main: split doMount into its own file

Ongoing effort to reduce the size of main().

2 files changed, 224 insertions, 207 deletions

diff --git a/main.go b/main.go
index 9fc9b6b..467a143 100644
--- a/main.go
+++ b/main.go
@@ -1,29 +1,17 @@
 package main
 
 import (
-	"encoding/json"
 	"fmt"
-	"log/syslog"
 	"os"
-	"os/exec"
-	"os/signal"
+
 	"path/filepath"
 	"runtime"
 	"runtime/pprof"
 	"strconv"
-	"strings"
-	"syscall"
 	"time"
 
-	"github.com/hanwen/go-fuse/fuse"
-	"github.com/hanwen/go-fuse/fuse/nodefs"
-	"github.com/hanwen/go-fuse/fuse/pathfs"
-
 	"github.com/rfjakob/gocryptfs/internal/configfile"
 	"github.com/rfjakob/gocryptfs/internal/contentenc"
-	"github.com/rfjakob/gocryptfs/internal/cryptocore"
-	"github.com/rfjakob/gocryptfs/internal/fusefrontend"
-	"github.com/rfjakob/gocryptfs/internal/fusefrontend_reverse"
 	"github.com/rfjakob/gocryptfs/internal/readpassword"
 	"github.com/rfjakob/gocryptfs/internal/stupidgcm"
 	"github.com/rfjakob/gocryptfs/internal/tlog"
@@ -62,7 +50,7 @@ Options:
 	flagSet.PrintDefaults()
 }
 
-// loadConfig - load the config file "filename", prompting the user for the password
+// loadConfig loads the config file "args.config", prompting the user for the password
 func loadConfig(args *argContainer) (masterkey []byte, confFile *configfile.ConfFile) {
 	// Check if the file can be opened at all before prompting for a password
 	fd, err := os.Open(args.config)
@@ -78,7 +66,6 @@ func loadConfig(args *argContainer) (masterkey []byte, confFile *configfile.Conf
 		tlog.Fatal.Println(err)
 		os.Exit(ErrExitLoadConf)
 	}
-
 	return masterkey, confFile
 }
 
@@ -227,196 +214,5 @@ func main() {
 		changePassword(&args) // does not return
 	}
 	// Mount
-	// Check mountpoint
-	if flagSet.NArg() != 2 {
-		tlog.Fatal.Printf("Usage: %s [OPTIONS] CIPHERDIR MOUNTPOINT", tlog.ProgramName)
-		os.Exit(ErrExitUsage)
-	}
-	args.mountpoint, err = filepath.Abs(flagSet.Arg(1))
-	if err != nil {
-		tlog.Fatal.Printf("Invalid mountpoint: %v", err)
-		os.Exit(ErrExitMountPoint)
-	}
-	if args.nonempty {
-		err = checkDir(args.mountpoint)
-	} else {
-		err = checkDirEmpty(args.mountpoint)
-	}
-	if err != nil {
-		tlog.Fatal.Printf("Invalid mountpoint: %v", err)
-		os.Exit(ErrExitMountPoint)
-	}
-	// Get master key
-	var masterkey []byte
-	var confFile *configfile.ConfFile
-	if args.masterkey != "" {
-		// "-masterkey"
-		tlog.Info.Printf("Using explicit master key.")
-		masterkey = parseMasterKey(args.masterkey)
-		tlog.Info.Printf(tlog.ColorYellow +
-			"THE MASTER KEY IS VISIBLE VIA \"ps ax\" AND MAY BE STORED IN YOUR SHELL HISTORY!\n" +
-			"ONLY USE THIS MODE FOR EMERGENCIES." + tlog.ColorReset)
-	} else if args.zerokey {
-		// "-zerokey"
-		tlog.Info.Printf("Using all-zero dummy master key.")
-		tlog.Info.Printf(tlog.ColorYellow +
-			"ZEROKEY MODE PROVIDES NO SECURITY AT ALL AND SHOULD ONLY BE USED FOR TESTING." +
-			tlog.ColorReset)
-		masterkey = make([]byte, cryptocore.KeyLen)
-	} else {
-		// Load master key from config file
-		masterkey, confFile = loadConfig(&args)
-		printMasterKey(masterkey)
-	}
-	// Initialize FUSE server
-	tlog.Debug.Printf("cli args: %v", args)
-	srv := initFuseFrontend(masterkey, args, confFile)
-	tlog.Info.Println(tlog.ColorGreen + "Filesystem mounted and ready." + tlog.ColorReset)
-	// We have been forked into the background, as evidenced by the set
-	// "notifypid".
