state: expose aids and use instance id as key

Fortify state store instances was specific to aids due to outdated design decisions carried over from the ego rewrite. That no longer makes sense in the current application, so the interface now enables a single store object to manage all transient state.

Signed-off-by: Ophestra Umiker <cat@ophivana.moe>

internal/app/seal.go

@@ -218,7 +218,7 @@ func (a *app) Seal(config *fst.Config) error {
 	// open process state store
 	// the simple store only starts holding an open file after first action
 	// store activity begins after Start is called and must end before Wait
-	seal.store = state.NewSimple(seal.RunDirPath, seal.sys.user.as)
+	seal.store = state.NewMulti(seal.RunDirPath)
 
 	// initialise system interface with full uid
 	seal.sys.I = system.New(seal.sys.user.uid)

internal/app/start.go

@@ -76,8 +76,8 @@ func (a *app) Start() error {
 
 		// register process state
 		var err0 = new(StateStoreError)
-		err0.Inner, err0.DoErr = a.seal.store.Do(func(b state.Backend) {
-			err0.InnerErr = b.Save(&sd)
+		err0.Inner, err0.DoErr = a.seal.store.Do(a.seal.sys.user.aid, func(c state.Cursor) {
+			err0.InnerErr = c.Save(&sd)
 		})
 		a.seal.sys.saveState = true
 		return err0.equiv("cannot save process state:")
@@ -199,11 +199,11 @@ func (a *app) Wait() (int, error) {
 
 	// update store and revert app setup transaction
 	e := new(StateStoreError)
-	e.Inner, e.DoErr = a.seal.store.Do(func(b state.Backend) {
+	e.Inner, e.DoErr = a.seal.store.Do(a.seal.sys.user.aid, func(b state.Cursor) {
 		e.InnerErr = func() error {
 			// destroy defunct state entry
 			if cmd := a.shim.Unwrap(); cmd != nil && a.seal.sys.saveState {
-				if err := b.Destroy(cmd.Process.Pid); err != nil {
+				if err := b.Destroy(*a.id); err != nil {
 					return err
 				}
 			}

internal/state/multi.go

@@ -3,54 +3,135 @@ package state
 import (
 	"encoding/gob"
 	"errors"
+	"fmt"
 	"io/fs"
 	"os"
 	"path"
 	"strconv"
 	"sync"
 	"syscall"
+
+	"git.ophivana.moe/security/fortify/fst"
+	"git.ophivana.moe/security/fortify/internal/fmsg"
 )
 
 // fine-grained locking and access
 type multiStore struct {
-	path []string
+	base string
 
-	// created/opened by prepare
-	lockfile *os.File
-	// enforce prepare method
-	init sync.Once
-	// error returned by prepare
-	initErr error
+	// initialised backends
+	backends *sync.Map
 
-	lock sync.Mutex
+	lock sync.RWMutex
 }
 
-func (s *multiStore) Do(f func(b Backend)) (bool, error) {
-	s.init.Do(s.prepare)
-	if s.initErr != nil {
-		return false, s.initErr
-	}
+func (s *multiStore) Do(aid int, f func(c Cursor)) (bool, error) {
+	s.lock.RLock()
+	defer s.lock.RUnlock()
 
-	s.lock.Lock()
-	defer s.lock.Unlock()
+	// load or initialise new backend
+	b := new(multiBackend)
+	if v, ok := s.backends.LoadOrStore(aid, b); ok {
+		b = v.(*multiBackend)
+	} else {
+		b.lock.Lock()
+		b.path = path.Join(s.base, strconv.Itoa(aid))
 
-	// lock store
-	if err := s.lockFile(); err != nil {
+		// ensure directory
+		if err := os.MkdirAll(b.path, 0700); err != nil && !errors.Is(err, fs.ErrExist) {
+			s.backends.CompareAndDelete(aid, b)
 			return false, err
 		}
 
-	// initialise new backend for caller
-	b := new(multiBackend)
-	b.path = path.Join(s.path...)
-	f(b)
-	// disable backend
-	b.lock.Lock()
+		// open locker file
+		if l, err := os.OpenFile(b.path+".lock", os.O_RDWR|os.O_CREATE, 0600); err != nil {
+			s.backends.CompareAndDelete(aid, b)
+			return false, err
+		} else {
+			b.lockfile = l
+		}
+		b.lock.Unlock()
+	}
 
