accounts/scwallet: flag to specify path to smartcard daemon (#19439)

* accounts/scwallet: Add a switch to enable smartcard support

* accounts: change the meaning of the switch

* disable card support in windows until tested
* only activate account if pcscd socket file is present
* the switch is now the path to the socket file

* accounts/scwallet: holiman's review feedback

* accounts/scwallet: send the path to go-pcsclite

* accounts/scwallet: add default, per platform path

* accounts/scwallet: fix error log warning

* accounts/scwallet: update pcsc lib to latest

* accounts/scwallet: use default path from pcsclite

* scwallet: forgot to change switch name

* cmd: minor style cleanups (error handling first, then happy path)

3 files changed, 29 insertions, 0 deletions

diff --git a/cmd/geth/main.go b/cmd/geth/main.go
index 1b23cbd9f..d0a9bb08a 100644
--- a/cmd/geth/main.go
+++ b/cmd/geth/main.go
@@ -66,6 +66,7 @@ var (
 		utils.KeyStoreDirFlag,
 		utils.ExternalSignerFlag,
 		utils.NoUSBFlag,
+		utils.SmartCardDaemonPathFlag,
 		utils.DashboardEnabledFlag,
 		utils.DashboardAddrFlag,
 		utils.DashboardPortFlag,
diff --git a/cmd/geth/usage.go b/cmd/geth/usage.go
index 67b0027f2..4cc77b912 100644
--- a/cmd/geth/usage.go
+++ b/cmd/geth/usage.go
@@ -72,6 +72,7 @@ var AppHelpFlagGroups = []flagGroup{
 			utils.AncientFlag,
 			utils.KeyStoreDirFlag,
 			utils.NoUSBFlag,
+			utils.SmartCardDaemonPathFlag,
 			utils.NetworkIdFlag,
 			utils.TestnetFlag,
 			utils.RinkebyFlag,
diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index 93d162370..7e19ebc0c 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -58,6 +58,7 @@ import (
 	"github.com/ethereum/go-ethereum/p2p/netutil"
 	"github.com/ethereum/go-ethereum/params"
 	whisper "github.com/ethereum/go-ethereum/whisper/whisperv6"
+	pcsclite "github.com/gballet/go-libpcsclite"
 	cli "gopkg.in/urfave/cli.v1"
 )
 
@@ -129,6 +130,11 @@ var (
 		Name:  "nousb",
 		Usage: "Disables monitoring for and managing USB hardware wallets",
 	}
+	SmartCardDaemonPathFlag = cli.StringFlag{
+		Name:  "pcscdpath",
+		Usage: "Path to the smartcard daemon (pcscd) socket file",
+		Value: pcsclite.PCSCDSockName,
+	}
 	NetworkIdFlag = cli.Uint64Flag{
 		Name:  "networkid",
 		Usage: "Network identifier (integer, 1=Frontier, 2=Morden (disused), 3=Ropsten, 4=Rinkeby)",
@@ -1126,6 +1132,7 @@ func SetNodeConfig(ctx *cli.Context, cfg *node.Config) {
 	setWS(ctx, cfg)
 	setNodeUserIdent(ctx, cfg)
 	setDataDir(ctx, cfg)
+	setSmartCard(ctx, cfg)
 
 	if ctx.GlobalIsSet(ExternalSignerFlag.Name) {
 		cfg.ExternalSigner = ctx.GlobalString(ExternalSignerFlag.Name)
@@ -1145,6 +1152,26 @@ func SetNodeConfig(ctx *cli.Context, cfg *node.Config) {
 	}
 }
 
+func setSmartCard(ctx *cli.Context, cfg *node.Config) {
+	// Skip enabling smartcards if no path is set
+	path := ctx.GlobalString(SmartCardDaemonPathFlag.Name)
+	if path == "" {
+		return
+	}
+	// Sanity check that the smartcard path is valid
+	fi, err := os.Stat(path)
+	if err != nil {
+		log.Error("Failed to verify smartcard daemon path", "path", path, "err", err)
+		return
+	}
+	if fi.Mode()&os.ModeType != os.ModeSocket {
+		log.Error("Invalid smartcard daemon path", "path", path, "type", fi.Mode().String())
+		return
+	}
+	// Smartcard daemon path exists and is a socket, enable it
+	cfg.SmartCardDaemonPath = path
+}
+
 func setDataDir(ctx *cli.Context, cfg *node.Config) {
 	switch {
 	case ctx.GlobalIsSet(DataDirFlag.Name):