internal: beforeExit before reachable fatal calls

These are the only two calls to log.Fatal* reachable during suspended output. Call fmsg.BeforeExit here to catch that.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/fpkg/bundle.go

@@ -2,10 +2,10 @@ package main
 
 import (
 	"encoding/json"
+	"log"
 	"os"
 
 	"git.gensokyo.uk/security/fortify/dbus"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
 	"git.gensokyo.uk/security/fortify/internal/system"
 )
 
@@ -63,18 +63,18 @@ func loadBundleInfo(name string, beforeFail func()) *bundleInfo {
 	bundle := new(bundleInfo)
 	if f, err := os.Open(name); err != nil {
 		beforeFail()
-		fmsg.Fatalf("cannot open bundle: %v", err)
+		log.Fatalf("cannot open bundle: %v", err)
 	} else if err = json.NewDecoder(f).Decode(&bundle); err != nil {
 		beforeFail()
-		fmsg.Fatalf("cannot parse bundle metadata: %v", err)
+		log.Fatalf("cannot parse bundle metadata: %v", err)
 	} else if err = f.Close(); err != nil {
-		fmsg.Printf("cannot close bundle metadata: %v", err)
+		log.Printf("cannot close bundle metadata: %v", err)
 		// not fatal
 	}
 
 	if bundle.ID == "" {
 		beforeFail()
-		fmsg.Fatal("application identifier must not be empty")
+		log.Fatal("application identifier must not be empty")
 	}
 
 	return bundle
@@ -82,7 +82,7 @@ func loadBundleInfo(name string, beforeFail func()) *bundleInfo {
 
 func formatHostname(name string) string {
 	if h, err := os.Hostname(); err != nil {
-		fmsg.Printf("cannot get hostname: %v", err)
+		log.Printf("cannot get hostname: %v", err)
 		return "fortify-" + name
 	} else {
 		return h + "-" + name

cmd/fpkg/install.go

@@ -3,10 +3,12 @@ package main
 import (
 	"encoding/json"
 	"flag"
+	"log"
 	"os"
 	"path"
 
 	"git.gensokyo.uk/security/fortify/fst"
+	"git.gensokyo.uk/security/fortify/internal"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
 )
 
@@ -25,12 +27,12 @@ func actionInstall(args []string) {
 	args = set.Args()
 
 	if len(args) != 1 {
-		fmsg.Fatal("invalid argument")
+		log.Fatal("invalid argument")
 	}
 	pkgPath := args[0]
 	if !path.IsAbs(pkgPath) {
 		if dir, err := os.Getwd(); err != nil {
-			fmsg.Fatalf("cannot get current directory: %v", err)
+			log.Fatalf("cannot get current directory: %v", err)
 		} else {
 			pkgPath = path.Join(dir, pkgPath)
 		}
@@ -54,7 +56,7 @@ func actionInstall(args []string) {
 
 	var workDir string
 	if p, err := os.MkdirTemp("", "fpkg.*"); err != nil {
-		fmsg.Fatalf("cannot create temporary directory: %v", err)
+		log.Fatalf("cannot create temporary directory: %v", err)
 	} else {
 		workDir = p
 	}
@@ -78,19 +80,17 @@ func actionInstall(args []string) {
 	if s, err := os.Stat(pathSet.metaPath); err != nil {
 		if !os.IsNotExist(err) {
 			cleanup()
-			fmsg.Fatalf("cannot access %q: %v", pathSet.metaPath, err)
+			log.Fatalf("cannot access %q: %v", pathSet.metaPath, err)
-			panic("unreachable")
 		}
 		// did not modify app, clean installation condition met later
 	} else if s.IsDir() {
 		cleanup()
-		fmsg.Fatalf("metadata path %q is not a file", pathSet.metaPath)
+		log.Fatalf("metadata path %q is not a file", pathSet.metaPath)
-		panic("unreachable")
 	} else {
 		app = loadBundleInfo(pathSet.metaPath, cleanup)
 		if app.ID != bundle.ID {
 			cleanup()
-			fmsg.Fatalf("app %q claims to have identifier %q", bundle.ID, app.ID)
+			log.Fatalf("app %q claims to have identifier %q", bundle.ID, app.ID)
 		}
 		// sec: should verify credentials
 	}
@@ -102,21 +102,20 @@ func actionInstall(args []string) {
 			app.Launcher == bundle.Launcher &&
 			app.ActivationPackage == bundle.ActivationPackage {
 			cleanup()
-			fmsg.Printf("package %q is identical to local application %q", pkgPath, app.ID)
+			log.Printf("package %q is identical to local application %q", pkgPath, app.ID)
-			fmsg.Exit(0)
+			internal.Exit(0)
 		}
 
 		// AppID determines uid
 		if app.AppID != bundle.AppID {
 			cleanup()
-			fmsg.Fatalf("package %q app id %d differs from installed %d", pkgPath, bundle.AppID, app.AppID)
+			log.Fatalf("package %q app id %d differs from installed %d", pkgPath, bundle.AppID, app.AppID)
-			panic("unreachable")
 		}
 
 		// sec: should compare version string
-		fmsg.VPrintf("installing application %q version %q over local %q", bundle.ID, bundle.Version, app.Version)
+		fmsg.Verbosef("installing application %q version %q over local %q", bundle.ID, bundle.Version, app.Version)
 	} else {
-		fmsg.VPrintf("application %q clean installation", bundle.ID)
+		fmsg.Verbosef("application %q clean installation", bundle.ID)
 		// sec: should install credentials
 	}
 
@@ -174,21 +173,18 @@ func actionInstall(args []string) {
 	// serialise metadata to ensure consistency
 	if f, err := os.OpenFile(pathSet.metaPath+"~", os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0644); err != nil {
 		cleanup()
-		fmsg.Fatalf("cannot create metadata file: %v", err)
+		log.Fatalf("cannot create metadata file: %v", err)
-		panic("unreachable")
 	} else if err = json.NewEncoder(f).Encode(bundle); err != nil {
 		cleanup()
-		fmsg.Fatalf("cannot write metadata: %v", err)
+		log.Fatalf("cannot write metadata: %v", err)
-		panic("unreachable")
 	} else if err = f.Close(); err != nil {
-		fmsg.Printf("cannot close metadata file: %v", err)
+		log.Printf("cannot close metadata file: %v", err)
 		// not fatal
 	}
 
 	if err := os.Rename(pathSet.metaPath+"~", pathSet.metaPath); err != nil {
 		cleanup()
-		fmsg.Fatalf("cannot rename metadata file: %v", err)
+		log.Fatalf("cannot rename metadata file: %v", err)
-		panic("unreachable")
 	}
 
 	cleanup()

cmd/fpkg/main.go

@@ -2,8 +2,10 @@ package main
 
 import (
 	"flag"
+	"log"
 	"os"
 
+	"git.gensokyo.uk/security/fortify/internal"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
 )
 
@@ -11,7 +13,7 @@ const shell = "/run/current-system/sw/bin/bash"
 
 func init() {
 	if err := os.Setenv("SHELL", shell); err != nil {
-		fmsg.Fatalf("cannot set $SHELL: %v", err)
+		log.Fatalf("cannot set $SHELL: %v", err)
 	}
 }
 
@@ -24,14 +26,14 @@ func init() {
 }
 
 func main() {
-	fmsg.SetPrefix("fpkg")
+	fmsg.Prepare("fpkg")
 
 	flag.Parse()
-	fmsg.SetVerbose(flagVerbose)
+	fmsg.Store(flagVerbose)
 
 	args := flag.Args()
 	if len(args) < 1 {
-		fmsg.Fatal("invalid argument")
+		log.Fatal("invalid argument")
 	}
 
 	switch args[0] {
@@ -41,8 +43,8 @@ func main() {
 		actionStart(args[1:])
 
 	default:
-		fmsg.Fatal("invalid argument")
+		log.Fatal("invalid argument")
 	}
 
-	fmsg.Exit(0)
+	internal.Exit(0)
 }

cmd/fpkg/paths.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"log"
 	"os"
 	"os/exec"
 	"path"
@@ -25,8 +26,8 @@ func init() {
 
 func lookPath(file string) string {
 	if p, err := exec.LookPath(file); err != nil {
-		fmsg.Fatalf("%s: command not found", file)
+		log.Fatalf("%s: command not found", file)
-		panic("unreachable")
+		return ""
 	} else {
 		return p
 	}
@@ -35,15 +36,14 @@ func lookPath(file string) string {
 var beforeRunFail = new(atomic.Pointer[func()])
 
 func mustRun(name string, arg ...string) {
-	fmsg.VPrintf("spawning process: %q %q", name, arg)
+	fmsg.Verbosef("spawning process: %q %q", name, arg)
 	cmd := exec.Command(name, arg...)
 	cmd.Stdin, cmd.Stdout, cmd.Stderr = os.Stdin, os.Stdout, os.Stderr
 	if err := cmd.Run(); err != nil {
 		if f := beforeRunFail.Swap(nil); f != nil {
 			(*f)()
 		}
-		fmsg.Fatalf("%s: %v", name, err)
+		log.Fatalf("%s: %v", name, err)
-		panic("unreachable")
 	}
 }
 

cmd/fpkg/proc.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"io"
+	"log"
 	"os"
 	"os/exec"
 
