reader-pcsc: Set flag denoting change when reader is removed

When the removed reader is detected for the first time,
set SC_READER_CARD_CHANGED denoting change. Remove
the flag when the condition is hit again.

Before this change, when reader was removed
the reader->flags in refresh_attributes() was updated
from 0x00000001 (SC_READER_CARD_PRESENT) to 0x00000020
(SC_READER_REMOVED). However, when the reader is still
removed by another call to refresh_attributes(),
the flags remained as 0x00000020 (SC_READER_REMOVED).

Now the flags should change with SC_READER_CARD_CHANGED.

src/libopensc/reader-pcsc.c

@@ -406,7 +406,13 @@ static int refresh_attributes(sc_reader_t *reader)
  || rv == (LONG)SCARD_E_NO_READERS_AVAILABLE
 #endif
  || rv == (LONG)SCARD_E_SERVICE_STOPPED) {
- reader->flags &= ~(SC_READER_CARD_PRESENT);
+ /* Set flag when state changes */
+ if (reader->flags & SC_READER_REMOVED) {
+ reader->flags &= ~SC_READER_CARD_CHANGED;
+ } else {
+ reader->flags |= SC_READER_CARD_CHANGED;
+ }
+ reader->flags &= ~SC_READER_CARD_PRESENT;
  reader->flags |= SC_READER_REMOVED;
  priv->gpriv->removed_reader = reader;
  SC_FUNC_RETURN(reader->ctx, SC_LOG_DEBUG_VERBOSE, SC_SUCCESS);