github.com/cbysal/go-ethereum@v1.9.7/internal/build/gosrc.go (about)

     1  // Copyright 2019 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum 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-ethereum 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-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package build
    18  
    19  import (
    20  	"bytes"
    21  	"crypto/sha256"
    22  	"fmt"
    23  	"io/ioutil"
    24  	"net/http"
    25  	"os"
    26  	"path/filepath"
    27  	"strings"
    28  )
    29  
    30  // EnsureGoSources ensures that path contains a file with the given SHA256 hash,
    31  // and if not, it downloads a fresh Go source package from upstream and replaces
    32  // path with it (if the hash matches).
    33  func EnsureGoSources(version string, hash []byte, path string) error {
    34  	// Sanity check the destination path to ensure we don't do weird things
    35  	if !strings.HasSuffix(path, ".tar.gz") {
    36  		return fmt.Errorf("destination path (%s) must end with .tar.gz", path)
    37  	}
    38  	// If the file exists, validate it's hash
    39  	if archive, err := ioutil.ReadFile(path); err == nil { // Go sources are ~20MB, it's fine to read all
    40  		hasher := sha256.New()
    41  		hasher.Write(archive)
    42  		have := hasher.Sum(nil)
    43  
    44  		if bytes.Equal(have, hash) {
    45  			fmt.Printf("Go %s [%x] available at %s\n", version, hash, path)
    46  			return nil
    47  		}
    48  		fmt.Printf("Go %s hash mismatch (have %x, want %x) at %s, deleting old archive\n", version, have, hash, path)
    49  		if err := os.Remove(path); err != nil {
    50  			return err
    51  		}
    52  	}
    53  	// Archive missing or bad hash, download a new one
    54  	fmt.Printf("Downloading Go %s [want %x] into %s\n", version, hash, path)
    55  
    56  	res, err := http.Get(fmt.Sprintf("https://dl.google.com/go/go%s.src.tar.gz", version))
    57  	if err != nil || res.StatusCode != http.StatusOK {
    58  		return fmt.Errorf("failed to access Go sources: code %d, err %v", res.StatusCode, err)
    59  	}
    60  	defer res.Body.Close()
    61  
    62  	archive, err := ioutil.ReadAll(res.Body)
    63  	if err != nil {
    64  		return err
    65  	}
    66  	// Sanity check the downloaded archive, save if checks out
    67  	hasher := sha256.New()
    68  	hasher.Write(archive)
    69  
    70  	if have := hasher.Sum(nil); !bytes.Equal(have, hash) {
    71  		return fmt.Errorf("downloaded Go %s hash mismatch (have %x, want %x)", version, have, hash)
    72  	}
    73  	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
    74  		return err
    75  	}
    76  	if err := ioutil.WriteFile(path, archive, 0644); err != nil {
    77  		return err
    78  	}
    79  	fmt.Printf("Downloaded Go %s [%x] into %s\n", version, hash, path)
    80  	return nil
    81  }