@@ -25,14 +26,12 @@ func fortifyApp(config *fst.Config, beforeFail func()) {
 	)
 	if p, ok := internal.Path(Fmain); !ok {
 		beforeFail()
-		fmsg.Fatal("invalid fortify path, this copy of fpkg is not compiled correctly")
+		log.Fatal("invalid fortify path, this copy of fpkg is not compiled correctly")
-		panic("unreachable")
 	} else if r, w, err := os.Pipe(); err != nil {
 		beforeFail()
-		fmsg.Fatalf("cannot pipe: %v", err)
+		log.Fatalf("cannot pipe: %v", err)
-		panic("unreachable")
 	} else {
-		if fmsg.Verbose() {
+		if fmsg.Load() {
 			cmd = exec.Command(p, "-v", "app", "3")
 		} else {
 			cmd = exec.Command(p, "app", "3")
@@ -45,26 +44,22 @@ func fortifyApp(config *fst.Config, beforeFail func()) {
 	go func() {
 		if err := json.NewEncoder(st).Encode(config); err != nil {
 			beforeFail()
-			fmsg.Fatalf("cannot send configuration: %v", err)
+			log.Fatalf("cannot send configuration: %v", err)
-			panic("unreachable")
 		}
 	}()
 
 	if err := cmd.Start(); err != nil {
 		beforeFail()
-		fmsg.Fatalf("cannot start fortify: %v", err)
+		log.Fatalf("cannot start fortify: %v", err)
-		panic("unreachable")
 	}
 	if err := cmd.Wait(); err != nil {
 		var exitError *exec.ExitError
 		if errors.As(err, &exitError) {
 			beforeFail()
-			fmsg.Exit(exitError.ExitCode())
+			internal.Exit(exitError.ExitCode())
-			panic("unreachable")
 		} else {
 			beforeFail()
-			fmsg.Fatalf("cannot wait: %v", err)
+			log.Fatalf("cannot wait: %v", err)
-			panic("unreachable")
 		}
 	}
 }

cmd/fpkg/start.go

@@ -2,11 +2,12 @@ package main
 
 import (
 	"flag"
+	"log"
 	"path"
 
 	"git.gensokyo.uk/security/fortify/fst"
 	"git.gensokyo.uk/security/fortify/helper/bwrap"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
+	"git.gensokyo.uk/security/fortify/internal"
 )
 
 func actionStart(args []string) {
@@ -26,7 +27,7 @@ func actionStart(args []string) {
 	args = set.Args()
 
 	if len(args) < 1 {
-		fmsg.Fatal("invalid argument")
+		log.Fatal("invalid argument")
 	}
 
 	/*
@@ -37,7 +38,7 @@ func actionStart(args []string) {
 	pathSet := pathSetByApp(id)
 	app := loadBundleInfo(pathSet.metaPath, func() {})
 	if app.ID != id {
-		fmsg.Fatalf("app %q claims to have identifier %q", id, app.ID)
+		log.Fatalf("app %q claims to have identifier %q", id, app.ID)
 	}
 
 	/*
@@ -144,7 +145,7 @@ func actionStart(args []string) {
 	*/
 
 	fortifyApp(config, func() {})
-	fmsg.Exit(0)
+	internal.Exit(0)
 }
 
 func appendGPUFilesystem(config *fst.Config) {

cmd/fpkg/with.go

@@ -6,7 +6,7 @@ import (
 
 	"git.gensokyo.uk/security/fortify/fst"
 	"git.gensokyo.uk/security/fortify/helper/bwrap"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
+	"git.gensokyo.uk/security/fortify/internal"
 )
 
 func withNixDaemon(
@@ -95,7 +95,7 @@ func fortifyAppDropShell(config *fst.Config, dropShell bool, beforeFail func())
 		config.Command = []string{shell, "-l"}
 		fortifyApp(config, beforeFail)
 		beforeFail()
-		fmsg.Exit(0)
+		internal.Exit(0)
 	}
 	fortifyApp(config, beforeFail)
 }

error.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"errors"
+	"log"
 
 	"git.gensokyo.uk/security/fortify/internal/app"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
@@ -10,13 +11,13 @@ import (
 func logWaitError(err error) {
 	var e *fmsg.BaseError
 	if !fmsg.AsBaseError(err, &e) {
-		fmsg.Println("wait failed:", err)
+		log.Println("wait failed:", err)
 	} else {
 		// Wait only returns either *app.ProcessError or *app.StateStoreError wrapped in a *app.BaseError
 		var se *app.StateStoreError
 		if !errors.As(err, &se) {
 			// does not need special handling
-			fmsg.Print(e.Message())
+			log.Print(e.Message())
 		} else {
 			// inner error are either unwrapped store errors
 			// or joined errors returned by *appSealTx revert
@@ -24,7 +25,7 @@ func logWaitError(err error) {
 			var ej app.RevertCompoundError
 			if !errors.As(se.InnerErr, &ej) {
 				// does not require special handling
-				fmsg.Print(e.Message())
+				log.Print(e.Message())
 			} else {
 				errs := ej.Unwrap()
 
@@ -33,10 +34,10 @@ func logWaitError(err error) {
 					var eb *fmsg.BaseError
 					if !errors.As(ei, &eb) {
 						// unreachable
-						fmsg.Println("invalid error type returned by revert:", ei)
+						log.Println("invalid error type returned by revert:", ei)
 					} else {
 						// print inner *app.BaseError message
-						fmsg.Print(eb.Message())
+						log.Print(eb.Message())
 					}
 				}
 			}
@@ -48,8 +49,8 @@ func logBaseError(err error, message string) {
 	var e *fmsg.BaseError
 
 	if fmsg.AsBaseError(err, &e) {
-		fmsg.Print(e.Message())
+		log.Print(e.Message())
 	} else {
-		fmsg.Println(message, err)
+		log.Println(message, err)
 	}
 }

fst/sandbox.go

@@ -53,7 +53,7 @@ func (s *SandboxConfig) Bwrap(os linux.System) (*bwrap.Config, error) {
 	}
 
 	if s.Syscall == nil {
-		fmsg.VPrintln("syscall filter not configured, PROCEED WITH CAUTION")
+		fmsg.Verbose("syscall filter not configured, PROCEED WITH CAUTION")
 	}
 
 	var uid int
@@ -121,11 +121,11 @@ func (s *SandboxConfig) Bwrap(os linux.System) (*bwrap.Config, error) {
 						// get parent dir of socket
 						dir := path.Dir(pair[1])
 						if dir == "." || dir == "/" {
-							fmsg.VPrintf("dbus socket %q is in an unusual location", pair[1])
+							fmsg.Verbosef("dbus socket %q is in an unusual location", pair[1])
 						}
 						hidePaths = append(hidePaths, dir)
 					} else {
-						fmsg.VPrintf("dbus socket %q is not absolute", pair[1])
+						fmsg.Verbosef("dbus socket %q is not absolute", pair[1])
 					}
 				}
 			}
@@ -169,7 +169,7 @@ func (s *SandboxConfig) Bwrap(os linux.System) (*bwrap.Config, error) {
 				return nil, err
 			} else if ok {
 				hidePathMatch[i] = true
-				fmsg.VPrintf("hiding paths from %q", c.Src)
+				fmsg.Verbosef("hiding paths from %q", c.Src)
 			}
 		}
 
@@ -221,7 +221,7 @@ func evalSymlinks(os linux.System, v *string) error {
 		if !errors.Is(err, fs.ErrNotExist) {
 			return err
 		}
-		fmsg.VPrintf("path %q does not yet exist", *v)
+		fmsg.Verbosef("path %q does not yet exist", *v)
 	} else {
 		*v = p
 	}

helper/bwrap/builder.go

@@ -78,11 +78,22 @@ CopyBind(dest, payload, true) copy from FD to file which is bind-mounted on DEST
 (--bind-data FD DEST)
 */
 func (c *Config) CopyBind(dest string, payload []byte, opts ...bool) *Config {
+	var p *[]byte
+	c.CopyBindRef(dest, &p, opts...)
+	*p = payload
+	return c
+}
+
+// CopyBindRef is the same as CopyBind but writes the address of DataConfig.Data.
+func (c *Config) CopyBindRef(dest string, payloadRef **[]byte, opts ...bool) *Config {
 	t := DataROBind
 	if len(opts) > 0 && opts[0] {
 		t = DataBind
 	}
-	c.Filesystem = append(c.Filesystem, &DataConfig{Dest: dest, Data: payload, Type: t})
+	d := &DataConfig{Dest: dest, Type: t}
+	*payloadRef = &d.Data
+
+	c.Filesystem = append(c.Filesystem, d)
 	return c
 }
 

helper/bwrap/config_test.go

@@ -1,6 +1,7 @@
 package bwrap_test
 
 import (
+	"log"
 	"os"
 	"slices"
 	"testing"
@@ -8,11 +9,10 @@ import (
 	"git.gensokyo.uk/security/fortify/helper/bwrap"
 	"git.gensokyo.uk/security/fortify/helper/proc"
 	"git.gensokyo.uk/security/fortify/helper/seccomp"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
 )
 
 func TestConfig_Args(t *testing.T) {
-	seccomp.CPrintln = fmsg.Println
+	seccomp.CPrintln = log.Println
 	t.Cleanup(func() { seccomp.CPrintln = nil })
 
 	testCases := []struct {

helper/seccomp/export_test.go

@@ -4,12 +4,12 @@ import (
 	"crypto/sha512"
 	"errors"
 	"io"
+	"log"
 	"slices"
 	"syscall"
 	"testing"
 
 	"git.gensokyo.uk/security/fortify/helper/seccomp"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
 )
 
 func TestExport(t *testing.T) {
@@ -79,7 +79,7 @@ func TestExport(t *testing.T) {
 	buf := make([]byte, 8)
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			seccomp.CPrintln = fmsg.Println
+			seccomp.CPrintln = log.Println
 			t.Cleanup(func() { seccomp.CPrintln = nil })
 
 			e := seccomp.New(tc.opts)

helper/stub.go

@@ -14,7 +14,7 @@ import (
 
 	"git.gensokyo.uk/security/fortify/helper/bwrap"
 	"git.gensokyo.uk/security/fortify/helper/proc"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
+	"git.gensokyo.uk/security/fortify/internal"
 )
 
 // InternalChildStub is an internal function but exported because it is cross-package;
@@ -40,7 +40,7 @@ func InternalChildStub() {
 		genericStub(flagRestoreFiles(4, ap, sp))
 	}
 
-	fmsg.Exit(0)
+	internal.Exit(0)
 }
 
 // InternalReplaceExecCommand is an internal function but exported because it is cross-package;

internal/app/app.go

@@ -5,8 +5,8 @@ import (
 	"sync"
 
 	"git.gensokyo.uk/security/fortify/fst"
+	"git.gensokyo.uk/security/fortify/internal/app/shim"
 	"git.gensokyo.uk/security/fortify/internal/linux"
-	"git.gensokyo.uk/security/fortify/internal/priv/shim"
 )
 
 type App interface {

internal/app/init/early.go

@@ -4,7 +4,7 @@ import (
 	"os"
 	"path"
 
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
+	"git.gensokyo.uk/security/fortify/internal"
 )
 
