diff options
| -rw-r--r-- | external/default.nix | 29 | ||||
| -rw-r--r-- | external/main.go | 159 |
2 files changed, 188 insertions, 0 deletions
diff --git a/external/default.nix b/external/default.nix new file mode 100644 index 000000000000..79d559c05498 --- /dev/null +++ b/external/default.nix @@ -0,0 +1,29 @@ +# Copyright 2019 Google LLC. +# SPDX-License-Identifier: Apache-2.0 +{ runCommand, go, jq, ripgrep, program }: + +let + # Collect all non-vendored dependencies from the Go standard library + # into a file that can be used to filter them out when processing + # dependencies. + stdlibPackages = runCommand "stdlib-pkgs.json" {} '' + export GOPATH=/dev/null + ${go}/bin/go list all | \ + ${ripgrep}/bin/rg -v 'vendor' | \ + ${jq}/bin/jq -R '.' | \ + ${jq}/bin/jq -c -s 'map({key: ., value: true}) | from_entries' \ + > $out + ''; + + analyser = program { + name = "analyser"; + + srcs = [ + ./main.go + ]; + + x_defs = { + "main.stdlibList" = "${stdlibPackages}"; + }; + }; +in analyser diff --git a/external/main.go b/external/main.go new file mode 100644 index 000000000000..0f8834fc99c9 --- /dev/null +++ b/external/main.go @@ -0,0 +1,159 @@ +// Copyright 2019 Google LLC. +// SPDX-License-Identifier: Apache-2.0 + +// This tool analyses external (i.e. not built with `buildGo.nix`) Go +// packages to determine a build plan that Nix can import. +package main + +import ( + "encoding/json" + "flag" + "fmt" + "go/build" + "io/ioutil" + "log" + "os" + "path/filepath" + "strings" +) + +// Path to a JSON file describing all standard library import paths. +// This file is generated and set here by Nix during the build +// process. +var stdlibList string + +// pkg describes a single Go package within the specified source +// directory. +// +// Return information includes the local (relative from project root) +// and external (none-stdlib) dependencies of this package. +type pkg struct { + Name string `json:"name"` + Source string `json:"source"` + Files []string `json:"files"` + LocalDeps []string `json:"localDeps"` + ForeignDeps []string `json:"foreignDeps"` +} + +// findGoDirs returns a filepath.WalkFunc that identifies all +// directories that contain Go source code in a certain tree. +func findGoDirs(at string) ([]string, error) { + var goDirs []string + dir := "" + + err := filepath.Walk(at, func(path string, info os.FileInfo, err error) error { + // Skip testdata + if info.IsDir() && info.Name() == "testdata" { + return filepath.SkipDir + } + + // Keep track of the last seen directory. + if info.IsDir() { + dir = path + return nil + } + + // If the directory has already been "popped", nothing else needs + // to happen. + if dir == "" { + return nil + } + + // If the current file is a Go file, then the directory is popped + // (i.e. marked as a Go directory). + if strings.HasSuffix(info.Name(), ".go") && !strings.HasSuffix(info.Name(), "_test.go") { + goDirs = append(goDirs, dir) + dir = "" + return nil + } + + return nil + }) + + if err != nil { + return nil, err + } + + return goDirs, nil +} + +// analysePackage loads and analyses the imports of a single Go +// package, returning the data that is required by the Nix code to +// generate a derivation for this package. +func analysePackage(root, source, path string, stdlib map[string]bool) (pkg, error) { + ctx := build.Default + + p, err := ctx.ImportDir(source, build.IgnoreVendor) + if err != nil { + return pkg{}, err + } + + local := []string{} + foreign := []string{} + + for _, i := range p.Imports { + if stdlib[i] { + continue + } + + if strings.HasPrefix(i, path) { + local = append(local, i) + } else { + foreign = append(foreign, i) + } + } + + analysed := pkg{ + Name: strings.TrimPrefix(source, root+"/"), + Source: source, + Files: p.GoFiles, + LocalDeps: local, + ForeignDeps: foreign, + } + + return analysed, nil +} + +func loadStdlibPkgs(from string) (pkgs map[string]bool, err error) { + f, err := ioutil.ReadFile(from) + if err != nil { + return + } + + err = json.Unmarshal(f, &pkgs) + return +} + +func main() { + // TODO(tazjin): Remove default values + source := flag.String("source", "/nix/store/fzp67ris29zg5zfs65z0q245x0fahgll-source", "path to directory with sources to process") + path := flag.String("path", "github.com/golang/protobuf", "import path for the package") + + flag.Parse() + + if *source == "" { + log.Fatalf("-source flag must be specified") + } + + stdlibPkgs, err := loadStdlibPkgs(stdlibList) + if err != nil { + log.Fatalf("failed to load standard library index from %q: %s\n", stdlibList, err) + } + + goDirs, err := findGoDirs(*source) + if err != nil { + log.Fatalf("failed to walk source directory '%s': %s\n", source, err) + } + + all := []pkg{} + for _, d := range goDirs { + analysed, err := analysePackage(*source, d, *path, stdlibPkgs) + if err != nil { + log.Fatalf("failed to analyse package at %q: %s", d, err) + } + all = append(all, analysed) + } + + j, _ := json.MarshalIndent(all, "", " ") // TODO: no indent + fmt.Println(string(j)) +} |