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// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package stdlib supports special handling of the Go standard library.
// Regardless of the how the standard library has been split into modules for
// development and testing, the discovery site treats it as a single module
// named "std".
package stdlib
import (
"archive/zip"
"bytes"
"fmt"
"io"
"os"
"path"
"path/filepath"
"regexp"
"strings"
"time"
"golang.org/x/mod/semver"
"golang.org/x/pkgsite/internal/derrors"
"golang.org/x/pkgsite/internal/testing/testhelper"
"github.com/go-git/go-billy/v5/osfs"
"github.com/go-git/go-git/v5"
"github.com/go-git/go-git/v5/config"
"github.com/go-git/go-git/v5/plumbing"
"github.com/go-git/go-git/v5/plumbing/filemode"
"github.com/go-git/go-git/v5/plumbing/object"
"github.com/go-git/go-git/v5/storage/memory"
)
// ModulePath is the name of the module for the standard library.
const ModulePath = "std"
var (
// Regexp for matching go tags. The groups are:
// 1 the major.minor version
// 2 the patch version, or empty if none
// 3 the entire prerelease, if present
// 4 the prerelease type ("beta" or "rc")
// 5 the prerelease number
tagRegexp = regexp.MustCompile(`^go(\d+\.\d+)(\.\d+|)((beta|rc)(\d+))?$`)
)
// VersionForTag returns the semantic version for the Go tag, or "" if
// tag doesn't correspond to a Go release or beta tag.
// Examples:
// "go1" => "v1.0.0"
// "go1.2" => "v1.2.0"
// "go1.13beta1" => "v1.13.0-beta.1"
// "go1.9rc2" => "v1.9.0-rc.2"
func VersionForTag(tag string) string {
// Special cases for go1.
if tag == "go1" {
return "v1.0.0"
}
if tag == "go1.0" {
return ""
}
m := tagRegexp.FindStringSubmatch(tag)
if m == nil {
return ""
}
version := "v" + m[1]
if m[2] != "" {
version += m[2]
} else {
version += ".0"
}
if m[3] != "" {
version += "-" + m[4] + "." + m[5]
}
return version
}
// TagForVersion returns the Go standard library repository tag corresponding
// to semver. The Go tags differ from standard semantic versions in a few ways,
// such as beginning with "go" instead of "v".
func TagForVersion(version string) (_ string, err error) {
defer derrors.Wrap(&err, "TagForVersion(%q)", version)
// Special case: v1.0.0 => go1.
if version == "v1.0.0" {
return "go1", nil
}
if !semver.IsValid(version) {
return "", fmt.Errorf("%w: requested version is not a valid semantic version: %q ", derrors.InvalidArgument, version)
}
goVersion := semver.Canonical(version)
prerelease := semver.Prerelease(goVersion)
versionWithoutPrerelease := strings.TrimSuffix(goVersion, prerelease)
patch := strings.TrimPrefix(versionWithoutPrerelease, semver.MajorMinor(goVersion)+".")
if patch == "0" {
versionWithoutPrerelease = strings.TrimSuffix(versionWithoutPrerelease, ".0")
}
goVersion = fmt.Sprintf("go%s", strings.TrimPrefix(versionWithoutPrerelease, "v"))
if prerelease != "" {
// Go prereleases look like "beta1" instead of "beta.1".
// "beta1" is bad for sorting (since beta10 comes before beta9), so
// require the dot form.
i := finalDigitsIndex(prerelease)
if i >= 1 {
if prerelease[i-1] != '.' {
return "", fmt.Errorf("%w: final digits in a prerelease must follow a period", derrors.InvalidArgument)
}
// Remove the dot.
prerelease = prerelease[:i-1] + prerelease[i:]
}
goVersion += strings.TrimPrefix(prerelease, "-")
}
return goVersion, nil
}
// MajorVersionForVersion returns the Go major version for version.
// E.g. "v1.13.3" => "go1".
func MajorVersionForVersion(version string) (_ string, err error) {
defer derrors.Wrap(&err, "MajorVersionForVersion(%q)", version)
tag, err := TagForVersion(version)
if err != nil {
return "", err
}
if tag == "go1" {
return tag, nil
}
i := strings.IndexRune(tag, '.')
if i < 0 {
return "", fmt.Errorf("no '.' in go tag %q", tag)
}
return tag[:i], nil
}
// finalDigitsIndex returns the index of the first digit in the sequence of digits ending s.