 // used by the parent process
@@ -13,6 +13,6 @@ import (
 func TryArgv0() {
 	if len(os.Args) > 0 && path.Base(os.Args[0]) == "init" {
 		Main()
-		fmsg.Exit(0)
+		internal.Exit(0)
 	}
 }

internal/app/init/main.go

@@ -2,6 +2,7 @@ package init0
 
 import (
 	"errors"
+	"log"
 	"os"
 	"os/exec"
 	"os/signal"
@@ -24,17 +25,15 @@ const (
 func Main() {
 	// sharing stdout with shim
 	// USE WITH CAUTION
-	fmsg.SetPrefix("init")
+	fmsg.Prepare("init")
 
 	// setting this prevents ptrace
 	if err := internal.PR_SET_DUMPABLE__SUID_DUMP_DISABLE(); err != nil {
-		fmsg.Fatalf("cannot set SUID_DUMP_DISABLE: %s", err)
+		log.Fatalf("cannot set SUID_DUMP_DISABLE: %s", err)
-		panic("unreachable")
 	}
 
 	if os.Getpid() != 1 {
-		fmsg.Fatal("this process must run as pid 1")
+		log.Fatal("this process must run as pid 1")
-		panic("unreachable")
 	}
 
 	// receive setup payload
@@ -44,30 +43,29 @@ func Main() {
 	)
 	if f, err := proc.Receive(Env, &payload); err != nil {
 		if errors.Is(err, proc.ErrInvalid) {
-			fmsg.Fatal("invalid config descriptor")
+			log.Fatal("invalid config descriptor")
 		}
 		if errors.Is(err, proc.ErrNotSet) {
-			fmsg.Fatal("FORTIFY_INIT not set")
+			log.Fatal("FORTIFY_INIT not set")
 		}
 
-		fmsg.Fatalf("cannot decode init setup payload: %v", err)
+		log.Fatalf("cannot decode init setup payload: %v", err)
-		panic("unreachable")
 	} else {
-		fmsg.SetVerbose(payload.Verbose)
+		fmsg.Store(payload.Verbose)
 		closeSetup = f
 
 		// child does not need to see this
 		if err = os.Unsetenv(Env); err != nil {
-			fmsg.Printf("cannot unset %s: %v", Env, err)
+			log.Printf("cannot unset %s: %v", Env, err)
 			// not fatal
 		} else {
-			fmsg.VPrintln("received configuration")
+			fmsg.Verbose("received configuration")
 		}
 	}
 
 	// die with parent
 	if err := internal.PR_SET_PDEATHSIG__SIGKILL(); err != nil {
-		fmsg.Fatalf("prctl(PR_SET_PDEATHSIG, SIGKILL): %v", err)
+		log.Fatalf("prctl(PR_SET_PDEATHSIG, SIGKILL): %v", err)
 	}
 
 	cmd := exec.Command(payload.Argv0)
@@ -76,13 +74,13 @@ func Main() {
 	cmd.Env = os.Environ()
 
 	if err := cmd.Start(); err != nil {
-		fmsg.Fatalf("cannot start %q: %v", payload.Argv0, err)
+		log.Fatalf("cannot start %q: %v", payload.Argv0, err)
 	}
 	fmsg.Suspend()
 
 	// close setup pipe as setup is now complete
 	if err := closeSetup(); err != nil {
-		fmsg.Println("cannot close setup pipe:", err)
+		log.Println("cannot close setup pipe:", err)
 		// not fatal
 	}
 
@@ -119,7 +117,7 @@ func Main() {
 			}
 		}
 		if !errors.Is(err, syscall.ECHILD) {
-			fmsg.Println("unexpected wait4 response:", err)
+			log.Println("unexpected wait4 response:", err)
 		}
 
 		close(done)
@@ -132,9 +130,12 @@ func Main() {
 	for {
 		select {
 		case s := <-sig:
-			fmsg.VPrintln("received", s.String())
+			if fmsg.Resume() {
-			fmsg.Resume() // output could still be withheld at this point, so resume is called
+				fmsg.Verbosef("terminating on %s after process start", s.String())
-			fmsg.Exit(0)
+			} else {
+				fmsg.Verbosef("terminating on %s", s.String())
+			}
+			internal.Exit(0)
 		case w := <-info:
 			if w.wpid == cmd.Process.Pid {
 				// initial process exited, output is most likely available again
@@ -155,10 +156,10 @@ func Main() {
 				}()
 			}
 		case <-done:
-			fmsg.Exit(r)
+			internal.Exit(r)
 		case <-timeout:
-			fmsg.Println("timeout exceeded waiting for lingering processes")
+			log.Println("timeout exceeded waiting for lingering processes")
-			fmsg.Exit(r)
+			internal.Exit(r)
 		}
 	}
 }

internal/app/seal.go

@@ -191,7 +191,7 @@ func (a *app) Seal(config *fst.Config) error {
 
 	// map sandbox config to bwrap
 	if config.Confinement.Sandbox == nil {
-		fmsg.VPrintln("sandbox configuration not supplied, PROCEED WITH CAUTION")
+		fmsg.Verbose("sandbox configuration not supplied, PROCEED WITH CAUTION")
 
 		// permissive defaults
 		conf := &fst.SandboxConfig{
@@ -264,7 +264,7 @@ func (a *app) Seal(config *fst.Config) error {
 	}
 
 	// verbose log seal information
-	fmsg.VPrintf("created application seal for uid %s (%s) groups: %v, command: %s",
+	fmsg.Verbosef("created application seal for uid %s (%s) groups: %v, command: %s",
 		seal.sys.user.us, seal.sys.user.username, config.Confinement.Groups, config.Command)
 
 	// seal app and release lock

internal/app/share.go

@@ -143,7 +143,7 @@ func (seal *appSeal) setupShares(bus [2]*dbus.Config, os linux.System) error {
 	if seal.et.Has(system.EWayland) {
 		var socketPath string
 		if name, ok := os.LookupEnv(wl.WaylandDisplay); !ok {
-			fmsg.VPrintln(wl.WaylandDisplay + " is not set, assuming " + wl.FallbackName)
+			fmsg.Verbose(wl.WaylandDisplay + " is not set, assuming " + wl.FallbackName)
 			socketPath = path.Join(seal.RuntimePath, wl.FallbackName)
 		} else if !path.IsAbs(name) {
 			socketPath = path.Join(seal.RuntimePath, name)
@@ -166,7 +166,7 @@ func (seal *appSeal) setupShares(bus [2]*dbus.Config, os linux.System) error {
 			seal.sys.Wayland(outerPath, socketPath, appID, seal.id)
 			seal.sys.bwrap.Bind(outerPath, innerPath)
 		} else { // bind mount wayland socket (insecure)
-			fmsg.VPrintln("direct wayland access, PROCEED WITH CAUTION")
+			fmsg.Verbose("direct wayland access, PROCEED WITH CAUTION")
 			seal.sys.bwrap.Bind(socketPath, innerPath)
 
 			// ensure Wayland socket ACL (e.g. `/run/user/%d/wayland-%d`)
@@ -229,7 +229,7 @@ func (seal *appSeal) setupShares(bus [2]*dbus.Config, os linux.System) error {
 		// publish current user's pulse cookie for target user
 		if src, err := discoverPulseCookie(os); err != nil {
 			// not fatal
-			fmsg.VPrintln(strings.TrimSpace(err.(*fmsg.BaseError).Message()))
+			fmsg.Verbose(strings.TrimSpace(err.(*fmsg.BaseError).Message()))
 		} else {
 			dst := path.Join(seal.share, "pulse-cookie")
 			innerDst := fst.Tmp + "/pulse-cookie"

internal/app/shim/main.go

@@ -3,6 +3,7 @@ package shim
 import (
 	"context"
 	"errors"
+	"log"
 	"os"
 	"os/exec"
 	"os/signal"
@@ -15,8 +16,8 @@ import (
 	"git.gensokyo.uk/security/fortify/helper/proc"
 	"git.gensokyo.uk/security/fortify/helper/seccomp"
 	"git.gensokyo.uk/security/fortify/internal"
+	init0 "git.gensokyo.uk/security/fortify/internal/app/init"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
-	init0 "git.gensokyo.uk/security/fortify/internal/priv/init"
 )
 
 // everything beyond this point runs as unconstrained target user
@@ -25,12 +26,11 @@ import (
 func Main() {
 	// sharing stdout with fortify
 	// USE WITH CAUTION
-	fmsg.SetPrefix("shim")
+	fmsg.Prepare("shim")
 
 	// setting this prevents ptrace
 	if err := internal.PR_SET_DUMPABLE__SUID_DUMP_DISABLE(); err != nil {
-		fmsg.Fatalf("cannot set SUID_DUMP_DISABLE: %s", err)
+		log.Fatalf("cannot set SUID_DUMP_DISABLE: %s", err)
-		panic("unreachable")
 	}
 
 	// receive setup payload
@@ -40,21 +40,20 @@ func Main() {
 	)
 	if f, err := proc.Receive(Env, &payload); err != nil {
 		if errors.Is(err, proc.ErrInvalid) {
-			fmsg.Fatal("invalid config descriptor")
+			log.Fatal("invalid config descriptor")
 		}
 		if errors.Is(err, proc.ErrNotSet) {
-			fmsg.Fatal("FORTIFY_SHIM not set")
+			log.Fatal("FORTIFY_SHIM not set")
 		}
 
-		fmsg.Fatalf("cannot decode shim setup payload: %v", err)
+		log.Fatalf("cannot decode shim setup payload: %v", err)
-		panic("unreachable")
 	} else {
-		fmsg.SetVerbose(payload.Verbose)
+		fmsg.Store(payload.Verbose)
 		closeSetup = f
 	}
 
 	if payload.Bwrap == nil {
-		fmsg.Fatal("bwrap config not supplied")
+		log.Fatal("bwrap config not supplied")
 	}
 
 	// restore bwrap sync fd
@@ -65,7 +64,7 @@ func Main() {
 
 	// close setup socket
 	if err := closeSetup(); err != nil {
-		fmsg.Println("cannot close setup pipe:", err)
+		log.Println("cannot close setup pipe:", err)
 		// not fatal
 	}
 
