Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 122 insertions, 0 deletions

diff --git a/pkg/sentry/platform/filemem/filemem_test.go b/pkg/sentry/platform/filemem/filemem_test.go
new file mode 100644
index 000000000..46ffcf116
--- /dev/null
+++ b/pkg/sentry/platform/filemem/filemem_test.go
@@ -0,0 +1,122 @@
+// Copyright 2018 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package filemem
+
+import (
+	"testing"
+
+	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
+)
+
+const (
+	page     = usermem.PageSize
+	hugepage = usermem.HugePageSize
+)
+
+func TestFindUnallocatedRange(t *testing.T) {
+	for _, test := range []struct {
+		desc      string
+		usage     *usageSegmentDataSlices
+		length    uint64
+		alignment uint64
+		start     uint64
+	}{
+		{
+			desc:      "Initial allocation succeeds",
+			usage:     &usageSegmentDataSlices{},
+			length:    page,
+			alignment: page,
+			start:     0,
+		},
+		{
+			desc: "Allocation begins at start of file",
+			usage: &usageSegmentDataSlices{
+				Start:  []uint64{page},
+				End:    []uint64{2 * page},
+				Values: []usageInfo{{refs: 1}},
+			},
+			length:    page,
+			alignment: page,
+			start:     0,
+		},
+		{
+			desc: "In-use frames are not allocatable",
+			usage: &usageSegmentDataSlices{
+				Start:  []uint64{0, page},
+				End:    []uint64{page, 2 * page},
+				Values: []usageInfo{{refs: 1}, {refs: 2}},
+			},
+			length:    page,
+			alignment: page,
+			start:     2 * page,
+		},
+		{
+			desc: "Reclaimable frames are not allocatable",
+			usage: &usageSegmentDataSlices{
+				Start:  []uint64{0, page, 2 * page},
+				End:    []uint64{page, 2 * page, 3 * page},
+				Values: []usageInfo{{refs: 1}, {refs: 0}, {refs: 1}},
+			},
+			length:    page,
+			alignment: page,
+			start:     3 * page,
+		},
+		{
+			desc: "Gaps between in-use frames are allocatable",
+			usage: &usageSegmentDataSlices{
+				Start:  []uint64{0, 2 * page},
+				End:    []uint64{page, 3 * page},
+				Values: []usageInfo{{refs: 1}, {refs: 1}},
+			},
+			length:    page,
+			alignment: page,
+			start:     page,
+		},
+		{
+			desc: "Inadequately-sized gaps are rejected",
+			usage: &usageSegmentDataSlices{
+				Start:  []uint64{0, 2 * page},
+				End:    []uint64{page, 3 * page},
+				Values: []usageInfo{{refs: 1}, {refs: 1}},
+			},
+			length:    2 * page,
+			alignment: page,
+			start:     3 * page,
+		},
+		{
+			desc: "Hugepage alignment is honored",
+			usage: &usageSegmentDataSlices{
+				Start: []uint64{0, hugepage + page},
+				// Hugepage-sized gap here that shouldn't be allocated from
+				// since it's incorrectly aligned.
+				End:    []uint64{page, hugepage + 2*page},
+				Values: []usageInfo{{refs: 1}, {refs: 1}},
+			},
+			length:    hugepage,
+			alignment: hugepage,
+			start:     2 * hugepage,
+		},
+	} {
+		t.Run(test.desc, func(t *testing.T) {
+			var usage usageSet
+			if err := usage.ImportSortedSlices(test.usage); err != nil {
+				t.Fatalf("Failed to initialize usage from %v: %v", test.usage, err)
+			}
+			if got, want := findUnallocatedRange(&usage, test.length, test.alignment), test.start; got != want {
+				t.Errorf("findUnallocatedRange(%v, %d, %d): got %d, wanted %d", test.usage, test.length, test.alignment, got, want)
+			}
+		})
+	}
+}