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Fix a race in adding references #321

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Merged
runcom merged 1 commit into from
Sep 11, 2018
Merged

Fix a race in adding references #321

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5 changes: 5 additions & 0 deletions reference/store.go
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Original file line number Diff line number Diff line change
Expand Up @@ -128,6 +128,11 @@ func (store *store) addReference(ref Named, id digest.Digest, force bool) error
oldID, exists := repository[refStr]

if exists {
if oldID == id {
// Nothing to do. The caller may have checked for this using store.Get in advance, but store.mu was unlocked in the meantime, so this can legitimately happen nevertheless.
return nil
}

// force only works for tags
if digested, isDigest := ref.(Canonical); isDigest {
return fmt.Errorf("Cannot overwrite digest %s", digested.Digest().String())
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8 changes: 8 additions & 0 deletions reference/store_test.go
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Expand Up @@ -160,6 +160,10 @@ func TestAddDeleteGet(t *testing.T) {
if err = store.AddTag(ref4, testImageID2, false); err != nil {
t.Fatalf("error adding to store: %v", err)
}
// Write the same values again; should silently succeed
if err = store.AddTag(ref4, testImageID2, false); err != nil {
t.Fatalf("error redundantly adding to store: %v", err)
}

ref5, err := ParseNamed("username/repo3@sha256:58153dfb11794fad694460162bf0cb0a4fa710cfa3f60979c177d920813e267c")
if err != nil {
Expand All @@ -168,6 +172,10 @@ func TestAddDeleteGet(t *testing.T) {
if err = store.AddDigest(ref5.(Canonical), testImageID2, false); err != nil {
t.Fatalf("error adding to store: %v", err)
}
// Write the same values again; should silently succeed
if err = store.AddDigest(ref5.(Canonical), testImageID2, false); err != nil {
t.Fatalf("error redundantly adding to store: %v", err)
}

// Attempt to overwrite with force == false
if err = store.AddTag(ref4, testImageID3, false); err == nil || !strings.HasPrefix(err.Error(), "Conflict:") {
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