fmsg: implement suspend in writer

This removes the requirement to call fmsg.Exit on every exit path, and enables direct use of the "log" package. However, fmsg.BeforeExit is still encouraged when possible to catch exit on suspended output.

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

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"
@@ -11,9 +12,7 @@ import (
 	"sync"
 	"syscall"
 
-	"git.gensokyo.uk/security/fortify/helper/proc"
 	"git.gensokyo.uk/security/fortify/internal"
-	"git.gensokyo.uk/security/fortify/internal/fmsg"
 )
 
 // Std implements System using the standard library.
@@ -33,13 +32,13 @@ 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 +73,9 @@ 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")
-		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