智能卡服务在 Windows 8 上的行为有所不同，并且 MSDN 尚未更新其文档。谁能提供有关如何正确调用 SCardGetStatusChange 以监视 Windows 8 上的智能卡操作的代码片段？提前致谢！
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2 回答
3
这是我为个人博客项目编写的 C++ 模板函数。它使用我在 github 上开发的一个库，但您也可以将逻辑重新设计到您自己的上下文中。
template<typename SetContext, typename ClearContext, typename Wait, typename Report>
unique_winerror monitor_smartcard_readers(
SetContext&& setContext,
ClearContext&& clearContext,
Wait&& wait,
Report&& report
)
{
unique_winerror winerror;
std::vector<wchar_t> readernames;
std::vector<SCARD_READERSTATE> readers;
while (winerror)
{
//
// make sure that the scard service has started
// and that the loop has not been cancelled
//
if (!std::forward<Wait>(wait)())
{
return winerror_cast(SCARD_E_CANCELLED);
}
monitor_error_contract(
[&] ()
{
unique_close_scardcontext context;
ON_UNWIND_AUTO(
[&]
{
std::forward<ClearContext>(clearContext)();
}
);
//
// need a fresh context whenever we start over.
// lots of sytem changes could have caused this
// restart including the scard service stopping
// and then restarting.
//
winerror.reset(
SCardEstablishContext(
SCARD_SCOPE_USER,
NULL,
NULL,
context.replace()
)
);
if (!winerror || !context)
{
return;
}
std::forward<SetContext>(setContext)(context.get());
//
// make sure that loop has not been cancelled.
// without this there is a race where the new
// context is not cancelled because the caller
// cancelled at a time when there was no
// context yet.
//
if (!std::forward<Wait>(wait)())
{
winerror = winerror_cast(SCARD_E_CANCELLED);
return;
}
if (readers.empty())
{
//
// add PnP state query
// setting the state to unaware causes SCardGetStatusChange
// to return immediately with the actual pnp state.
//
readers.push_back(make(L"\\\\?PnP?\\Notification"));
}
for(;;)
{
auto readersstaterange = lib::rng::make_range_raw(readers);
winerror.reset(
SCardGetStatusChange(
context.get(),
INFINITE,
readersstaterange.begin(),
lib::rng::size_cast<DWORD>(readersstaterange.size())
)
);
if (!winerror)
{
// exit
return;
}
//
// report changes
//
auto readersrange = lib::rng::make_range_raw(readers, 0, -1);
if (!readersrange.empty())
{
std::forward<Report>(report)(readersrange);
}
//
// record the changes we have reported
//
for (auto& state : readers)
{
state.dwCurrentState = state.dwEventState;
}
if ((readers.back().dwEventState & SCARD_STATE_CHANGED) == SCARD_STATE_CHANGED)
{
// Pnp event - list readers.
break;
}
}
// keep the old allocations for use to build the new list.
std::vector<wchar_t> oldreadernames(std::move(readernames));
std::vector<SCARD_READERSTATE> oldreaders(std::move(readers));
// exclude the pnp reader
auto oldreaderssortedrange = lib::rng::make_range(oldreaders, 0, -1);
LPWSTR concatreaderstrings = nullptr;
ON_UNWIND_AUTO(
[&] { if (concatreaderstrings) {SCardFreeMemory(context.get(), concatreaderstrings);};}
);
DWORD totallength = SCARD_AUTOALLOCATE;
winerror.reset(
SCardListReaders(
context.get(),
nullptr,
reinterpret_cast<LPWSTR>(&concatreaderstrings),
&totallength
)
);
if (winerror == winerror_cast(SCARD_E_NO_READERS_AVAILABLE))
{
// no readers is not an error, loop around to wait
// for a reader to be connected
winerror.suppress().release();
return;
}
else if (!winerror)
{
return;
}
// keep the names around because the state array will have pointers into this
readernames.assign(concatreaderstrings, concatreaderstrings + totallength);
auto readerstateless = [](const SCARD_READERSTATE& lhs, const SCARD_READERSTATE& rhs) -> bool
{
return _wcsicmp(lhs.szReader, rhs.szReader) < 0;
};
//
// all the reader names are concatenated in this array with
// embedded nulls for each and two nulls to mark the end
//
auto cursorreadernames = lib::rng::make_range_raw(readernames);
while(!cursorreadernames.empty() && cursorreadernames.front() != L'\0')
{
// access the current name
auto namerange = lib::rng::make_range(
cursorreadernames,
0,
wcslen(cursorreadernames.begin()) - cursorreadernames.size()
);
// skip to the next name
cursorreadernames = lib::rng::make_range(namerange, namerange.size() + 1, 0);
auto oldreader = std::equal_range(
oldreaderssortedrange.begin(),
oldreaderssortedrange.end(),
make(namerange.begin()),
readerstateless
);
if (oldreader.first != oldreader.second)
{
// keep the old state for this reader
readers.push_back(*oldreader.first);
// must use the new string allocation,
// the old one will be gone soon
readers.back().szReader = namerange.begin();
}
else
{
readers.push_back(make(namerange.begin()));
}
}
// keeping them sorted makes the updates more stable and allows the
// equal_range above instead of a linear find.
std::sort(readers.begin(), readers.end(), readerstateless);
//
// add PnP state query
// keep the existing state, and keep it at the
// end, out of the sorted area.
