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// Copyright 2023 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 proxy provides functions for writing module data to a directory
// in proxy format, so that it can be used as a module proxy by setting
// GOPROXY="file://<dir>".
// This is copied from golang.org/x/tools/gopls/internal/{proxydir,proxy}.
package proxy
import (
"archive/zip"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"golang.org/x/mod/module"
)
// WriteProxy creates a new proxy file tree using the provided content,
// and returns its URL.
func WriteProxy(tmpdir string, files map[string][]byte) (string, error) {
type moduleVersion struct {
modulePath, version string
}
// Transform into the format expected by the proxydir package.
filesByModule := make(map[moduleVersion]map[string][]byte)
for name, data := range files {
modulePath, version, suffix := splitModuleVersionPath(name)
mv := moduleVersion{modulePath, version}
if _, ok := filesByModule[mv]; !ok {
filesByModule[mv] = make(map[string][]byte)
}
filesByModule[mv][suffix] = data
}
for mv, files := range filesByModule {
if err := writeModuleVersion(tmpdir, mv.modulePath, mv.version, files); err != nil {
return "", fmt.Errorf("error writing %s@%s: %v", mv.modulePath, mv.version, err)
}
}
return toURL(tmpdir), nil
}
// splitModuleVersionPath extracts module information from files stored in the
// directory structure modulePath@version/suffix.
// For example:
//
// splitModuleVersionPath("mod.com@v1.2.3/package") = ("mod.com", "v1.2.3", "package")
func splitModuleVersionPath(path string) (modulePath, version, suffix string) {
parts := strings.Split(path, "/")
var modulePathParts []string
for i, p := range parts {
if strings.Contains(p, "@") {
mv := strings.SplitN(p, "@", 2)
modulePathParts = append(modulePathParts, mv[0])
return strings.Join(modulePathParts, "/"), mv[1], strings.Join(parts[i+1:], "/")
}
modulePathParts = append(modulePathParts, p)
}
// Default behavior: this is just a module path.
return path, "", ""
}
// writeModuleVersion creates a directory in the proxy dir for a module.
func writeModuleVersion(rootDir, mod, ver string, files map[string][]byte) (rerr error) {
dir := filepath.Join(rootDir, mod, "@v")
if err := os.MkdirAll(dir, 0755); err != nil {
return err
}
// The go command checks for versions by looking at the "list" file. Since
// we are supporting multiple versions, create this file if it does not exist
// or append the version number to the preexisting file.
f, err := os.OpenFile(filepath.Join(dir, "list"), os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
if err != nil {
return err
}
defer checkClose("list file", f, &rerr)
if _, err := f.WriteString(ver + "\n"); err != nil {
return err
}
// Serve the go.mod file on the <version>.mod url, if it exists. Otherwise,
// serve a stub.
modContents, ok := files["go.mod"]
if !ok {
modContents = []byte("module " + mod)
}
if err := os.WriteFile(filepath.Join(dir, ver+".mod"), modContents, 0644); err != nil {
return err
}
// info file, just the bare bones.
infoContents := []byte(fmt.Sprintf(`{"Version": "%v", "Time":"2017-12-14T13:08:43Z"}`, ver))
if err := os.WriteFile(filepath.Join(dir, ver+".info"), infoContents, 0644); err != nil {
return err
}
// zip of all the source files.
f, err = os.OpenFile(filepath.Join(dir, ver+".zip"), os.O_CREATE|os.O_WRONLY, 0644)
if err != nil {
return err
}
defer checkClose("zip file", f, &rerr)
z := zip.NewWriter(f)
defer checkClose("zip writer", z, &rerr)
for name, contents := range files {
zf, err := z.Create(mod + "@" + ver + "/" + name)
if err != nil {
return err
}
if _, err := zf.Write(contents); err != nil {
return err
}
}
// Populate the /module/path/@latest that is used by @latest query.
if module.IsPseudoVersion(ver) {
latestFile := filepath.Join(rootDir, mod, "@latest")
if err := os.WriteFile(latestFile, infoContents, 0644); err != nil {
return err
}
}
return nil
}
func checkClose(name string, closer io.Closer, err *error) {
if cerr := closer.Close(); cerr != nil && *err == nil {
*err = fmt.Errorf("closing %s: %v", name, cerr)
}
}
// toURL returns the file uri for a proxy directory.
func toURL(dir string) string {
// file URLs on Windows must start with file:///. See golang.org/issue/6027.
path := filepath.ToSlash(dir)
if !strings.HasPrefix(path, "/") {
path = "/" + path
}
return "file://" + path
}