-	// unlock store
-	return true, s.unlockFile()
+	// lock backend
+	if err := b.lockFile(); err != nil {
+		return false, err
+	}
+
+	// expose backend methods without exporting the pointer
+	c := new(struct{ *multiBackend })
+	c.multiBackend = b
+	f(b)
+	// disable access to the backend on a best-effort basis
+	c.multiBackend = nil
+
+	// unlock backend
+	return true, b.unlockFile()
 }
 
-func (s *multiStore) lockFileAct(lt int) (err error) {
+func (s *multiStore) List() ([]int, error) {
+	var entries []os.DirEntry
+
+	// read base directory to get all aids
+	if v, err := os.ReadDir(s.base); err != nil && !errors.Is(err, os.ErrNotExist) {
+		return nil, err
+	} else {
+		entries = v
+	}
+
+	aidsBuf := make([]int, 0, len(entries))
+	for _, e := range entries {
+		// skip non-directories
+		if !e.IsDir() {
+			fmsg.VPrintf("skipped non-directory entry %q", e.Name())
+			continue
+		}
+
+		// skip non-numerical names
+		if v, err := strconv.Atoi(e.Name()); err != nil {
+			fmsg.VPrintf("skipped non-aid entry %q", e.Name())
+			continue
+		} else {
+			if v < 0 || v > 9999 {
+				fmsg.VPrintf("skipped out of bounds entry %q", e.Name())
+				continue
+			}
+
+			aidsBuf = append(aidsBuf, v)
+		}
+	}
+
+	return append([]int(nil), aidsBuf...), nil
+}
+
+func (s *multiStore) Close() error {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+
+	var errs []error
+	s.backends.Range(func(_, value any) bool {
+		b := value.(*multiBackend)
+		errs = append(errs, b.close())
+		return true
+	})
+
+	return errors.Join(errs...)
+}
+
+type multiBackend struct {
+	path string
+
+	// created/opened by prepare
+	lockfile *os.File
+
+	lock sync.RWMutex
+}
+
+func (b *multiBackend) filename(id *fst.ID) string {
+	return path.Join(b.path, id.String())
+}
+
+func (b *multiBackend) lockFileAct(lt int) (err error) {
 	op := "LockAct"
 	switch lt {
 	case syscall.LOCK_EX:
@@ -60,7 +141,7 @@ func (s *multiStore) lockFileAct(lt int) (err error) {
 	}
 
 	for {
-		err = syscall.Flock(int(s.lockfile.Fd()), lt)
+		err = syscall.Flock(int(b.lockfile.Fd()), lt)
 		if !errors.Is(err, syscall.EINTR) {
 			break
 		}
@@ -68,81 +149,53 @@ func (s *multiStore) lockFileAct(lt int) (err error) {
 	if err != nil {
 		return &fs.PathError{
 			Op:   op,
-			Path: s.lockfile.Name(),
+			Path: b.lockfile.Name(),
 			Err:  err,
 		}
 	}
 	return nil
 }
 
-func (s *multiStore) lockFile() error {
-	return s.lockFileAct(syscall.LOCK_EX)
+func (b *multiBackend) lockFile() error {
+	return b.lockFileAct(syscall.LOCK_EX)
 }
 
-func (s *multiStore) unlockFile() error {
-	return s.lockFileAct(syscall.LOCK_UN)
-}
-
-func (s *multiStore) prepare() {
-	s.initErr = func() error {
-		prefix := path.Join(s.path...)
-		// ensure directory
-		if err := os.MkdirAll(prefix, 0700); err != nil && !errors.Is(err, fs.ErrExist) {
-			return err
-		}
-
-		// open locker file
-		if f, err := os.OpenFile(prefix+".lock", os.O_RDWR|os.O_CREATE, 0600); err != nil {
-			return err
-		} else {
-			s.lockfile = f
-		}
-
-		return nil
-	}()
-}
-
-func (s *multiStore) Close() error {
-	s.lock.Lock()
-	defer s.lock.Unlock()
-
-	err := s.lockfile.Close()
-	if err == nil || errors.Is(err, os.ErrInvalid) || errors.Is(err, os.ErrClosed) {
-		return nil
-	}
-	return err
-}
-
-type multiBackend struct {
-	path string
-
-	lock sync.RWMutex
-}
-
-func (b *multiBackend) filename(pid int) string {
-	return path.Join(b.path, strconv.Itoa(pid))
+func (b *multiBackend) unlockFile() error {
+	return b.lockFileAct(syscall.LOCK_UN)
 }
 
 // reads all launchers in simpleBackend
 // file contents are ignored if decode is false
-func (b *multiBackend) load(decode bool) ([]*State, error) {
+func (b *multiBackend) load(decode bool) (Entries, error) {
 	b.lock.RLock()
 	defer b.lock.RUnlock()
 