// If s doesn't end in digits, it returns -1.
func finalDigitsIndex(s string) int {
// Assume ASCII (since the semver package does anyway).
var i int
for i = len(s) - 1; i >= 0; i-- {
if s[i] < '0' || s[i] > '9' {
break
}
}
if i == len(s)-1 {
return -1
}
return i + 1
}
const (
GoRepoURL = "https://go.googlesource.com/go"
GoSourceRepoURL = "https://github.com/golang/go"
)
// UseTestData determines whether to really clone the Go repo, or use
// stripped-down versions of the repo from the testdata directory.
var UseTestData = false
// TestCommitTime is the time used for all commits when UseTestData is true.
var TestCommitTime = time.Date(2019, 9, 4, 1, 2, 3, 0, time.UTC)
// getGoRepo returns a repo object for the Go repo at version.
func getGoRepo(version string) (_ *git.Repository, err error) {
tag, err := TagForVersion(version)
if err != nil {
return nil, err
}
return git.Clone(memory.NewStorage(), nil, &git.CloneOptions{
URL: GoRepoURL,
ReferenceName: plumbing.NewTagReferenceName(tag),
SingleBranch: true,
Depth: 1,
Tags: git.NoTags,
})
}
// getTestGoRepo gets a Go repo for testing.
func getTestGoRepo(version string) (_ *git.Repository, err error) {
fs := osfs.New(filepath.Join(testhelper.TestDataPath("testdata"), version))
repo, err := git.Init(memory.NewStorage(), fs)
if err != nil {
return nil, err
}
wt, err := repo.Worktree()
if err != nil {
return nil, err
}
// Add all files in the directory.
if _, err := wt.Add(""); err != nil {
return nil, err
}
_, err = wt.Commit("", &git.CommitOptions{All: true, Author: &object.Signature{
Name: "Joe Random",
Email: "joe@example.com",
When: TestCommitTime,
}})
if err != nil {
return nil, err
}
return repo, nil
}
// Versions returns all the versions of Go that are relevant to the discovery
// site. These are all release versions (tags of the forms "goN.N" and
// "goN.N.N", where N is a number) and beta or rc versions (tags of the forms
// "goN.NbetaN" and "goN.N.NbetaN", and similarly for "rc" replacing "beta").
func Versions() (_ []string, err error) {
defer derrors.Wrap(&err, "Versions()")
var refNames []plumbing.ReferenceName
if UseTestData {
refNames = testRefs
} else {
re := git.NewRemote(memory.NewStorage(), &config.RemoteConfig{
URLs: []string{GoRepoURL},
})
refs, err := re.List(&git.ListOptions{})
if err != nil {
return nil, err
}
for _, r := range refs {
refNames = append(refNames, r.Name())
}
}
var versions []string
for _, name := range refNames {
if !name.IsTag() {
continue
}
v := VersionForTag(name.Short())
if v != "" {
versions = append(versions, v)
}
}
return versions, nil
}
// Directory returns the directory of the standard library relative to the repo root.
func Directory(version string) string {
// For versions older than v1.4.0-beta.1, the stdlib is in src/pkg.
if semver.Compare(version, "v1.4.0-beta.1") < 0 {
return "src/pkg"
}
return "src"
}
// Zip creates a module zip representing the entire Go standard library at the
// given version and returns a reader to it. It also returns the time of the
// commit for that version. The zip file is in module form, with each path
// prefixed by ModuleName + "@" + version.
//
// Zip reads the standard library at the Go repository tag corresponding to to
// the given semantic version.
//
// Zip ignores go.mod files in the standard library, treating it as if it were a
// single module named "std" at the given version.
func Zip(version string) (_ *zip.Reader, commitTime time.Time, err error) {
// This code taken, with modifications, from
// https://github.com/shurcooL/play/blob/master/256/moduleproxy/std/std.go.
defer derrors.Wrap(&err, "stdlib.Zip(%q)", version)
knownVersions, err := Versions()
if err != nil {
return nil, time.Time{}, err
}
found := false
for _, v := range knownVersions {
if v == version {
found = true
break
}
}
if !found {
return nil, time.Time{}, fmt.Errorf("%w: requested version unknown: %q", derrors.InvalidArgument, version)
}
var repo *git.Repository
if UseTestData {
repo, err = getTestGoRepo(version)
} else {
repo, err = getGoRepo(version)
}
if err != nil {
return nil, time.Time{}, err
}
var buf bytes.Buffer
z := zip.NewWriter(&buf)
head, err := repo.Head()
if err != nil {
return nil, time.Time{}, err
}
commit, err := repo.CommitObject(head.Hash())
if err != nil {
return nil, time.Time{}, err
}
root, err := repo.TreeObject(commit.TreeHash)
if err != nil {
return nil, time.Time{}, err
}
prefixPath := ModulePath + "@" + version
// Add top-level files.