@@ -73,15 +72,15 @@ func Main() {
 	if s, err := os.Stat(payload.Home); err != nil {
 		if os.IsNotExist(err) {
 			if err = os.Mkdir(payload.Home, 0700); err != nil {
-				fmsg.Fatalf("cannot create home directory: %v", err)
+				log.Fatalf("cannot create home directory: %v", err)
 			}
 		} else {
-			fmsg.Fatalf("cannot access home directory: %v", err)
+			log.Fatalf("cannot access home directory: %v", err)
 		}
 
 		// home directory is created, proceed
 	} else if !s.IsDir() {
-		fmsg.Fatalf("data path %q is not a directory", payload.Home)
+		log.Fatalf("data path %q is not a directory", payload.Home)
 	}
 
 	var ic init0.Payload
@@ -95,10 +94,10 @@ func Main() {
 		// no argv, look up shell instead
 		var ok bool
 		if payload.Bwrap.SetEnv == nil {
-			fmsg.Fatal("no command was specified and environment is unset")
+			log.Fatal("no command was specified and environment is unset")
 		}
 		if ic.Argv0, ok = payload.Bwrap.SetEnv["SHELL"]; !ok {
-			fmsg.Fatal("no command was specified and $SHELL was unset")
+			log.Fatal("no command was specified and $SHELL was unset")
 		}
 
 		ic.Argv = []string{ic.Argv0}
@@ -110,20 +109,20 @@ func Main() {
 
 	// serve setup payload
 	if fd, encoder, err := proc.Setup(&extraFiles); err != nil {
-		fmsg.Fatalf("cannot pipe: %v", err)
+		log.Fatalf("cannot pipe: %v", err)
 	} else {
 		conf.SetEnv[init0.Env] = strconv.Itoa(fd)
 		go func() {
-			fmsg.VPrintln("transmitting config to init")
+			fmsg.Verbose("transmitting config to init")
 			if err = encoder.Encode(&ic); err != nil {
-				fmsg.Fatalf("cannot transmit init config: %v", err)
+				log.Fatalf("cannot transmit init config: %v", err)
 			}
 		}()
 	}
 
 	helper.BubblewrapName = payload.Exec[0] // resolved bwrap path by parent
-	if fmsg.Verbose() {
+	if fmsg.Load() {
-		seccomp.CPrintln = fmsg.Println
+		seccomp.CPrintln = log.Println
 	}
 	if b, err := helper.NewBwrap(
 		conf, path.Join(fst.Tmp, "sbin/init"),
@@ -131,7 +130,7 @@ func Main() {
 		extraFiles,
 		syncFd,
 	); err != nil {
-		fmsg.Fatalf("malformed sandbox config: %v", err)
+		log.Fatalf("malformed sandbox config: %v", err)
 	} else {
 		b.Stdin(os.Stdin).Stdout(os.Stdout).Stderr(os.Stderr)
 		ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
@@ -139,15 +138,15 @@ func Main() {
 
 		// run and pass through exit code
 		if err = b.Start(ctx, false); err != nil {
-			fmsg.Fatalf("cannot start target process: %v", err)
+			log.Fatalf("cannot start target process: %v", err)
 		} else if err = b.Wait(); err != nil {
 			var exitError *exec.ExitError
 			if !errors.As(err, &exitError) {
-				fmsg.Println("wait:", err)
+				log.Printf("wait: %v", err)
-				fmsg.Exit(127)
+				internal.Exit(127)
 				panic("unreachable")
 			}
-			fmsg.Exit(exitError.ExitCode())
+			internal.Exit(exitError.ExitCode())
 			panic("unreachable")
 		}
 	}

internal/app/shim/manager.go

@@ -54,8 +54,8 @@ func (s *Shim) Start(
 	// prepare user switcher invocation
 	var fsu string
 	if p, ok := internal.Path(internal.Fsu); !ok {
-		fmsg.Fatal("invalid fsu path, this copy of fortify is not compiled correctly")
+		return nil, fmsg.WrapError(errors.New("bad fsu path"),
-		panic("unreachable")
+			"invalid fsu path, this copy of fortify is not compiled correctly")
 	} else {
 		fsu = p
 	}
@@ -75,7 +75,7 @@ func (s *Shim) Start(
 
 	// format fsu supplementary groups
 	if len(supp) > 0 {
-		fmsg.VPrintf("attaching supplementary group ids %s", supp)
+		fmsg.Verbosef("attaching supplementary group ids %s", supp)
 		s.cmd.Env = append(s.cmd.Env, "FORTIFY_GROUPS="+strings.Join(supp, " "))
 	}
 	s.cmd.Stdin, s.cmd.Stdout, s.cmd.Stderr = os.Stdin, os.Stdout, os.Stderr
@@ -87,7 +87,7 @@ func (s *Shim) Start(
 		s.sync = &fd
 	}
 
-	fmsg.VPrintln("starting shim via fsu:", s.cmd)
+	fmsg.Verbose("starting shim via fsu:", s.cmd)
 	// withhold messages to stderr
 	fmsg.Suspend()
 	if err := s.cmd.Start(); err != nil {

internal/app/start.go

@@ -4,14 +4,15 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"log"
 	"os/exec"
 	"path/filepath"
 	"strings"
 	"time"
 
 	"git.gensokyo.uk/security/fortify/helper"
+	"git.gensokyo.uk/security/fortify/internal/app/shim"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
-	"git.gensokyo.uk/security/fortify/internal/priv/shim"
 	"git.gensokyo.uk/security/fortify/internal/state"
 	"git.gensokyo.uk/security/fortify/internal/system"
 )
@@ -81,7 +82,7 @@ func (a *app) Run(ctx context.Context, rs *RunState) error {
 			Bwrap: a.seal.sys.bwrap,
 			Home:  a.seal.sys.user.data,
 
-			Verbose: fmsg.Verbose(),
+			Verbose: fmsg.Load(),
 		}); err != nil {
 			return err
 		}
@@ -119,8 +120,8 @@ func (a *app) Run(ctx context.Context, rs *RunState) error {
 		} else {
 			rs.ExitCode = a.shim.Unwrap().ProcessState.ExitCode()
 		}
-		if fmsg.Verbose() {
+		if fmsg.Load() {
-			fmsg.VPrintf("process %d exited with exit code %d", a.shim.Unwrap().Process.Pid, rs.ExitCode)
+			fmsg.Verbosef("process %d exited with exit code %d", a.shim.Unwrap().Process.Pid, rs.ExitCode)
 		}
 
 	// this is reached when a fault makes an already running shim impossible to continue execution
@@ -128,11 +129,11 @@ func (a *app) Run(ctx context.Context, rs *RunState) error {
 	// the effects of this is similar to the alternative exit path and ensures shim death
 	case err := <-a.shim.WaitFallback():
 		rs.ExitCode = 255
-		fmsg.Printf("cannot terminate shim on faulted setup: %v", err)
+		log.Printf("cannot terminate shim on faulted setup: %v", err)
 
 	// alternative exit path relying on shim behaviour on monitor process exit
 	case <-ctx.Done():
-		fmsg.VPrintln("alternative exit path selected")
+		fmsg.Verbose("alternative exit path selected")
 	}
 
 	// child process exited, resume output
@@ -163,10 +164,10 @@ func (a *app) Run(ctx context.Context, rs *RunState) error {
 			} else {
 				if l := len(states); l == 0 {
 					// cleanup globals as the final launcher
-					fmsg.VPrintln("no other launchers active, will clean up globals")
+					fmsg.Verbose("no other launchers active, will clean up globals")
 					ec.Set(system.User)
 				} else {
-					fmsg.VPrintf("found %d active launchers, cleaning up without globals", l)
+					fmsg.Verbosef("found %d active launchers, cleaning up without globals", l)
 				}
 
 				// accumulate capabilities of other launchers
@@ -174,7 +175,7 @@ func (a *app) Run(ctx context.Context, rs *RunState) error {
 					if s.Config != nil {
 						*rt |= s.Config.Confinement.Enablements
 					} else {
-						fmsg.Printf("state entry %d does not contain config", i)
+						log.Printf("state entry %d does not contain config", i)
 					}
 				}
 			}
@@ -184,7 +185,7 @@ func (a *app) Run(ctx context.Context, rs *RunState) error {
 					ec.Set(i)
 				}
 			}
-			if fmsg.Verbose() {
+			if fmsg.Load() {
 				labels := make([]string, 0, system.ELen+1)
 				for i := system.Enablement(0); i < system.Enablement(system.ELen+2); i++ {
 					if ec.Has(i) {
@@ -192,7 +193,7 @@ func (a *app) Run(ctx context.Context, rs *RunState) error {
 					}
 				}
 				if len(labels) > 0 {
-					fmsg.VPrintln("reverting operations labelled", strings.Join(labels, ", "))
+					fmsg.Verbose("reverting operations labelled", strings.Join(labels, ", "))
 				}
 			}
 

internal/executable.go

@@ -1,6 +1,7 @@
-package proc
+package internal
 
 import (
+	"log"
 	"os"
 	"sync"
 
