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git attribute: test proper cancellation and unify nul-byte reader

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This commit is contained in:
oliverpool 2024-03-29 13:25:54 +01:00
parent bc04183e47
commit 0bb7758cb0
2 changed files with 359 additions and 250 deletions
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285
modules/git/repo_attribute.go
View file

@ -4,18 +4,76 @@
package git
import (
"bufio"
"bytes"
"context"
"fmt"
"io"
"os"
"strings"
"sync/atomic"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/optional"
)
var LinguistAttributes = []string{"linguist-vendored", "linguist-generated", "linguist-language", "gitlab-language", "linguist-documentation", "linguist-detectable"}
// newCheckAttrStdoutReader parses the nul-byte separated output of git check-attr on each call of
// the returned function. The first reading error will stop the reading and be returned on all
// subsequent calls.
func newCheckAttrStdoutReader(r io.Reader, count int) func() (map[string]GitAttribute, error) {
scanner := bufio.NewScanner(r)
// adapted from bufio.ScanLines to split on nul-byte \x00
scanner.Split(func(data []byte, atEOF bool) (advance int, token []byte, err error) {
if atEOF && len(data) == 0 {
return 0, nil, nil
}
if i := bytes.IndexByte(data, '\x00'); i >= 0 {
// We have a full nul-terminated line.
return i + 1, data[0:i], nil
}
// If we're at EOF, we have a final, non-terminated line. Return it.
if atEOF {
return len(data), data, nil
}
// Request more data.
return 0, nil, nil
})
var err error
nextText := func() string {
if err != nil {
return ""
}
if !scanner.Scan() {
err = scanner.Err()
if err == nil {
err = io.ErrUnexpectedEOF
}
return ""
}
return scanner.Text()
}
nextAttribute := func() (string, GitAttribute, error) {
nextText() // discard filename
key := nextText()
value := GitAttribute(nextText())
return key, value, err
}
return func() (map[string]GitAttribute, error) {
values := make(map[string]GitAttribute, count)
for range count {
k, v, err := nextAttribute()
if err != nil {
return values, err
}
values[k] = v
}
return values, scanner.Err()
}
}
// GitAttribute exposes an attribute from the .gitattribute file
type GitAttribute string //nolint:revive
@ -54,29 +112,15 @@ func (ca GitAttribute) Bool() optional.Option[bool] {
return optional.None[bool]()
}
// GitAttributeFirst returns the first specified attribute
//
// If treeish is empty, the gitattribute will be read from the current repo (which MUST be a working directory and NOT bare).
func (repo *Repository) GitAttributeFirst(treeish, filename string, attributes ...string) (GitAttribute, error) {
values, err := repo.GitAttributes(treeish, filename, attributes...)
if err != nil {
return "", err
}
for _, a := range attributes {
if values[a].IsSpecified() {
return values[a], nil
}
}
return "", nil
}
// gitCheckAttrCommand prepares the "git check-attr" command for later use as one-shot or streaming
// instanciation.
func (repo *Repository) gitCheckAttrCommand(treeish string, attributes ...string) (*Command, *RunOpts, context.CancelFunc, error) {
if len(attributes) == 0 {
return nil, nil, nil, fmt.Errorf("no provided attributes to check-attr")
}
env := os.Environ()
var deleteTemporaryFile context.CancelFunc
var removeTempFiles context.CancelFunc = func() {}
// git < 2.40 cannot run check-attr on bare repo, but needs INDEX + WORK_TREE
hasIndex := treeish == ""
@ -85,7 +129,7 @@ func (repo *Repository) gitCheckAttrCommand(treeish string, attributes ...string
if err != nil {
return nil, nil, nil, err
}
deleteTemporaryFile = cancel
removeTempFiles = cancel
env = append(env, "GIT_INDEX_FILE="+indexFilename, "GIT_WORK_TREE="+worktree)
@ -94,16 +138,8 @@ func (repo *Repository) gitCheckAttrCommand(treeish string, attributes ...string
// clear treeish to read from provided index/work_tree
treeish = ""
}
ctx, cancel := context.WithCancel(repo.Ctx)
if deleteTemporaryFile != nil {
ctxCancel := cancel
cancel = func() {
ctxCancel()
deleteTemporaryFile()
}
}
cmd := NewCommand(ctx, "check-attr", "-z")
cmd := NewCommand(repo.Ctx, "check-attr", "-z")
if hasIndex {
cmd.AddArguments("--cached")
@ -126,18 +162,34 @@ func (repo *Repository) gitCheckAttrCommand(treeish string, attributes ...string
return cmd, &RunOpts{
Env: env,
Dir: repo.Path,
}, cancel, nil
}, removeTempFiles, nil
}
// GitAttributes returns gitattribute.
