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fs/diff: support symlink to abspath with second-precision mtime

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Previously, `Changes()` for a symlink to absolute path, with second-precision
mtime of the link itself always resulted in ENOENT.

This is because `compareFileContent()` was called for the link target path, without changing the root path.

Fix moby/buildkit#172

Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>
This commit is contained in:
Akihiro Suda 2017-11-20 09:14:48 +00:00
parent 1bd39d36ed
commit a3aeb398fe
5 changed files with 88 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
fs/diff_test.go
View File

@ -150,27 +150,27 @@ func TestUpdateWithSameTime(t *testing.T) {
t2 := tt.Add(6 * time.Nanosecond)
l1 := fstest.Apply(
fstest.CreateFile("/file-modified-time", []byte("1"), 0644),
fstest.Chtime("/file-modified-time", t1),
fstest.Chtimes("/file-modified-time", t1, t1),
fstest.CreateFile("/file-no-change", []byte("1"), 0644),
fstest.Chtime("/file-no-change", t1),
fstest.Chtimes("/file-no-change", t1, t1),
fstest.CreateFile("/file-same-time", []byte("1"), 0644),
fstest.Chtime("/file-same-time", t1),
fstest.Chtimes("/file-same-time", t1, t1),
fstest.CreateFile("/file-truncated-time-1", []byte("1"), 0644),
fstest.Chtime("/file-truncated-time-1", t1),
fstest.Chtimes("/file-truncated-time-1", t1, t1),
fstest.CreateFile("/file-truncated-time-2", []byte("1"), 0644),
fstest.Chtime("/file-truncated-time-2", tt),
fstest.Chtimes("/file-truncated-time-2", tt, tt),
)
l2 := fstest.Apply(
fstest.CreateFile("/file-modified-time", []byte("2"), 0644),
fstest.Chtime("/file-modified-time", t2),
fstest.Chtimes("/file-modified-time", t2, t2),
fstest.CreateFile("/file-no-change", []byte("1"), 0644),
fstest.Chtime("/file-no-change", tt), // use truncated time, should be regarded as no change
fstest.Chtimes("/file-no-change", tt, tt), // use truncated time, should be regarded as no change
fstest.CreateFile("/file-same-time", []byte("2"), 0644),
fstest.Chtime("/file-same-time", t1),
fstest.Chtimes("/file-same-time", t1, t1),
fstest.CreateFile("/file-truncated-time-1", []byte("2"), 0644),
fstest.Chtime("/file-truncated-time-1", tt),
fstest.Chtimes("/file-truncated-time-1", tt, tt),
fstest.CreateFile("/file-truncated-time-2", []byte("2"), 0644),
fstest.Chtime("/file-truncated-time-2", tt),
fstest.Chtimes("/file-truncated-time-2", tt, tt),
)
diff := []TestChange{
// "/file-same-time" excluded because matching non-zero nanosecond values
@ -184,6 +184,28 @@ func TestUpdateWithSameTime(t *testing.T) {
}
}
// buildkit#172
func TestLchtimes(t *testing.T) {
skipDiffTestOnWindows(t)
mtimes := []time.Time{
time.Unix(0, 0), // nsec is 0
time.Unix(0, 42), // nsec > 0
}
for _, mtime := range mtimes {
atime := time.Unix(424242, 42)
l1 := fstest.Apply(
fstest.CreateFile("/foo", []byte("foo"), 0644),
fstest.Symlink("/foo", "/lnk0"),
fstest.Lchtimes("/lnk0", atime, mtime),
)
l2 := fstest.Apply() // empty
diff := []TestChange{}
if err := testDiffWithBase(l1, l2, diff); err != nil {
t.Fatalf("Failed diff with base: %+v", err)
}
}
}
func testDiffWithBase(base, diff fstest.Applier, expected []TestChange) error {
t1, err := ioutil.TempDir("", "diff-with-base-lower-")
if err != nil {

7
fs/fstest/file.go
View File

@ -71,10 +71,11 @@ func Chown(name string, uid, gid int) Applier {
})
}
// Chtime changes access and mod time of file
func Chtime(name string, t time.Time) Applier {
// Chtimes changes access and mod time of file.
// Use Lchtimes for symbolic links.
func Chtimes(name string, atime, mtime time.Time) Applier {
return applyFn(func(root string) error {
return os.Chtimes(filepath.Join(root, name), t, t)
return os.Chtimes(filepath.Join(root, name), atime, mtime)
})
}

19
fs/fstest/file_unix.go
View File

@ -2,7 +2,13 @@
package fstest
import "github.com/containerd/continuity/sysx"
import (
"path/filepath"
"time"
"github.com/containerd/continuity/sysx"
"golang.org/x/sys/unix"
)
// SetXAttr sets the xatter for the file
func SetXAttr(name, key, value string) Applier {
@ -10,3 +16,14 @@ func SetXAttr(name, key, value string) Applier {
return sysx.LSetxattr(name, key, []byte(value), 0)
})
}
// Lchtimes changes access and mod time of file without following symlink
func Lchtimes(name string, atime, mtime time.Time) Applier {
return applyFn(func(root string) error {
path := filepath.Join(root, name)
at := unix.NsecToTimespec(atime.UnixNano())
mt := unix.NsecToTimespec(mtime.UnixNano())
utimes := [2]unix.Timespec{at, mt}
return unix.UtimesNanoAt(unix.AT_FDCWD, path, utimes[0:], unix.AT_SYMLINK_NOFOLLOW)
})
}

14
fs/fstest/file_windows.go Normal file
View File

@ -0,0 +1,14 @@
package fstest
import (
"time"
"github.com/containerd/containerd/errdefs"
)
// Lchtimes changes access and mod time of file without following symlink
func Lchtimes(name string, atime, mtime time.Time) Applier {
return applyFn(func(root string) error {
return errdefs.ErrNotImplemented
})
}

21
fs/path.go
View File

@ -74,12 +74,15 @@ func sameFile(f1, f2 *currentPath) (bool, error) {
// If the timestamp may have been truncated in one of the
// files, check content of file to determine difference
if t1.Nanosecond() == 0 || t2.Nanosecond() == 0 {
if f1.f.Size() > 0 {
eq, err := compareFileContent(f1.fullPath, f2.fullPath)
var eq bool
if (f1.f.Mode() & os.ModeSymlink) == os.ModeSymlink {
eq, err = compareSymlinkTarget(f1.fullPath, f2.fullPath)
} else if f1.f.Size() > 0 {
eq, err = compareFileContent(f1.fullPath, f2.fullPath)
}
if err != nil || !eq {
return eq, err
}
}
} else if t1.Nanosecond() != t2.Nanosecond() {
return false, nil
}
@ -88,6 +91,18 @@ func sameFile(f1, f2 *currentPath) (bool, error) {
return true, nil
}
func compareSymlinkTarget(p1, p2 string) (bool, error) {
t1, err := os.Readlink(p1)
if err != nil {
return false, err
}
t2, err := os.Readlink(p2)
if err != nil {
return false, err
}
return t1 == t2, nil
}
const compareChuckSize = 32 * 1024
// compareFileContent compares the content of 2 same sized files