@@ -14,7 +15,8 @@ var (
 
 func copyExecutable() {
 	if name, err := os.Executable(); err != nil {
-		fmsg.Fatalf("cannot read executable path: %v", err)
+		fmsg.BeforeExit()
+		log.Fatalf("cannot read executable path: %v", err)
 	} else {
 		executable = name
 	}

internal/exit.go

@@ -0,0 +1,9 @@
+package internal
+
+import (
+	"os"
+
+	"git.gensokyo.uk/security/fortify/internal/fmsg"
+)
+
+func Exit(code int) { fmsg.BeforeExit(); os.Exit(code) }

internal/fmsg/defer.go

@@ -1,98 +0,0 @@
-package fmsg
-
-import (
-	"os"
-	"sync"
-	"sync/atomic"
-)
-
-var (
-	wstate   atomic.Bool
-	dropped  atomic.Uint64
-	withhold = make(chan struct{}, 1)
-	msgbuf   = make(chan dOp, 64) // these ops are tiny so a large buffer is allocated for withholding output
-
-	dequeueOnce sync.Once
-	queueSync   sync.WaitGroup
-)
-
-func dequeue() {
-	go func() {
-		for {
-			select {
-			case op := <-msgbuf:
-				op.Do()
-				queueSync.Done()
-			case <-withhold:
-				<-withhold
-			}
-		}
-	}()
-}
-
-// queue submits ops to msgbuf but drops messages
-// when the buffer is full and dequeue is withholding
-func queue(op dOp) {
-	queueSync.Add(1)
-
-	select {
-	case msgbuf <- op:
-	default:
-		// send the op anyway if not withholding
-		// as dequeue will get to it eventually
-		if !wstate.Load() {
-			msgbuf <- op
-		} else {
-			queueSync.Done()
-			// increment dropped message count
-			dropped.Add(1)
-		}
-	}
-}
-
-type dOp interface{ Do() }
-
-func Exit(code int) {
-	Resume() // resume here to avoid deadlock
-	queueSync.Wait()
-	os.Exit(code)
-}
-
-func Suspend() {
-	dequeueOnce.Do(dequeue)
-	if wstate.CompareAndSwap(false, true) {
-		queueSync.Wait()
-		withhold <- struct{}{}
-	}
-}
-
-func Resume() {
-	dequeueOnce.Do(dequeue)
-	if wstate.CompareAndSwap(true, false) {
-		withhold <- struct{}{}
-		if d := dropped.Swap(0); d != 0 {
-			Printf("dropped %d messages during withhold", d)
-		}
-	}
-}
-
-type dPrint []any
-
-func (v dPrint) Do() {
-	std.Print(v...)
-}
-
-type dPrintf struct {
-	format string
-	v      []any
-}
-
-func (d *dPrintf) Do() {
-	std.Printf(d.format, d.v...)
-}
-
-type dPrintln []any
-
-func (v dPrintln) Do() {
-	std.Println(v...)
-}

internal/fmsg/fmsg.go

@@ -2,39 +2,85 @@
 package fmsg
 
 import (
+	"bytes"
+	"io"
 	"log"
 	"os"
+	"sync"
+	"sync/atomic"
+	"syscall"
 )
 
-var std = log.New(os.Stderr, "fortify: ", 0)
+const (
+	bufSize    = 4 * 1024
+	bufSizeMax = 16 * 1024 * 1024
+)
 
-func SetPrefix(prefix string) {
+var o = &suspendable{w: os.Stderr}
-	prefix += ": "
+
-	std.SetPrefix(prefix)
+// Prepare configures the system logger for [Suspend] and [Resume] to take effect.
-	std.SetPrefix(prefix)
+func Prepare(prefix string) { log.SetPrefix(prefix + ": "); log.SetFlags(0); log.SetOutput(o) }
+
+type suspendable struct {
+	w io.Writer
+	s atomic.Bool
+
+	buf     bytes.Buffer
+	bufOnce sync.Once
+	bufMu   sync.Mutex
+	dropped int
 }
 
-func Print(v ...any) {
+func (s *suspendable) Write(p []byte) (n int, err error) {
-	dequeueOnce.Do(dequeue)
+	if !s.s.Load() {
-	queue(dPrint(v))
+		return s.w.Write(p)
+	}
+	s.bufOnce.Do(func() { s.prepareBuf() })
+
+	s.bufMu.Lock()
+	defer s.bufMu.Unlock()
+
+	if l := len(p); s.buf.Len()+l > bufSizeMax {
+		s.dropped += l
+		return 0, syscall.ENOMEM
+	}
+	return s.buf.Write(p)
 }
 
-func Printf(format string, v ...any) {
+func (s *suspendable) prepareBuf()   { s.buf.Grow(bufSize) }
-	dequeueOnce.Do(dequeue)
+func (s *suspendable) Suspend() bool { return o.s.CompareAndSwap(false, true) }
-	queue(&dPrintf{format, v})
+func (s *suspendable) Resume() (resumed bool, dropped uintptr, n int64, err error) {
+	if o.s.CompareAndSwap(true, false) {
+		o.bufMu.Lock()
+		defer o.bufMu.Unlock()
+
+		resumed = true
+		dropped = uintptr(o.dropped)
+
+		o.dropped = 0
+		n, err = io.Copy(s.w, &s.buf)
+		s.buf = bytes.Buffer{}
+		s.prepareBuf()
+	}
+	return
 }
 
-func Println(v ...any) {
+func Suspend() bool { return o.Suspend() }
-	dequeueOnce.Do(dequeue)
+func Resume() bool {
-	queue(dPrintln(v))
+	resumed, dropped, _, err := o.Resume()
+	if err != nil {
+		// probably going to result in an error as well,
+		// so this call is as good as unreachable
+		log.Printf("cannot dump buffer on resume: %v", err)
+	}
+	if resumed && dropped > 0 {
+		log.Fatalf("dropped %d bytes while output is suspended", dropped)
+	}
+	return resumed
 }
 
-func Fatal(v ...any) {
+func BeforeExit() {
-	Print(v...)
+	if Resume() {
-	Exit(1)
+		log.Printf("beforeExit reached on suspended output")
 	}
-
-func Fatalf(format string, v ...any) {
-	Printf(format, v...)
-	Exit(1)
 }

internal/fmsg/verbose.go

@@ -1,25 +1,23 @@
 package fmsg
 
-import "sync/atomic"
+import (
+	"log"
+	"sync/atomic"
+)
 
 var verbose = new(atomic.Bool)
 
-func Verbose() bool {
+func Load() bool   { return verbose.Load() }
-	return verbose.Load()
+func Store(v bool) { verbose.Store(v) }
-}
 
-func SetVerbose(v bool) {
+func Verbosef(format string, v ...any) {
-	verbose.Store(v)
-}
-
-func VPrintf(format string, v ...any) {
 	if verbose.Load() {
-		Printf(format, v...)
+		log.Printf(format, v...)
 	}
 }
 
-func VPrintln(v ...any) {
+func Verbose(v ...any) {
 	if verbose.Load() {
-		Println(v...)
+		log.Println(v...)
 	}
 }

internal/linux/interface.go

@@ -54,7 +54,7 @@ type Paths struct {
 func CopyPaths(os System, v *Paths) {
 	v.SharePath = path.Join(os.TempDir(), "fortify."+strconv.Itoa(os.Geteuid()))
 
-	fmsg.VPrintf("process share directory at %q", v.SharePath)
+	fmsg.Verbosef("process share directory at %q", v.SharePath)
 
 	if r, ok := os.LookupEnv(xdgRuntimeDir); !ok || r == "" || !path.IsAbs(r) {
 		// fall back to path in share since fortify has no hard XDG dependency
@@ -65,5 +65,5 @@ func CopyPaths(os System, v *Paths) {
 		v.RunDirPath = path.Join(v.RuntimePath, "fortify")
 	}
 
-	fmsg.VPrintf("runtime directory at %q", v.RunDirPath)
+	fmsg.Verbosef("runtime directory at %q", v.RunDirPath)
 }

internal/linux/std.go

@@ -3,6 +3,7 @@ package linux
 import (
 	"errors"
 	"io/fs"
+	"log"
 	"os"
 	"os/exec"
 	"os/user"
@@ -11,7 +12,6 @@ import (
 	"sync"
 	"syscall"
 
-	"git.gensokyo.uk/security/fortify/helper/proc"
 	"git.gensokyo.uk/security/fortify/internal"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
 )
@@ -33,13 +33,13 @@ func (s *Std) Geteuid() int                                 { return os.Geteuid(
 func (s *Std) LookupEnv(key string) (string, bool)          { return os.LookupEnv(key) }
 func (s *Std) TempDir() string                              { return os.TempDir() }
 func (s *Std) LookPath(file string) (string, error)         { return exec.LookPath(file) }
-func (s *Std) MustExecutable() string                       { return proc.MustExecutable() }
+func (s *Std) MustExecutable() string                       { return internal.MustExecutable() }
 func (s *Std) LookupGroup(name string) (*user.Group, error) { return user.LookupGroup(name) }
 func (s *Std) ReadDir(name string) ([]os.DirEntry, error)   { return os.ReadDir(name) }
 func (s *Std) Stat(name string) (fs.FileInfo, error)        { return os.Stat(name) }
 func (s *Std) Open(name string) (fs.File, error)            { return os.Open(name) }
 func (s *Std) EvalSymlinks(path string) (string, error)     { return filepath.EvalSymlinks(path) }
-func (s *Std) Exit(code int)                                { fmsg.Exit(code) }
+func (s *Std) Exit(code int)                                { internal.Exit(code) }
 
 const xdgRuntimeDir = "XDG_RUNTIME_DIR"
 
@@ -74,8 +74,10 @@ func (s *Std) Uid(aid int) (int, error) {
 
 	u.uid = -1
 	if fsu, ok := internal.Check(internal.Fsu); !ok {
-		fmsg.Fatal("invalid fsu path, this copy of fortify is not compiled correctly")
+		fmsg.BeforeExit()
-		panic("unreachable")
+		log.Fatal("invalid fsu path, this copy of fortify is not compiled correctly")
+		// unreachable
+		return 0, syscall.EBADE
 	} else {
 		cmd := exec.Command(fsu)
 		cmd.Path = fsu

internal/state/multi.go

@@ -85,17 +85,17 @@ func (s *multiStore) List() ([]int, error) {
 	for _, e := range entries {
 		// skip non-directories
 		if !e.IsDir() {
-			fmsg.VPrintf("skipped non-directory entry %q", e.Name())
+			fmsg.Verbosef("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())
+			fmsg.Verbosef("skipped non-aid entry %q", e.Name())
 			continue
 		} else {
 			if v < 0 || v > 9999 {
-				fmsg.VPrintf("skipped out of bounds entry %q", e.Name())
+				fmsg.Verbosef("skipped out of bounds entry %q", e.Name())
 				continue
 			}
 

internal/system/acl.go

@@ -36,18 +36,18 @@ func (a *ACL) Type() Enablement {
 }
 
 func (a *ACL) apply(sys *I) error {
-	fmsg.VPrintln("applying ACL", a)
+	fmsg.Verbose("applying ACL", a)
 	return fmsg.WrapErrorSuffix(acl.UpdatePerm(a.path, sys.uid, a.perms...),
 		fmt.Sprintf("cannot apply ACL entry to %q:", a.path))
 }
 
 func (a *ACL) revert(sys *I, ec *Criteria) error {
 	if ec.hasType(a) {
-		fmsg.VPrintln("stripping ACL", a)
+		fmsg.Verbose("stripping ACL", a)
 		return fmsg.WrapErrorSuffix(acl.UpdatePerm(a.path, sys.uid),
 			fmt.Sprintf("cannot strip ACL entry from %q:", a.path))
 	} else {
-		fmsg.VPrintln("skipping ACL", a)
+		fmsg.Verbose("skipping ACL", a)
 		return nil
 	}
 }

internal/system/dbus.go

@@ -3,6 +3,7 @@ package system
 import (
 	"bytes"
 	"errors"
+	"log"
 	"strings"
 	"sync"
 