// GitAttributeFirst returns the first specified attribute of the given filename.
//
// If treeish is empty, the gitattribute will be read from the current repo (which MUST be a working directory and NOT bare).
func (repo *Repository) GitAttributeFirst(treeish, filename string, attributes ...string) (GitAttribute, error) {
values, err := repo.GitAttributes(treeish, filename, attributes...)
if err != nil {
return "", err
}
for _, a := range attributes {
if values[a].IsSpecified() {
return values[a], nil
}
}
return "", nil
}
// GitAttributes returns the gitattribute of the given filename.
//
// If treeish is empty, the gitattribute will be read from the current repo (which MUST be a working directory and NOT bare).
func (repo *Repository) GitAttributes(treeish, filename string, attributes ...string) (map[string]GitAttribute, error) {
cmd, runOpts, cancel, err := repo.gitCheckAttrCommand(treeish, attributes...)
cmd, runOpts, removeTempFiles, err := repo.gitCheckAttrCommand(treeish, attributes...)
if err != nil {
return nil, err
}
defer cancel()
defer removeTempFiles()
stdOut := new(bytes.Buffer)
runOpts.Stdout = stdOut
@ -151,163 +203,84 @@ func (repo *Repository) GitAttributes(treeish, filename string, attributes ...st
return nil, fmt.Errorf("failed to run check-attr: %w\n%s\n%s", err, stdOut.String(), stdErr.String())
}
// FIXME: This is incorrect on versions < 1.8.5
fields := bytes.Split(stdOut.Bytes(), []byte{'\000'})
if len(fields)%3 != 1 {
return nil, fmt.Errorf("wrong number of fields in return from check-attr")
return newCheckAttrStdoutReader(stdOut, len(attributes))()
}
values := make(map[string]GitAttribute, len(attributes))
for ; len(fields) >= 3; fields = fields[3:] {
// filename := string(fields[0])
attribute := string(fields[1])
value := string(fields[2])
values[attribute] = GitAttribute(value)
}
return values, nil
}
type attributeTriple struct {
Filename string
Attribute string
Value string
}
type nulSeparatedAttributeWriter struct {
tmp []byte
attributes chan attributeTriple
closed chan struct{}
working attributeTriple
pos int
}
func (wr *nulSeparatedAttributeWriter) Write(p []byte) (n int, err error) {
l, read := len(p), 0
nulIdx := bytes.IndexByte(p, '\x00')
for nulIdx >= 0 {
wr.tmp = append(wr.tmp, p[:nulIdx]...)
switch wr.pos {
case 0:
wr.working = attributeTriple{
Filename: string(wr.tmp),
}
case 1:
wr.working.Attribute = string(wr.tmp)
case 2:
wr.working.Value = string(wr.tmp)
}
wr.tmp = wr.tmp[:0]
wr.pos++
if wr.pos > 2 {
wr.attributes <- wr.working
wr.pos = 0
}
read += nulIdx + 1
if l > read {
p = p[nulIdx+1:]
nulIdx = bytes.IndexByte(p, '\x00')
} else {
return l, nil
}
}
wr.tmp = append(wr.tmp, p...)
return len(p), nil
}
func (wr *nulSeparatedAttributeWriter) Close() error {
select {
case <-wr.closed:
return nil
default:
}
close(wr.attributes)
close(wr.closed)
return nil
}
// GitAttributeChecker creates an AttributeChecker for the given repository and provided commit ID.
// GitAttributeChecker creates an AttributeChecker for the given repository and provided commit ID
// to retrieve the attributes of multiple files. The AttributeChecker must be closed after use.
