fortify/internal/app/app.go

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package app
import (
"sync"
"sync/atomic"
"git.gensokyo.uk/security/fortify/cmd/fshim/ipc/shim"
"git.gensokyo.uk/security/fortify/fst"
"git.gensokyo.uk/security/fortify/internal/linux"
)
type App interface {
// ID returns a copy of App's unique ID.
ID() fst.ID
// Start sets up the system and starts the App.
Start() error
// Wait waits for App's process to exit and reverts system setup.
Wait() (int, error)
// WaitErr returns error returned by the underlying wait syscall.
WaitErr() error
Seal(config *fst.Config) error
String() string
}
type app struct {
// single-use config reference
ct *appCt
// application unique identifier
id *fst.ID
// operating system interface
os linux.System
// shim process manager
shim *shim.Shim
// child process related information
seal *appSeal
// error returned waiting for process
waitErr error
lock sync.RWMutex
}
func (a *app) ID() fst.ID {
return *a.id
}
func (a *app) String() string {
if a == nil {
return "(invalid fortified app)"
}
a.lock.RLock()
defer a.lock.RUnlock()
if a.shim != nil {
return a.shim.String()
}
if a.seal != nil {
return "(sealed fortified app as uid " + a.seal.sys.user.us + ")"
}
return "(unsealed fortified app)"
}
func (a *app) WaitErr() error {
return a.waitErr
}
func New(os linux.System) (App, error) {
a := new(app)
a.id = new(fst.ID)
a.os = os
return a, fst.NewAppID(a.id)
}
// appCt ensures its wrapped val is only accessed once
type appCt struct {
val *fst.Config
done *atomic.Bool
}
func (a *appCt) Unwrap() *fst.Config {
if !a.done.Load() {
defer a.done.Store(true)
return a.val
}
panic("attempted to access config reference twice")
}
func newAppCt(config *fst.Config) (ct *appCt) {
ct = new(appCt)
ct.done = new(atomic.Bool)
ct.val = config
return ct
}