@@ -47,12 +48,12 @@ func (sys *I) ProxyDBus(session, system *dbus.Config, sessionPath, systemPath st
 	d.proxy = dbus.New(sessionBus, systemBus)
 
 	defer func() {
-		if fmsg.Verbose() && d.proxy.Sealed() {
+		if fmsg.Load() && d.proxy.Sealed() {
-			fmsg.VPrintln("sealed session proxy", session.Args(sessionBus))
+			fmsg.Verbose("sealed session proxy", session.Args(sessionBus))
 			if system != nil {
-				fmsg.VPrintln("sealed system proxy", system.Args(systemBus))
+				fmsg.Verbose("sealed system proxy", system.Args(systemBus))
 			}
-			fmsg.VPrintln("message bus proxy final args:", d.proxy)
+			fmsg.Verbose("message bus proxy final args:", d.proxy)
 		}
 	}()
 
@@ -78,9 +79,9 @@ func (d *DBus) Type() Enablement {
 }
 
 func (d *DBus) apply(sys *I) error {
-	fmsg.VPrintf("session bus proxy on %q for upstream %q", d.proxy.Session()[1], d.proxy.Session()[0])
+	fmsg.Verbosef("session bus proxy on %q for upstream %q", d.proxy.Session()[1], d.proxy.Session()[0])
 	if d.system {
-		fmsg.VPrintf("system bus proxy on %q for upstream %q", d.proxy.System()[1], d.proxy.System()[0])
+		fmsg.Verbosef("system bus proxy on %q for upstream %q", d.proxy.System()[1], d.proxy.System()[0])
 	}
 
 	// this starts the process and blocks until ready
@@ -89,15 +90,15 @@ func (d *DBus) apply(sys *I) error {
 		return fmsg.WrapErrorSuffix(err,
 			"cannot start message bus proxy:")
 	}
-	fmsg.VPrintln("starting message bus proxy:", d.proxy)
+	fmsg.Verbose("starting message bus proxy:", d.proxy)
 	return nil
 }
 
 func (d *DBus) revert(_ *I, _ *Criteria) error {
 	// criteria ignored here since dbus is always process-scoped
-	fmsg.VPrintln("terminating message bus proxy")
+	fmsg.Verbose("terminating message bus proxy")
 	d.proxy.Close()
-	defer fmsg.VPrintln("message bus proxy exit")
+	defer fmsg.Verbose("message bus proxy exit")
 	return fmsg.WrapErrorSuffix(d.proxy.Wait(), "message bus proxy error:")
 }
 
@@ -144,7 +145,7 @@ func (s *scanToFmsg) write(p []byte, a int) (int, error) {
 func (s *scanToFmsg) Dump() {
 	s.mu.RLock()
 	for _, msg := range s.msgbuf {
-		fmsg.Println(msg)
+		log.Println(msg)
 	}
 	s.mu.RUnlock()
 }

internal/system/link.go

@@ -0,0 +1,53 @@
+package system
+
+import (
+	"fmt"
+	"os"
+
+	"git.gensokyo.uk/security/fortify/internal/fmsg"
+)
+
+// Link registers an Op that links dst to src.
+func (sys *I) Link(oldname, newname string) *I { return sys.LinkFileType(Process, oldname, newname) }
+
+// LinkFileType registers a file linking Op labelled with type et.
+func (sys *I) LinkFileType(et Enablement, oldname, newname string) *I {
+	sys.lock.Lock()
+	defer sys.lock.Unlock()
+
+	sys.ops = append(sys.ops, &Hardlink{et, newname, oldname})
+
+	return sys
+}
+
+type Hardlink struct {
+	et       Enablement
+	dst, src string
+}
+
+func (l *Hardlink) Type() Enablement { return l.et }
+
+func (l *Hardlink) apply(_ *I) error {
+	fmsg.Verbose("linking ", l)
+	return fmsg.WrapErrorSuffix(os.Link(l.src, l.dst),
+		fmt.Sprintf("cannot link %q:", l.dst))
+}
+
+func (l *Hardlink) revert(_ *I, ec *Criteria) error {
+	if ec.hasType(l) {
+		fmsg.Verbosef("removing hard link %q", l.dst)
+		return fmsg.WrapErrorSuffix(os.Remove(l.dst),
+			fmt.Sprintf("cannot remove hard link %q:", l.dst))
+	} else {
+		fmsg.Verbosef("skipping hard link %q", l.dst)
+		return nil
+	}
+}
+
+func (l *Hardlink) Is(o Op) bool {
+	l0, ok := o.(*Hardlink)
+	return ok && l0 != nil && *l == *l0
+}
+
+func (l *Hardlink) Path() string   { return l.src }
+func (l *Hardlink) String() string { return fmt.Sprintf("%q from %q", l.dst, l.src) }

internal/system/mkdir.go

@@ -40,7 +40,7 @@ func (m *Mkdir) Type() Enablement {
 }
 
 func (m *Mkdir) apply(_ *I) error {
-	fmsg.VPrintln("ensuring directory", m)
+	fmsg.Verbose("ensuring directory", m)
 
 	// create directory
 	err := os.Mkdir(m.path, m.perm)
@@ -61,11 +61,11 @@ func (m *Mkdir) revert(_ *I, ec *Criteria) error {
 	}
 
 	if ec.hasType(m) {
-		fmsg.VPrintln("destroying ephemeral directory", m)
+		fmsg.Verbose("destroying ephemeral directory", m)
 		return fmsg.WrapErrorSuffix(os.Remove(m.path),
 			fmt.Sprintf("cannot remove ephemeral directory %q:", m.path))
 	} else {
-		fmsg.VPrintln("skipping ephemeral directory", m)
+		fmsg.Verbose("skipping ephemeral directory", m)
 		return nil
 	}
 }

internal/system/op.go

@@ -3,6 +3,7 @@ package system
 import (
 	"context"
 	"errors"
+	"log"
 	"os"
 	"sync"
 
@@ -105,9 +106,9 @@ func (sys *I) Commit(ctx context.Context) error {
 		// sp is set to nil when all ops are applied
 		if sp != nil {
 			// rollback partial commit
-			fmsg.VPrintf("commit faulted after %d ops, rolling back partial commit", len(sp.ops))
+			fmsg.Verbosef("commit faulted after %d ops, rolling back partial commit", len(sp.ops))
 			if err := sp.Revert(&Criteria{nil}); err != nil {
-				fmsg.Println("errors returned reverting partial commit:", err)
+				log.Println("errors returned reverting partial commit:", err)
 			}
 		}
 	}()

internal/system/tmpfiles.go

@@ -27,24 +27,8 @@ func (sys *I) CopyFileType(et Enablement, dst, src string) *I {
 	return sys
 }
 
-// Link registers an Op that links dst to src.
-func (sys *I) Link(oldname, newname string) *I {
-	return sys.LinkFileType(Process, oldname, newname)
-}
-
-// LinkFileType registers a file linking Op labelled with type et.
-func (sys *I) LinkFileType(et Enablement, oldname, newname string) *I {
-	sys.lock.Lock()
-	defer sys.lock.Unlock()
-
-	sys.ops = append(sys.ops, &Tmpfile{et, tmpfileLink, newname, oldname})
-
-	return sys
-}
-
 const (
 	tmpfileCopy uint8 = iota
-	tmpfileLink
 )
 
 type Tmpfile struct {
@@ -60,13 +44,9 @@ func (t *Tmpfile) Type() Enablement {
 func (t *Tmpfile) apply(_ *I) error {
 	switch t.method {
 	case tmpfileCopy:
-		fmsg.VPrintln("publishing tmpfile", t)
+		fmsg.Verbose("publishing tmpfile", t)
 		return fmsg.WrapErrorSuffix(copyFile(t.dst, t.src),
 			fmt.Sprintf("cannot copy tmpfile %q:", t.dst))
-	case tmpfileLink:
-		fmsg.VPrintln("linking tmpfile", t)
-		return fmsg.WrapErrorSuffix(os.Link(t.src, t.dst),
-			fmt.Sprintf("cannot link tmpfile %q:", t.dst))
 	default:
 		panic("invalid tmpfile method " + strconv.Itoa(int(t.method)))
 	}
@@ -74,11 +54,11 @@ func (t *Tmpfile) apply(_ *I) error {
 
 func (t *Tmpfile) revert(_ *I, ec *Criteria) error {
 	if ec.hasType(t) {
-		fmsg.VPrintf("removing tmpfile %q", t.dst)
+		fmsg.Verbosef("removing tmpfile %q", t.dst)
 		return fmsg.WrapErrorSuffix(os.Remove(t.dst),
 			fmt.Sprintf("cannot remove tmpfile %q:", t.dst))
 	} else {
-		fmsg.VPrintf("skipping tmpfile %q", t.dst)
+		fmsg.Verbosef("skipping tmpfile %q", t.dst)
 		return nil
 	}
 }
@@ -94,8 +74,6 @@ func (t *Tmpfile) String() string {
 	switch t.method {
 	case tmpfileCopy:
 		return fmt.Sprintf("%q from %q", t.dst, t.src)
-	case tmpfileLink:
-		return fmt.Sprintf("%q from %q", t.dst, t.src)
 	default:
 		panic("invalid tmpfile method " + strconv.Itoa(int(t.method)))
 	}

