[Pcsclite-muscle] A recent change causes SCardCancel() to block?

[Frank Morgner]

I'm observing the same issue with pcsc-lite version 1.8.16 in OpenSC, where
we've activated a blocking SCardGetStatusChange recently. As a result,
OpenSC currently stalls Firefox when the browser is closed or the module is
unloaded. See also the OpenSC ticket
<https://github.com/OpenSC/OpenSC/issues/1065>.

Regards, Frank.

2017-06-14 11:43 GMT+02:00 Ran Benita <ran234 at gmail.com>:

> Hello,
>
> I have noticed a change in behavior in one of the recent pcsclite
> releases. I am using pcsclite 1.8.21 and ccid 1.4.27 on ArchLinux.
>
> The program below calls a blocking SCardGetStatusChange, but before that
> spwans a thread which waits for a key press, then calls SCardCancel (on
> the same context). It is a port of the Rust program here:
> https://raw.githubusercontent.com/bluetech/pcsc-rust/
> 01bd4d80e366ef00f7006dabee45c8cb356d8566/pcsc/examples/cancel.rs
>
> Previously, the SCardCancel would return immediately and would cause
> SCardGetStatusChange to return SCARD_E_CANCELLED immediately.
>
> Now, SCardCancel blocks until SCardGetStatusChange times out, and only
> then returns SCARD_S_SUCCESS.
>
> Is this an intended change, or a regression? Or maybe I'm doing
> something wrong?
>
> Thanks,
> Ran
>
> // gcc -Wall -pthread $(pkg-config --libs --cflags libpcsclite) cancel.c
> -o cancel
> #include <stdio.h>
> #include <unistd.h>
> #include <assert.h>
> #include <pthread.h>
>
> #include <PCSC/winscard.h>
>
> static SCARDCONTEXT context;
>
> static void *canceler_thread(void *arg) {
>     LONG ret;
>
>     getchar();
>
>     printf("Calling SCardCancel...\n");
>     ret = SCardCancel(context);
>     assert(ret == SCARD_S_SUCCESS);
>     printf("SCardCancel returned SCARD_S_SUCCESS\n");
>
>     return NULL;
> }
>
> int main(void) {
>     LONG ret;
>
>     ret = SCardEstablishContext(SCARD_SCOPE_USER, NULL, NULL, &context);
>     assert(ret == SCARD_S_SUCCESS);
>
>     // Spawn a thread which waits for a key-press then cancels the
> operation.
>     pthread_t thread;
>     ret = pthread_create(&thread, NULL, canceler_thread, NULL);
>
>     // Set up the blocking call, and wait for cancel or timeout.
>     printf("Entering blocking call; press Enter to cancel\n");
>     SCARD_READERSTATE reader_states[] = {
>         {
>             .szReader = "\\\\?PnP?\\Notification",
>             .pvUserData = NULL,
>             .dwCurrentState = SCARD_STATE_UNAWARE,
>             .dwEventState = SCARD_STATE_UNAWARE,
>         },
>     };
>
>     ret = SCardGetStatusChange(context, 5000, reader_states, 1);
>     switch (ret) {
>     case SCARD_S_SUCCESS:
>         printf("Blocking call exited normally\n");
>         break;
>
>     case SCARD_E_CANCELLED:
>         printf("Blocking call canceled\n");
>         break;
>
>     case SCARD_E_TIMEOUT:
>         printf("Blocking call timed out\n");
>         break;
>
>     default:
>         fprintf(stderr, "Failed to get status changes: %ld", ret);
>         break;
>     }
>
>     printf("Sleeping before existing main thread...\n");
>     sleep(5);
>
>     return 0;
> }
>
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