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Update nanosecond diff comparison

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Only check content of files if both files have zero nanosecond times.
A zero nanosecond time is considered ambiguous as to whether or
not the timestamp has been truncated by tar. Previously the diff
algorithm was attempting to account for comparisons from a source
to a directory with an applied tar. This condition is no longer
relevant since there is no support for recreating tars directories
which have had a tar extracted. In the case where the older directory
has a truncated timestamp and the newer one does not, this may always
be considered a change. In the case where both are zero, treat the
timestamp as ambiguous and compare content.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>
This commit is contained in:
Derek McGowan 2017-12-26 13:03:20 -08:00
parent c07ede497d
commit 88d59d37fa
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GPG Key ID: F58C5D0A4405ACDB
2 changed files with 16 additions and 7 deletions
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19
fs/diff_test.go
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@ -161,27 +161,36 @@ func TestUpdateWithSameTime(t *testing.T) {
fstest.CreateFile("/file-same-time", []byte("1"), 0644),
fstest.Chtimes("/file-same-time", t1, t1),
fstest.CreateFile("/file-truncated-time-1", []byte("1"), 0644),
fstest.Chtimes("/file-truncated-time-1", t1, t1),
fstest.Chtimes("/file-truncated-time-1", tt, tt),
fstest.CreateFile("/file-truncated-time-2", []byte("1"), 0644),
fstest.Chtimes("/file-truncated-time-2", tt, tt),
fstest.CreateFile("/file-truncated-time-3", []byte("1"), 0644),
fstest.Chtimes("/file-truncated-time-3", t1, t1),
)
l2 := fstest.Apply(
fstest.CreateFile("/file-modified-time", []byte("2"), 0644),
fstest.Chtimes("/file-modified-time", t2, t2),
fstest.CreateFile("/file-no-change", []byte("1"), 0644),
fstest.Chtimes("/file-no-change", tt, tt), // use truncated time, should be regarded as no change
fstest.Chtimes("/file-no-change", t1, t1),
fstest.CreateFile("/file-same-time", []byte("2"), 0644),
fstest.Chtimes("/file-same-time", t1, t1),
fstest.CreateFile("/file-truncated-time-1", []byte("2"), 0644),
fstest.Chtimes("/file-truncated-time-1", tt, tt),
fstest.CreateFile("/file-truncated-time-1", []byte("1"), 0644),
fstest.Chtimes("/file-truncated-time-1", t1, t1),
fstest.CreateFile("/file-truncated-time-2", []byte("2"), 0644),
fstest.Chtimes("/file-truncated-time-2", tt, tt),
fstest.CreateFile("/file-truncated-time-3", []byte("1"), 0644),
fstest.Chtimes("/file-truncated-time-3", tt, tt),
)
diff := []TestChange{
// "/file-same-time" excluded because matching non-zero nanosecond values
Modify("/file-modified-time"),
// Include changes with truncated timestamps. Comparing newly
// extracted tars which have truncated timestamps will be
// expected to produce changes. The expectation is that diff
// archives are generated once and kept, newly generated diffs
// will not consider cases where only one side is truncated.
Modify("/file-truncated-time-1"),
Modify("/file-truncated-time-2"),
Modify("/file-truncated-time-3"),
}
if err := testDiffWithBase(l1, l2, diff); err != nil {

4
fs/path.go
View File

@ -71,9 +71,9 @@ func sameFile(f1, f2 *currentPath) (bool, error) {
return false, nil
}
// If the timestamp may have been truncated in one of the
// If the timestamp may have been truncated in both of the
// files, check content of file to determine difference
if t1.Nanosecond() == 0 || t2.Nanosecond() == 0 {
if t1.Nanosecond() == 0 && t2.Nanosecond() == 0 {
var eq bool
if (f1.f.Mode() & os.ModeSymlink) == os.ModeSymlink {
eq, err = compareSymlinkTarget(f1.fullPath, f2.fullPath)