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src: improve get_card_readers logic

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- Use SCARD_AUTOALLOCATE if available. It avoids one extra call to
  SCardListReaders.
- If it's not available handle SCARD_E_INSUFFICIENT_BUFFER error by
  retrying get_card_readers.
This commit is contained in:
Santiago Gimeno
2015-12-29 10:13:45 +01:00
parent c3dcecdb63
commit b63f33c7a0
1 changed files with 41 additions and 9 deletions
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44
src/pcsclite.cpp
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@@ -222,7 +222,12 @@ void PCSCLite::CloseCallback(uv_handle_t *handle) {
/* cleanup process */
AsyncBaton* async_baton = static_cast<AsyncBaton*>(handle->data);
AsyncResult* ar = async_baton->async_result;
#ifdef SCARD_AUTOALLOCATE
PCSCLite* pcsclite = async_baton->pcsclite;
SCardFreeMemory(pcsclite->m_card_context, ar->readers_name);
#else
delete [] ar->readers_name;
#endif
delete ar;
async_baton->callback.Reset();
delete async_baton;
@@ -230,31 +235,58 @@ void PCSCLite::CloseCallback(uv_handle_t *handle) {
LONG PCSCLite::get_card_readers(PCSCLite* pcsclite, AsyncResult* async_result) {
DWORD readers_name_length;
LPTSTR readers_name;
LONG result = SCARD_S_SUCCESS;
/* Reset the readers_name in the baton */
async_result->readers_name = NULL;
async_result->readers_name_length = 0;
#ifdef SCARD_AUTOALLOCATE
readers_name_length = SCARD_AUTOALLOCATE;
result = SCardListReaders(pcsclite->m_card_context,
NULL,
(LPTSTR)&readers_name,
&readers_name_length);
#else
/* Find out ReaderNameLength */
DWORD readers_name_length;
result = SCardListReaders(pcsclite->m_card_context, NULL, NULL, &readers_name_length);
result = SCardListReaders(pcsclite->m_card_context,
NULL,
NULL,
&readers_name_length);
if (result != SCARD_S_SUCCESS) {
return result;
}
/* Allocate Memory for ReaderName and retrieve all readers in the terminal */
char* readers_name = new char[readers_name_length];
result = SCardListReaders(pcsclite->m_card_context, NULL, readers_name, &readers_name_length);
/*
* Allocate Memory for ReaderName and retrieve all readers in the terminal
*/
readers_name = new char[readers_name_length];
result = SCardListReaders(pcsclite->m_card_context,
NULL,
readers_name,
&readers_name_length);
#endif
if (result != SCARD_S_SUCCESS) {
#ifndef SCARD_AUTOALLOCATE
delete [] readers_name;
#endif
readers_name = NULL;
readers_name_length = 0;
#ifndef SCARD_AUTOALLOCATE
/* Retry in case of insufficient buffer error */
if (result == SCARD_E_INSUFFICIENT_BUFFER) {
result = get_card_readers(pcsclite, async_result);
}
#endif
} else {
/* Store the readers_name in the baton */
async_result->readers_name = readers_name;
async_result->readers_name_length = readers_name_length;
}
return result;
}