum(nil)
+	s2 := h2.Sum(nil)
+	same = bytes.Equal(s1, s2)
+	// same = bytes.Equal(h1.Sum(nil), h2.Sum(nil))
+	return
+}
+
+// <0 = first newer than second
+// =0 = same date
+// >1 = first older than second
+func CompareLastChangeTime(first, second string) (result int, err error) {
+	var info os.FileInfo
+
+	if info, err = os.Stat(first); err != nil {
+		return
+	}
+
+	if info, err = os.Stat(second); err != nil {
+		return
+	}
+
+	tFirst := info.ModTime()
+	tSecond := info.ModTime()
+	if tFirst.After(tSecond) {
+		result = -1
+	} else if tFirst.Before(tSecond) {
+		result = 1
+	} else {
+		result = 0
+	}
+	return
+}
+
+func LoadFile(filePath string) (data []byte, err error) {
+	data, err = os.ReadFile(filePath)
+	if err != nil {
+		err = fmt.Errorf("error reading file %q: %w", filePath, err)
+	}
+	return
+}