fmsg: produce all output through fmsg

The behaviour of print functions from package fmt is not thread safe. Functions provided by fmsg wrap around Logger methods. This makes prefix much cleaner and makes it easy to deal with future changes to logging.

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

internal/shim/main.go

@@ -4,7 +4,6 @@ import (
 	"encoding/gob"
 	"errors"
 	"flag"
-	"fmt"
 	"net"
 	"os"
 	"path"
@@ -12,29 +11,29 @@ import (
 	"syscall"
 
 	"git.ophivana.moe/security/fortify/helper"
+	"git.ophivana.moe/security/fortify/internal/fmsg"
 	init0 "git.ophivana.moe/security/fortify/internal/init"
-	"git.ophivana.moe/security/fortify/internal/verbose"
 )
 
 // everything beyond this point runs as target user
 // proceed with caution!
 
 func doShim(socket string) {
+	fmsg.SetPrefix("shim")
+
 	// re-exec
 	if len(os.Args) > 0 && os.Args[0] != "fortify" && path.IsAbs(os.Args[0]) {
 		if err := syscall.Exec(os.Args[0], []string{"fortify", "shim"}, os.Environ()); err != nil {
-			fmt.Println("fortify-shim: cannot re-exec self:", err)
+			fmsg.Println("cannot re-exec self:", err)
 			// continue anyway
 		}
 	}
 
-	verbose.Prefix = "fortify-shim:"
-
 	// dial setup socket
 	var conn *net.UnixConn
 	if c, err := net.DialUnix("unix", nil, &net.UnixAddr{Name: socket, Net: "unix"}); err != nil {
-		fmt.Println("fortify-shim: cannot dial setup socket:", err)
-		os.Exit(1)
+		fmsg.Fatal("cannot dial setup socket:", err)
+		panic("unreachable")
 	} else {
 		conn = c
 	}
@@ -42,25 +41,22 @@ func doShim(socket string) {
 	// decode payload gob stream
 	var payload Payload
 	if err := gob.NewDecoder(conn).Decode(&payload); err != nil {
-		fmt.Println("fortify-shim: cannot decode shim payload:", err)
-		os.Exit(1)
+		fmsg.Fatal("cannot decode shim payload:", err)
 	} else {
 		// sharing stdout with parent
 		// USE WITH CAUTION
-		verbose.Set(payload.Verbose)
+		fmsg.SetVerbose(payload.Verbose)
 	}
 
 	if payload.Bwrap == nil {
-		fmt.Println("fortify-shim: bwrap config not supplied")
-		os.Exit(1)
+		fmsg.Fatal("bwrap config not supplied")
 	}
 
 	// receive wayland fd over socket
 	wfd := -1
 	if payload.WL {
 		if fd, err := receiveWLfd(conn); err != nil {
-			fmt.Println("fortify-shim: cannot receive wayland fd:", err)
-			os.Exit(1)
+			fmsg.Fatal("cannot receive wayland fd:", err)
 		} else {
 			wfd = fd
 		}
@@ -68,7 +64,7 @@ func doShim(socket string) {
 
 	// close setup socket
 	if err := conn.Close(); err != nil {
-		fmt.Println("fortify-shim: cannot close setup socket:", err)
+		fmsg.Println("cannot close setup socket:", err)
 		// not fatal
 	}
 
@@ -83,8 +79,7 @@ func doShim(socket string) {
 		// no argv, look up shell instead
 		var ok bool
 		if ic.Argv0, ok = os.LookupEnv("SHELL"); !ok {
-			fmt.Println("fortify-shim: no command was specified and $SHELL was unset")
-			os.Exit(1)
+			fmsg.Fatal("no command was specified and $SHELL was unset")
 		}
 
 		ic.Argv = []string{ic.Argv0}
@@ -106,41 +101,37 @@ func doShim(socket string) {
 
 	// share config pipe
 	if r, w, err := os.Pipe(); err != nil {
-		fmt.Println("fortify-shim: cannot pipe:", err)
-		os.Exit(1)
+		fmsg.Fatal("cannot pipe:", err)
 	} else {
 		conf.SetEnv[init0.EnvInit] = strconv.Itoa(3 + len(extraFiles))
 		extraFiles = append(extraFiles, r)
 
-		verbose.Println("transmitting config to init")
+		fmsg.VPrintln("transmitting config to init")
 		go func() {
 			// stream config to pipe
 			if err = gob.NewEncoder(w).Encode(&ic); err != nil {
-				fmt.Println("fortify-shim: cannot transmit init config:", err)
-				os.Exit(1)
+				fmsg.Fatal("cannot transmit init config:", err)
 			}
 		}()
 	}
 
 	helper.BubblewrapName = payload.Exec[1] // resolved bwrap path by parent
 	if b, err := helper.NewBwrap(conf, nil, payload.Exec[0], func(int, int) []string { return []string{"init"} }); err != nil {
-		fmt.Println("fortify-shim: malformed sandbox config:", err)
-		os.Exit(1)
+		fmsg.Fatal("malformed sandbox config:", err)
 	} else {
 		cmd := b.Unwrap()
 		cmd.Stdin, cmd.Stdout, cmd.Stderr = os.Stdin, os.Stdout, os.Stderr
 		cmd.ExtraFiles = extraFiles
 
-		if verbose.Get() {
-			verbose.Println("bwrap args:", conf.Args())
+		if fmsg.Verbose() {
+			fmsg.VPrintln("bwrap args:", conf.Args())
 		}
 
 		// run and pass through exit code
 		if err = b.Start(); err != nil {
-			fmt.Println("fortify-shim: cannot start target process:", err)
-			os.Exit(1)
+			fmsg.Fatal("cannot start target process:", err)
 		} else if err = b.Wait(); err != nil {
-			verbose.Println("wait:", err)
+			fmsg.VPrintln("wait:", err)
 		}
 		if b.Unwrap().ProcessState != nil {
 			os.Exit(b.Unwrap().ProcessState.ExitCode())