226 lines
5.8 KiB
Go
226 lines
5.8 KiB
Go
// Copyright 2019 Google LLC.
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// SPDX-License-Identifier: Apache-2.0
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// This tool analyses external (i.e. not built with `buildGo.nix`) Go
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// packages to determine a build plan that Nix can import.
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package main
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import (
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"encoding/json"
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"flag"
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"fmt"
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"go/build"
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"io/ioutil"
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"log"
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"os"
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"path"
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"path/filepath"
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"strings"
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)
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// Path to a JSON file describing all standard library import paths.
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// This file is generated and set here by Nix during the build
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// process.
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var stdlibList string
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// pkg describes a single Go package within the specified source
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// directory.
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//
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// Return information includes the local (relative from project root)
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// and external (none-stdlib) dependencies of this package.
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type pkg struct {
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Name string `json:"name"`
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PackageName string `json:"packageName"`
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Locator []string `json:"locator"`
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Files []string `json:"files"`
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CgoFiles []string `json:"cgofiles"`
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SFiles []string `json:"sfiles"`
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CFiles []string `json:"cfiles"`
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CXXFiles []string `json:"cxxfiles"`
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LocalDeps [][]string `json:"localDeps"`
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ForeignDeps []foreignDep `json:"foreignDeps"`
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IsCommand bool `json:"isCommand"`
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CgoCFLAGS []string `json:"cgocflags"`
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CgoLDFLAGS []string `json:"cgoldflags"`
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}
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type foreignDep struct {
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Path string `json:"path"`
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// filename, column and line number of the import, if known
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Position string `json:"position"`
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}
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// findGoDirs returns a filepath.WalkFunc that identifies all
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// directories that contain Go source code in a certain tree.
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func findGoDirs(at string) ([]string, error) {
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dirSet := make(map[string]bool)
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err := filepath.Walk(at, func(path string, info os.FileInfo, err error) error {
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if err != nil {
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return err
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}
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name := info.Name()
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// Skip folders that are guaranteed to not be relevant
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if info.IsDir() && (name == "testdata" || name == ".git") {
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return filepath.SkipDir
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}
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// If the current file is a Go file, then the directory is popped
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// (i.e. marked as a Go directory).
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if !info.IsDir() && strings.HasSuffix(name, ".go") && !strings.HasSuffix(name, "_test.go") {
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dirSet[filepath.Dir(path)] = true
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}
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return nil
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})
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if err != nil {
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return nil, err
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}
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goDirs := []string{}
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for k, _ := range dirSet {
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goDirs = append(goDirs, k)
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}
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return goDirs, nil
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}
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func forceEmpty[T any](m []T) []T {
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if m == nil {
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return make([]T, 0)
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}
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return m
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}
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// analysePackage loads and analyses the imports of a single Go
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// package, returning the data that is required by the Nix code to
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// generate a derivation for this package.
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func analysePackage(root, source, importpath string, stdlib map[string]bool, tags []string, cgo bool) (pkg, error) {
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ctx := build.Default
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ctx.CgoEnabled = cgo
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ctx.BuildTags = tags
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p, err := ctx.ImportDir(source, build.IgnoreVendor)
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if err != nil {
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return pkg{}, err
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}
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local := [][]string{}
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foreign := []foreignDep{}
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for _, i := range p.Imports {
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if stdlib[i] {
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continue
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}
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if i == importpath {
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local = append(local, []string{})
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} else if strings.HasPrefix(i, importpath+"/") {
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local = append(local, strings.Split(strings.TrimPrefix(i, importpath+"/"), "/"))
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} else {
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// The import positions is a map keyed on the import name.
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// The value is a list, presumably because an import can appear
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// multiple times in a package. Let’s just take the first one,
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// should be enough for a good error message.
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firstPos := p.ImportPos[i][0].String()
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foreign = append(foreign, foreignDep{Path: i, Position: firstPos})
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}
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}
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prefix := strings.TrimPrefix(source, root+"/")
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locator := []string{}
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if len(prefix) != len(source) {
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locator = strings.Split(prefix, "/")
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} else {
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// Otherwise, the locator is empty since its the root package and
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// no prefix should be added to files.
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prefix = ""
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}
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prependPrefix := func(fs []string) []string {
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out := make([]string, len(fs))
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for n, f := range fs {
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out[n] = path.Join(prefix, f)
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}
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return out
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}
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return pkg{
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Name: path.Join(importpath, prefix),
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PackageName: p.Name,
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Locator: locator,
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Files: prependPrefix(p.GoFiles),
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CgoFiles: prependPrefix(p.CgoFiles),
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SFiles: prependPrefix(p.SFiles),
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CFiles: prependPrefix(p.CFiles),
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CXXFiles: prependPrefix(p.CXXFiles),
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LocalDeps: local,
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ForeignDeps: foreign,
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IsCommand: p.IsCommand(),
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CgoCFLAGS: forceEmpty(p.CgoCFLAGS),
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CgoLDFLAGS: forceEmpty(p.CgoLDFLAGS),
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}, nil
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}
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func loadStdlibPkgs(from string) (pkgs map[string]bool, err error) {
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f, err := ioutil.ReadFile(from)
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if err != nil {
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return
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}
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err = json.Unmarshal(f, &pkgs)
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return
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}
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func main() {
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source := flag.String("source", "", "path to directory with sources to process")
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path := flag.String("path", "", "import path for the package")
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tagsStr := flag.String("tags", "", "tags, space-separated")
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cgo := flag.Bool("cgo", false, "cgo")
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flag.Parse()
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if *source == "" {
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log.Fatalf("-source flag must be specified")
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}
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var tags []string
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if len(*tagsStr) > 0 {
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tags = strings.Split(*tagsStr, " ")
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}
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stdlibPkgs, err := loadStdlibPkgs(stdlibList)
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if err != nil {
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log.Fatalf("failed to load standard library index from %q: %s\n", stdlibList, err)
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}
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goDirs, err := findGoDirs(*source)
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if err != nil {
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log.Fatalf("failed to walk source directory '%s': %s", *source, err)
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}
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all := []pkg{}
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for _, d := range goDirs {
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analysed, err := analysePackage(*source, d, *path, stdlibPkgs, tags, *cgo)
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// If the Go source analysis returned "no buildable Go files",
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// that directory should be skipped.
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//
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// This might be due to `+build` flags on the platform and other
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// reasons (such as test files).
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if _, ok := err.(*build.NoGoError); ok {
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continue
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}
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if err != nil {
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log.Fatalf("failed to analyse package at %q: %s", d, err)
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}
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all = append(all, analysed)
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}
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j, _ := json.Marshal(all)
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fmt.Println(string(j))
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}
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