internal/system/tmpfiles_test.go

@@ -57,7 +57,7 @@ func TestLink(t *testing.T) {
 			sys := New(150)
 			sys.Link(tc.src, tc.dst)
 			(&tcOp{Process, tc.src}).test(t, sys.ops, []Op{
-				&Tmpfile{Process, tmpfileLink, tc.dst, tc.src},
+				&Hardlink{Process, tc.dst, tc.src},
 			}, "Link")
 		})
 	}
@@ -76,7 +76,7 @@ func TestLinkFileType(t *testing.T) {
 			sys := New(150)
 			sys.LinkFileType(tc.et, tc.path, tc.dst)
 			tc.test(t, sys.ops, []Op{
-				&Tmpfile{tc.et, tmpfileLink, tc.dst, tc.path},
+				&Hardlink{tc.et, tc.dst, tc.path},
 			}, "LinkFileType")
 		})
 	}
@@ -101,10 +101,6 @@ func TestTmpfile_String(t *testing.T) {
 	}{
 		{tmpfileCopy, "/tmp/fortify.1971/4b6bdc9182fb2f1d3a965c5fa8b9b66e/pulse-cookie", "/home/ophestra/xdg/config/pulse/cookie",
 			`"/tmp/fortify.1971/4b6bdc9182fb2f1d3a965c5fa8b9b66e/pulse-cookie" from "/home/ophestra/xdg/config/pulse/cookie"`},
-		{tmpfileLink, "/run/user/1971/fortify/4b6bdc9182fb2f1d3a965c5fa8b9b66e/wayland", "/run/user/1971/wayland-0",
-			`"/run/user/1971/fortify/4b6bdc9182fb2f1d3a965c5fa8b9b66e/wayland" from "/run/user/1971/wayland-0"`},
-		{tmpfileLink, "/run/user/1971/fortify/4b6bdc9182fb2f1d3a965c5fa8b9b66e/pulse", "/run/user/1971/pulse/native",
-			`"/run/user/1971/fortify/4b6bdc9182fb2f1d3a965c5fa8b9b66e/pulse" from "/run/user/1971/pulse/native"`},
 	}
 
 	for _, tc := range testCases {

internal/system/wayland.go

@@ -45,7 +45,7 @@ func (w Wayland) apply(sys *I) error {
 		return fmsg.WrapErrorSuffix(err,
 			fmt.Sprintf("cannot attach to wayland on %q:", w.pair[1]))
 	} else {
-		fmsg.VPrintf("wayland attached on %q", w.pair[1])
+		fmsg.Verbosef("wayland attached on %q", w.pair[1])
 	}
 
 	if sp, err := w.conn.Bind(w.pair[0], w.appID, w.instanceID); err != nil {
@@ -53,7 +53,7 @@ func (w Wayland) apply(sys *I) error {
 			fmt.Sprintf("cannot bind to socket on %q:", w.pair[0]))
 	} else {
 		sys.sp = sp
-		fmsg.VPrintf("wayland listening on %q", w.pair[0])
+		fmsg.Verbosef("wayland listening on %q", w.pair[0])
 		return fmsg.WrapErrorSuffix(errors.Join(os.Chmod(w.pair[0], 0), acl.UpdatePerm(w.pair[0], sys.uid, acl.Read, acl.Write, acl.Execute)),
 			fmt.Sprintf("cannot chmod socket on %q:", w.pair[0]))
 	}
@@ -61,16 +61,16 @@ func (w Wayland) apply(sys *I) error {
 
 func (w Wayland) revert(_ *I, ec *Criteria) error {
 	if ec.hasType(w) {
-		fmsg.VPrintf("removing wayland socket on %q", w.pair[0])
+		fmsg.Verbosef("removing wayland socket on %q", w.pair[0])
 		if err := os.Remove(w.pair[0]); err != nil && !errors.Is(err, os.ErrNotExist) {
 			return err
 		}
 
-		fmsg.VPrintf("detaching from wayland on %q", w.pair[1])
+		fmsg.Verbosef("detaching from wayland on %q", w.pair[1])
 		return fmsg.WrapErrorSuffix(w.conn.Close(),
 			fmt.Sprintf("cannot detach from wayland on %q:", w.pair[1]))
 	} else {
-		fmsg.VPrintf("skipping wayland cleanup on %q", w.pair[0])
+		fmsg.Verbosef("skipping wayland cleanup on %q", w.pair[0])
 		return nil
 	}
 }

internal/system/xhost.go

@@ -24,18 +24,18 @@ func (x XHost) Type() Enablement {
 }
 
 func (x XHost) apply(_ *I) error {
-	fmsg.VPrintf("inserting entry %s to X11", x)
+	fmsg.Verbosef("inserting entry %s to X11", x)
 	return fmsg.WrapErrorSuffix(xcb.ChangeHosts(xcb.HostModeInsert, xcb.FamilyServerInterpreted, "localuser\x00"+string(x)),
 		fmt.Sprintf("cannot insert entry %s to X11:", x))
 }
 
 func (x XHost) revert(_ *I, ec *Criteria) error {
 	if ec.hasType(x) {
-		fmsg.VPrintf("deleting entry %s from X11", x)
+		fmsg.Verbosef("deleting entry %s from X11", x)
 		return fmsg.WrapErrorSuffix(xcb.ChangeHosts(xcb.HostModeDelete, xcb.FamilyServerInterpreted, "localuser\x00"+string(x)),
 			fmt.Sprintf("cannot delete entry %s from X11:", x))
 	} else {
-		fmsg.VPrintf("skipping entry %s in X11", x)
+		fmsg.Verbosef("skipping entry %s in X11", x)
 		return nil
 	}
 }

main.go

@@ -5,6 +5,7 @@ import (
 	_ "embed"
 	"flag"
 	"fmt"
+	"log"
 	"os"
 	"os/signal"
 	"os/user"
@@ -20,10 +21,10 @@ import (
 	"git.gensokyo.uk/security/fortify/helper/seccomp"
 	"git.gensokyo.uk/security/fortify/internal"
 	"git.gensokyo.uk/security/fortify/internal/app"
+	init0 "git.gensokyo.uk/security/fortify/internal/app/init"
+	"git.gensokyo.uk/security/fortify/internal/app/shim"
 	"git.gensokyo.uk/security/fortify/internal/fmsg"
 	"git.gensokyo.uk/security/fortify/internal/linux"
-	init0 "git.gensokyo.uk/security/fortify/internal/priv/init"
-	"git.gensokyo.uk/security/fortify/internal/priv/shim"
 	"git.gensokyo.uk/security/fortify/internal/state"
 	"git.gensokyo.uk/security/fortify/internal/system"
 )
@@ -37,6 +38,8 @@ var (
 )
 
 func init() {
+	fmsg.Prepare("fortify")
+
 	flag.BoolVar(&flagVerbose, "v", false, "Verbose output")
 	flag.BoolVar(&flagJSON, "json", false, "Format output in JSON when applicable")
 }
@@ -62,13 +65,12 @@ func main() {
 	init0.TryArgv0()
 
 	if err := internal.PR_SET_DUMPABLE__SUID_DUMP_DISABLE(); err != nil {
-		fmsg.Printf("cannot set SUID_DUMP_DISABLE: %s", err)
+		log.Printf("cannot set SUID_DUMP_DISABLE: %s", err)
 		// not fatal: this program runs as the privileged user
 	}
 
 	if os.Geteuid() == 0 {
-		fmsg.Fatal("this program must not run as root")
+		log.Fatal("this program must not run as root")
-		panic("unreachable")
 	}
 
 	flag.CommandLine.Usage = func() {
@@ -96,12 +98,12 @@ func main() {
 		fmt.Println()
 	}
 	flag.Parse()
-	fmsg.SetVerbose(flagVerbose)
+	fmsg.Store(flagVerbose)
 
 	args := flag.Args()
 	if len(args) == 0 {
 		flag.CommandLine.Usage()
-		fmsg.Exit(0)
+		internal.Exit(0)
 	}
 
 	switch args[0] {
@@ -111,16 +113,20 @@ func main() {
 		} else {
 			fmt.Println("impure")
 		}
-		fmsg.Exit(0)
+		internal.Exit(0)
+
 	case "license": // print embedded license
 		fmt.Println(license)
-		fmsg.Exit(0)
+		internal.Exit(0)
+
 	case "template": // print full template configuration
 		printJSON(os.Stdout, false, fst.Template())
-		fmsg.Exit(0)
+		internal.Exit(0)
+
 	case "help": // print help message
 		flag.CommandLine.Usage()
-		fmsg.Exit(0)
+		internal.Exit(0)
+
 	case "ps": // print all state info
 		set := flag.NewFlagSet("ps", flag.ExitOnError)
 		var short bool
@@ -130,7 +136,8 @@ func main() {
 		_ = set.Parse(args[1:])
 
 		printPs(os.Stdout, time.Now().UTC(), state.NewMulti(sys.Paths().RunDirPath), short)
-		fmsg.Exit(0)
+		internal.Exit(0)
+
 	case "show": // pretty-print app info
 		set := flag.NewFlagSet("show", flag.ExitOnError)
 		var short bool
@@ -142,6 +149,7 @@ func main() {
 		switch len(set.Args()) {
 		case 0: // system
 			printShowSystem(os.Stdout, short)
+
 		case 1: // instance
 			name := set.Args()[0]
 			config, instance := tryShort(name)
@@ -149,14 +157,15 @@ func main() {
 				config = tryPath(name)
 			}
 			printShowInstance(os.Stdout, time.Now().UTC(), instance, config, short)
-		default:
-			fmsg.Fatal("show requires 1 argument")
-		}
 
-		fmsg.Exit(0)
+		default:
+			log.Fatal("show requires 1 argument")
+		}
+		internal.Exit(0)
+
 	case "app": // launch app from configuration file
 		if len(args) < 2 {
-			fmsg.Fatal("app requires at least 1 argument")
+			log.Fatal("app requires at least 1 argument")
 		}
 
 		// config extraArgs...
@@ -166,6 +175,7 @@ func main() {
 		// invoke app
 		runApp(config)
 		panic("unreachable")
+
 	case "run": // run app in permissive defaults usage pattern
 		set := flag.NewFlagSet("run", flag.ExitOnError)
 
@@ -208,8 +218,7 @@ func main() {
 		}
 
 		if aid < 0 || aid > 9999 {
-			fmsg.Fatalf("aid %d out of range", aid)
+			log.Fatalf("aid %d out of range", aid)
-			panic("unreachable")
 		}
 