if err := addFiles(z, repo, root, prefixPath, false); err != nil {
return nil, time.Time{}, err
}
// Add files from the stdlib directory.
libdir := root
for _, d := range strings.Split(Directory(version), "/") {
libdir, err = subTree(repo, libdir, d)
if err != nil {
return nil, time.Time{}, err
}
}
if err := addFiles(z, repo, libdir, prefixPath, true); err != nil {
return nil, time.Time{}, err
}
if err := z.Close(); err != nil {
return nil, time.Time{}, err
}
br := bytes.NewReader(buf.Bytes())
zr, err := zip.NewReader(br, int64(br.Len()))
if err != nil {
return nil, time.Time{}, err
}
return zr, commit.Committer.When, nil
}
// addFiles adds the files in t to z, using dirpath as the path prefix.
// If recursive is true, it also adds the files in all subdirectories.
func addFiles(z *zip.Writer, r *git.Repository, t *object.Tree, dirpath string, recursive bool) error {
for _, e := range t.Entries {
if strings.HasPrefix(e.Name, ".") || strings.HasPrefix(e.Name, "_") {
continue
}
if e.Name == "go.mod" {
// ignore; we'll synthesize our own
continue
}
if e.Name == "README.vendor" && !strings.Contains(dirpath, "/") {
// For versions newer than v1.4.0-beta.1, the stdlib is in src/pkg.
// This means that our construction of the zip files will return
// two READMEs at the root:
// https://golang.org/README.md and
// https://golang.org/src/README.vendor
// We only want to display the README.md, so ignore README.vendor.
// However, we do want to store the README.vendor in
// std@<version>/cmd.
continue
}
switch e.Mode {
case filemode.Regular, filemode.Executable:
blob, err := r.BlobObject(e.Hash)
if err != nil {
return err
}
src, err := blob.Reader()
if err != nil {
return err
}
if err := writeZipFile(z, path.Join(dirpath, e.Name), src); err != nil {
_ = src.Close()
return err
}
if err := src.Close(); err != nil {
return err
}
case filemode.Dir:
if !recursive || e.Name == "testdata" {
continue
}
t2, err := r.TreeObject(e.Hash)
if err != nil {
return err
}
if err := addFiles(z, r, t2, path.Join(dirpath, e.Name), recursive); err != nil {
return err
}
}
}
return nil
}
func writeZipFile(z *zip.Writer, pathname string, src io.Reader) error {
dst, err := z.Create(pathname)
if err != nil {
return err
}
_, err = io.Copy(dst, src)
return err
}
// subTree looks non-recursively for a directory with the given name in t,
// and returns the corresponding tree.
// If a directory with such name doesn't exist in t, it returns os.ErrNotExist.
func subTree(r *git.Repository, t *object.Tree, name string) (*object.Tree, error) {
for _, e := range t.Entries {
if e.Name == name {
return r.TreeObject(e.Hash)
}
}
return nil, os.ErrNotExist
}
// Contains reports whether the given import path could be part of the Go standard library,
// by reporting whether the first component lacks a '.'.
func Contains(path string) bool {
if i := strings.IndexByte(path, '/'); i != -1 {
path = path[:i]
}
return !strings.Contains(path, ".")
}
// References used for Versions during testing.
var testRefs = []plumbing.ReferenceName{
// stdlib versions
"refs/tags/go1.2.1",
"refs/tags/go1.3.2",
"refs/tags/go1.4.2",
"refs/tags/go1.4.3",
"refs/tags/go1.6",
"refs/tags/go1.6.3",
"refs/tags/go1.6beta1",
"refs/tags/go1.8",
"refs/tags/go1.8rc2",
"refs/tags/go1.9rc1",
"refs/tags/go1.11",
"refs/tags/go1.12",
"refs/tags/go1.12.1",
"refs/tags/go1.12.5",
"refs/tags/go1.12.9",
"refs/tags/go1.13",
"refs/tags/go1.13beta1",
"refs/tags/go1.14.6",
// other tags
"refs/changes/56/93156/13",
"refs/tags/release.r59",
"refs/tags/weekly.2011-04-13",
}