exitcodes: get rid of generic "Mount" exit code

Instead, create three new specific exit codes:
* FuseNewServer = 19
* CtlSock = 20
* PanicLogCreate = 21

internal/exitcodes/exitcodes.go

@@ -8,12 +8,12 @@ import (
 )
 
 const (
-	// Usage error: cli syntax etc
+	// Usage - usage error like wrong cli syntax, wrong number of parameters.
 	Usage = 1
 	// 2 is reserved because it is used by Go panic
+	// 3 is reserved because it was used by earlier gocryptfs version as a generic
+	// "mount" error.
 
-	// Mount is an error on mount
-	Mount = 3
 	// CipherDir means that the CIPHERDIR does not exist
 	CipherDir = 6
 	// Init is an error on filesystem init
@@ -26,7 +26,8 @@ const (
 	MountPoint = 10
 	// Other error - please inspect the message
 	Other = 11
-	// PasswordIncorrect - the password was incorrect
+	// PasswordIncorrect - the password was incorrect when mounting or when
+	// changing the password.
 	PasswordIncorrect = 12
 	// ScryptParams means that scrypt was called with invalid parameters
 	ScryptParams = 13
@@ -35,12 +36,20 @@ const (
 	MasterKey = 14
 	// SigInt means we got SIGINT
 	SigInt = 15
-	// PanicLog means the panic log was not empty when we were unmounted
+	// PanicLogNotEmpty means the panic log was not empty when we were unmounted
-	PanicLog = 16
+	PanicLogNotEmpty = 16
 	// ForkChild means forking the worker child failed
 	ForkChild = 17
 	// OpenSSL means you tried to enable OpenSSL, but we were compiled without it.
 	OpenSSL = 18
+	// FuseNewServer - this exit code means that the call to fuse.NewServer failed.
+	// This usually means that there was a problem executing fusermount, or
+	// fusermount could not attach the mountpoint to the kernel.
+	FuseNewServer = 19
+	// CtlSock - the control socket file could not be created.
+	CtlSock = 20
+	// PanicLogCreate - there was a problem creating the /tmp/gocryptfs_paniclog.XYZ file.
+	PanicLogCreate = 21
 )
 
 // Err wraps an error with an associated numeric exit code

mount.go

@@ -64,7 +64,7 @@ func doMount(args *argContainer) int {
 		sock, err = net.Listen("unix", args.ctlsock)
 		if err != nil {
 			tlog.Fatal.Printf("ctlsock: %v", err)
-			os.Exit(exitcodes.Mount)
+			os.Exit(exitcodes.CtlSock)
 		}
 		args._ctlsockFd = sock
 		// Close also deletes the socket file
@@ -118,7 +118,7 @@ func doMount(args *argContainer) int {
 			paniclog, err = ioutil.TempFile("", "gocryptfs_paniclog.")
 			if err != nil {
 				tlog.Fatal.Printf("Failed to create gocryptfs_paniclog: %v", err)
-				os.Exit(exitcodes.Mount)
+				os.Exit(exitcodes.PanicLogCreate)
 			}
 			// Switch all of our logs and the generic logger to syslog
 			tlog.Info.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_INFO)
@@ -165,7 +165,7 @@ func doMount(args *argContainer) int {
 		} else if fi.Size() > 0 {
 			tlog.Warn.Printf("paniclog at %q is not empty (size %d). Not deleting it.",
 				paniclog.Name(), fi.Size())
-			return exitcodes.PanicLog
+			return exitcodes.PanicLogNotEmpty
 		} else {
 			syscall.Unlink(paniclog.Name())
 		}
@@ -306,8 +306,8 @@ func initFuseFrontend(key []byte, args *argContainer, confFile *configfile.ConfF
 	}
 	srv, err := fuse.NewServer(conn.RawFS(), args.mountpoint, &mOpts)
 	if err != nil {
-		tlog.Fatal.Printf("Mount failed: %v", err)
+		tlog.Fatal.Printf("fuse.NewServer failed: %v", err)
-		os.Exit(exitcodes.Mount)
+		os.Exit(exitcodes.FuseNewServer)
 	}
 	srv.SetDebug(args.fusedebug)