 		// resolve home/username from os when flag is unset
@@ -219,13 +228,13 @@ func main() {
 			passwdFunc = func() {
 				var us string
 				if uid, err := sys.Uid(aid); err != nil {
-					fmsg.Fatalf("cannot obtain uid from fsu: %v", err)
+					log.Fatalf("cannot obtain uid from fsu: %v", err)
 				} else {
 					us = strconv.Itoa(uid)
 				}
 
 				if u, err := user.LookupId(us); err != nil {
-					fmsg.VPrintf("cannot look up uid %s", us)
+					fmsg.Verbosef("cannot look up uid %s", us)
 					passwd = &user.User{
 						Uid:      us,
 						Gid:      us,
@@ -267,7 +276,7 @@ func main() {
 				config.Confinement.SessionBus = dbus.NewConfig(fid, true, mpris)
 			} else {
 				if c, err := dbus.NewConfigFromFile(dbusConfigSession); err != nil {
-					fmsg.Fatalf("cannot load session bus proxy config from %q: %s", dbusConfigSession, err)
+					log.Fatalf("cannot load session bus proxy config from %q: %s", dbusConfigSession, err)
 				} else {
 					config.Confinement.SessionBus = c
 				}
@@ -276,7 +285,7 @@ func main() {
 			// system bus proxy is optional
 			if dbusConfigSystem != "nil" {
 				if c, err := dbus.NewConfigFromFile(dbusConfigSystem); err != nil {
-					fmsg.Fatalf("cannot load system bus proxy config from %q: %s", dbusConfigSystem, err)
+					log.Fatalf("cannot load system bus proxy config from %q: %s", dbusConfigSystem, err)
 				} else {
 					config.Confinement.SystemBus = c
 				}
@@ -291,17 +300,18 @@ func main() {
 
 		// invoke app
 		runApp(config)
+		panic("unreachable")
 
 	// internal commands
 	case "shim":
 		shim.Main()
-		fmsg.Exit(0)
+		internal.Exit(0)
 	case "init":
 		init0.Main()
-		fmsg.Exit(0)
+		internal.Exit(0)
 
 	default:
-		fmsg.Fatalf("%q is not a valid command", args[0])
+		log.Fatalf("%q is not a valid command", args[0])
 	}
 
 	panic("unreachable")
@@ -313,15 +323,15 @@ func runApp(config *fst.Config) {
 		syscall.SIGINT, syscall.SIGTERM)
 	defer stop() // unreachable
 
-	if fmsg.Verbose() {
+	if fmsg.Load() {
-		seccomp.CPrintln = fmsg.Println
+		seccomp.CPrintln = log.Println
 	}
 
 	if a, err := app.New(sys); err != nil {
-		fmsg.Fatalf("cannot create app: %s\n", err)
+		log.Fatalf("cannot create app: %s", err)
 	} else if err = a.Seal(config); err != nil {
 		logBaseError(err, "cannot seal app:")
-		fmsg.Exit(1)
+		internal.Exit(1)
 	} else if err = a.Run(ctx, rs); err != nil {
 		if !rs.Start {
 			logBaseError(err, "cannot start app:")
@@ -334,8 +344,7 @@ func runApp(config *fst.Config) {
 		}
 	}
 	if rs.WaitErr != nil {
-		fmsg.Println("inner wait failed:", rs.WaitErr)
+		log.Println("inner wait failed:", rs.WaitErr)
 	}
-	fmsg.Exit(rs.ExitCode)
+	internal.Exit(rs.ExitCode)
-	panic("unreachable")
 }

parse.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"io"
+	"log"
 	"os"
 	"strconv"
 	"strings"
@@ -21,11 +22,10 @@ func tryPath(name string) (config *fst.Config) {
 	if name != "-" {
 		r = tryFd(name)
 		if r == nil {
-			fmsg.VPrintln("load configuration from file")
+			fmsg.Verbose("load configuration from file")
 
 			if f, err := os.Open(name); err != nil {
-				fmsg.Fatalf("cannot access configuration file %q: %s", name, err)
+				log.Fatalf("cannot access configuration file %q: %s", name, err)
-				panic("unreachable")
 			} else {
 				// finalizer closes f
 				r = f
@@ -33,7 +33,7 @@ func tryPath(name string) (config *fst.Config) {
 		} else {
 			defer func() {
 				if err := r.(io.ReadCloser).Close(); err != nil {
-					fmsg.Printf("cannot close config fd: %v", err)
+					log.Printf("cannot close config fd: %v", err)
 				}
 			}()
 		}
@@ -42,8 +42,7 @@ func tryPath(name string) (config *fst.Config) {
 	}
 
 	if err := json.NewDecoder(r).Decode(&config); err != nil {
-		fmsg.Fatalf("cannot load configuration: %v", err)
+		log.Fatalf("cannot load configuration: %v", err)
-		panic("unreachable")
 	}
 
 	return
@@ -51,7 +50,7 @@ func tryPath(name string) (config *fst.Config) {
 
 func tryFd(name string) io.ReadCloser {
 	if v, err := strconv.Atoi(name); err != nil {
-		fmsg.VPrintf("name cannot be interpreted as int64: %v", err)
+		fmsg.Verbosef("name cannot be interpreted as int64: %v", err)
 		return nil
 	} else {
 		fd := uintptr(v)
@@ -59,7 +58,7 @@ func tryFd(name string) io.ReadCloser {
 			if errors.Is(errno, syscall.EBADF) {
 				return nil
 			}
-			fmsg.Fatalf("cannot get fd %d: %v", fd, errno)
+			log.Fatalf("cannot get fd %d: %v", fd, errno)
 		}
 		return os.NewFile(fd, strconv.Itoa(v))
 	}
@@ -83,11 +82,11 @@ func tryShort(name string) (config *fst.Config, instance *state.State) {
 
 	// try to match from state store
 	if likePrefix && len(name) >= 8 {
-		fmsg.VPrintln("argument looks like prefix")
+		fmsg.Verbose("argument looks like prefix")
 
 		s := state.NewMulti(sys.Paths().RunDirPath)
 		if entries, err := state.Join(s); err != nil {
-			fmsg.Printf("cannot join store: %v", err)
+			log.Printf("cannot join store: %v", err)
 			// drop to fetch from file
 		} else {
 			for id := range entries {
@@ -99,7 +98,7 @@ func tryShort(name string) (config *fst.Config, instance *state.State) {
 					break
 				}
 
-				fmsg.VPrintf("instance %s skipped", v)
+				fmsg.Verbosef("instance %s skipped", v)
 			}
 		}
 	}

print.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"log"
 	"slices"
 	"strconv"
 	"strings"
@@ -12,7 +13,6 @@ import (
 
 	"git.gensokyo.uk/security/fortify/dbus"
 	"git.gensokyo.uk/security/fortify/fst"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
 	"git.gensokyo.uk/security/fortify/internal/state"
 )
 
@@ -24,7 +24,7 @@ func printShowSystem(output io.Writer, short bool) {
 
 	// get fid by querying uid of aid 0
 	if uid, err := sys.Uid(0); err != nil {
-		fmsg.Fatalf("cannot obtain uid from fsu: %v", err)
+		log.Fatalf("cannot obtain uid from fsu: %v", err)
 	} else {
 		info.User = (uid / 10000) - 100
 	}
@@ -190,12 +190,12 @@ func printShowInstance(
 func printPs(output io.Writer, now time.Time, s state.Store, short bool) {
 	var entries state.Entries
 	if e, err := state.Join(s); err != nil {
-		fmsg.Fatalf("cannot join store: %v", err)
+		log.Fatalf("cannot join store: %v", err)
 	} else {
 		entries = e
 	}
 	if err := s.Close(); err != nil {
-		fmsg.Printf("cannot close store: %v", err)
+		log.Printf("cannot close store: %v", err)
 	}
 
 	if !short && flagJSON {
@@ -212,13 +212,13 @@ func printPs(output io.Writer, now time.Time, s state.Store, short bool) {
 	for id, instance := range entries {
 		// gracefully skip nil states
 		if instance == nil {
-			fmsg.Printf("got invalid state entry %s", id.String())
+			log.Printf("got invalid state entry %s", id.String())
 			continue
 		}
 
 		// gracefully skip inconsistent states
 		if id != instance.ID {
-			fmsg.Printf("possible store corruption: entry %s has id %s",
+			log.Printf("possible store corruption: entry %s has id %s",
 				id.String(), instance.ID.String())
 			continue
 		}
@@ -273,8 +273,7 @@ func printJSON(output io.Writer, short bool, v any) {
 		encoder.SetIndent("", "  ")
 	}
 	if err := encoder.Encode(v); err != nil {
-		fmsg.Fatalf("cannot serialise: %v", err)
+		log.Fatalf("cannot serialise: %v", err)
-		panic("unreachable")
 	}
 }
 
@@ -284,31 +283,26 @@ type tp struct{ *tabwriter.Writer }
 
 func (p *tp) Printf(format string, a ...any) {
 	if _, err := fmt.Fprintf(p, format, a...); err != nil {
-		fmsg.Fatalf("cannot write to tabwriter: %v", err)
+		log.Fatalf("cannot write to tabwriter: %v", err)
-		panic("unreachable")
 	}
 }
 func (p *tp) Println(a ...any) {
 	if _, err := fmt.Fprintln(p, a...); err != nil {
-		fmsg.Fatalf("cannot write to tabwriter: %v", err)
+		log.Fatalf("cannot write to tabwriter: %v", err)
-		panic("unreachable")
 	}
 }
 func (p *tp) MustFlush() {
 	if err := p.Writer.Flush(); err != nil {
-		fmsg.Fatalf("cannot flush tabwriter: %v", err)
+		log.Fatalf("cannot flush tabwriter: %v", err)
-		panic("unreachable")
 	}
 }
 func mustPrint(output io.Writer, a ...any) {
 	if _, err := fmt.Fprint(output, a...); err != nil {
-		fmsg.Fatalf("cannot print: %v", err)
+		log.Fatalf("cannot print: %v", err)
-		panic("unreachable")
 	}
 }
 func mustPrintln(output io.Writer, a ...any) {
 	if _, err := fmt.Fprintln(output, a...); err != nil {
-		fmsg.Fatalf("cannot print: %v", err)
+		log.Fatalf("cannot print: %v", err)
-		panic("unreachable")
 	}
 }