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// Copyright 2020 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 modload
import (
"context"
"errors"
"os"
"sort"
"cmd/go/internal/modfetch"
"golang.org/x/mod/module"
"golang.org/x/mod/semver"
)
// cmpVersion implements the comparison for versions in the module loader.
//
// It is consistent with semver.Compare except that as a special case,
// the version "" is considered higher than all other versions.
// The main module (also known as the target) has no version and must be chosen
// over other versions of the same module in the module dependency graph.
func cmpVersion(v1, v2 string) int {
if v2 == "" {
if v1 == "" {
return 0
}
return -1
}
if v1 == "" {
return 1
}
return semver.Compare(v1, v2)
}
// mvsReqs implements mvs.Reqs for module semantic versions,
// with any exclusions or replacements applied internally.
type mvsReqs struct {
roots []module.Version
}
func (r *mvsReqs) Required(mod module.Version) ([]module.Version, error) {
if mod == Target {
// Use the build list as it existed when r was constructed, not the current
// global build list.
return r.roots, nil
}
if mod.Version == "none" {
return nil, nil
}
summary, err := goModSummary(mod)
if err != nil {
return nil, err
}
return summary.require, nil
}
// Max returns the maximum of v1 and v2 according to semver.Compare.
//
// As a special case, the version "" is considered higher than all other
// versions. The main module (also known as the target) has no version and must
// be chosen over other versions of the same module in the module dependency
// graph.
func (*mvsReqs) Max(v1, v2 string) string {
if cmpVersion(v1, v2) < 0 {
return v2
}
return v1
}
// Upgrade is a no-op, here to implement mvs.Reqs.
// The upgrade logic for go get -u is in ../modget/get.go.
func (*mvsReqs) Upgrade(m module.Version) (module.Version, error) {
return m, nil
}
func versions(ctx context.Context, path string, allowed AllowedFunc) ([]string, error) {
// Note: modfetch.Lookup and repo.Versions are cached,
// so there's no need for us to add extra caching here.
var versions []string
err := modfetch.TryProxies(func(proxy string) error {
repo, err := lookupRepo(proxy, path)
if err != nil {
return err
}
allVersions, err := repo.Versions("")
if err != nil {
return err
}
allowedVersions := make([]string, 0, len(allVersions))
for _, v := range allVersions {
if err := allowed(ctx, module.Version{Path: path, Version: v}); err == nil {
allowedVersions = append(allowedVersions, v)
} else if !errors.Is(err, ErrDisallowed) {
return err
}
}
versions = allowedVersions
return nil
})
return versions, err
}
// previousVersion returns the tagged version of m.Path immediately prior to
// m.Version, or version "none" if no prior version is tagged.
//
// Since the version of Target is not found in the version list,
// it has no previous version.
func previousVersion(m module.Version) (module.Version, error) {
// TODO(golang.org/issue/38714): thread tracing context through MVS.
if m == Target {
return module.Version{Path: m.Path, Version: "none"}, nil
}
list, err := versions(context.TODO(), m.Path, CheckAllowed)
if err != nil {
if errors.Is(err, os.ErrNotExist) {
return module.Version{Path: m.Path, Version: "none"}, nil
}
return module.Version{}, err
}
i := sort.Search(len(list), func(i int) bool { return semver.Compare(list[i], m.Version) >= 0 })
if i > 0 {
return module.Version{Path: m.Path, Version: list[i-1]}, nil
}
return module.Version{Path: m.Path, Version: "none"}, nil
}
func (*mvsReqs) Previous(m module.Version) (module.Version, error) {
return previousVersion(m)
}