160 lines
3.7 KiB
Go
160 lines
3.7 KiB
Go
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// 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/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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Source string `json:"source"`
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Files []string `json:"files"`
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LocalDeps []string `json:"localDeps"`
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ForeignDeps []string `json:"foreignDeps"`
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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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var goDirs []string
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dir := ""
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err := filepath.Walk(at, func(path string, info os.FileInfo, err error) error {
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// Skip testdata
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if info.IsDir() && info.Name() == "testdata" {
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return filepath.SkipDir
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}
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// Keep track of the last seen directory.
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if info.IsDir() {
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dir = path
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return nil
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}
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// If the directory has already been "popped", nothing else needs
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// to happen.
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if dir == "" {
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return nil
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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 strings.HasSuffix(info.Name(), ".go") && !strings.HasSuffix(info.Name(), "_test.go") {
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goDirs = append(goDirs, dir)
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dir = ""
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return nil
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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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return goDirs, nil
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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, path string, stdlib map[string]bool) (pkg, error) {
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ctx := build.Default
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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 := []string{}
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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 strings.HasPrefix(i, path) {
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local = append(local, i)
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} else {
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foreign = append(foreign, i)
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}
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}
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analysed := pkg{
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Name: strings.TrimPrefix(source, root+"/"),
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Source: source,
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Files: p.GoFiles,
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LocalDeps: local,
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ForeignDeps: foreign,
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}
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return analysed, 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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// TODO(tazjin): Remove default values
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source := flag.String("source", "/nix/store/fzp67ris29zg5zfs65z0q245x0fahgll-source", "path to directory with sources to process")
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path := flag.String("path", "github.com/golang/protobuf", "import path for the package")
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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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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\n", 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)
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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.MarshalIndent(all, "", " ") // TODO: no indent
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fmt.Println(string(j))
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}
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