//
// If treeish is empty, the gitattribute will be read from the current repo (which MUST be a working directory and NOT bare).
func (repo *Repository) GitAttributeChecker(treeish string, attributes ...string) (AttributeChecker, error) {
cmd, runOpts, cancel, err := repo.gitCheckAttrCommand(treeish, attributes...)
cmd, runOpts, removeTempFiles, err := repo.gitCheckAttrCommand(treeish, attributes...)
if err != nil {
return AttributeChecker{}, err
}
ac := AttributeChecker{
attributeNumber: len(attributes),
ctx: cmd.parentContext,
cancel: cancel, // will be cancelled on Close
}
stdinReader, stdinWriter, err := os.Pipe()
if err != nil {
ac.cancel()
return AttributeChecker{}, err
}
ac.stdinWriter = stdinWriter // will be closed on Close
lw := new(nulSeparatedAttributeWriter)
lw.attributes = make(chan attributeTriple, len(attributes))
lw.closed = make(chan struct{})
ac.attributesCh = lw.attributes
cmd.AddArguments("--stdin")
// os.Pipe is needed (and not io.Pipe), otherwise cmd.Wait will wait for the stdinReader
// to be closed before returning (which would require another goroutine)
// https://go.dev/issue/23019
stdinReader, stdinWriter, err := os.Pipe() // reader closed in goroutine / writer closed on ac.Close
if err != nil {
return AttributeChecker{}, err
}
stdoutReader, stdoutWriter := io.Pipe() // closed in goroutine
ac := AttributeChecker{
removeTempFiles: removeTempFiles, // called on ac.Close
stdinWriter: stdinWriter,
readStdout: newCheckAttrStdoutReader(stdoutReader, len(attributes)),
err: &atomic.Value{},
}
go func() {
defer stdinReader.Close()
defer lw.Close()
defer stdoutWriter.Close() // in case of a panic (no-op if already closed by CloseWithError at the end)
stdErr := new(bytes.Buffer)
runOpts.Stdin = stdinReader
runOpts.Stdout = lw
runOpts.Stdout = stdoutWriter
runOpts.Stderr = stdErr
err := cmd.Run(runOpts)
if err != nil && // If there is an error we need to return but:
cmd.parentContext.Err() != err && // 1. Ignore the context error if the context is cancelled or exceeds the deadline (RunWithContext could return c.ctx.Err() which is Canceled or DeadlineExceeded)
err.Error() != "signal: killed" { // 2. We should not pass up errors due to the program being killed
log.Error("failed to run attr-check. Error: %v\nStderr: %s", err, stdErr.String())
// if the context was cancelled, Run error is irrelevant
if e := cmd.parentContext.Err(); e != nil {
err = e
}
if err != nil { // decorate the returned error
err = fmt.Errorf("git check-attr (stderr: %q): %w", strings.TrimSpace(stdErr.String()), err)
ac.err.Store(err)
}
stdoutWriter.CloseWithError(err)
}()
return ac, nil
}
type AttributeChecker struct {
ctx context.Context
cancel context.CancelFunc
stdinWriter *os.File
attributeNumber int
attributesCh <-chan attributeTriple
removeTempFiles context.CancelFunc
stdinWriter io.WriteCloser
readStdout func() (map[string]GitAttribute, error)
err *atomic.Value
}
func (ac AttributeChecker) CheckPath(path string) (map[string]GitAttribute, error) {
if err := ac.ctx.Err(); err != nil {
return nil, err
}
if _, err := ac.stdinWriter.Write([]byte(path + "\x00")); err != nil {
return nil, err
// try to return the Run error if available, since it is likely more helpful
// than just "broken pipe"
if aerr, _ := ac.err.Load().(error); aerr != nil {
return nil, aerr
}
return nil, fmt.Errorf("git check-attr: %w", err)
}
rs := make(map[string]GitAttribute)
for i := 0; i < ac.attributeNumber; i++ {
select {
case attr, ok := <-ac.attributesCh:
if !ok {
return nil, ac.ctx.Err()
}
rs[attr.Attribute] = GitAttribute(attr.Value)
case <-ac.ctx.Done():
return nil, ac.ctx.Err()
}
}
return rs, nil
return ac.readStdout()
}
func (ac AttributeChecker) Close() error {
ac.cancel()
ac.removeTempFiles()
return ac.stdinWriter.Close()
}

328
modules/git/repo_attribute_test.go
View file

@ -4,7 +4,14 @@
package git
import (
"context"
"fmt"
"io"
"io/fs"
"os"
"path/filepath"
"runtime"
"strings"
"testing"
"time"
@ -14,90 +21,63 @@ import (
"github.com/stretchr/testify/require"
)
func Test_nulSeparatedAttributeWriter_ReadAttribute(t *testing.T) {
wr := &nulSeparatedAttributeWriter{
