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session.go
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session.go
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package getparty
import (
"bufio"
"encoding/json"
"fmt"
"io"
"log"
"os"
"strings"
"sync/atomic"
"time"
"github.com/pkg/errors"
"github.com/vbauerster/mpb/v7"
"github.com/vbauerster/mpb/v7/decor"
)
// Session represents download session state
type Session struct {
location string
URL string
SuggestedFileName string
ContentMD5 string
AcceptRanges string
ContentType string
StatusCode int
ContentLength int64
Redirected bool
Elapsed time.Duration
HeaderMap map[string]string
Parts []*Part
}
func (s Session) isResumable() bool {
return strings.EqualFold(s.AcceptRanges, "bytes") && s.ContentLength > 0
}
func (s *Session) calcParts(parts uint) error {
if !s.isResumable() {
parts = 1
}
fragment := s.ContentLength / int64(parts)
if parts != 1 && fragment < 64 {
return errors.New("Too fragmented")
}
s.Parts = make([]*Part, parts)
s.Parts[0] = &Part{
FileName: s.SuggestedFileName,
}
var stop int64
start := s.ContentLength
for i := parts - 1; i > 0; i-- {
stop = start - 1
start = stop - fragment
s.Parts[i] = &Part{
FileName: fmt.Sprintf("%s.%02d", s.SuggestedFileName, i),
Start: start,
Stop: stop,
}
}
s.Parts[0].Stop = start - 1
return nil
}
func (s Session) concatenateParts(dlogger *log.Logger, progress *mpb.Progress) (size int64, err error) {
fpart0, err := os.OpenFile(s.Parts[0].FileName, os.O_APPEND|os.O_WRONLY, 0644)
if err != nil {
return 0, err
}
if len(s.Parts) > 1 {
bar := progress.New(int64(len(s.Parts)-1),
mpb.BarStyle().Lbound(" ").Rbound(" "),
mpb.BarFillerTrim(),
mpb.BarPriority(len(s.Parts)+1),
mpb.PrependDecorators(
decor.Name("Concatenating", decor.WCSyncWidthR),
decor.NewPercentage("%d", decor.WCSyncSpace),
),
mpb.AppendDecorators(
decor.OnComplete(decor.AverageETA(decor.ET_STYLE_MMSS), "Done"),
),
)
defer func() {
if err != nil {
bar.Abort(false)
}
}()
for i := 1; i < len(s.Parts); i++ {
fparti, err := os.Open(s.Parts[i].FileName)
if err != nil {
return 0, err
}
dlogger.Printf("concatenating: %s", fparti.Name())
if _, err := io.Copy(fpart0, fparti); err != nil {
return 0, err
}
for _, err := range [...]error{fparti.Close(), os.Remove(fparti.Name())} {
if err != nil {
dlogger.Printf("concatenateParts: %q %s", fparti.Name(), err.Error())
}
}
bar.Increment()
}
}
stat, err := fpart0.Stat()
if err != nil {
return 0, err
}
return stat.Size(), fpart0.Close()
}
func (s *Session) loadState(fileName string) error {
src, err := os.Open(fileName)
if err != nil {
return err
}
err = json.NewDecoder(bufio.NewReader(src)).Decode(s)
if e := src.Close(); err == nil {
err = e
}
return err
}
func (s Session) totalWritten() int64 {
var total int64
for _, p := range s.Parts {
total += p.Written
}
return total
}
func (s Session) writeSummary(w io.Writer, quiet bool) {
if quiet {
return
}
format := fmt.Sprintf("Length: %%s [%s]\n", s.ContentType)
lengthSummary := "unknown"
if s.ContentLength >= 0 {
lengthSummary = fmt.Sprintf("%d (%.1f)", s.ContentLength, decor.SizeB1024(s.ContentLength))
if totalWritten := s.totalWritten(); totalWritten > 0 {
remaining := s.ContentLength - totalWritten
lengthSummary += fmt.Sprintf(", %d (%.1f) remaining", remaining, decor.SizeB1024(remaining))
}
}
fmt.Fprintf(w, format, lengthSummary)
if s.ContentMD5 != "" {
fmt.Fprintf(w, "MD5: %s\n", s.ContentMD5)
}
if !s.isResumable() {
fmt.Fprintln(w, "HTTP server doesn't seem to support byte ranges. Cannot resume.")
}
if len(s.Parts) != 0 {
fmt.Fprintf(w, "Saving to: %q\n\n", s.SuggestedFileName)
}
}
func (s Session) checkExistingFile(w io.Writer, forceOverwrite bool) error {
stat, err := os.Stat(s.SuggestedFileName)
if err != nil {
if errors.Is(err, os.ErrNotExist) {
return nil
}
return err
}
if stat.IsDir() {
return fmt.Errorf("%v: %q is a directory", os.ErrInvalid, stat.Name())
}
if forceOverwrite {
return os.Remove(s.SuggestedFileName)
}
var answer string
fmt.Fprintf(w, "File %q already exists, overwrite? [y/n] ", stat.Name())
if _, err := fmt.Scanf("%s", &answer); err != nil {
return err
}
switch strings.ToLower(answer) {
case "y", "yes":
return os.Remove(s.SuggestedFileName)
default:
return ErrCanceledByUser
}
}
func (s Session) checkSums(other *Session) error {
if s.ContentMD5 != other.ContentMD5 {
return fmt.Errorf(
"ContentMD5 mismatch: expected %q got %q",
s.ContentMD5, other.ContentMD5,
)
}
if s.ContentLength != other.ContentLength {
return fmt.Errorf(
"ContentLength mismatch: expected %d got %d",
s.ContentLength, other.ContentLength,
)
}
return nil
}
func (s Session) checkPartsSize() error {
for _, part := range s.Parts {
if part.Skip {
continue
}
stat, err := os.Stat(part.FileName)
if err != nil {
return err
}
if fileSize := stat.Size(); part.Written != fileSize {
return fmt.Errorf(
"%q size mismatch: expected %d got %d",
part.FileName, part.Written, fileSize,
)
}
}
return nil
}
func (s Session) makeTotalBar(progress *mpb.Progress, partsDone *uint32) (bar *mpb.Bar) {
if len(s.Parts) <= 1 {
return
}
totalDecorator := func(_ decor.Statistics) string {
return fmt.Sprintf("TOTAL(%d/%d)", atomic.LoadUint32(partsDone), len(s.Parts))
}
bar = progress.New(s.ContentLength,
totalBarStyle(),
mpb.BarFillerTrim(),
mpb.PrependDecorators(
decor.Any(totalDecorator, decor.WCSyncWidthR),
decor.OnComplete(decor.NewPercentage("%.2f", decor.WCSyncSpace), "100%"),
),
mpb.AppendDecorators(
decor.OnComplete(decor.AverageETA(decor.ET_STYLE_MMSS, decor.WCSyncWidthR), "Avg:"),
decor.AverageSpeed(decor.UnitKiB, "%.1f", decor.WCSyncSpace),
),
)
if tw := s.totalWritten(); tw > 0 {
bar.SetCurrent(tw)
bar.DecoratorAverageAdjust(time.Now().Add(-s.Elapsed))
}
return bar
}