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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 kernel
import (
"gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/sentry/context"
)
// contextID is the kernel package's type for context.Context.Value keys.
type contextID int
const (
// CtxCanTrace is a Context.Value key for a function with the same
// signature and semantics as kernel.Task.CanTrace.
CtxCanTrace contextID = iota
// CtxKernel is a Context.Value key for a Kernel.
CtxKernel
// CtxPIDNamespace is a Context.Value key for a PIDNamespace.
CtxPIDNamespace
// CtxTask is a Context.Value key for a Task.
CtxTask
// CtxUTSNamespace is a Context.Value key for a UTSNamespace.
CtxUTSNamespace
// CtxIPCNamespace is a Context.Value key for a IPCNamespace.
CtxIPCNamespace
)
// ContextCanTrace returns true if ctx is permitted to trace t, in the same sense
// as kernel.Task.CanTrace.
func ContextCanTrace(ctx context.Context, t *Task, attach bool) bool {
if v := ctx.Value(CtxCanTrace); v != nil {
return v.(func(*Task, bool) bool)(t, attach)
}
return false
}
// KernelFromContext returns the Kernel in which ctx is executing, or nil if
// there is no such Kernel.
func KernelFromContext(ctx context.Context) *Kernel {
if v := ctx.Value(CtxKernel); v != nil {
return v.(*Kernel)
}
return nil
}
// PIDNamespaceFromContext returns the PID namespace in which ctx is executing,
// or nil if there is no such PID namespace.
func PIDNamespaceFromContext(ctx context.Context) *PIDNamespace {
if v := ctx.Value(CtxPIDNamespace); v != nil {
return v.(*PIDNamespace)
}
return nil
}
// UTSNamespaceFromContext returns the UTS namespace in which ctx is executing,
// or nil if there is no such UTS namespace.
func UTSNamespaceFromContext(ctx context.Context) *UTSNamespace {
if v := ctx.Value(CtxUTSNamespace); v != nil {
return v.(*UTSNamespace)
}
return nil
}
// IPCNamespaceFromContext returns the IPC namespace in which ctx is executing,
// or nil if there is no such IPC namespace.
func IPCNamespaceFromContext(ctx context.Context) *IPCNamespace {
if v := ctx.Value(CtxIPCNamespace); v != nil {
return v.(*IPCNamespace)
}
return nil
}
// TaskFromContext returns the Task associated with ctx, or nil if there is no
// such Task.
func TaskFromContext(ctx context.Context) *Task {
if v := ctx.Value(CtxTask); v != nil {
return v.(*Task)
}
return nil
}
// AsyncContext returns a context.Context that may be used by goroutines that
// do work on behalf of t and therefore share its contextual values, but are
// not t's task goroutine (e.g. asynchronous I/O).
func (t *Task) AsyncContext() context.Context {
return taskAsyncContext{t: t}
}
type taskAsyncContext struct {
context.NoopSleeper
t *Task
}
// Debugf implements log.Logger.Debugf.
func (ctx taskAsyncContext) Debugf(format string, v ...interface{}) {
ctx.t.Debugf(format, v...)
}
// Infof implements log.Logger.Infof.
func (ctx taskAsyncContext) Infof(format string, v ...interface{}) {
ctx.t.Infof(format, v...)
}
// Warningf implements log.Logger.Warningf.
func (ctx taskAsyncContext) Warningf(format string, v ...interface{}) {
ctx.t.Warningf(format, v...)
}
// IsLogging implements log.Logger.IsLogging.
func (ctx taskAsyncContext) IsLogging(level log.Level) bool {
return ctx.t.IsLogging(level)
}
// Value implements context.Context.Value.
func (ctx taskAsyncContext) Value(key interface{}) interface{} {
return ctx.t.Value(key)
}
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