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ef06a5f44a
go:embed disallows using symlinked files by design. crypto/elliptic is the first std package to use it as of CL 380475, and unfortunately that broke the TestRepeatBootstrap long test. The reason it uses symlinks is for speed; it wants to copy GOROOT/src, but regular files aren't going to be modified in any way, so a symlink, if supported, means not needing to copy the contents. Replace the symlink attempt with hard links, which will mean regular files remain as such, fixing go:embed. It's worth noting that on many systems hard links won't work, as the temporary filesystem tends to be separate, but it doesn't hurt to try. In my system, where /tmp is tmpfs, the test now copies more bytes. With the added Logf, I can see overlayDir goes from ~30ms to ~100ms. This makes sense, as GOROOT/src currently weighs around 100MiB. To alleviate that slow-down, stop copying testdata directories, as they currently weigh around 20MiB and aren't needed for the test. This gets overlayDir on my system down to an acceptable ~70ms. I briefly considered teaching overlayDir what files can be symlinks, but that seemed fairly complex long-term, as any file could be embedded. While here, start using testing.T.TempDir and fs.WalkDir. For #50995. Change-Id: I17947e6bdee96237e1ca0606ad0b95e7c5987bc1 Reviewed-on: https://go-review.googlesource.com/c/go/+/383995 Trust: Daniel Martí <mvdan@mvdan.cc> Trust: Bryan Mills <bcmills@google.com> Run-TryBot: Bryan Mills <bcmills@google.com> Reviewed-by: Bryan Mills <bcmills@google.com> TryBot-Result: Gopher Robot <gobot@golang.org>
86 lines
2.1 KiB
Go
86 lines
2.1 KiB
Go
// Copyright 2019 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package reboot_test
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import (
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"io"
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"io/fs"
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"os"
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"path/filepath"
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"strings"
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)
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// overlayDir makes a minimal-overhead copy of srcRoot in which new files may be added.
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//
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// TODO: Once we no longer need to support the misc module in GOPATH mode,
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// factor this function out into a package to reduce duplication.
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func overlayDir(dstRoot, srcRoot string) error {
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dstRoot = filepath.Clean(dstRoot)
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if err := os.MkdirAll(dstRoot, 0777); err != nil {
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return err
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}
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srcRoot, err := filepath.Abs(srcRoot)
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if err != nil {
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return err
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}
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return filepath.WalkDir(srcRoot, func(srcPath string, entry fs.DirEntry, err error) error {
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if err != nil || srcPath == srcRoot {
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return err
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}
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if filepath.Base(srcPath) == "testdata" {
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// We're just building, so no need to copy those.
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return fs.SkipDir
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}
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suffix := strings.TrimPrefix(srcPath, srcRoot)
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for len(suffix) > 0 && suffix[0] == filepath.Separator {
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suffix = suffix[1:]
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}
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dstPath := filepath.Join(dstRoot, suffix)
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info, err := entry.Info()
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perm := info.Mode() & os.ModePerm
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if info.Mode()&os.ModeSymlink != 0 {
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info, err = os.Stat(srcPath)
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if err != nil {
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return err
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}
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perm = info.Mode() & os.ModePerm
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}
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// Always make copies of directories.
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// If we add a file in the overlay, we don't want to add it in the original.
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if info.IsDir() {
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return os.MkdirAll(dstPath, perm|0200)
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}
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// If we can use a hard link, do that instead of copying bytes.
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// Go builds don't like symlinks in some cases, such as go:embed.
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if err := os.Link(srcPath, dstPath); err == nil {
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return nil
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}
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// Otherwise, copy the bytes.
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src, err := os.Open(srcPath)
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if err != nil {
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return err
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}
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defer src.Close()
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dst, err := os.OpenFile(dstPath, os.O_WRONLY|os.O_CREATE|os.O_EXCL, perm)
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if err != nil {
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return err
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}
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_, err = io.Copy(dst, src)
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if closeErr := dst.Close(); err == nil {
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err = closeErr
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}
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return err
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})
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}
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