main: factor out cli arg parsing

The main function has gotten way too big.

cli_args.go

@@ -0,0 +1,76 @@
+package main
+
+import (
+	"flag"
+	"os"
+	"strconv"
+
+	"github.com/rfjakob/gocryptfs/internal/configfile"
+	"github.com/rfjakob/gocryptfs/internal/prefer_openssl"
+	"github.com/rfjakob/gocryptfs/internal/tlog"
+)
+
+// argContainer stores the parsed CLI arguments
+type argContainer struct {
+	debug, init, zerokey, fusedebug, openssl, passwd, foreground, version,
+	plaintextnames, quiet, nosyslog, wpanic,
+	longnames, allow_other, ro, reverse bool
+	masterkey, mountpoint, cipherdir, cpuprofile, config, extpass,
+	memprofile, o string
+	notifypid, scryptn int
+}
+
+var flagSet *flag.FlagSet
+
+// parseCliArgs - parse command line arguments
+func parseCliArgs() (args argContainer) {
+	var err error
+	var opensslAuto string
+
+	flagSet = flag.NewFlagSet(tlog.ProgramName, flag.ExitOnError)
+	flagSet.Usage = usageText
+	flagSet.BoolVar(&args.debug, "d", false, "")
+	flagSet.BoolVar(&args.debug, "debug", false, "Enable debug output")
+	flagSet.BoolVar(&args.fusedebug, "fusedebug", false, "Enable fuse library debug output")
+	flagSet.BoolVar(&args.init, "init", false, "Initialize encrypted directory")
+	flagSet.BoolVar(&args.zerokey, "zerokey", false, "Use all-zero dummy master key")
+	// Tri-state true/false/auto
+	flagSet.StringVar(&opensslAuto, "openssl", "auto", "Use OpenSSL instead of built-in Go crypto")
+	flagSet.BoolVar(&args.passwd, "passwd", false, "Change password")
+	flagSet.BoolVar(&args.foreground, "f", false, "Stay in the foreground")
+	flagSet.BoolVar(&args.version, "version", false, "Print version and exit")
+	flagSet.BoolVar(&args.plaintextnames, "plaintextnames", false, "Do not encrypt file names")
+	flagSet.BoolVar(&args.quiet, "q", false, "")
+	flagSet.BoolVar(&args.quiet, "quiet", false, "Quiet - silence informational messages")
+	flagSet.BoolVar(&args.nosyslog, "nosyslog", false, "Do not redirect output to syslog when running in the background")
+	flagSet.BoolVar(&args.wpanic, "wpanic", false, "When encountering a warning, panic and exit immediately")
+	flagSet.BoolVar(&args.longnames, "longnames", true, "Store names longer than 176 bytes in extra files")
+	flagSet.BoolVar(&args.allow_other, "allow_other", false, "Allow other users to access the filesystem. "+
+		"Only works if user_allow_other is set in /etc/fuse.conf.")
+	flagSet.BoolVar(&args.ro, "ro", false, "Mount the filesystem read-only")
+	flagSet.BoolVar(&args.reverse, "reverse", false, "Reverse mode")
+	flagSet.StringVar(&args.masterkey, "masterkey", "", "Mount with explicit master key")
+	flagSet.StringVar(&args.cpuprofile, "cpuprofile", "", "Write cpu profile to specified file")
+	flagSet.StringVar(&args.memprofile, "memprofile", "", "Write memory profile to specified file")
+	flagSet.StringVar(&args.config, "config", "", "Use specified config file instead of CIPHERDIR/gocryptfs.conf")
+	flagSet.StringVar(&args.extpass, "extpass", "", "Use external program for the password prompt")
+	flagSet.StringVar(&args.o, "o", "", "Pass additional mount options to the kernel, comma-separated list")
+	flagSet.IntVar(&args.notifypid, "notifypid", 0, "Send USR1 to the specified process after "+
+		"successful mount - used internally for daemonization")
+	flagSet.IntVar(&args.scryptn, "scryptn", configfile.ScryptDefaultLogN, "scrypt cost parameter logN. "+
+		"Setting this to a lower value speeds up mounting but makes the password susceptible to brute-force attacks")
+	flagSet.Parse(os.Args[1:])
+
+	// "-openssl" needs some post-processing
+	if opensslAuto == "auto" {
+		args.openssl = prefer_openssl.PreferOpenSSL()
+	} else {
+		args.openssl, err = strconv.ParseBool(opensslAuto)
+		if err != nil {
+			tlog.Fatal.Printf("Invalid \"-openssl\" setting: %v", err)
+			os.Exit(ERREXIT_USAGE)
+		}
+	}
+
+	return args
+}

main.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"encoding/json"
-	"flag"
 	"fmt"
 	"log/syslog"
 	"os"
@@ -26,7 +25,6 @@ import (
 	"github.com/rfjakob/gocryptfs/internal/fusefrontend"
 	"github.com/rfjakob/gocryptfs/internal/fusefrontend_reverse"
 	"github.com/rfjakob/gocryptfs/internal/nametransform"
-	"github.com/rfjakob/gocryptfs/internal/prefer_openssl"
 	"github.com/rfjakob/gocryptfs/internal/readpassword"
 	"github.com/rfjakob/gocryptfs/internal/tlog"
 )
@@ -41,17 +39,6 @@ const (
 	ERREXIT_MOUNTPOINT = 10
 )
 
