travis, build, internal: use own Go bundle for PPA builds (#20240)

* build: bump PPAs to Go 1.13 (via longsleep), keep Trusty on 1.11

* travis, build, vendor: use own Go bundle for PPA builds

* travis, build, internal, vendor: smarter Go bundler, own untar

* build: updated ci-notes with new Go bundling, only make, don't test

internal/build/archive.go

@@ -183,3 +183,49 @@ func (a *TarballArchive) Close() error {
 	}
 	return a.file.Close()
 }
+
+func ExtractTarballArchive(archive string, dest string) error {
+	// We're only interested in gzipped archives, wrap the reader now
+	ar, err := os.Open(archive)
+	if err != nil {
+		return err
+	}
+	defer ar.Close()
+
+	gzr, err := gzip.NewReader(ar)
+	if err != nil {
+		return err
+	}
+	defer gzr.Close()
+
+	// Iterate over all the files in the tarball
+	tr := tar.NewReader(gzr)
+	for {
+		// Fetch the next tarball header and abort if needed
+		header, err := tr.Next()
+		if err != nil {
+			if err == io.EOF {
+				return nil
+			}
+			return err
+		}
+		// Figure out the target and create it
+		target := filepath.Join(dest, header.Name)
+
+		switch header.Typeflag {
+		case tar.TypeDir:
+			if err := os.MkdirAll(target, 0755); err != nil {
+				return err
+			}
+		case tar.TypeReg:
+			file, err := os.OpenFile(target, os.O_CREATE|os.O_RDWR, os.FileMode(header.Mode))
+			if err != nil {
+				return err
+			}
+			if _, err := io.Copy(file, tr); err != nil {
+				return err
+			}
+			file.Close()
+		}
+	}
+}

internal/build/gosrc.go

@@ -0,0 +1,81 @@
+// 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 (
+	"bytes"
+	"crypto/sha256"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// EnsureGoSources ensures that path contains a file with the given SHA256 hash,
+// and if not, it downloads a fresh Go source package from upstream and replaces
+// path with it (if the hash matches).
+func EnsureGoSources(version string, hash []byte, path string) error {
+	// Sanity check the destination path to ensure we don't do weird things
+	if !strings.HasSuffix(path, ".tar.gz") {
+		return fmt.Errorf("destination path (%s) must end with .tar.gz", path)
+	}
+	// If the file exists, validate it's hash
+	if archive, err := ioutil.ReadFile(path); err == nil { // Go sources are ~20MB, it's fine to read all
+		hasher := sha256.New()
+		hasher.Write(archive)
+		have := hasher.Sum(nil)
+
+		if bytes.Equal(have, hash) {
+			fmt.Printf("Go %s [%x] available at %s\n", version, hash, path)
+			return nil
+		}
+		fmt.Printf("Go %s hash mismatch (have %x, want %x) at %s, deleting old archive\n", version, have, hash, path)
+		if err := os.Remove(path); err != nil {
+			return err
+		}
+	}
+	// Archive missing or bad hash, download a new one
+	fmt.Printf("Downloading Go %s [want %x] into %s\n", version, hash, path)
+
+	res, err := http.Get(fmt.Sprintf("https://dl.google.com/go/go%s.src.tar.gz", version))
+	if err != nil || res.StatusCode != http.StatusOK {
+		return fmt.Errorf("failed to access Go sources: code %d, err %v", res.StatusCode, err)
+	}
+	defer res.Body.Close()
+
+	archive, err := ioutil.ReadAll(res.Body)
+	if err != nil {
+		return err
+	}
+	// Sanity check the downloaded archive, save if checks out
+	hasher := sha256.New()
+	hasher.Write(archive)
+
+	if have := hasher.Sum(nil); !bytes.Equal(have, hash) {
+		return fmt.Errorf("downloaded Go %s hash mismatch (have %x, want %x)", version, have, hash)
+	}
+	if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
+		return err
+	}
+	if err := ioutil.WriteFile(path, archive, 0644); err != nil {
+		return err
+	}
+	fmt.Printf("Downloaded Go %s [%x] into %s\n", version, hash, path)
+	return nil
+}