-	if args.notifypid > 0 {
-		// Chdir to the root directory so we don't block unmounting the CWD
-		os.Chdir("/")
-		// Switch to syslog
-		if !args.nosyslog {
-			tlog.Info.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_INFO)
-			tlog.Debug.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_DEBUG)
-			tlog.Warn.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_WARNING)
-			tlog.SwitchLoggerToSyslog(syslog.LOG_USER | syslog.LOG_WARNING)
-			// Daemons should close all fds (and we don't want to get killed by
-			// SIGPIPE if any of those get closed on the other end)
-			os.Stderr.Close()
-			os.Stdout.Close()
-			os.Stdin.Close()
-		}
-		// Send SIGUSR1 to our parent
-		sendUsr1(args.notifypid)
-	}
-	// Wait for SIGINT in the background and unmount ourselves if we get it.
-	// This prevents a dangling "Transport endpoint is not connected"
-	// mountpoint if the user hits CTRL-C.
-	handleSigint(srv, args.mountpoint)
-	// Jump into server loop. Returns when it gets an umount request from the kernel.
-	srv.Serve()
-	// main exits with code 0
-}
-
-// initFuseFrontend - initialize gocryptfs/fusefrontend
-// Calls os.Exit on errors
-func initFuseFrontend(key []byte, args argContainer, confFile *configfile.ConfFile) *fuse.Server {
-	// Reconciliate CLI and config file arguments into a fusefrontend.Args struct
-	// that is passed to the filesystem implementation
-	cryptoBackend := cryptocore.BackendGoGCM
-	if args.openssl {
-		cryptoBackend = cryptocore.BackendOpenSSL
-	}
-	if args.aessiv {
-		cryptoBackend = cryptocore.BackendAESSIV
-	}
-	frontendArgs := fusefrontend.Args{
-		Cipherdir:      args.cipherdir,
-		Masterkey:      key,
-		PlaintextNames: args.plaintextnames,
-		LongNames:      args.longnames,
-		CryptoBackend:  cryptoBackend,
-	}
-	// confFile is nil when "-zerokey" or "-masterkey" was used
-	if confFile != nil {
-		// Settings from the config file override command line args
-		frontendArgs.PlaintextNames = confFile.IsFeatureFlagSet(configfile.FlagPlaintextNames)
-		if confFile.IsFeatureFlagSet(configfile.FlagAESSIV) {
-			frontendArgs.CryptoBackend = cryptocore.BackendAESSIV
-		} else if args.reverse {
-			tlog.Fatal.Printf("AES-SIV is required by reverse mode, but not enabled in the config file")
-			os.Exit(ErrExitUsage)
-		}
-	}
-	// If allow_other is set and we run as root, try to give newly created files to
-	// the right user.
-	if args.allow_other && os.Getuid() == 0 {
-		frontendArgs.PreserveOwner = true
-	}
-	jsonBytes, _ := json.MarshalIndent(frontendArgs, "", "\t")
-	tlog.Debug.Printf("frontendArgs: %s", string(jsonBytes))
-	var finalFs pathfs.FileSystem
-	if args.reverse {
-		finalFs = fusefrontend_reverse.NewFS(frontendArgs)
-	} else {
-		finalFs = fusefrontend.NewFS(frontendArgs)
-	}
-	pathFsOpts := &pathfs.PathNodeFsOptions{ClientInodes: true}
-	pathFs := pathfs.NewPathNodeFs(finalFs, pathFsOpts)
-	fuseOpts := &nodefs.Options{
-		// These options are to be compatible with libfuse defaults,
-		// making benchmarking easier.
