Improved SCardGetStatusChange() for "\\?PnP?\Notification" special reader

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>

#include <winscard.h>

#define CHECK(f, rv, panic) \
 printf(f "(): 0x%08lX, %s\n", rv, pcsc_stringify_error(rv)); \
 if ((SCARD_S_SUCCESS != rv) && panic) \
 { \
  return -1; \
 }

#define PANIC true
#define DONT_PANIC false

#define MAX_READERS 16

int main(void)
{
    LONG rv;
    SCARDCONTEXT hContext;
    LPTSTR mszReaders;
    DWORD dwReaders = 0;
    char *ptr, *readers[MAX_READERS] = {};
    int nb_readers;
    SCARD_READERSTATE rgReaderStates[MAX_READERS];

    rv = SCardEstablishContext(SCARD_SCOPE_SYSTEM, NULL, NULL, &hContext);
    CHECK("SCardEstablishContext", rv, PANIC)

    rv = SCardListReaders(hContext, NULL, NULL, &dwReaders);
    CHECK("SCardListReaders", rv, DONT_PANIC)

    mszReaders = calloc(dwReaders, sizeof(char));
    rv = SCardListReaders(hContext, NULL, mszReaders, &dwReaders);
    CHECK("SCardListReaders", rv, DONT_PANIC)
    printf("Found readers:\n");
    nb_readers = 0;
    for (ptr=mszReaders; *ptr; ptr += strlen(ptr) +1)
    {
        printf(" %s\n", ptr);
        readers[nb_readers++] = ptr;
    }
    printf("Found %d readers\n", nb_readers);

    /* add the special reader */
    readers[nb_readers++] = "\\\\?PnP?\\Notification";

    /* get the initial states */
    for (int i=0; i<nb_readers; i++)
    {
        rgReaderStates[i].szReader = readers[i];
        rgReaderStates[i].dwCurrentState = SCARD_STATE_UNAWARE;
    }
    rv = SCardGetStatusChange(hContext, 0, rgReaderStates, nb_readers);
    CHECK("SCardGetStatusChange", rv, DONT_PANIC)

    /* set the current state */
    for (int i=0; i<nb_readers; i++)
    {
        rgReaderStates[i].dwCurrentState = rgReaderStates[i].dwEventState;
        printf("reader: %s, events #: %d\n",
            readers[i], rgReaderStates[i].dwEventState >> 16);
        printf("reader: %s, events state 0x%04X\n",
            readers[i], rgReaderStates[i].dwEventState & 0xFFFF);
    }

    /* wait for a change */
    rv = SCardGetStatusChange(hContext, INFINITE, rgReaderStates, nb_readers);
    CHECK("SCardGetStatusChange", rv, PANIC)

    /* new state */
    for (int i=0; i<nb_readers; i++)
    {
        printf("reader: %s, events #: %d\n",
            readers[i], rgReaderStates[i].dwEventState >> 16);
        printf("reader: %s, events state 0x%04X\n",
            readers[i], rgReaderStates[i].dwEventState & 0xFFFF);
    }

    free(mszReaders);

    rv = SCardReleaseContext(hContext);
    CHECK("SCardReleaseContext", rv, PANIC)

    return 0;
}

# Linux
PCSC_CFLAGS := $(shell pkg-config --cflags libpcsclite)
LDLIBS := $(shell pkg-config --libs libpcsclite)

CFLAGS = $(PCSC_CFLAGS) -g

sample: sample.c

clean:
    rm -f sample