C
C
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 C Downloads
#include <C_CkSCard.h>
#include <C_CkJsonObject.h>
#include <C_CkStringBuilder.h>
#include <C_CkStringTable.h>
void ChilkatSample(void)
{
BOOL success;
HCkSCard scard;
HCkJsonObject json;
const char *name;
HCkStringBuilder sbState;
int i;
int count_i;
HCkStringTable stReaders;
int numReaders;
HCkJsonObject json2;
BOOL changed;
const char *state;
const char *atr;
int numChanged;
success = FALSE;
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.
scard = CkSCard_Create();
// First establish a context to the PC/SC Resource Manager
success = CkSCard_EstablishContext(scard,"user");
if (success == FALSE) {
printf("%s\n",CkSCard_lastErrorText(scard));
CkSCard_Dispose(scard);
return;
}
// 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 = CkJsonObject_Create();
success = CkSCard_FindSmartcards(scard,json);
if (success == FALSE) {
printf("%s\n",CkSCard_lastErrorText(scard));
CkSCard_Dispose(scard);
CkJsonObject_Dispose(json);
return;
}
// 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_putEmitCompact(json,FALSE);
printf("%s\n",CkJsonObject_emit(json));
printf(" \n");
// We can iterate over the JSON to find the readers with a smart card already inserted..
sbState = CkStringBuilder_Create();
i = 0;
count_i = CkJsonObject_SizeOfArray(json,"reader");
while (i < count_i) {
CkJsonObject_putI(json,i);
name = CkJsonObject_stringOf(json,"reader[i].name");
CkStringBuilder_Clear(sbState);
CkJsonObject_StringOfSb(json,"reader[i].state",sbState);
if (CkStringBuilder_Contains(sbState,"present",TRUE) == TRUE) {
printf("%s has a smart card inserted.\n",name);
}
else {
printf("%s does not have a smart card inserted.\n",name);
}
i = i + 1;
}
printf(" \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 = CkStringTable_Create();
success = CkSCard_ListReaders(scard,stReaders);
if (success == FALSE) {
printf("%s\n",CkSCard_lastErrorText(scard));
CkSCard_Dispose(scard);
CkJsonObject_Dispose(json);
CkStringBuilder_Dispose(sbState);
CkStringTable_Dispose(stReaders);
return;
}
// Show the reader names..
numReaders = CkStringTable_getCount(stReaders);
i = 0;
while (i < numReaders) {
printf("%d: %s\n",i,CkStringTable_stringAt(stReaders,i));
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 = CkJsonObject_Create();
success = CkSCard_GetStatusChange(scard,30000,stReaders,json2);
if (success == FALSE) {
printf("%s\n",CkSCard_lastErrorText(scard));
CkSCard_Dispose(scard);
CkJsonObject_Dispose(json);
CkStringBuilder_Dispose(sbState);
CkStringTable_Dispose(stReaders);
CkJsonObject_Dispose(json2);
return;
}
printf(" \n");
// Let's see what happened...
CkJsonObject_putEmitCompact(json2,FALSE);
printf("%s\n",CkJsonObject_emit(json2));
printf(" \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 = CkJsonObject_IntOf(json2,"numChanged");
printf("number of readers with a changed state: %d\n",numChanged);
i = 0;
count_i = CkJsonObject_SizeOfArray(json2,"reader");
while (i < count_i) {
CkJsonObject_putI(json2,i);
changed = CkJsonObject_BoolOf(json2,"reader[i].changed");
if (changed == TRUE) {
name = CkJsonObject_stringOf(json2,"reader[i].name");
state = CkJsonObject_stringOf(json2,"reader[i].state");
printf("Changed: \n");
printf(" reader name: %s\n",name);
printf(" new state: %s\n",state);
// If a card is now in this reader, we should have the ATR of the card..
if (CkJsonObject_HasMember(json2,"reader[i].atr") == TRUE) {
atr = CkJsonObject_stringOf(json2,"reader[i].atr");
printf(" ATR of card inserted into this reader: %s\n",atr);
}
}
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 = CkSCard_ReleaseContext(scard);
if (success == FALSE) {
printf("%s\n",CkSCard_lastErrorText(scard));
}
CkSCard_Dispose(scard);
CkJsonObject_Dispose(json);
CkStringBuilder_Dispose(sbState);
CkStringTable_Dispose(stReaders);
CkJsonObject_Dispose(json2);
}