forked from TrueCloudLab/restic
restore: allow overwrite to replace empty directories and symlinks
With an already existing file tree an old directory or symlink may exist in a place where restore wants to create a new file. Thus, check for unexpected file types and clean up if necessary.
This commit is contained in:
Michael Eischer
parent
267cd62ae4
commit
f19b69af25
2 changed files with 156 additions and 27 deletions
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@ -1,11 +1,15 @@
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package restorer
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import (
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"fmt"
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stdfs "io/fs"
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"os"
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"sync"
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"syscall"
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"github.com/cespare/xxhash/v2"
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"github.com/restic/restic/internal/debug"
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"github.com/restic/restic/internal/errors"
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"github.com/restic/restic/internal/fs"
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)
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@ -39,13 +43,26 @@ func newFilesWriter(count int) *filesWriter {
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}
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}
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func createFile(path string, createSize int64, sparse bool) (*os.File, error) {
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f, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY, 0600)
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func openFile(path string) (*os.File, error) {
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f, err := os.OpenFile(path, os.O_WRONLY|fs.O_NOFOLLOW, 0600)
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if err != nil {
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if !fs.IsAccessDenied(err) {
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return nil, err
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}
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return nil, err
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}
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fi, err := f.Stat()
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if err != nil {
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_ = f.Close()
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return nil, err
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}
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if !fi.Mode().IsRegular() {
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_ = f.Close()
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return nil, fmt.Errorf("unexpected file type %v at %q", fi.Mode().Type(), path)
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}
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return f, nil
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}
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func createFile(path string, createSize int64, sparse bool) (*os.File, error) {
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f, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY|fs.O_NOFOLLOW, 0600)
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if err != nil && fs.IsAccessDenied(err) {
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// If file is readonly, clear the readonly flag by resetting the
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// permissions of the file and try again
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// as the metadata will be set again in the second pass and the
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@ -53,40 +70,75 @@ func createFile(path string, createSize int64, sparse bool) (*os.File, error) {
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if err = fs.ResetPermissions(path); err != nil {
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return nil, err
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}
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if f, err = os.OpenFile(path, os.O_WRONLY, 0600); err != nil {
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if f, err = os.OpenFile(path, os.O_WRONLY|fs.O_NOFOLLOW, 0600); err != nil {
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return nil, err
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}
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} else if err != nil && (errors.Is(err, syscall.ELOOP) || errors.Is(err, syscall.EISDIR)) {
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// symlink or directory, try to remove it later on
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f = nil
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} else if err != nil {
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return nil, err
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}
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var fi stdfs.FileInfo
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if f != nil {
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// stat to check that we've opened a regular file
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fi, err = f.Stat()
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if err != nil {
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_ = f.Close()
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return nil, err
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}
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}
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if f == nil || !fi.Mode().IsRegular() {
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// close handle if we still have it
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if f != nil {
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if err := f.Close(); err != nil {
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return nil, err
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}
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}
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// not what we expected, try to get rid of it
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if err := os.Remove(path); err != nil {
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return nil, err
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}
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// create a new file, pass O_EXCL to make sure there are no surprises
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f, err = os.OpenFile(path, os.O_CREATE|os.O_WRONLY|os.O_EXCL|fs.O_NOFOLLOW, 0600)
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if err != nil {
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return nil, err
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}
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fi, err = f.Stat()
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if err != nil {
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_ = f.Close()
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return nil, err
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}
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}
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return ensureSize(f, fi, createSize, sparse)
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}
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func ensureSize(f *os.File, fi stdfs.FileInfo, createSize int64, sparse bool) (*os.File, error) {
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if sparse {
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err = truncateSparse(f, createSize)
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err := truncateSparse(f, createSize)
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if err != nil {
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_ = f.Close()
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return nil, err
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}
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} else {
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info, err := f.Stat()
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} else if fi.Size() > createSize {
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// file is too long must shorten it
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err := f.Truncate(createSize)
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if err != nil {
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_ = f.Close()
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return nil, err
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}
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if info.Size() > createSize {
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// file is too long must shorten it
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err = f.Truncate(createSize)
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if err != nil {
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_ = f.Close()
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return nil, err
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}
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} else if createSize > 0 {
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err := fs.PreallocateFile(f, createSize)
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if err != nil {
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// Just log the preallocate error but don't let it cause the restore process to fail.
