(Perl) 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.

Note: This functionality was introduced in Chilkat v9.5.0.87.

Chilkat Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux, Solaris

use chilkat();

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

$scard = chilkat::CkSCard->new();

# First establish a context to the PC/SC Resource Manager
$success = $scard->EstablishContext("user");
if ($success == 0) {
    print $scard->lastErrorText() . "\r\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.
$json = chilkat::CkJsonObject->new();
$success = $scard->FindSmartcards($json);
if ($success == 0) {
    print $scard->lastErrorText() . "\r\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->put_EmitCompact(0);
print $json->emit() . "\r\n";
print " " . "\r\n";

# We can iterate over the JSON to find the readers with a smart card already inserted..

$sbState = chilkat::CkStringBuilder->new();

$i = 0;
$count_i = $json->SizeOfArray("reader");
while ($i < $count_i) {
    $json->put_I($i);
    $name = $json->stringOf("reader[i].name");

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

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

    $i = $i + 1;
}

print " " . "\r\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.
$stReaders = chilkat::CkStringTable->new();
$success = $scard->ListReaders($stReaders);
if ($success == 0) {
    print $scard->lastErrorText() . "\r\n";
    exit;
}

# Show the reader names..
$numReaders = $stReaders->get_Count();
$i = 0;
while ($i < $numReaders) {
    print $i . ": " . $stReaders->stringAt($i) . "\r\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.
$json2 = chilkat::CkJsonObject->new();
$success = $scard->GetStatusChange(30000,$stReaders,$json2);
if ($success == 0) {
    print $scard->lastErrorText() . "\r\n";
    exit;
}

print " " . "\r\n";

# Let's see what happened...
$json2->put_EmitCompact(0);
print $json2->emit() . "\r\n";
print " " . "\r\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...

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

$i = 0;
$count_i = $json2->SizeOfArray("reader");
while ($i < $count_i) {
    $json2->put_I($i);
    $changed = $json2->BoolOf("reader[i].changed");
    if ($changed == 1) {
        $name = $json2->stringOf("reader[i].name");
        $state = $json2->stringOf("reader[i].state");

        print "Changed: " . "\r\n";
        print "    reader name: " . $name . "\r\n";
        print "    new state: " . $state . "\r\n";

        # If a card is now in this reader, we should have the ATR of the card..
        if ($json2->HasMember("reader[i].atr") == 1) {
            $atr = $json2->stringOf("reader[i].atr");
            print "    ATR of card inserted into this reader: " . $atr . "\r\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 == 0) {
    print $scard->lastErrorText() . "\r\n";
}