-		NegativeTimeout: time.Second,
-		AttrTimeout:     time.Second,
-		EntryTimeout:    time.Second,
-	}
-	conn := nodefs.NewFileSystemConnector(pathFs.Root(), fuseOpts)
-	var mOpts fuse.MountOptions
-	mOpts.AllowOther = false
-	if args.allow_other {
-		tlog.Info.Printf(tlog.ColorYellow + "The option \"-allow_other\" is set. Make sure the file " +
-			"permissions protect your data from unwanted access." + tlog.ColorReset)
-		mOpts.AllowOther = true
-		// Make the kernel check the file permissions for us
-		mOpts.Options = append(mOpts.Options, "default_permissions")
-	}
-	if args.nonempty {
-		mOpts.Options = append(mOpts.Options, "nonempty")
-	}
-	// Set values shown in "df -T" and friends
-	// First column, "Filesystem"
-	mOpts.Options = append(mOpts.Options, "fsname="+args.cipherdir)
-	// Second column, "Type", will be shown as "fuse." + Name
-	mOpts.Name = "gocryptfs"
-	if args.reverse {
-		mOpts.Name += "-reverse"
-	}
-
-	// The kernel enforces read-only operation, we just have to pass "ro".
-	// Reverse mounts are always read-only
-	if args.ro || args.reverse {
-		mOpts.Options = append(mOpts.Options, "ro")
-	}
-	// Add additional mount options (if any) after the stock ones, so the user has
-	// a chance to override them.
-	if args.o != "" {
-		parts := strings.Split(args.o, ",")
-		tlog.Debug.Printf("Adding -o mount options: %v", parts)
-		mOpts.Options = append(mOpts.Options, parts...)
-	}
-	srv, err := fuse.NewServer(conn.RawFS(), args.mountpoint, &mOpts)
-	if err != nil {
-		tlog.Fatal.Printf("Mount failed: %v", err)
-		os.Exit(ErrExitMount)
-	}
-	srv.SetDebug(args.fusedebug)
-
-	// All FUSE file and directory create calls carry explicit permission
-	// information. We need an unrestricted umask to create the files and
-	// directories with the requested permissions.
-	syscall.Umask(0000)
-
-	return srv
-}
-
-func handleSigint(srv *fuse.Server, mountpoint string) {
-	ch := make(chan os.Signal, 1)
-	signal.Notify(ch, os.Interrupt)
-	signal.Notify(ch, syscall.SIGTERM)
-	go func() {
-		<-ch
-		err := srv.Unmount()
-		if err != nil {
-			tlog.Warn.Print(err)
-			tlog.Info.Printf("Trying lazy unmount")
-			cmd := exec.Command("fusermount", "-u", "-z", mountpoint)
-			cmd.Stdout = os.Stdout
-			cmd.Stderr = os.Stderr
-			cmd.Run()
-		}
-		os.Exit(1)
-	}()
+	os.Exit(doMount(&args))
 }
diff --git a/mount.go b/mount.go
new file mode 100644
index 0000000..56f1dc1
--- /dev/null
+++ b/mount.go
@@ -0,0 +1,221 @@
+package main
+
+import (
+	"encoding/json"
+	"log/syslog"
+	"os"
+	"os/exec"
+	"os/signal"
+	"path/filepath"
+	"strings"
+	"syscall"
+	"time"
+
+	"github.com/hanwen/go-fuse/fuse"
+	"github.com/hanwen/go-fuse/fuse/nodefs"
+	"github.com/hanwen/go-fuse/fuse/pathfs"
+
+	"github.com/rfjakob/gocryptfs/internal/configfile"
+	"github.com/rfjakob/gocryptfs/internal/cryptocore"
+	"github.com/rfjakob/gocryptfs/internal/fusefrontend"
+	"github.com/rfjakob/gocryptfs/internal/fusefrontend_reverse"
+	"github.com/rfjakob/gocryptfs/internal/tlog"
+)
+
+// doMount mounts an encrypted directory.
+// Called from main.
