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ericchiangericchiang
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piv/internal/pcsc: add pure go pcsc client implementation
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4 files changed

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‎piv/internal/pcsc/pcsc.go

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// Copyright 2021 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package pcsc
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import (
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"bytes"
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"context"
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"encoding/binary"
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"fmt"
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"io"
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"net"
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"os"
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)
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var nativeByteOrder binary.ByteOrder
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const (
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pcscSocketPathEnv = "PCSCLITE_CSOCK_NAME"
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pcscSocketPath = "/run/pcscd/pcscd.comm"
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)
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const (
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scardSSuccess = 0
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// https://github.com/LudovicRousseau/PCSC/blob/1.9.0/src/winscard_msg.h#L76
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commandVersion = 0x11
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commandGetReadersState = 0x12
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)
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type Client struct {
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conn net.Conn
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}
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func (c *Client) Close() error {
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return c.conn.Close()
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}
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func (c *Client) version() (major, minor int32, err error) {
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req := struct {
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Major int32
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Minor int32
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RV uint32
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}{4, 4, scardSSuccess}
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var resp struct {
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Major int32
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Minor int32
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RV uint32
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}
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if err := c.sendMessage(commandVersion, req, &resp); err != nil {
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return 0, 0, fmt.Errorf("send message: %v", err)
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}
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if resp.RV != scardSSuccess {
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return 0, 0, fmt.Errorf("invalid response value: %x", resp.RV)
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}
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return resp.Major, resp.Minor, nil
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}
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const (
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// https://github.com/LudovicRousseau/PCSC/blob/1.9.0/src/PCSC/pcsclite.h.in#L286
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maxReaderNameSize = 128
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// https://github.com/LudovicRousseau/PCSC/blob/1.9.0/src/PCSC/pcsclite.h.in#L59
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maxAttributeSize = 33
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// https://github.com/LudovicRousseau/PCSC/blob/1.9.0/src/PCSC/pcsclite.h.in#L284
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maxReaders = 16
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)
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// https://github.com/LudovicRousseau/PCSC/blob/1.9.0/src/eventhandler.h#L52
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// typedef struct pubReaderStatesList
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// {
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// char readerName[MAX_READERNAME]; /**< reader name */
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// uint32_t eventCounter; /**< number of card events */
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// uint32_t readerState; /**< SCARD_* bit field */
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// int32_t readerSharing; /**< PCSCLITE_SHARING_* sharing status */
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//
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// UCHAR cardAtr[MAX_ATR_SIZE]; /**< ATR */
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// uint32_t cardAtrLength; /**< ATR length */
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// uint32_t cardProtocol; /**< SCARD_PROTOCOL_* value */
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// }
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// READER_STATE;
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type readerState struct {
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Name [maxReaderNameSize]byte
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EventCounter uint32
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State uint32
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Sharing uint32
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Attr [maxAttributeSize]byte
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AttrSize uint32
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Protocol uint32
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}
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func (r readerState) name() string {
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if r.Name[0] == 0x00 {
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return ""
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}
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i := len(r.Name)
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for ; i > 0; i-- {
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if r.Name[i-1] != 0x00 {
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break
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}
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}
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return string(r.Name[:i])
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}
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func (c *Client) readers() ([]string, error) {
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var resp [maxReaders]readerState
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if err := c.sendMessage(commandGetReadersState, nil, &resp); err != nil {
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return nil, fmt.Errorf("send message: %v", err)
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}
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var names []string
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for _, r := range resp {
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name := r.name()
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if name != "" {
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names = append(names, name)
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}
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}
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return names, nil
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}
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func (c *Client) sendMessage(command uint32, req, resp interface{}) error {
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var data []byte
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if req != nil {
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b := &bytes.Buffer{}
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if err := binary.Write(b, nativeByteOrder, req); err != nil {
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return fmt.Errorf("marshaling message body: %v", err)
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}
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size := uint32(b.Len())
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data = make([]byte, b.Len()+4+4)
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nativeByteOrder.PutUint32(data[0:4], size)
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nativeByteOrder.PutUint32(data[4:8], command)
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io.ReadFull(b, data[8:])
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} else {
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data = make([]byte, 4+4)
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nativeByteOrder.PutUint32(data[0:4], 0)
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nativeByteOrder.PutUint32(data[4:8], command)
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}
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if _, err := c.conn.Write(data); err != nil {
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return fmt.Errorf("write request bytes: %v", err)
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}
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if err := binary.Read(c.conn, nativeByteOrder, resp); err != nil {
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return fmt.Errorf("read response: %v", err)
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}
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return nil
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}
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type Config struct {
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SocketPath string
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}
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func NewClient(ctx context.Context, c *Config) (*Client, error) {
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p := c.SocketPath
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if p == "" {
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p = os.Getenv(pcscSocketPathEnv)
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}
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if p == "" {
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p = pcscSocketPath
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}
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var d net.Dialer
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conn, err := d.DialContext(ctx, "unix", p)
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if err != nil {
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return nil, fmt.Errorf("dial unix socket: %v", err)
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}
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return &Client{
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conn: conn,
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}, nil
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}

‎piv/internal/pcsc/pcsc_big.go

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// Copyright 2021 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// +build armbe arm64be ppc64 mips mips64 mips64p32 ppc sparc sparc64 s390 s390x
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package pcsc
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import "encoding/binary"
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func init() {
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nativeByteOrder = binary.BigEndian
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}

‎piv/internal/pcsc/pcsc_little.go

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// Copyright 2021 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// +build 386 amd64 amd64p32 arm arm64 mipsle mis64le mips64p32le riscv riscv64
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package pcsc
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import "encoding/binary"
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func init() {
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nativeByteOrder = binary.LittleEndian
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}

‎piv/internal/pcsc/pcsc_test.go

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// Copyright 2021 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package pcsc
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import (
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"context"
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"testing"
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)
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func TestVersion(t *testing.T) {
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c, err := NewClient(context.Background(), &Config{})
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if err != nil {
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t.Fatalf("create client: %v", err)
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}
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defer c.Close()
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major, minor, err := c.version()
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if err != nil {
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t.Fatalf("getting client version: %v", err)
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}
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t.Log(major, minor)
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}
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func TestListReaders(t *testing.T) {
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c, err := NewClient(context.Background(), &Config{})
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if err != nil {
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t.Fatalf("create client: %v", err)
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}
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defer c.Close()
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readers, err := c.readers()
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if err != nil {
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t.Fatalf("listing readers: %v", err)
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}
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t.Log(readers)
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}

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