I see you have a .travis.yml file.
Maybe you could add a travis button in the README.md to link to the Travis results?
https://travis-ci.org/ebfe/scard

Hi,

I am using go version go1.11 linux/amd64 on Ubuntu 16.04. When I try to get the code with go get github.com/ebfe/scard I get the following error:

# github.com/ebfe/go.pcsclite/scard
cgo-gcc-prolog: In function ‘_cgo_7cdefc941711_Cfunc_SCardGetStatusChange’:
cgo-gcc-prolog:209:56: warning: passing argument 3 of ‘SCardGetStatusChange’ from incompatible pointer type [-Wincompatible-pointer-types]
In file included from ../../../go/src/github.com/ebfe/go.pcsclite/scard/scard.go:12:0:
/usr/include/PCSC/winscard.h:87:16: note: expected ‘LPSCARD_READERSTATE {aka struct <anonymous> *}’ but argument is of type ‘struct <anonymous> *’
  PCSC_API LONG SCardGetStatusChange(SCARDCONTEXT hContext,
                ^
# github.com/ebfe/go.pcsclite/scard
../../../go/src/github.com/ebfe/go.pcsclite/scard/scard.go:150:31: cannot use _Ctype_LPSCARD_READERSTATE(unsafe.Pointer(&crs[0])) (type Ctype_LPSCARD_READERSTATE) as type *_Ctype_struct___2 in argument to func literal

Any ideas?

Kind Regards,
Antonio

In darwin, the struct SCARD_READERSTATE is declared as packed with alignment of 1 byte.

type scardReaderState struct { 
        szReader       uintptr
        pvUserData     uintptr
        dwCurrentState uint32
        dwEventState   uint32
        cbAtr          uint32
        rgbAtr         [33]byte
}

Go adds 3 bytes of padding at the end of this struct. So the cast of states in scard_darwin.go is invalid, because there are bytes between the elements of the array which shouldn't be there:

func scardGetStatusChange(ctx uintptr, timeout uint32, states []scardReaderState) Error {                        
        r := C.SCardGetStatusChange(C.SCARDCONTEXT(ctx), C.uint32_t(timeout), (C.LPSCARD_READERSTATE_A)(unsafe.Pointer(&states[0])), C.uint32_t(len(states)))
        return Error(r)
}

As a result, code using GetStatusChange in darwin segfaults.

go get -u github.com/ebfe/scard

github.com/ebfe/scard

../github.com/ebfe/scard/scard_darwin.go:7:11: fatal error: 'PCSC/winscard.h' file not found
#include <PCSC/winscard.h>

Environment: go1.8 , linux

Error during compilation.

Error Message:
cgo-gcc-prolog:198:2: warning: passing argument 3 of ‘SCardGetStatusChange’ from incompatible pointer type [enabled by default]

/usr/include/PCSC/winscard.h:64:16: note: expected ‘LPSCARD_READERSTATE’ but argument is of type ‘struct *’
PCSC_API LONG SCardGetStatusChange(SCARDCONTEXT hContext,

Thanks for this repo, I got example running:

Found 1 readers:
[0] ACS ACR122U PICC Interface
Waiting for a Card
Connecting to card in  ACS ACR122U PICC Interface
Card status:
	reader: ACS ACR122U PICC Interface
	state: 54
	active protocol: 2
	atr: 3b 80 80 01 01
Transmit:
	c-apdu: 00 a4 00 0c 02 3f 00
	r-apdu: 6a 82

But wondering, how do I read the NDEF URI tag my device is sending. Is that a call to transmit with some payload or a simpler way?

I'm using this module via https://github.com/yawn/ykoath/blob/master/ykoath.go and running into something I'd like to implement.

Right now, if I have multiple yubikeys plugged in, they get the same reader name, suffixed with an integer, but the naming is based on insertion order, so it changes depending on which device I plug in first.

As an example:

package main

import (
	"fmt"

	"github.com/ebfe/scard"
)

func main() {
	context, err := scard.EstablishContext()
	if err != nil {
		panic(err)
	}

	readers, err := context.ListReaders()
	if err != nil {
		panic(err)
	}

	for _, reader := range readers {
		fmt.Println(reader)
	}
}

❯ go run ./main.go
Yubico YubiKey OTP+FIDO+CCID
Yubico YubiKey OTP+FIDO+CCID 01

I poked around a bit at this library to see if there's a way to pull a unique identifier from the attributes, but this seems like the obly attributes that the yubikey supports (thought supports is a bit of a stretch, given that most of them are blank):

Yubico YubiKey OTP+FIDO+CCID 01: AttrChannelId:
Yubico YubiKey OTP+FIDO+CCID 01: AttrIccPresence:
Yubico YubiKey OTP+FIDO+CCID 01: AttrIccInterfaceStatus:
Yubico YubiKey OTP+FIDO+CCID 01: AttrAtrString: ;��1��s�!�WYubiKey@
Yubico YubiKey OTP+FIDO+CCID 01: AttrMaxinput: �

Yubico YubiKey OTP+FIDO+CCID 01: AttrVendorName: Yubico
Yubico YubiKey OTP+FIDO+CCID 01: AttrVendorIfdVersion: C
Yubico YubiKey OTP+FIDO+CCID 01: AttrVendorIfdSerialNo:

Are you aware of a way I can differentiate between the smartcards in a deterministic way?

Hi,
I am using your go lang bindings to connect to a eid card.
The problem is that i can connect to it and send commands using transmit and get successful status from the card, but i am not able to read the data out of the response just the status code.

Can you please help me with this?

There is a lot of overlap between this project and https://github.com/sf1/go-card.

I am currently using this project because I need GetStatusChange, but sf1/go-card has some nice things too, like the ISO Command APDU factory functions, the Reader struct with IsCardPresent() and WaitForCardPresent().

How do you feel about merging those features into ebfe/scard?

See also: sf1/go-card#1