+func doMount(args *argContainer) int {
+	// Check mountpoint
+	if flagSet.NArg() != 2 {
+		tlog.Fatal.Printf("Usage: %s [OPTIONS] CIPHERDIR MOUNTPOINT", tlog.ProgramName)
+		os.Exit(ErrExitUsage)
+	}
+	var err error
+	args.mountpoint, err = filepath.Abs(flagSet.Arg(1))
+	if err != nil {
+		tlog.Fatal.Printf("Invalid mountpoint: %v", err)
+		os.Exit(ErrExitMountPoint)
+	}
+	if args.nonempty {
+		err = checkDir(args.mountpoint)
+	} else {
+		err = checkDirEmpty(args.mountpoint)
+	}
+	if err != nil {
+		tlog.Fatal.Printf("Invalid mountpoint: %v", err)
+		os.Exit(ErrExitMountPoint)
+	}
+	// Get master key
+	var masterkey []byte
+	var confFile *configfile.ConfFile
+	if args.masterkey != "" {
+		// "-masterkey"
+		tlog.Info.Printf("Using explicit master key.")
+		masterkey = parseMasterKey(args.masterkey)
+		tlog.Info.Printf(tlog.ColorYellow +
+			"THE MASTER KEY IS VISIBLE VIA \"ps ax\" AND MAY BE STORED IN YOUR SHELL HISTORY!\n" +
+			"ONLY USE THIS MODE FOR EMERGENCIES." + tlog.ColorReset)
+	} else if args.zerokey {
+		// "-zerokey"
+		tlog.Info.Printf("Using all-zero dummy master key.")
+		tlog.Info.Printf(tlog.ColorYellow +
+			"ZEROKEY MODE PROVIDES NO SECURITY AT ALL AND SHOULD ONLY BE USED FOR TESTING." +
+			tlog.ColorReset)
+		masterkey = make([]byte, cryptocore.KeyLen)
+	} else {
+		// Load master key from config file
+		masterkey, confFile = loadConfig(args)
+		printMasterKey(masterkey)
+	}
+	// Initialize FUSE server
+	tlog.Debug.Printf("cli args: %v", args)
+	srv := initFuseFrontend(masterkey, args, confFile)
+	tlog.Info.Println(tlog.ColorGreen + "Filesystem mounted and ready." + tlog.ColorReset)
+	// We have been forked into the background, as evidenced by the set
+	// "notifypid".
+	if args.notifypid > 0 {
+		// Chdir to the root directory so we don't block unmounting the CWD
+		os.Chdir("/")
+		// Switch to syslog
+		if !args.nosyslog {
+			tlog.Info.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_INFO)
+			tlog.Debug.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_DEBUG)
+			tlog.Warn.SwitchToSyslog(syslog.LOG_USER | syslog.LOG_WARNING)
+			tlog.SwitchLoggerToSyslog(syslog.LOG_USER | syslog.LOG_WARNING)
+			// Daemons should close all fds (and we don't want to get killed by
+			// SIGPIPE if any of those get closed on the other end)
+			os.Stderr.Close()
+			os.Stdout.Close()
+			os.Stdin.Close()
+		}
+		// Send SIGUSR1 to our parent
+		sendUsr1(args.notifypid)
+	}
+	// Wait for SIGINT in the background and unmount ourselves if we get it.
+	// This prevents a dangling "Transport endpoint is not connected"
+	// mountpoint if the user hits CTRL-C.
+	handleSigint(srv, args.mountpoint)
+	// Jump into server loop. Returns when it gets an umount request from the kernel.
+	srv.Serve()
+	return 0
+}
+
+// initFuseFrontend - initialize gocryptfs/fusefrontend
+// Calls os.Exit on errors
+func initFuseFrontend(key []byte, args *argContainer, confFile *configfile.ConfFile) *fuse.Server {
+	// Reconciliate CLI and config file arguments into a fusefrontend.Args struct
+	// that is passed to the filesystem implementation
+	cryptoBackend := cryptocore.BackendGoGCM
+	if args.openssl {
+		cryptoBackend = cryptocore.BackendOpenSSL
+	}
+	if args.aessiv {
+		cryptoBackend = cryptocore.BackendAESSIV
+	}
+	frontendArgs := fusefrontend.Args{
+		Cipherdir:      args.cipherdir,
+		Masterkey:      key,
+		PlaintextNames: args.plaintextnames,
+		LongNames:      args.longnames,
+		CryptoBackend:  cryptoBackend,
+	}
+	// confFile is nil when "-zerokey" or "-masterkey" was used
+	if confFile != nil {
+		// Settings from the config file override command line args
+		frontendArgs.PlaintextNames = confFile.IsFeatureFlagSet(configfile.FlagPlaintextNames)
+		if confFile.IsFeatureFlagSet(configfile.FlagAESSIV) {
+			frontendArgs.CryptoBackend = cryptocore.BackendAESSIV
+		} else if args.reverse {
+			tlog.Fatal.Printf("AES-SIV is required by reverse mode, but not enabled in the config file")
+			os.Exit(ErrExitUsage)
+		}
+	}
+	// If allow_other is set and we run as root, try to give newly created files to
+	// the right user.