attributes: make(chan attributeTriple, 5),
}
func TestNewCheckAttrStdoutReader(t *testing.T) {
t.Run("two_times", func(t *testing.T) {
read := newCheckAttrStdoutReader(strings.NewReader(
".gitignore\x00linguist-vendored\x00unspecified\x00"+
".gitignore\x00linguist-vendored\x00specified",
), 1)
testStr := ".gitignore\"\n\x00linguist-vendored\x00unspecified\x00"
n, err := wr.Write([]byte(testStr))
assert.Len(t, testStr, n)
// first read
attr, err := read()
assert.NoError(t, err)
select {
case attr := <-wr.attributes:
assert.Equal(t, ".gitignore\"\n", attr.Filename)
assert.Equal(t, "linguist-vendored", attr.Attribute)
assert.Equal(t, "unspecified", attr.Value)
case <-time.After(100 * time.Millisecond):
assert.FailNow(t, "took too long to read an attribute from the list")
}
// Write a second attribute again
n, err = wr.Write([]byte(testStr))
assert.Len(t, testStr, n)
assert.NoError(t, err)
select {
case attr := <-wr.attributes:
assert.Equal(t, ".gitignore\"\n", attr.Filename)
assert.Equal(t, "linguist-vendored", attr.Attribute)
assert.Equal(t, "unspecified", attr.Value)
case <-time.After(100 * time.Millisecond):
assert.FailNow(t, "took too long to read an attribute from the list")
}
// Write a partial attribute
_, err = wr.Write([]byte("incomplete-file"))
assert.NoError(t, err)
_, err = wr.Write([]byte("name\x00"))
assert.NoError(t, err)
select {
case <-wr.attributes:
assert.FailNow(t, "There should not be an attribute ready to read")
case <-time.After(100 * time.Millisecond):
}
_, err = wr.Write([]byte("attribute\x00"))
assert.NoError(t, err)
select {
case <-wr.attributes:
assert.FailNow(t, "There should not be an attribute ready to read")
case <-time.After(100 * time.Millisecond):
}
_, err = wr.Write([]byte("value\x00"))
assert.NoError(t, err)
attr := <-wr.attributes
assert.Equal(t, "incomplete-filename", attr.Filename)
assert.Equal(t, "attribute", attr.Attribute)
assert.Equal(t, "value", attr.Value)
_, err = wr.Write([]byte("shouldbe.vendor\x00linguist-vendored\x00set\x00shouldbe.vendor\x00linguist-generated\x00unspecified\x00shouldbe.vendor\x00linguist-language\x00unspecified\x00"))
assert.NoError(t, err)
attr = <-wr.attributes
assert.NoError(t, err)
assert.EqualValues(t, attributeTriple{
Filename: "shouldbe.vendor",
Attribute: "linguist-vendored",
Value: "set",
assert.Equal(t, map[string]GitAttribute{
"linguist-vendored": GitAttribute("unspecified"),
}, attr)
attr = <-wr.attributes
// second read
attr, err = read()
assert.NoError(t, err)
assert.EqualValues(t, attributeTriple{
Filename: "shouldbe.vendor",
Attribute: "linguist-generated",
Value: "unspecified",
assert.Equal(t, map[string]GitAttribute{
"linguist-vendored": GitAttribute("specified"),
}, attr)
attr = <-wr.attributes
})
t.Run("incomplete", func(t *testing.T) {
read := newCheckAttrStdoutReader(strings.NewReader(
"filename\x00linguist-vendored",
), 1)
_, err := read()
assert.Equal(t, io.ErrUnexpectedEOF, err)
})
t.Run("three_times", func(t *testing.T) {
read := newCheckAttrStdoutReader(strings.NewReader(
"shouldbe.vendor\x00linguist-vendored\x00set\x00"+
"shouldbe.vendor\x00linguist-generated\x00unspecified\x00"+
"shouldbe.vendor\x00linguist-language\x00unspecified\x00",
), 1)
// first read
attr, err := read()
assert.NoError(t, err)
assert.EqualValues(t, attributeTriple{
Filename: "shouldbe.vendor",
Attribute: "linguist-language",
Value: "unspecified",
assert.Equal(t, map[string]GitAttribute{
"linguist-vendored": GitAttribute("set"),
}, attr)
// second read
attr, err = read()
assert.NoError(t, err)
assert.Equal(t, map[string]GitAttribute{
"linguist-generated": GitAttribute("unspecified"),
}, attr)
// third read
attr, err = read()
assert.NoError(t, err)
assert.Equal(t, map[string]GitAttribute{
"linguist-language": GitAttribute("unspecified"),
}, attr)
})
}
func TestGitAttributeBareNonBare(t *testing.T) {
@ -114,25 +94,6 @@ func TestGitAttributeBareNonBare(t *testing.T) {
"8fee858da5796dfb37704761701bb8e800ad9ef3",
"341fca5b5ea3de596dc483e54c2db28633cd2f97",
} {
t.Run("GitAttributeChecker/"+commitID, func(t *testing.T) {
bareChecker, err := gitRepo.GitAttributeChecker(commitID, LinguistAttributes...)
