Go
Go
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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success := false
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.
scard := chilkat.NewSCard()
// First establish a context to the PC/SC Resource Manager
success = scard.EstablishContext("user")
if success == false {
fmt.Println(scard.LastErrorText())
scard.DisposeSCard()
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 := chilkat.NewJsonObject()
success = scard.FindSmartcards(json)
if success == false {
fmt.Println(scard.LastErrorText())
scard.DisposeSCard()
json.DisposeJsonObject()
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"
// }
// ]
// }
json.SetEmitCompact(false)
fmt.Println(*json.Emit())
fmt.Println(" ")
// We can iterate over the JSON to find the readers with a smart card already inserted..
var name *string = new(string)
sbState := chilkat.NewStringBuilder()
i := 0
count_i := json.SizeOfArray("reader")
for i < count_i {
json.SetI(i)
name = json.StringOf("reader[i].name")
sbState.Clear()
json.StringOfSb("reader[i].state",sbState)
if sbState.Contains("present",true) == true {
fmt.Println(*name, " has a smart card inserted.")
} else {
fmt.Println(*name, " does not have a smart card inserted.")
}
i = i + 1
}
fmt.Println(" ")
// 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.NewStringTable()
success = scard.ListReaders(stReaders)
if success == false {
fmt.Println(scard.LastErrorText())
scard.DisposeSCard()
json.DisposeJsonObject()
sbState.DisposeStringBuilder()
stReaders.DisposeStringTable()
return
}
// Show the reader names..
numReaders := stReaders.Count()
i = 0
for i < numReaders {
fmt.Println(i, ": ", *stReaders.StringAt(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 := chilkat.NewJsonObject()
success = scard.GetStatusChange(30000,stReaders,json2)
if success == false {
fmt.Println(scard.LastErrorText())
scard.DisposeSCard()
json.DisposeJsonObject()
sbState.DisposeStringBuilder()
stReaders.DisposeStringTable()
json2.DisposeJsonObject()
return
}
fmt.Println(" ")
// Let's see what happened...
json2.SetEmitCompact(false)
fmt.Println(*json2.Emit())
fmt.Println(" ")
// 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...
var changed bool
var state *string = new(string)
var atr *string = new(string)
numChanged := json2.IntOf("numChanged")
fmt.Println("number of readers with a changed state: ", numChanged)
i = 0
count_i = json2.SizeOfArray("reader")
for i < count_i {
json2.SetI(i)
changed = json2.BoolOf("reader[i].changed")
if changed == true {
name = json2.StringOf("reader[i].name")
state = json2.StringOf("reader[i].state")
fmt.Println("Changed: ")
fmt.Println(" reader name: ", *name)
fmt.Println(" new state: ", *state)
// If a card is now in this reader, we should have the ATR of the card..
if json2.HasMember("reader[i].atr") == true {
atr = json2.StringOf("reader[i].atr")
fmt.Println(" ATR of card inserted into this reader: ", *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 = scard.ReleaseContext()
if success == false {
fmt.Println(scard.LastErrorText())
}
scard.DisposeSCard()
json.DisposeJsonObject()
sbState.DisposeStringBuilder()
stReaders.DisposeStringTable()
json2.DisposeJsonObject()