-type argContainer struct {
-	debug, init, zerokey, fusedebug, openssl, passwd, foreground, version,
-	plaintextnames, quiet, nosyslog, wpanic,
-	longnames, allow_other, ro, reverse bool
-	masterkey, mountpoint, cipherdir, cpuprofile, config, extpass,
-	memprofile, o string
-	notifypid, scryptn int
-}
-
-var flagSet *flag.FlagSet
-
 const pleaseBuildBash = "[not set - please compile using ./build.bash]"
 
 // gocryptfs version according to git, set by build.bash
@@ -169,54 +156,8 @@ func printVersion() {
 func main() {
 	runtime.GOMAXPROCS(4)
 	var err error
-	var args argContainer
 
-	// Parse command line arguments
+	args := parseCliArgs()
-	var opensslAuto string
-	flagSet = flag.NewFlagSet(tlog.ProgramName, flag.ExitOnError)
-	flagSet.Usage = usageText
-	flagSet.BoolVar(&args.debug, "d", false, "")
-	flagSet.BoolVar(&args.debug, "debug", false, "Enable debug output")
-	flagSet.BoolVar(&args.fusedebug, "fusedebug", false, "Enable fuse library debug output")
-	flagSet.BoolVar(&args.init, "init", false, "Initialize encrypted directory")
-	flagSet.BoolVar(&args.zerokey, "zerokey", false, "Use all-zero dummy master key")
-	// Tri-state true/false/auto
-	flagSet.StringVar(&opensslAuto, "openssl", "auto", "Use OpenSSL instead of built-in Go crypto")
-	flagSet.BoolVar(&args.passwd, "passwd", false, "Change password")
-	flagSet.BoolVar(&args.foreground, "f", false, "Stay in the foreground")
-	flagSet.BoolVar(&args.version, "version", false, "Print version and exit")
-	flagSet.BoolVar(&args.plaintextnames, "plaintextnames", false, "Do not encrypt file names")
-	flagSet.BoolVar(&args.quiet, "q", false, "")
-	flagSet.BoolVar(&args.quiet, "quiet", false, "Quiet - silence informational messages")
-	flagSet.BoolVar(&args.nosyslog, "nosyslog", false, "Do not redirect output to syslog when running in the background")
-	flagSet.BoolVar(&args.wpanic, "wpanic", false, "When encountering a warning, panic and exit immediately")
-	flagSet.BoolVar(&args.longnames, "longnames", true, "Store names longer than 176 bytes in extra files")
-	flagSet.BoolVar(&args.allow_other, "allow_other", false, "Allow other users to access the filesystem. "+
-		"Only works if user_allow_other is set in /etc/fuse.conf.")
-	flagSet.BoolVar(&args.ro, "ro", false, "Mount the filesystem read-only")
-	flagSet.BoolVar(&args.reverse, "reverse", false, "Reverse mode")
-	flagSet.StringVar(&args.masterkey, "masterkey", "", "Mount with explicit master key")
-	flagSet.StringVar(&args.cpuprofile, "cpuprofile", "", "Write cpu profile to specified file")
-	flagSet.StringVar(&args.memprofile, "memprofile", "", "Write memory profile to specified file")
-	flagSet.StringVar(&args.config, "config", "", "Use specified config file instead of CIPHERDIR/gocryptfs.conf")
-	flagSet.StringVar(&args.extpass, "extpass", "", "Use external program for the password prompt")
-	flagSet.StringVar(&args.o, "o", "", "Pass additional mount options to the kernel, comma-separated list")
-	flagSet.IntVar(&args.notifypid, "notifypid", 0, "Send USR1 to the specified process after "+
-		"successful mount - used internally for daemonization")
-	flagSet.IntVar(&args.scryptn, "scryptn", configfile.ScryptDefaultLogN, "scrypt cost parameter logN. "+
-		"Setting this to a lower value speeds up mounting but makes the password susceptible to brute-force attacks")
-	flagSet.Parse(os.Args[1:])
-
-	// "-openssl" needs some post-processing
-	if opensslAuto == "auto" {
-		args.openssl = prefer_openssl.PreferOpenSSL()
-	} else {
-		args.openssl, err = strconv.ParseBool(opensslAuto)
-		if err != nil {
-			tlog.Fatal.Printf("Invalid \"-openssl\" setting: %v", err)
-			os.Exit(ERREXIT_USAGE)
-		}
-	}
 
 	// Fork a child into the background if "-f" is not set AND we are mounting a filesystem
 	if !args.foreground && flagSet.NArg() == 2 {