-	var (
-		r []*State
-		f *os.File
-	)
-
-	// read directory contents, should only contain files named after PIDs
+	// read directory contents, should only contain files named after ids
+	var entries []os.DirEntry
 	if pl, err := os.ReadDir(b.path); err != nil {
 		return nil, err
 	} else {
-		for _, e := range pl {
+		entries = pl
+	}
+
+	// allocate as if every entry is valid
+	// since that should be the case assuming no external interference happens
+	r := make(Entries, len(entries))
+
+	for _, e := range entries {
+		if e.IsDir() {
+			return nil, fmt.Errorf("unexpected directory %q in store", e.Name())
+		}
+
+		id := new(fst.ID)
+		if err := fst.ParseAppID(id, e.Name()); err != nil {
+			return nil, err
+		}
+
 		// run in a function to better handle file closing
-			if err = func() error {
+		if err := func() error {
 			// open state file for reading
-				if f, err = os.Open(path.Join(b.path, e.Name())); err != nil {
+			if f, err := os.Open(path.Join(b.path, e.Name())); err != nil {
 				return err
 			} else {
 				defer func() {
@@ -152,21 +205,26 @@ func (b *multiBackend) load(decode bool) ([]*State, error) {
 					}
 				}()
 
-					var s State
-					r = append(r, &s)
+				s := new(State)
+				r[*id] = s
 
 				// append regardless, but only parse if required, used to implement Len
 				if decode {
-						return gob.NewDecoder(f).Decode(&s)
-					} else {
-						return nil
+					if err = gob.NewDecoder(f).Decode(s); err != nil {
+						return err
 					}
+
+					if s.ID != *id {
+						return fmt.Errorf("state entry %s has unexpected id %s", id, &s.ID)
+					}
+				}
+
+				return nil
 			}
 		}(); err != nil {
 			return nil, err
 		}
 	}
-	}
 
 	return r, nil
 }
@@ -180,7 +238,7 @@ func (b *multiBackend) Save(state *State) error {
 		return errors.New("state does not contain config")
 	}
 
-	statePath := b.filename(state.PID)
+	statePath := b.filename(&state.ID)
 
 	// create and open state data file
 	if f, err := os.OpenFile(statePath, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600); err != nil {
@@ -197,14 +255,14 @@ func (b *multiBackend) Save(state *State) error {
 	}
 }
 
-func (b *multiBackend) Destroy(pid int) error {
+func (b *multiBackend) Destroy(id fst.ID) error {
 	b.lock.Lock()
 	defer b.lock.Unlock()
 
-	return os.Remove(b.filename(pid))
+	return os.Remove(b.filename(&id))
 }
 
-func (b *multiBackend) Load() ([]*State, error) {
+func (b *multiBackend) Load() (Entries, error) {
 	return b.load(true)
 }
 
@@ -214,9 +272,21 @@ func (b *multiBackend) Len() (int, error) {
 	return len(rn), err
 }
 
-// NewSimple returns an instance of a file-based store.
-func NewSimple(runDir string, prefix ...string) Store {
+func (b *multiBackend) close() error {
+	b.lock.Lock()
+	defer b.lock.Unlock()
+
+	err := b.lockfile.Close()
+	if err == nil || errors.Is(err, os.ErrInvalid) || errors.Is(err, os.ErrClosed) {
+		return nil
+	}
+	return err
+}
+
+// NewMulti returns an instance of the multi-file store.
+func NewMulti(runDir string) Store {
 	b := new(multiStore)
-	b.path = append([]string{runDir, "state"}, prefix...)
+	b.base = path.Join(runDir, "state")
+	b.backends = new(sync.Map)
 	return b
 }

internal/state/multi_test.go

@@ -0,0 +1,11 @@
+package state_test
+
+import (
+	"testing"
+
+	"git.ophivana.moe/security/fortify/internal/state"
+)
+
+func TestMulti(t *testing.T) {
+	testStore(t, state.NewMulti(t.TempDir()))
+}

internal/state/print.go

@@ -1,11 +1,8 @@
 package state
 
 import (
-	"errors"
 	"fmt"
 	"os"
-	"path"
-	"strconv"
 	"strings"
 	"text/tabwriter"
 	"time"
@@ -18,45 +15,31 @@ import (
 // in an implementation-specific way.
 func MustPrintLauncherStateSimpleGlobal(w **tabwriter.Writer, runDir string) {
 	now := time.Now().UTC()
+	s := NewMulti(runDir)
 
