Perl Requires Chilkat v9.5.0.87+

PC/SC Wait for Smart Card Status Change (Inserted, Removed from Reader, etc.)

See more SCard Examples

Demonstrates how to synchronously wait for a status change, such as for a smart card to be inserted into a reader, or removed from a reader. Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

my $scard = Chilkat2::SCard->new;

# First establish a context to the PC/SC Resource Manager
my $success = $scard->EstablishContext('user');
if (!$success) {
    print $scard->LastErrorText, "\n";
    exit;
}

# First we'll examine the state of all connected readers to see which have smartcards already inserted..
# Get JSON containing information about the smartcards currently inserted into readers.
# This also includes information about USB security tokens.
my $json = Chilkat2::JsonObject->new;
$success = $scard->FindSmartcards($json);
if (!$success) {
    print $scard->LastErrorText, "\n";
    exit;
}

# When writing this example, I have 3 smart card readers plugged into my system.
# One of them has a smart card inserted.
# Here's the JSON returned by FindSmartcards...

# {
#   "reader": [
#     {
#       "name": "Alcor Micro USB Smart Card Reader 0",
#       "state": "empty"
#     },
#     {
#       "name": "Generic Smart Card Reader Interface 0",
#       "state": "present",
#       "vendorName": "Generic",
#       "serialNumber": "3230303730383138303030303030303030",
#       "systemName": "Generic Smart Card Reader Interface 0",
#       "card": {
#         "atr": "3BFC180000813180459067464A00641606F2727E00E0",
#         "windows": {
#           "miniDriver": "tagliov70px.dll",
#           "cryptoProvider": "Microsoft Base Smart Card Crypto Provider",
#           "keyStorageProvider": "Microsoft Smart Card Key Storage Provider"
#         }
#       }
#     },
#     {
#       "name": "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0",
#       "state": "empty"
#     }
#   ]
# }

$json->EmitCompact(0);
print $json->Emit(), "\n";
print " \n";

# We can iterate over the JSON to find the readers with a smart card already inserted..
my $name = '';
my $sbState = Chilkat2::StringBuilder->new;

my $i = 0;
my $count_i = $json->SizeOfArray('reader');
while ($i < $count_i) {
    $json->I($i);
    $name = $json->StringOf('reader[i].name');

    $sbState->Clear();
    $json->StringOfSb('reader[i].state', $sbState);

    if ($sbState->Contains('present', 1)) {
        print $name, " has a smart card inserted.\n";
    } else {
        print $name, " does not have a smart card inserted.\n";
    }

    $i = $i + 1;
}

print " \n";

# Now let's begin the code to wait for a change (where a smart card gets inserted or removed)

# Get the list of all readers.
my $stReaders = Chilkat2::StringTable->new;
$success = $scard->ListReaders($stReaders);
if (!$success) {
    print $scard->LastErrorText, "\n";
    exit;
}

# Show the reader names..
my $numReaders = $stReaders->Count;
$i = 0;
while ($i < $numReaders) {
    print $i, ': ', $stReaders->StringAt($i), "\n";
    $i = $i + 1;
}

# Sample output from the above loop.
# 0: Alcor Micro USB Smart Card Reader 0
# 1: Generic Smart Card Reader Interface 0
# 2: SCM Microsystems Inc. SCR33x USB Smart Card Reader 0
#

# Synchronously wait 30 seconds for a card to be inserted or removed from any of the above readers.
my $json2 = Chilkat2::JsonObject->new;
$success = $scard->GetStatusChange(30000, $stReaders, $json2);
if (!$success) {
    print $scard->LastErrorText, "\n";
    exit;
}

print " \n";

# Let's see what happened...
$json2->EmitCompact(0);
print $json2->Emit(), "\n";
print " \n";

# This is what json2 contains.
# A card was inserted into the reader named "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0"
# The "numChanged" indicates that one reader's status changed.
# The "changed":true indicates the reader that changed.   The state is now "present".

# {
#   "numChanged": 1,
#   "reader": [
#     {
#       "name": "Alcor Micro USB Smart Card Reader 0",
#       "changed": false,
#       "state": "empty"
#     },
#     {
#       "name": "Generic Smart Card Reader Interface 0",
#       "changed": false,
#       "state": "present",
#       "atr": "3BFC180000813180459067464A00641606F2727E00E0"
#     },
#     {
#       "name": "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0",
#       "changed": true,
#       "state": "present",
#       "atr": "3BDF96FF8131FE455A018048494443313158587300011B09"
#     }
#   ]
# }

# Find the reader that changed...
my $changed = 0;
my $state = '';
my $atr = '';

my $numChanged = $json2->IntOf('numChanged');
print 'number of readers with a changed state: ', $numChanged, "\n";

$i = 0;
$count_i = $json2->SizeOfArray('reader');
while ($i < $count_i) {
    $json2->I($i);
    $changed = $json2->BoolOf('reader[i].changed');
    if ($changed) {
        $name = $json2->StringOf('reader[i].name');
        $state = $json2->StringOf('reader[i].state');

        print "Changed: \n";
        print '    reader name: ', $name, "\n";
        print '    new state: ', $state, "\n";

        # If a card is now in this reader, we should have the ATR of the card..
        if ($json2->HasMember('reader[i].atr')) {
            $atr = $json2->StringOf('reader[i].atr');
            print '    ATR of card inserted into this reader: ', $atr, "\n";
        }
    }

    $i = $i + 1;
}

# The output from the above loop:

# number of readers with a changed state: 1
# Changed:
#     reader name: SCM Microsystems Inc. SCR33x USB Smart Card Reader 0
#     new state: present
#     ATR of card inserted into this reader: 3BDF96FF8131FE455A018048494443313158587300011B09

# Applications should always release the context when finished.
$success = $scard->ReleaseContext();
if (!$success) {
    print $scard->LastErrorText, "\n";
}