mirror of
https://github.com/tailscale/tailscale.git
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71029cea2d
This updates all source files to use a new standard header for copyright and license declaration. Notably, copyright no longer includes a date, and we now use the standard SPDX-License-Identifier header. This commit was done almost entirely mechanically with perl, and then some minimal manual fixes. Updates #6865 Signed-off-by: Will Norris <will@tailscale.com>
185 lines
3.8 KiB
Go
185 lines
3.8 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// nardump is like nix-store --dump, but in Go, writing a NAR
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// file (tar-like, but focused on being reproducible) to stdout
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// or to a hash with the --sri flag.
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//
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// It lets us calculate a Nix sha256 without the person running
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// git-pull-oss.sh having Nix available.
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package main
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// For the format, see:
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// See https://gist.github.com/jbeda/5c79d2b1434f0018d693
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import (
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"bufio"
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"crypto/sha256"
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"encoding/base64"
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"encoding/binary"
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"flag"
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"fmt"
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"io"
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"io/fs"
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"log"
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"os"
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"path"
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"sort"
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)
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var sri = flag.Bool("sri", false, "print SRI")
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func main() {
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flag.Parse()
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if flag.NArg() != 1 {
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log.Fatal("usage: nardump <dir>")
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}
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arg := flag.Arg(0)
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if err := os.Chdir(arg); err != nil {
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log.Fatal(err)
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}
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if *sri {
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hash := sha256.New()
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if err := writeNAR(hash, os.DirFS(".")); err != nil {
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log.Fatal(err)
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}
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fmt.Printf("sha256-%s\n", base64.StdEncoding.EncodeToString(hash.Sum(nil)))
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return
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}
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bw := bufio.NewWriter(os.Stdout)
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if err := writeNAR(bw, os.DirFS(".")); err != nil {
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log.Fatal(err)
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}
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bw.Flush()
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}
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// writeNARError is a sentinel panic type that's recovered by writeNAR
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// and converted into the wrapped error.
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type writeNARError struct{ err error }
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// narWriter writes NAR files.
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type narWriter struct {
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w io.Writer
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fs fs.FS
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}
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// writeNAR writes a NAR file to w from the root of fs.
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func writeNAR(w io.Writer, fs fs.FS) (err error) {
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defer func() {
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if e := recover(); e != nil {
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if we, ok := e.(writeNARError); ok {
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err = we.err
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return
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}
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panic(e)
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}
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}()
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nw := &narWriter{w: w, fs: fs}
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nw.str("nix-archive-1")
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return nw.writeDir(".")
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}
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func (nw *narWriter) writeDir(dirPath string) error {
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ents, err := fs.ReadDir(nw.fs, dirPath)
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if err != nil {
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return err
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}
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sort.Slice(ents, func(i, j int) bool {
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return ents[i].Name() < ents[j].Name()
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})
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nw.str("(")
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nw.str("type")
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nw.str("directory")
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for _, ent := range ents {
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nw.str("entry")
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nw.str("(")
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nw.str("name")
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nw.str(ent.Name())
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nw.str("node")
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mode := ent.Type()
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sub := path.Join(dirPath, ent.Name())
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var err error
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switch {
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case mode.IsRegular():
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err = nw.writeRegular(sub)
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case mode.IsDir():
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err = nw.writeDir(sub)
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default:
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// TODO(bradfitz): symlink, but requires fighting io/fs a bit
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// to get at Readlink or the osFS via fs. But for now
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// we don't need symlinks because they're not in Go's archive.
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return fmt.Errorf("unsupported file type %v at %q", sub, mode)
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}
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if err != nil {
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return err
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}
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nw.str(")")
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}
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nw.str(")")
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return nil
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}
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func (nw *narWriter) writeRegular(path string) error {
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nw.str("(")
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nw.str("type")
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nw.str("regular")
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fi, err := fs.Stat(nw.fs, path)
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if err != nil {
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return err
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}
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if fi.Mode()&0111 != 0 {
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nw.str("executable")
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nw.str("")
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}
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contents, err := fs.ReadFile(nw.fs, path)
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if err != nil {
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return err
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}
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nw.str("contents")
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if err := writeBytes(nw.w, contents); err != nil {
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return err
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}
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nw.str(")")
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return nil
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}
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func (nw *narWriter) str(s string) {
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if err := writeString(nw.w, s); err != nil {
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panic(writeNARError{err})
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}
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}
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func writeString(w io.Writer, s string) error {
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var buf [8]byte
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binary.LittleEndian.PutUint64(buf[:], uint64(len(s)))
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if _, err := w.Write(buf[:]); err != nil {
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return err
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}
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if _, err := io.WriteString(w, s); err != nil {
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return err
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}
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return writePad(w, len(s))
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}
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func writeBytes(w io.Writer, b []byte) error {
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var buf [8]byte
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binary.LittleEndian.PutUint64(buf[:], uint64(len(b)))
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if _, err := w.Write(buf[:]); err != nil {
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return err
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}
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if _, err := w.Write(b); err != nil {
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return err
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}
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return writePad(w, len(b))
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}
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func writePad(w io.Writer, n int) error {
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pad := n % 8
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if pad == 0 {
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return nil
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}
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var zeroes [8]byte
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_, err := w.Write(zeroes[:8-pad])
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return err
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}
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