 	// read runtime directory to get all UIDs
-	if dirs, err := os.ReadDir(path.Join(runDir, "state")); err != nil && !errors.Is(err, os.ErrNotExist) {
-		fmsg.Fatal("cannot read runtime directory:", err)
+	if aids, err := s.List(); err != nil {
+		fmsg.Fatal("cannot list store:", err)
 	} else {
-		for _, e := range dirs {
-			// skip non-directories
-			if !e.IsDir() {
-				fmsg.VPrintf("skipped non-directory entry %q", e.Name())
-				continue
-			}
-
-			// skip non-numerical names
-			if _, err = strconv.Atoi(e.Name()); err != nil {
-				fmsg.VPrintf("skipped non-uid entry %q", e.Name())
-				continue
-			}
-
-			// obtain temporary store
-			s := NewSimple(runDir, e.Name()).(*multiStore)
-
+		for _, aid := range aids {
 			// print states belonging to this store
-			s.mustPrintLauncherState(w, now)
+			s.(*multiStore).mustPrintLauncherState(aid, w, now)
+		}
+	}
 
 	// mustPrintLauncherState causes store activity so store needs to be closed
-			if err = s.Close(); err != nil {
-				fmsg.Printf("cannot close store for user %q: %s", e.Name(), err)
-			}
-		}
+	if err := s.Close(); err != nil {
+		fmsg.Printf("cannot close store: %v", err)
 	}
 }
 
-func (s *multiStore) mustPrintLauncherState(w **tabwriter.Writer, now time.Time) {
+func (s *multiStore) mustPrintLauncherState(aid int, w **tabwriter.Writer, now time.Time) {
 	var innerErr error
 
-	if ok, err := s.Do(func(b Backend) {
+	if ok, err := s.Do(aid, func(c Cursor) {
 		innerErr = func() error {
 			// read launcher states
-			states, err := b.Load()
+			states, err := c.Load()
 			if err != nil {
 				return err
 			}
@@ -111,25 +94,25 @@ func (s *multiStore) mustPrintLauncherState(w **tabwriter.Writer, now time.Time)
 				}
 
 				if !fmsg.Verbose() {
-					_, _ = fmt.Fprintf(*w, "\t%d\t%s\t%s\t%s\t%s\n",
-						state.PID, s.path[len(s.path)-1], now.Sub(state.Time).Round(time.Second).String(), strings.TrimPrefix(ets.String(), ", "), cs)
+					_, _ = fmt.Fprintf(*w, "\t%d\t%d\t%s\t%s\t%s\n",
+						state.PID, aid, now.Sub(state.Time).Round(time.Second).String(), strings.TrimPrefix(ets.String(), ", "), cs)
 				} else {
 					// emit argv instead when verbose
-					_, _ = fmt.Fprintf(*w, "\t%d\t%s\t%s\n",
-						state.PID, s.path[len(s.path)-1], state.ID)
+					_, _ = fmt.Fprintf(*w, "\t%d\t%d\t%s\n",
+						state.PID, aid, state.ID)
 				}
 			}
 
 			return nil
 		}()
 	}); err != nil {
-		fmsg.Printf("cannot perform action on store %q: %s", path.Join(s.path...), err)
+		fmsg.Printf("cannot perform action on app %d: %v", aid, err)
 		if !ok {
 			fmsg.Fatal("store faulted before printing")
 		}
 	}
 
 	if innerErr != nil {
-		fmsg.Fatalf("cannot print launcher state for store %q: %s", path.Join(s.path...), innerErr)
+		fmsg.Fatalf("cannot print launcher state of app %d: %s", aid, innerErr)
 	}
 }

internal/state/state.go

@@ -6,21 +6,27 @@ import (
 	"git.ophivana.moe/security/fortify/fst"
 )
 
+type Entries map[fst.ID]*State
+
 type Store interface {
 	// Do calls f exactly once and ensures store exclusivity until f returns.
 	// Returns whether f is called and any errors during the locking process.
-	// Backend provided to f becomes invalid as soon as f returns.
-	Do(f func(b Backend)) (bool, error)
+	// Cursor provided to f becomes invalid as soon as f returns.
+	Do(aid int, f func(c Cursor)) (ok bool, err error)
+
+	// List queries the store and returns a list of aids known to the store.
+	// Note that some or all returned aids might not have any active apps.
+	List() (aids []int, err error)
 
