Official Go implementation of the Ethereum protocol
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go-ethereum/internal/build/download.go

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3.6 KiB

// Copyright 2019 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package build
import (
"bufio"
"crypto/sha256"
"encoding/hex"
"fmt"
"io"
"log"
"net/http"
"os"
"path/filepath"
"strings"
)
// ChecksumDB keeps file checksums.
type ChecksumDB struct {
allChecksums []string
}
// MustLoadChecksums loads a file containing checksums.
func MustLoadChecksums(file string) *ChecksumDB {
content, err := os.ReadFile(file)
if err != nil {
log.Fatal("can't load checksum file: " + err.Error())
}
return &ChecksumDB{strings.Split(strings.ReplaceAll(string(content), "\r\n", "\n"), "\n")}
}
// Verify checks whether the given file is valid according to the checksum database.
func (db *ChecksumDB) Verify(path string) error {
fd, err := os.Open(path)
if err != nil {
return err
}
defer fd.Close()
h := sha256.New()
if _, err := io.Copy(h, bufio.NewReader(fd)); err != nil {
return err
}
fileHash := hex.EncodeToString(h.Sum(nil))
if !db.findHash(filepath.Base(path), fileHash) {
return fmt.Errorf("invalid file hash: %s %s", fileHash, filepath.Base(path))
}
return nil
}
func (db *ChecksumDB) findHash(basename, hash string) bool {
want := hash + " " + basename
for _, line := range db.allChecksums {
if strings.TrimSpace(line) == want {
return true
}
}
return false
}
// DownloadFile downloads a file and verifies its checksum.
func (db *ChecksumDB) DownloadFile(url, dstPath string) error {
if err := db.Verify(dstPath); err == nil {
fmt.Printf("%s is up-to-date\n", dstPath)
return nil
}
fmt.Printf("%s is stale\n", dstPath)
fmt.Printf("downloading from %s\n", url)
resp, err := http.Get(url)
if err != nil {
return fmt.Errorf("download error: %v", err)
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
return fmt.Errorf("download error: status %d", resp.StatusCode)
}
if err := os.MkdirAll(filepath.Dir(dstPath), 0755); err != nil {
return err
}
fd, err := os.OpenFile(dstPath, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0644)
if err != nil {
return err
}
dst := newDownloadWriter(fd, resp.ContentLength)
_, err = io.Copy(dst, resp.Body)
dst.Close()
if err != nil {
return err
}
return db.Verify(dstPath)
}
type downloadWriter struct {
file *os.File
dstBuf *bufio.Writer
size int64
written int64
lastpct int64
}
func newDownloadWriter(dst *os.File, size int64) *downloadWriter {
return &downloadWriter{
file: dst,
dstBuf: bufio.NewWriter(dst),
size: size,
}
}
func (w *downloadWriter) Write(buf []byte) (int, error) {
n, err := w.dstBuf.Write(buf)
// Report progress.
w.written += int64(n)
pct := w.written * 10 / w.size * 10
if pct != w.lastpct {
if w.lastpct != 0 {
fmt.Print("...")
}
fmt.Print(pct, "%")
w.lastpct = pct
}
return n, err
}
func (w *downloadWriter) Close() error {
if w.lastpct > 0 {
fmt.Println() // Finish the progress line.
}
flushErr := w.dstBuf.Flush()
closeErr := w.file.Close()
if flushErr != nil {
return flushErr
}
return closeErr
}