assert.NoError(t, err)
t.Cleanup(func() { bareChecker.Close() })
bareStats, err := bareChecker.CheckPath("i-am-a-python.p")
assert.NoError(t, err)
defer test.MockVariableValue(&SupportCheckAttrOnBare, false)()
cloneChecker, err := gitRepo.GitAttributeChecker(commitID, LinguistAttributes...)
assert.NoError(t, err)
t.Cleanup(func() { cloneChecker.Close() })
cloneStats, err := cloneChecker.CheckPath("i-am-a-python.p")
assert.NoError(t, err)
assert.EqualValues(t, cloneStats, bareStats)
})
t.Run("GitAttributes/"+commitID, func(t *testing.T) {
bareStats, err := gitRepo.GitAttributes(commitID, "i-am-a-python.p", LinguistAttributes...)
assert.NoError(t, err)
@ -141,6 +102,27 @@ func TestGitAttributeBareNonBare(t *testing.T) {
assert.NoError(t, err)
assert.EqualValues(t, cloneStats, bareStats)
refStats := cloneStats
t.Run("GitAttributeChecker/"+commitID+"/SupportBare", func(t *testing.T) {
bareChecker, err := gitRepo.GitAttributeChecker(commitID, LinguistAttributes...)
assert.NoError(t, err)
defer bareChecker.Close()
bareStats, err := bareChecker.CheckPath("i-am-a-python.p")
assert.NoError(t, err)
assert.EqualValues(t, refStats, bareStats)
})
t.Run("GitAttributeChecker/"+commitID+"/NoBareSupport", func(t *testing.T) {
defer test.MockVariableValue(&SupportCheckAttrOnBare, false)()
cloneChecker, err := gitRepo.GitAttributeChecker(commitID, LinguistAttributes...)
assert.NoError(t, err)
defer cloneChecker.Close()
cloneStats, err := cloneChecker.CheckPath("i-am-a-python.p")
assert.NoError(t, err)
assert.EqualValues(t, refStats, cloneStats)
})
}
}
@ -208,3 +190,157 @@ func TestGitAttributeStruct(t *testing.T) {
assert.Equal(t, "text?token=Error", GitAttribute("text?token=Error").String())
assert.Equal(t, "text", GitAttribute("text?token=Error").Prefix())
}
func TestGitAttributeCheckerError(t *testing.T) {
prepareRepo := func(t *testing.T) *Repository {
t.Helper()
path := t.TempDir()
// we can't use unittest.CopyDir because of an import cycle (git.Init in unittest)
require.NoError(t, CopyFS(path, os.DirFS(filepath.Join(testReposDir, "language_stats_repo"))))
gitRepo, err := openRepositoryWithDefaultContext(path)
require.NoError(t, err)
return gitRepo
}
t.Run("RemoveAll/BeforeRun", func(t *testing.T) {
gitRepo := prepareRepo(t)
defer gitRepo.Close()
assert.NoError(t, os.RemoveAll(gitRepo.Path))
ac, err := gitRepo.GitAttributeChecker("", "linguist-language")
require.NoError(t, err)
_, err = ac.CheckPath("i-am-a-python.p")
assert.Error(t, err)
assert.Contains(t, err.Error(), `git check-attr (stderr: ""):`)
})
t.Run("RemoveAll/DuringRun", func(t *testing.T) {
gitRepo := prepareRepo(t)
defer gitRepo.Close()
ac, err := gitRepo.GitAttributeChecker("", "linguist-language")
require.NoError(t, err)
// calling CheckPath before would allow git to cache part of it and succesfully return later
assert.NoError(t, os.RemoveAll(gitRepo.Path))
_, err = ac.CheckPath("i-am-a-python.p")
assert.Error(t, err)
// Depending on the order of execution, the returned error can be:
// - a launch error "fork/exec /usr/bin/git: no such file or directory" (when the removal happens before the Run)