 	// Close releases any resources held by Store.
 	Close() error
 }
 
-// Backend provides access to the store
-type Backend interface {
+// Cursor provides access to the store
+type Cursor interface {
 	Save(state *State) error
-	Destroy(pid int) error
-	Load() ([]*State, error)
+	Destroy(id fst.ID) error
+	Load() (Entries, error)
 	Len() (int, error)
 }
 

internal/state/state_test.go

@@ -0,0 +1,126 @@
+package state_test
+
+import (
+	"math/rand/v2"
+	"reflect"
+	"slices"
+	"testing"
+	"time"
+
+	"git.ophivana.moe/security/fortify/fst"
+	"git.ophivana.moe/security/fortify/internal/state"
+)
+
+func testStore(t *testing.T, s state.Store) {
+	t.Run("list empty store", func(t *testing.T) {
+		if aids, err := s.List(); err != nil {
+			t.Fatalf("List: error = %v", err)
+		} else if len(aids) != 0 {
+			t.Fatalf("List: aids = %#v", aids)
+		}
+	})
+
+	const (
+		insertEntryChecked = iota
+		insertEntryNoCheck
+		insertEntryOtherApp
+
+		tl
+	)
+
+	var tc [tl]state.State
+	for i := 0; i < tl; i++ {
+		makeState(t, &tc[i])
+	}
+
+	do := func(aid int, f func(c state.Cursor)) {
+		if ok, err := s.Do(aid, f); err != nil {
+			t.Fatalf("Do: ok = %v, error = %v", ok, err)
+		}
+	}
+
+	insert := func(i, aid int) {
+		do(aid, func(c state.Cursor) {
+			if err := c.Save(&tc[i]); err != nil {
+				t.Fatalf("Save(&tc[%v]): error = %v", i, err)
+			}
+		})
+	}
+
+	check := func(i, aid int) {
+		do(aid, func(c state.Cursor) {
+			if entries, err := c.Load(); err != nil {
+				t.Fatalf("Load: error = %v", err)
+			} else if got, ok := entries[tc[i].ID]; !ok {
+				t.Fatalf("Load: entry %s missing",
+					&tc[i].ID)
+			} else {
+				got.Time = tc[i].Time
+				if !reflect.DeepEqual(got, &tc[i]) {
+					t.Fatalf("Load: entry %s got %#v, want %#v",
+						&tc[i].ID, got, &tc[i])
+				}
+			}
+		})
+	}
+
+	t.Run("insert entry checked", func(t *testing.T) {
+		insert(insertEntryChecked, 0)
+		check(insertEntryChecked, 0)
+	})
+
+	t.Run("insert entry unchecked", func(t *testing.T) {
+		insert(insertEntryNoCheck, 0)
+	})
+
+	t.Run("insert entry different aid", func(t *testing.T) {
+		insert(insertEntryOtherApp, 1)
+		check(insertEntryOtherApp, 1)
+	})
+
+	t.Run("check previous insertion", func(t *testing.T) {
+		check(insertEntryNoCheck, 0)
+	})
+
+	t.Run("list aids", func(t *testing.T) {
+		if aids, err := s.List(); err != nil {
+			t.Fatalf("List: error = %v", err)
+		} else {
+			slices.Sort(aids)
+			want := []int{0, 1}
+			if slices.Compare(aids, want) != 0 {
+				t.Fatalf("List() = %#v, want %#v", aids, want)
+			}
+		}
+	})
+
+	t.Run("clear aid 1", func(t *testing.T) {
+		do(1, func(c state.Cursor) {
+			if err := c.Destroy(tc[insertEntryOtherApp].ID); err != nil {
+				t.Fatalf("Destroy: error = %v", err)
+			}
+		})
+		do(1, func(c state.Cursor) {
+			if l, err := c.Len(); err != nil {
+				t.Fatalf("Len: error = %v", err)
+			} else if l != 0 {
+				t.Fatalf("Len() = %d, want 0", l)
+			}
+		})
+	})
+
+	t.Run("close store", func(t *testing.T) {
+		if err := s.Close(); err != nil {
+			t.Fatalf("Close: error = %v", err)
+		}
+	})
+}
+
+func makeState(t *testing.T, s *state.State) {
+	if err := fst.NewAppID(&s.ID); err != nil {
+		t.Fatalf("cannot create dummy state: %v", err)
+	}
+	s.Config = fst.Template()
+	s.PID = rand.Int()
+	s.Time = time.Now()
+}

test.nix

@@ -214,5 +214,8 @@ nixosTest {
     swaymsg("exit", succeed=False)
     machine.wait_until_fails("pgrep -x sway")
     machine.wait_for_file("/tmp/sway-exit-ok")
+
+    # Print fortify runDir contents:
+    print(machine.succeed("find /run/user/1000/fortify"))
   '';
 }