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// Copyright 2018 The gVisor Authors.
//
// 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 contexttest builds a test context.Context.
package contexttest
import (
"os"
"sync/atomic"
"testing"
"time"
"gvisor.dev/gvisor/pkg/memutil"
"gvisor.dev/gvisor/pkg/sentry/context"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
"gvisor.dev/gvisor/pkg/sentry/limits"
"gvisor.dev/gvisor/pkg/sentry/pgalloc"
"gvisor.dev/gvisor/pkg/sentry/platform"
"gvisor.dev/gvisor/pkg/sentry/platform/ptrace"
"gvisor.dev/gvisor/pkg/sentry/uniqueid"
)
// Context returns a Context that may be used in tests. Uses ptrace as the
// platform.Platform.
//
// Note that some filesystems may require a minimal kernel for testing, which
// this test context does not provide. For such tests, see kernel/contexttest.
func Context(tb testing.TB) context.Context {
const memfileName = "contexttest-memory"
memfd, err := memutil.CreateMemFD(memfileName, 0)
if err != nil {
tb.Fatalf("error creating application memory file: %v", err)
}
memfile := os.NewFile(uintptr(memfd), memfileName)
mf, err := pgalloc.NewMemoryFile(memfile, pgalloc.MemoryFileOpts{})
if err != nil {
memfile.Close()
tb.Fatalf("error creating pgalloc.MemoryFile: %v", err)
}
p, err := ptrace.New()
if err != nil {
tb.Fatal(err)
}
// Test usage of context.Background is fine.
return &TestContext{
Context: context.Background(),
l: limits.NewLimitSet(),
mf: mf,
platform: p,
creds: auth.NewAnonymousCredentials(),
otherValues: make(map[interface{}]interface{}),
}
}
// TestContext represents a context with minimal functionality suitable for
// running tests.
type TestContext struct {
context.Context
l *limits.LimitSet
mf *pgalloc.MemoryFile
platform platform.Platform
creds *auth.Credentials
otherValues map[interface{}]interface{}
}
// globalUniqueID tracks incremental unique identifiers for tests.
var globalUniqueID uint64
// globalUniqueIDProvider implements unix.UniqueIDProvider.
type globalUniqueIDProvider struct{}
// UniqueID implements unix.UniqueIDProvider.UniqueID.
func (*globalUniqueIDProvider) UniqueID() uint64 {
return atomic.AddUint64(&globalUniqueID, 1)
}
// lastInotifyCookie is a monotonically increasing counter for generating unique
// inotify cookies. Must be accessed using atomic ops.
var lastInotifyCookie uint32
// hostClock implements ktime.Clock.
type hostClock struct {
ktime.WallRateClock
ktime.NoClockEvents
}
// Now implements ktime.Clock.Now.
func (hostClock) Now() ktime.Time {
return ktime.FromNanoseconds(time.Now().UnixNano())
}
// RegisterValue registers additional values with this test context. Useful for
// providing values from external packages that contexttest can't depend on.
func (t *TestContext) RegisterValue(key, value interface{}) {
t.otherValues[key] = value
}
// Value implements context.Context.
func (t *TestContext) Value(key interface{}) interface{} {
switch key {
case auth.CtxCredentials:
return t.creds
case limits.CtxLimits:
return t.l
case pgalloc.CtxMemoryFile:
return t.mf
case pgalloc.CtxMemoryFileProvider:
return t
case platform.CtxPlatform:
return t.platform
case uniqueid.CtxGlobalUniqueID:
return (*globalUniqueIDProvider).UniqueID(nil)
case uniqueid.CtxGlobalUniqueIDProvider:
return &globalUniqueIDProvider{}
case uniqueid.CtxInotifyCookie:
return atomic.AddUint32(&lastInotifyCookie, 1)
case ktime.CtxRealtimeClock:
return hostClock{}
default:
if val, ok := t.otherValues[key]; ok {
return val
}
return t.Context.Value(key)
}
}
// MemoryFile implements pgalloc.MemoryFileProvider.MemoryFile.
func (t *TestContext) MemoryFile() *pgalloc.MemoryFile {
return t.mf
}
// RootContext returns a Context that may be used in tests that need root
// credentials. Uses ptrace as the platform.Platform.
func RootContext(tb testing.TB) context.Context {
return WithCreds(Context(tb), auth.NewRootCredentials(auth.NewRootUserNamespace()))
}
// WithCreds returns a copy of ctx carrying creds.
func WithCreds(ctx context.Context, creds *auth.Credentials) context.Context {
return &authContext{ctx, creds}
}
type authContext struct {
context.Context
creds *auth.Credentials
}
// Value implements context.Context.
func (ac *authContext) Value(key interface{}) interface{} {
switch key {
case auth.CtxCredentials:
return ac.creds
default:
return ac.Context.Value(key)
}
}
// WithLimitSet returns a copy of ctx carrying l.
func WithLimitSet(ctx context.Context, l *limits.LimitSet) context.Context {
return limitContext{ctx, l}
}
type limitContext struct {
context.Context
l *limits.LimitSet
}
// Value implements context.Context.
func (lc limitContext) Value(key interface{}) interface{} {
switch key {
case limits.CtxLimits:
return lc.l
default:
return lc.Context.Value(key)
}
}
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