fix: ListObjects should return NoSuchBucket for prefix on missing bucket

cmd/metacache-server-pool.go

@@ -71,21 +71,21 @@ func (z *erasureServerPools) listPath(ctx context.Context, o *listPathOptions) (
 	if o.Marker != "" && o.Prefix != "" {
 		// Marker not common with prefix is not implemented. Send an empty response
 		if !HasPrefix(o.Marker, o.Prefix) {
-			return entries, io.EOF
+			return entries, z.listPathShortcutEOF(ctx, o.Bucket)
 		}
 	}
 
 	// With max keys of zero we have reached eof, return right here.
 	if o.Limit == 0 {
-		return entries, io.EOF
+		return entries, z.listPathShortcutEOF(ctx, o.Bucket)
 	}
 
 	// For delimiter and prefix as '/' we do not list anything at all
 	// along // with the prefix. On a flat namespace with 'prefix'
 	// as '/' we don't have any entries, since all the keys are
 	// of form 'keyName/...'
 	if strings.HasPrefix(o.Prefix, SlashSeparator) {
-		return entries, io.EOF
+		return entries, z.listPathShortcutEOF(ctx, o.Bucket)
 	}
 
 	// If delimiter is slashSeparator we must return directories of
@@ -254,6 +254,21 @@ func (z *erasureServerPools) listPath(ctx context.Context, o *listPathOptions) (
 	return entries, nil
 }
 
+// listPathShortcutEOF is used by the listPath shortcuts that return an empty
+// result without ever consulting the storage layer (a slash-only prefix, a
+// zero limit, or a marker outside the prefix). Because they bypass the per-set
+// listing - which is what surfaces a missing bucket as errVolumeNotFound - they
+// must verify bucket existence explicitly, otherwise a listing on a
+// non-existent bucket is masked as an empty result. AWS S3 returns NoSuchBucket
+// regardless of the prefix/marker/max-keys supplied.
+// See https://github.com/pgsty/minio/issues/32
+func (z *erasureServerPools) listPathShortcutEOF(ctx context.Context, bucket string) error {
+	if _, err := z.GetBucketInfo(ctx, bucket, BucketOptions{}); err != nil {
+		return err
+	}
+	return io.EOF
+}
+
 // listMerged will list across all sets and return a merged results stream.
 // The result channel is closed when no more results are expected.
 func (z *erasureServerPools) listMerged(ctx context.Context, o listPathOptions, results chan<- metaCacheEntry) error {

cmd/object_api_suite_test.go

@@ -849,6 +849,41 @@ func testListObjectsTestsForNonExistentBucket(obj ObjectLayer, instanceType stri
 	}
 }
 
+// Wrapper for calling testListObjectsWithPrefixForNonExistentBucket for both Erasure and FS.
+func TestListObjectsWithPrefixForNonExistentBucket(t *testing.T) {
+	ExecObjectLayerTest(t, testListObjectsWithPrefixForNonExistentBucket)
+}
+
+// Tests validate that ListObjects on a non-existent bucket fails with
+// BucketNotFound even when a prefix (or other listing shortcut) is supplied.
+// AWS S3 returns NoSuchBucket regardless of the prefix/marker/max-keys values.
+// Regression: https://github.com/pgsty/minio/issues/32
+func testListObjectsWithPrefixForNonExistentBucket(obj ObjectLayer, instanceType string, t TestErrHandler) {
+	testCases := []struct {
+		prefix  string
+		marker  string
+		maxKeys int
+	}{
+		{prefix: "/", maxKeys: 1000},              // slash-only prefix shortcut (the issue reproduction)
+		{prefix: "foo/bar", maxKeys: 1000},        // regular prefix
+		{prefix: "obj", maxKeys: 1},               // max-keys==1 shortcut
+		{prefix: "obj", maxKeys: 0},               // zero-limit shortcut
+		{prefix: "a", marker: "b", maxKeys: 1000}, // marker outside the prefix shortcut
+	}
+	for i, tc := range testCases {
+		result, err := obj.ListObjects(context.Background(), "bucket", tc.prefix, tc.marker, "", tc.maxKeys)
+		if err == nil {
+			t.Fatalf("%s: test %d (prefix %q): Expected error but found nil.", instanceType, i+1, tc.prefix)
+		}
+		if len(result.Objects) != 0 {
+			t.Fatalf("%s: test %d (prefix %q): Expected 0 objects, but found %d", instanceType, i+1, tc.prefix, len(result.Objects))
+		}
+		if err.Error() != "Bucket not found: bucket" {
+			t.Errorf("%s: test %d (prefix %q): Expected error msg `%s`, but found `%s`", instanceType, i+1, tc.prefix, "Bucket not found: bucket", err.Error())
+		}
+	}
+}
+
 // Wrapper for calling testNonExistentObjectInBucket for both Erasure and FS.
 func TestNonExistentObjectInBucket(t *testing.T) {
 	ExecObjectLayerTest(t, testNonExistentObjectInBucket)