+	if args.allow_other && os.Getuid() == 0 {
+		frontendArgs.PreserveOwner = true
+	}
+	jsonBytes, _ := json.MarshalIndent(frontendArgs, "", "\t")
+	tlog.Debug.Printf("frontendArgs: %s", string(jsonBytes))
+	var finalFs pathfs.FileSystem
+	if args.reverse {
+		finalFs = fusefrontend_reverse.NewFS(frontendArgs)
+	} else {
+		finalFs = fusefrontend.NewFS(frontendArgs)
+	}
+	pathFsOpts := &pathfs.PathNodeFsOptions{ClientInodes: true}
+	pathFs := pathfs.NewPathNodeFs(finalFs, pathFsOpts)
+	fuseOpts := &nodefs.Options{
+		// These options are to be compatible with libfuse defaults,
+		// making benchmarking easier.
+		NegativeTimeout: time.Second,
+		AttrTimeout:     time.Second,
+		EntryTimeout:    time.Second,
+	}
+	conn := nodefs.NewFileSystemConnector(pathFs.Root(), fuseOpts)
+	var mOpts fuse.MountOptions
+	mOpts.AllowOther = false
+	if args.allow_other {
+		tlog.Info.Printf(tlog.ColorYellow + "The option \"-allow_other\" is set. Make sure the file " +
+			"permissions protect your data from unwanted access." + tlog.ColorReset)
+		mOpts.AllowOther = true
+		// Make the kernel check the file permissions for us
+		mOpts.Options = append(mOpts.Options, "default_permissions")
+	}
+	if args.nonempty {
+		mOpts.Options = append(mOpts.Options, "nonempty")
+	}
+	// Set values shown in "df -T" and friends
+	// First column, "Filesystem"
+	mOpts.Options = append(mOpts.Options, "fsname="+args.cipherdir)
+	// Second column, "Type", will be shown as "fuse." + Name
+	mOpts.Name = "gocryptfs"
+	if args.reverse {
+		mOpts.Name += "-reverse"
+	}
+
+	// The kernel enforces read-only operation, we just have to pass "ro".
+	// Reverse mounts are always read-only
+	if args.ro || args.reverse {
+		mOpts.Options = append(mOpts.Options, "ro")
+	}
+	// Add additional mount options (if any) after the stock ones, so the user has
+	// a chance to override them.
+	if args.o != "" {
+		parts := strings.Split(args.o, ",")
+		tlog.Debug.Printf("Adding -o mount options: %v", parts)
+		mOpts.Options = append(mOpts.Options, parts...)
+	}
+	srv, err := fuse.NewServer(conn.RawFS(), args.mountpoint, &mOpts)
+	if err != nil {
+		tlog.Fatal.Printf("Mount failed: %v", err)
+		os.Exit(ErrExitMount)
+	}
+	srv.SetDebug(args.fusedebug)
+
+	// All FUSE file and directory create calls carry explicit permission
+	// information. We need an unrestricted umask to create the files and
+	// directories with the requested permissions.
+	syscall.Umask(0000)
+
+	return srv
+}
+
+func handleSigint(srv *fuse.Server, mountpoint string) {
+	ch := make(chan os.Signal, 1)
+	signal.Notify(ch, os.Interrupt)
+	signal.Notify(ch, syscall.SIGTERM)
+	go func() {
+		<-ch
+		err := srv.Unmount()
+		if err != nil {
+			tlog.Warn.Print(err)
+			tlog.Info.Printf("Trying lazy unmount")
+			cmd := exec.Command("fusermount", "-u", "-z", mountpoint)
+			cmd.Stdout = os.Stdout
+			cmd.Stderr = os.Stderr
+			cmd.Run()
+		}
+		os.Exit(1)
+	}()
+}