//
readers.push_back(oldreaders.back());
}
);
}
return winerror;
}
用法如下所示：
#define WIN32_LEAN_AND_MEAN // Exclude rarely-used stuff from Windows headers
#define NOMINMAX
// Windows Header Files:
#include <windows.h>
#include <Unknwn.h>
#include <winscard.h>
#include <ncrypt.h>
#include <Wincrypt.h>
#include <credentialprovider.h>
// TODO: reference additional headers your program requires here
#include <type_traits>
#include <algorithm>
#include <new>
#include <memory>
#include <utility>
#include <limits>
#include <iterator>
#include <thread>
#include <future>
#include <mutex>
#include <vector>
#include <iostream>
#include <iomanip>
int wmain(int argc, WCHAR* argv[])
{
unique_winerror winerror;
for (;;)
{
SCARDCONTEXT context = NULL;
// if you monitor in a separate thread, then add a cancel or shutdown event
// into the waitfor array and handle it in the Wait lambda
HANDLE waitfor[] = {SCardAccessStartedEvent()};
ON_UNWIND_AUTO([] {SCardReleaseStartedEvent();});
winerror = smart_card::monitor_smartcard_readers(
[&](SCARDCONTEXT context)
{
context = context;
},
[&]()
{
context = NULL;
},
[&]() -> bool
{
if (WAIT_OBJECT_0 != WaitForMultipleObjects(lib::rng::size(waitfor), waitfor, FALSE, INFINITE))
{
// monitor_smardcard_readers will return SCARD_E_CANCELLED
return false;
}
return true;
},
[&](lib::rng::range<SCARD_READERSTATE*> readersrange)
{
for (auto& state : readersrange)
{
auto stateChanges = (state.dwCurrentState ^ state.dwEventState) & std::numeric_limits<unsigned short>::max();
std::wcout
<< L"nothread - "
<< state.szReader
<< L" changes: " << std::hex << std::showbase << stateChanges
<< L"["
;
printSCardState(std::wcout, stateChanges)
<< L"] state: " << std::hex << std::showbase << state.dwEventState
<< L"["
;
printSCardState(std::wcout, state.dwEventState)
<< L"]"
<< std::endl
;
if (state.dwCurrentState != SCARD_STATE_UNAWARE &&
((state.dwEventState & SCARD_STATE_PRESENT) != SCARD_STATE_PRESENT ||
stateChanges == SCARD_STATE_INUSE ||
stateChanges == SCARD_STATE_UNPOWERED ||
(state.dwEventState & (SCARD_STATE_UNPOWERED | SCARD_STATE_EMPTY | SCARD_STATE_IGNORE | SCARD_STATE_UNKNOWN | SCARD_STATE_UNAVAILABLE | SCARD_STATE_MUTE)) ||
state.cbAtr == 0))
{
// we have seen this reader before and one of:
// no card
// only flipped INUSE
// only flipped UNPOWERED
// UNPOWERED EMPTY UNKNOWN UNAVAILABLE MUTE
// no atr
//
// don't try to read the card
continue;
}
// read the card in the reader and list the certs on the card
}
}
);
winerror.suppress();
}
return 0;
}
于 2012-12-11T00:45:28.100 回答
3
我知道我迟到了 2 年多，但也许我的回复仍然可以帮助某人。
我有一些简单的代码作为进一步开发的起点。我首先在 Windows 7 上创建它；AFAICS 它在 Windows 8 上也可以正常工作。这只使用了一个阅读器，但之前的迭代使用了一个阅读器列表，并且效果一样好。相关部分如下。
读取器状态结构的初始化：
memset(&m_State, 0, sizeof(m_State));
m_State.szReader = _wcsdup(m_ReaderName.c_str());
m_State.dwCurrentState = SCARD_STATE_UNAWARE;
等待事件：
bool TSmartCardReader::WaitForEvent(DWORD Timeout, TCardEvent &CardEvent)
{
CardEvent = None;
// Reset reader structure, except the specific fields we need
// (because that's what the docs say: "Important: Each member of each structure
// in this array must be initialized to zero and then set to specific values as
// necessary. If this is not done, the function will fail in situations that
// involve remote card readers.")
const wchar_t *szReader = m_State.szReader;
DWORD dwCurrentState = m_State.dwCurrentState;
memset(&m_State, 0, sizeof(m_State));
m_State.szReader = szReader;
m_State.dwCurrentState = dwCurrentState;
LONG rv = SCardGetStatusChangeW(m_hContext, Timeout, &m_State, 1);
if (rv == SCARD_S_SUCCESS)
{
HandleStatusChange(CardEvent);
// I'm not sure we really need to reset the SCARD_STATE_CHANGED bit
m_State.dwCurrentState = m_State.dwEventState & ~SCARD_STATE_CHANGED;
}
else if (rv == SCARD_E_TIMEOUT)
return false; // No status changes
else if (rv == SCARD_E_NO_READERS_AVAILABLE)
throw ESCNoReaders("No readers available");
else
throw ESCWaitForEvent(GetErrorText(rv));
return CardEvent != None;
}
据我了解文档，关键是您将 set dwCurrentState 设置为您认为是读者的当前状态。SCardGetStatusChange() 会考虑当前状态来决定什么构成状态更改。
于 2014-12-02T09:27:16.570 回答