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import (
"bytes"
"encoding/binary"
"fmt"
"io"
"io/ioutil"
"log"
"os"
"strconv"
"strings"
"time"
)
func createTempFile(partFilename string, fileBegin, fileEnd int) {
buf := new(bytes.Buffer)
if err := binary.Write(buf, binary.LittleEndian, int64(fileBegin)); err != nil {
log.Fatal(err)
}
if err := binary.Write(buf, binary.LittleEndian, int64(fileEnd)); err != nil {
log.Fatal(err)
}
if err := ioutil.WriteFile(partFilename, buf.Bytes(), 0666); err != nil {
log.Fatal(err)
}
}
func writeBytes(partFilename string, reader []byte, byteStart, byteEnd int) error {
if err := os.MkdirAll(DownloadLocation+"/temp/", 0777); err != nil {
return err
}
if _, err := os.Stat(DownloadLocation + "/temp/" + partFilename); err != nil {
createTempFile(DownloadLocation+"/temp/"+partFilename, byteStart, byteEnd)
}
file, err := os.OpenFile(DownloadLocation+"/temp/"+partFilename, os.O_WRONLY|os.O_APPEND, 0666)
if err != nil {
return err
}
defer file.Close()
if _, err = file.WriteString(string(reader)); err != nil {
return err
}
return nil
}
func readHeader(partFilename string) (int, int) {
reader, err := ioutil.ReadFile(partFilename)
if err != nil {
log.Fatal(err)
}
header := reader[:16]
byteStart := int(binary.LittleEndian.Uint64(header[0:8])) + len(reader) - 16
byteEnd := int(binary.LittleEndian.Uint64(header[8:16]))
return byteStart, byteEnd
}
func mergeFiles(filename string, count int) {
tempFilename := strconv.Itoa(time.Now().Nanosecond()) + "_" + filename
fmt.Println("temp file name : " + tempFilename)
fmt.Println("file name : " + filename)
file, err := os.OpenFile(DownloadLocation+"/"+tempFilename, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0666)
if err != nil {
log.Fatal(err)
}
defer file.Close()
for i := 0; i < count; i++ {
partFilename := DownloadLocation + "/temp/" + filename + "_" + strconv.Itoa(i)
reader, err := ioutil.ReadFile(partFilename)
reader = reader[16:]
if err != nil {
log.Fatal(err)
}
if _, err = file.WriteString(string(reader)); err != nil {
log.Fatal(err)
}
}
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os.Rename(DownloadLocation+"/"+tempFilename, DownloadLocation+"/"+filename)
}
func isDirEmpty(name string) (bool, error) {
f, err := os.Open(name)
if err != nil {
return false, err
}
defer f.Close()
_, err = f.Readdir(1)
if err == io.EOF {
return true, nil
}
return false, err
}
func clearFiles(filename string, count int) {
for i := 0; i < count; i++ {
partFilename := DownloadLocation + "/temp/" + filename + "_" + strconv.Itoa(i)
os.Remove(partFilename)
}
empty, err := isDirEmpty(DownloadLocation + "/temp/")
if err != nil {
log.Fatal(err)
}
if empty {
os.Remove(DownloadLocation + "/temp/")
}
}
func noOfExistingConnection(filename string, length int) int {
existingFilename := DownloadLocation + "/temp/" + filename + "_0"
if _, err := os.Stat(existingFilename); err != nil {
log.Fatal("No file to resume downloading")
}
if _, err := os.Stat(existingFilename); err == nil {
reader, err := ioutil.ReadFile(existingFilename)
if err != nil {
log.Fatal(err)
}
if len(reader) < 16 {
log.Fatal("No file to resume downloading")
}
header := reader[:16]
interval := int(binary.LittleEndian.Uint64(header[8:16])) - int(binary.LittleEndian.Uint64(header[0:8]))
if interval == 0 {
log.Fatal("No file to resume downloading")
}
return (length / interval)
}
return 0
}
func getFilename(filename string) string {
j := 0
for j = 0; ; j++ {
if j == 1 {
filename += "(1)"
}
if (j != 0) && (j != 1) {
filename = strings.Replace(filename, "("+strconv.Itoa(j-1)+")", "("+strconv.Itoa(j)+")", 1)
}
if _, err := os.Stat(filename); os.IsNotExist(err) {
break
}
}
if j != 0 && j != 1 {
filename = strings.Replace(filename, "("+strconv.Itoa(j-1)+")", "("+strconv.Itoa(j)+")", 1)
}
return filename
}