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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"
"io/fs"
"os"
"path"
"regexp"
"strings"
"sync"
"time"
"golang.org/x/mod/semver"
"golang.org/x/pkgsite/internal/derrors"
"golang.org/x/pkgsite/internal/version"
"github.com/go-git/go-git/v5"
"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"
)
const (
// ModulePath is the name of the module for the standard library.
ModulePath = "std"
// DevFuzz is the branch name for fuzzing in beta.
DevFuzz = "dev.fuzz"
// DevBoringCrypto is the branch name for dev.boringcrypto.
DevBoringCrypto = "dev.boringcrypto"
)
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+))?$`)
)
// SupportedBranches are the branches of the stdlib repo supported by pkgsite.
var SupportedBranches = map[string]bool{
version.Master: true,
DevBoringCrypto: true,
DevFuzz: true,
}
// VersionForTag returns the semantic version for the Go tag, or "" if
// tag doesn't correspond to a Go release or beta tag. In special cases,
// when the tag specified is either `latest` or `master` it will return the 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"
// "latest" => "latest"
// "master" => "master"
func VersionForTag(tag string) string {
// Special cases for go1.
if tag == "go1" {
return "v1.0.0"
}
if tag == "go1.0" {
return ""
}
// Special case for latest and master.
if tag == version.Latest || SupportedBranches[tag] {
return tag
}
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(v string) (_ string, err error) {
defer derrors.Wrap(&err, "TagForVersion(%q)", v)
// Special case: master => master or dev.fuzz => dev.fuzz
if SupportedBranches[v] {
return v, nil
}
if strings.HasPrefix(v, "v0.0.0") {
return version.Master, nil
}
// Special case: v1.0.0 => go1.
if v == "v1.0.0" {
return "go1", nil
}
if !semver.IsValid(v) {
return "", fmt.Errorf("%w: requested version is not a valid semantic version: %q ", derrors.InvalidArgument, v)
}
goVersion := semver.Canonical(v)
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" || tag == "master" {
return "go1", 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://cs.opensource.google/go/go"
GitHubRepo = "github.com/golang/go"
)
// 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)
TestMasterVersion = "v0.0.0-20190904010203-89fb59e2e920"
TestDevFuzzVersion = "v0.0.0-20190904010203-12de34vf56uz"
)
var (
goRepoMu sync.Mutex
theGoRepo goRepo = &remoteGoRepo{}
)
func getGoRepo() goRepo {
goRepoMu.Lock()
defer goRepoMu.Unlock()
return theGoRepo
}
func swapGoRepo(gr goRepo) goRepo {
goRepoMu.Lock()
defer goRepoMu.Unlock()
old := theGoRepo
theGoRepo = gr
return old
}
// WithTestData arranges for this package to use a testing version of the Go repo.
// The returned function restores the previous state. Use with defer:
//
// defer WithTestData()()
func WithTestData() func() {
return withGoRepo(&testGoRepo{})
}
func withGoRepo(gr goRepo) func() {
old := swapGoRepo(gr)
return func() {
swapGoRepo(old)
}
}
// SetGoRepoPath tells this package to obtain the Go repo from the
// local filesystem at path, instead of cloning it.
func SetGoRepoPath(path string) error {
gr, err := newLocalGoRepo(path)
if err != nil {
return err
}
swapGoRepo(gr)
return nil
}
func refNameForVersion(v string) (plumbing.ReferenceName, error) {
if v == version.Master {
return plumbing.HEAD, nil
}
if SupportedBranches[v] {
return plumbing.NewBranchReferenceName(v), nil
}
tag, err := TagForVersion(v)
if err != nil {
return "", err
}
return plumbing.NewTagReferenceName(tag), 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, "stdlib.Versions()")
refs, err := getGoRepo().refs()
if err != nil {
return nil, err
}
var versions []string
for _, r := range refs {
v := VersionForTag(r.Name().Short())
if v != "" {
versions = append(versions, v)
}
}
return versions, nil
}
// ResolveSupportedBranches returns the current hashes for each ref in
// SupportedBranches.
func ResolveSupportedBranches() (_ map[string]string, err error) {
defer derrors.Wrap(&err, "ResolveSupportedBranches")
refs, err := getGoRepo().refs()
if err != nil {
return nil, err
}
m := map[string]string{}
for _, r := range refs {
name := r.Name().Short()
if SupportedBranches[name] {
m[name] = r.Hash().String()
}
}
return m, nil
}
// Directory returns the directory of the standard library relative to the repo root.
func Directory(v string) string {
if semver.Compare(v, "v1.4.0-beta.1") >= 0 ||
SupportedBranches[v] || strings.HasPrefix(v, "v0.0.0") {
return "src"
}
// For versions older than v1.4.0-beta.1, the stdlib is in src/pkg.
return "src/pkg"
}
// EstimatedZipSize is the approximate size of
// Zip("v1.15.2").
const EstimatedZipSize = 16 * 1024 * 1024
// ZipInfo returns the proxy .info information for the module std.
