github.com/bigzoro/my_simplechain@v0.0.0-20240315012955-8ad0a2a29bb9/internal/build/download.go (about) 1 // Copyright 2019 The go-simplechain Authors 2 // This file is part of the go-simplechain library. 3 // 4 // The go-simplechain library is free software: you can redistribute it and/or modify 5 // it under the terms of the GNU Lesser General Public License as published by 6 // the Free Software Foundation, either version 3 of the License, or 7 // (at your option) any later version. 8 // 9 // The go-simplechain library is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU Lesser General Public License for more details. 13 // 14 // You should have received a copy of the GNU Lesser General Public License 15 // along with the go-simplechain library. If not, see <http://www.gnu.org/licenses/>. 16 17 package build 18 19 import ( 20 "bufio" 21 "crypto/sha256" 22 "encoding/hex" 23 "fmt" 24 "io" 25 "io/ioutil" 26 "log" 27 "net/http" 28 "os" 29 "path/filepath" 30 "strings" 31 ) 32 33 // ChecksumDB keeps file checksums. 34 type ChecksumDB struct { 35 allChecksums []string 36 } 37 38 // MustLoadChecksums loads a file containing checksums. 39 func MustLoadChecksums(file string) *ChecksumDB { 40 content, err := ioutil.ReadFile(file) 41 if err != nil { 42 log.Fatal("can't load checksum file: " + err.Error()) 43 } 44 return &ChecksumDB{strings.Split(string(content), "\n")} 45 } 46 47 // Verify checks whether the given file is valid according to the checksum database. 48 func (db *ChecksumDB) Verify(path string) error { 49 fd, err := os.Open(path) 50 if err != nil { 51 return err 52 } 53 defer fd.Close() 54 55 h := sha256.New() 56 if _, err := io.Copy(h, bufio.NewReader(fd)); err != nil { 57 return err 58 } 59 fileHash := hex.EncodeToString(h.Sum(nil)) 60 if !db.findHash(filepath.Base(path), fileHash) { 61 return fmt.Errorf("invalid file hash %s", fileHash) 62 } 63 return nil 64 } 65 66 func (db *ChecksumDB) findHash(basename, hash string) bool { 67 want := hash + " " + basename 68 for _, line := range db.allChecksums { 69 if strings.TrimSpace(line) == want { 70 return true 71 } 72 } 73 return false 74 } 75 76 // DownloadFile downloads a file and verifies its checksum. 77 func (db *ChecksumDB) DownloadFile(url, dstPath string) error { 78 if err := db.Verify(dstPath); err == nil { 79 fmt.Printf("%s is up-to-date\n", dstPath) 80 return nil 81 } 82 fmt.Printf("%s is stale\n", dstPath) 83 fmt.Printf("downloading from %s\n", url) 84 85 resp, err := http.Get(url) 86 if err != nil || resp.StatusCode != http.StatusOK { 87 return fmt.Errorf("download error: code %d, err %v", resp.StatusCode, err) 88 } 89 defer resp.Body.Close() 90 if err := os.MkdirAll(filepath.Dir(dstPath), 0755); err != nil { 91 return err 92 } 93 fd, err := os.OpenFile(dstPath, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0644) 94 if err != nil { 95 return err 96 } 97 dst := newDownloadWriter(fd, resp.ContentLength) 98 _, err = io.Copy(dst, resp.Body) 99 dst.Close() 100 if err != nil { 101 return err 102 } 103 104 return db.Verify(dstPath) 105 } 106 107 type downloadWriter struct { 108 file *os.File 109 dstBuf *bufio.Writer 110 size int64 111 written int64 112 lastpct int64 113 } 114 115 func newDownloadWriter(dst *os.File, size int64) *downloadWriter { 116 return &downloadWriter{ 117 file: dst, 118 dstBuf: bufio.NewWriter(dst), 119 size: size, 120 } 121 } 122 123 func (w *downloadWriter) Write(buf []byte) (int, error) { 124 n, err := w.dstBuf.Write(buf) 125 126 // Report progress. 127 w.written += int64(n) 128 pct := w.written * 10 / w.size * 10 129 if pct != w.lastpct { 130 if w.lastpct != 0 { 131 fmt.Print("...") 132 } 133 fmt.Print(pct, "%") 134 w.lastpct = pct 135 } 136 return n, err 137 } 138 139 func (w *downloadWriter) Close() error { 140 if w.lastpct > 0 { 141 fmt.Println() // Finish the progress line. 142 } 143 flushErr := w.dstBuf.Flush() 144 closeErr := w.file.Close() 145 if flushErr != nil { 146 return flushErr 147 } 148 return closeErr 149 }