github.com/aigarnetwork/aigar@v0.0.0-20191115204914-d59a6eb70f8e/internal/build/gosrc.go (about)

     1  //  Copyright 2018 The go-ethereum Authors
     2  //  Copyright 2019 The go-aigar Authors
     3  //  This file is part of the go-aigar library.
     4  //
     5  //  The go-aigar library is free software: you can redistribute it and/or modify
     6  //  it under the terms of the GNU Lesser General Public License as published by
     7  //  the Free Software Foundation, either version 3 of the License, or
     8  //  (at your option) any later version.
     9  //
    10  //  The go-aigar library is distributed in the hope that it will be useful,
    11  //  but WITHOUT ANY WARRANTY; without even the implied warranty of
    12  //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    13  //  GNU Lesser General Public License for more details.
    14  //
    15  //  You should have received a copy of the GNU Lesser General Public License
    16  //  along with the go-aigar library. If not, see <http://www.gnu.org/licenses/>.
    17  
    18  package build
    19  
    20  import (
    21  	"bytes"
    22  	"crypto/sha256"
    23  	"fmt"
    24  	"io/ioutil"
    25  	"net/http"
    26  	"os"
    27  	"path/filepath"
    28  	"strings"
    29  )
    30  
    31  // EnsureGoSources ensures that path contains a file with the given SHA256 hash,
    32  // and if not, it downloads a fresh Go source package from upstream and replaces
    33  // path with it (if the hash matches).
    34  func EnsureGoSources(version string, hash []byte, path string) error {
    35  	// Sanity check the destination path to ensure we don't do weird things
    36  	if !strings.HasSuffix(path, ".tar.gz") {
    37  		return fmt.Errorf("destination path (%s) must end with .tar.gz", path)
    38  	}
    39  	// If the file exists, validate it's hash
    40  	if archive, err := ioutil.ReadFile(path); err == nil { // Go sources are ~20MB, it's fine to read all
    41  		hasher := sha256.New()
    42  		hasher.Write(archive)
    43  		have := hasher.Sum(nil)
    44  
    45  		if bytes.Equal(have, hash) {
    46  			fmt.Printf("Go %s [%x] available at %s\n", version, hash, path)
    47  			return nil
    48  		}
    49  		fmt.Printf("Go %s hash mismatch (have %x, want %x) at %s, deleting old archive\n", version, have, hash, path)
    50  		if err := os.Remove(path); err != nil {
    51  			return err
    52  		}
    53  	}
    54  	// Archive missing or bad hash, download a new one
    55  	fmt.Printf("Downloading Go %s [want %x] into %s\n", version, hash, path)
    56  
    57  	res, err := http.Get(fmt.Sprintf("https://dl.google.com/go/go%s.src.tar.gz", version))
    58  	if err != nil || res.StatusCode != http.StatusOK {
    59  		return fmt.Errorf("failed to access Go sources: code %d, err %v", res.StatusCode, err)
    60  	}
    61  	defer res.Body.Close()
    62  
    63  	archive, err := ioutil.ReadAll(res.Body)
    64  	if err != nil {
    65  		return err
    66  	}
    67  	// Sanity check the downloaded archive, save if checks out
    68  	hasher := sha256.New()
    69  	hasher.Write(archive)
    70  
    71  	if have := hasher.Sum(nil); !bytes.Equal(have, hash) {
    72  		return fmt.Errorf("downloaded Go %s hash mismatch (have %x, want %x)", version, have, hash)
    73  	}
    74  	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
    75  		return err
    76  	}
    77  	if err := ioutil.WriteFile(path, archive, 0644); err != nil {
    78  		return err
    79  	}
    80  	fmt.Printf("Downloaded Go %s [%x] into %s\n", version, hash, path)
    81  	return nil
    82  }