// - a git error (stderr: "fatal: Unable to read current working directory: No such file or directory"): exit status 128 (when the removal happens after the Run)
// (pipe error "write |1: broken pipe" should be replaced by one of the Run errors above)
assert.Contains(t, err.Error(), `git check-attr`)
})
t.Run("Cancelled/BeforeRun", func(t *testing.T) {
gitRepo := prepareRepo(t)
defer gitRepo.Close()
var cancel context.CancelFunc
gitRepo.Ctx, cancel = context.WithCancel(gitRepo.Ctx)
cancel()
ac, err := gitRepo.GitAttributeChecker("8fee858da5796dfb37704761701bb8e800ad9ef3", "linguist-language")
require.NoError(t, err)
_, err = ac.CheckPath("i-am-a-python.p")
assert.ErrorIs(t, err, context.Canceled)
})
t.Run("Cancelled/DuringRun", func(t *testing.T) {
gitRepo := prepareRepo(t)
defer gitRepo.Close()
var cancel context.CancelFunc
gitRepo.Ctx, cancel = context.WithCancel(gitRepo.Ctx)
ac, err := gitRepo.GitAttributeChecker("8fee858da5796dfb37704761701bb8e800ad9ef3", "linguist-language")
require.NoError(t, err)
attr, err := ac.CheckPath("i-am-a-python.p")
assert.NoError(t, err)
assert.Equal(t, "Python", attr["linguist-language"].String())
errCh := make(chan error)
go func() {
cancel()
for err == nil {
_, err = ac.CheckPath("i-am-a-python.p")
runtime.Gosched() // the cancellation must have time to propagate
}
errCh <- err
}()
select {
case <-time.After(time.Second):
t.Error("CheckPath did not complete within 1s")
case err = <-errCh:
assert.ErrorIs(t, err, context.Canceled)
}
})
t.Run("Closed/BeforeRun", func(t *testing.T) {
gitRepo := prepareRepo(t)
defer gitRepo.Close()
ac, err := gitRepo.GitAttributeChecker("8fee858da5796dfb37704761701bb8e800ad9ef3", "linguist-language")
require.NoError(t, err)
assert.NoError(t, ac.Close())
_, err = ac.CheckPath("i-am-a-python.p")
assert.ErrorIs(t, err, fs.ErrClosed)
})
t.Run("Closed/DuringRun", func(t *testing.T) {
gitRepo := prepareRepo(t)
defer gitRepo.Close()
ac, err := gitRepo.GitAttributeChecker("8fee858da5796dfb37704761701bb8e800ad9ef3", "linguist-language")
require.NoError(t, err)
attr, err := ac.CheckPath("i-am-a-python.p")
assert.NoError(t, err)
assert.Equal(t, "Python", attr["linguist-language"].String())
assert.NoError(t, ac.Close())
_, err = ac.CheckPath("i-am-a-python.p")
assert.ErrorIs(t, err, fs.ErrClosed)
})
}
// CopyFS is adapted from https://github.com/golang/go/issues/62484
// which should be available with go1.23
func CopyFS(dir string, fsys fs.FS) error {
return fs.WalkDir(fsys, ".", func(path string, d fs.DirEntry, _ error) error {
targ := filepath.Join(dir, filepath.FromSlash(path))
if d.IsDir() {
return os.MkdirAll(targ, 0o777)
}
r, err := fsys.Open(path)
if err != nil {
return err
}
defer r.Close()
info, err := r.Stat()
if err != nil {
return err
}
w, err := os.OpenFile(targ, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0o666|info.Mode()&0o777)
if err != nil {
return err
}
if _, err := io.Copy(w, r); err != nil {
w.Close()
return fmt.Errorf("copying %s: %v", path, err)
}
return w.Close()
})
}