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// Preallocate might return an error if the filesystem (implementation) does not
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// support preallocation or our parameters combination to the preallocate call
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// This should yield a syscall.ENOTSUP error, but some other errors might also
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// show up.
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debug.Log("Failed to preallocate %v with size %v: %v", path, createSize, err)
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}
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} else if createSize > 0 {
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err := fs.PreallocateFile(f, createSize)
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if err != nil {
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// Just log the preallocate error but don't let it cause the restore process to fail.
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// Preallocate might return an error if the filesystem (implementation) does not
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// support preallocation or our parameters combination to the preallocate call
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// This should yield a syscall.ENOTSUP error, but some other errors might also
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// show up.
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debug.Log("Failed to preallocate %v with size %v: %v", f.Name(), createSize, err)
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}
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}
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return f, nil
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@ -110,7 +162,7 @@ func (w *filesWriter) writeToFile(path string, blob []byte, offset int64, create
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if err != nil {
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return nil, err
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}
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} else if f, err = os.OpenFile(path, os.O_WRONLY, 0600); err != nil {
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} else if f, err = openFile(path); err != nil {
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return nil, err
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}
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@ -1,9 +1,13 @@
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package restorer
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import (
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"fmt"
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"os"
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"path/filepath"
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"syscall"
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"testing"
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"github.com/restic/restic/internal/errors"
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rtest "github.com/restic/restic/internal/test"
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)
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@ -34,3 +38,76 @@ func TestFilesWriterBasic(t *testing.T) {
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rtest.OK(t, err)
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rtest.Equals(t, []byte{2, 2}, buf)
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}
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func TestCreateFile(t *testing.T) {
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basepath := filepath.Join(t.TempDir(), "test")
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scenarios := []struct {
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name string
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create func(t testing.TB, path string)
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err error
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}{
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{
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"file",
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func(t testing.TB, path string) {
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rtest.OK(t, os.WriteFile(path, []byte("test-test-test-data"), 0o400))
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},
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nil,
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},
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{
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"empty dir",
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func(t testing.TB, path string) {
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rtest.OK(t, os.Mkdir(path, 0o400))
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},
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nil,
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},
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{
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"symlink",
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func(t testing.TB, path string) {
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rtest.OK(t, os.Symlink("./something", path))
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},
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nil,
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},
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{
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"filled dir",
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func(t testing.TB, path string) {
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rtest.OK(t, os.Mkdir(path, 0o700))
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rtest.OK(t, os.WriteFile(filepath.Join(path, "file"), []byte("data"), 0o400))
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},
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syscall.ENOTEMPTY,
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},
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}
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tests := []struct {
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size int64
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isSparse bool
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}{
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{5, false},
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{21, false},
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{100, false},
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{5, true},
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{21, true},
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{100, true},
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}
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for i, sc := range scenarios {
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t.Run(sc.name, func(t *testing.T) {
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for _, test := range tests {
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path := basepath + fmt.Sprintf("%v", i)
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sc.create(t, path)
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f, err := createFile(path, test.size, test.isSparse)
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if sc.err == nil {
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rtest.OK(t, err)
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fi, err := f.Stat()
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rtest.OK(t, err)
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rtest.Assert(t, fi.Mode().IsRegular(), "wrong filetype %v", fi.Mode())
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rtest.Assert(t, fi.Size() <= test.size, "unexpected file size expected %v, got %v", test.size, fi.Size())
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rtest.OK(t, f.Close())
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} else {
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rtest.Assert(t, errors.Is(err, sc.err), "unexpected error got %v expected %v", err, sc.err)
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}
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rtest.OK(t, os.RemoveAll(path))
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}
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})
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}
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}
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