(Tcl) 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.

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load ./chilkat.dll

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

set scard [new_CkSCard]

# First establish a context to the PC/SC Resource Manager
set success [CkSCard_EstablishContext $scard "user"]
if {$success == 0} then {
    puts [CkSCard_lastErrorText $scard]
    delete_CkSCard $scard
    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.
set json [new_CkJsonObject]

set success [CkSCard_FindSmartcards $scard $json]
if {$success == 0} then {
    puts [CkSCard_lastErrorText $scard]
    delete_CkSCard $scard
    delete_CkJsonObject $json
    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"
#     }
#   ]
# }

CkJsonObject_put_EmitCompact $json 0
puts [CkJsonObject_emit $json]
puts " "

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

set sbState [new_CkStringBuilder]

set i 0
set count_i [CkJsonObject_SizeOfArray $json "reader"]
while {$i < $count_i} {
    CkJsonObject_put_I $json $i
    set name [CkJsonObject_stringOf $json "reader[i].name"]

    CkStringBuilder_Clear $sbState
    CkJsonObject_StringOfSb $json "reader[i].state" $sbState

    if {[CkStringBuilder_Contains $sbState "present" 1] == 1} then {
        puts "$name has a smart card inserted."
    }     else {
        puts "$name does not have a smart card inserted."
    }

    set i [expr $i + 1]
}
puts " "

# 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.
set stReaders [new_CkStringTable]

set success [CkSCard_ListReaders $scard $stReaders]
if {$success == 0} then {
    puts [CkSCard_lastErrorText $scard]
    delete_CkSCard $scard
    delete_CkJsonObject $json
    delete_CkStringBuilder $sbState
    delete_CkStringTable $stReaders
    exit
}

# Show the reader names..
set numReaders [CkStringTable_get_Count $stReaders]
set i 0
while {$i < $numReaders} {
    puts "$i: [CkStringTable_stringAt $stReaders $i]"
    set i [expr $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.
set json2 [new_CkJsonObject]

set success [CkSCard_GetStatusChange $scard 30000 $stReaders $json2]
if {$success == 0} then {
    puts [CkSCard_lastErrorText $scard]
    delete_CkSCard $scard
    delete_CkJsonObject $json
    delete_CkStringBuilder $sbState
    delete_CkStringTable $stReaders
    delete_CkJsonObject $json2
    exit
}

puts " "

# Let's see what happened...
CkJsonObject_put_EmitCompact $json2 0
puts [CkJsonObject_emit $json2]
puts " "

# 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...

set numChanged [CkJsonObject_IntOf $json2 "numChanged"]
puts "number of readers with a changed state: $numChanged"

set i 0
set count_i [CkJsonObject_SizeOfArray $json2 "reader"]
while {$i < $count_i} {
    CkJsonObject_put_I $json2 $i
    set changed [CkJsonObject_BoolOf $json2 "reader[i].changed"]
    if {$changed == 1} then {
        set name [CkJsonObject_stringOf $json2 "reader[i].name"]
        set state [CkJsonObject_stringOf $json2 "reader[i].state"]

        puts "Changed: "
        puts "    reader name: $name"
        puts "    new state: $state"

        # If a card is now in this reader, we should have the ATR of the card..
        if {[CkJsonObject_HasMember $json2 "reader[i].atr"] == 1} then {
            set atr [CkJsonObject_stringOf $json2 "reader[i].atr"]
            puts "    ATR of card inserted into this reader: $atr"
        }

    }

    set i [expr $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.
set success [CkSCard_ReleaseContext $scard]
if {$success == 0} then {
    puts [CkSCard_lastErrorText $scard]
}


delete_CkSCard $scard
delete_CkJsonObject $json
delete_CkStringBuilder $sbState
delete_CkStringTable $stReaders
delete_CkJsonObject $json2