func ZipInfo(requestedVersion string) (resolvedVersion string, err error) {
defer derrors.Wrap(&err, "stdlib.ZipInfo(%q)", requestedVersion)
resolvedVersion, err = semanticVersion(requestedVersion)
if err != nil {
return "", err
}
return resolvedVersion, nil
}
func zipInternal(requestedVersion string) (_ *zip.Reader, resolvedVersion string, commitTime time.Time, prefix string, err error) {
if requestedVersion == version.Latest {
requestedVersion, err = semanticVersion(requestedVersion)
if err != nil {
return nil, "", time.Time{}, "", err
}
}
repo, refName, err := getGoRepo().repoAtVersion(requestedVersion)
if err != nil {
return nil, "", time.Time{}, "", err
}
var buf bytes.Buffer
z := zip.NewWriter(&buf)
ref, err := repo.Reference(refName, true)
if err != nil {
return nil, "", time.Time{}, "", err
}
commit, err := repo.CommitObject(ref.Hash())
if err != nil {
return nil, "", time.Time{}, "", err
}
resolvedVersion = requestedVersion
if SupportedBranches[requestedVersion] {
resolvedVersion = newPseudoVersion("v0.0.0", commit.Committer.When, commit.Hash)
}
root, err := repo.TreeObject(commit.TreeHash)
if err != nil {
return nil, "", time.Time{}, "", err
}
prefixPath := ModulePath + "@" + requestedVersion
// 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(resolvedVersion), "/") {
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, resolvedVersion, commit.Committer.When, prefixPath, nil
}
// ContentDir creates an fs.FS representing the entire Go standard library at the
// given version (which must have been resolved with ZipInfo) and returns a
// reader to it. It also returns the time of the commit for that version.
//
// Normally, ContentDir returns the resolved version it was passed. If the
// resolved version is a supported branch like "master", ContentDir returns a
// semantic version for the branch.
//
// ContentDir reads the standard library at the Go repository tag corresponding
// to to the given semantic version.
//
// ContentDir ignores go.mod files in the standard library, treating it as if it
// were a single module named "std" at the given version.
func ContentDir(requestedVersion string) (_ fs.FS, resolvedVersion string, commitTime time.Time, err error) {
defer derrors.Wrap(&err, "stdlib.ContentDir(%q)", requestedVersion)
zr, resolvedVersion, commitTime, prefix, err := zipInternal(requestedVersion)
if err != nil {
return nil, "", time.Time{}, err
}
cdir, err := fs.Sub(zr, prefix)
if err != nil {
return nil, "", time.Time{}, err
}
return cdir, resolvedVersion, commitTime, nil
}
const pseudoHashLen = 12
func newPseudoVersion(version string, commitTime time.Time, hash plumbing.Hash) string {
return fmt.Sprintf("%s-%s-%s", version, commitTime.Format("20060102150405"), hash.String()[:pseudoHashLen])
}
// VersionMatchesHash reports whether v is a pseudo-version whose hash
// part matches the prefix of the given hash.
func VersionMatchesHash(v, hash string) bool {
if !version.IsPseudo(v) {
return false
}
return v[len(v)-pseudoHashLen:] == hash[:pseudoHashLen]
}
// semanticVersion returns the semantic version corresponding to the
// requestedVersion. If the requested version is version.Master, then semanticVersion
// returns it as is. The branch name is resolved to a proper pseudo-version in
// Zip.
func semanticVersion(requestedVersion string) (_ string, err error) {
defer derrors.Wrap(&err, "semanticVersion(%q)", requestedVersion)
if SupportedBranches[requestedVersion] {
return requestedVersion, nil
}
knownVersions, err := Versions()
if err != nil {
return "", err
}
switch requestedVersion {
case version.Latest:
var latestVersion string
for _, v := range knownVersions {
if !strings.HasPrefix(v, "v") {
continue
}
versionType, err := version.ParseType(v)
if err != nil {
return "", err
}
if versionType != version.TypeRelease {
// We expect there to always be at least 1 release version.
continue
}
if semver.Compare(v, latestVersion) > 0 {
latestVersion = v
}
}
return latestVersion, nil
default:
for _, v := range knownVersions {
if v == requestedVersion {
return requestedVersion, nil
}
}
}
return "", fmt.Errorf("%w: requested version unknown: %q", derrors.InvalidArgument, requestedVersion)
}
// 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) (err error) {
defer derrors.Wrap(&err, "addFiles(zip, repository, tree, %q, %t)", dirpath, recursive)
for _, e := range t.Entries {
if strings.HasPrefix(e.Name, ".") || strings.HasPrefix(e.Name, "_") {
continue
}
if e.Name == "go.mod" {
// Ignore; we don't need it.
continue
}
if strings.HasPrefix(e.Name, "README") && !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 do not want to display the README.md
// or any README.vendor.
// However, we do want to store the README in
// other directories.
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) (err error) {
defer derrors.Wrap(&err, "writeZipFile(zip, %q, src)", pathname)
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, err error) {
defer derrors.Wrap(&err, "subTree(repository, tree, %q)", name)
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, ".")
}