PCSC那事儿(十六--SCardListReaders)

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SCardListReaders

SCardListReaders做了什么？

定义在winscard_clnt.c

实现如下：

3202 LONG SCardListReaders(SCARDCONTEXT hContext, /*@unused@*/ LPCSTR mszGroups,

3203 LPSTR mszReaders, LPDWORD pcchReaders)

3204 {

3205 DWORD dwReadersLen;

3206 int i;

3207 LONG dwContextIndex;

3208 LONG rv = SCARD_S_SUCCESS;

3209 char *buf = NULL;

3210

3211 (void)mszGroups;

3212 PROFILE_START

3213

3214 /*

3215 * Check for NULL parameters

3216 */

3217 if (pcchReaders == NULL)

3218 return SCARD_E_INVALID_PARAMETER;

3219

3220 rv = SCardCheckDaemonAvailability();

3221 if (rv != SCARD_S_SUCCESS)

3222 return rv;

3223

3224 /*

3225 * Make sure this context has been opened

3226 */

3227 dwContextIndex = SCardGetContextIndice(hContext);

3228 if (dwContextIndex == -1)

3229 return SCARD_E_INVALID_HANDLE;

3230

3231 (void)SYS_MutexLock(psContextMap[dwContextIndex].mMutex);

3232

3233 /* check the context is still opened */

3234 dwContextIndex = SCardGetContextIndice(hContext);

3235 if (dwContextIndex == -1)

3236 /* the context is now invalid

3237 * -> another thread may have called SCardReleaseContext

3238 * -> so the mMutex has been unlocked */

3239 return SCARD_E_INVALID_HANDLE;

3240

3241 dwReadersLen = 0;

3242 for (i = 0; i < PCSCLITE_MAX_READERS_CONTEXTS; i++)

3243 if ((readerStates[i])->readerID != 0)

3244 dwReadersLen += strlen((readerStates[i])->readerName) + 1;

3245

3246 /* for the last NULL byte */

3247 dwReadersLen += 1;

3248

3249 if (1 == dwReadersLen)

3250 {

3251 rv = SCARD_E_NO_READERS_AVAILABLE;

3252 goto end;

3253 }

3254

3255 if (SCARD_AUTOALLOCATE == *pcchReaders)

3256 {

3257 buf = malloc(dwReadersLen);

3258 if (NULL == buf)

3259 {

3260 rv = SCARD_E_NO_MEMORY;

3261 goto end;

3262 }

3263 if (NULL == mszReaders)

3264 {

3265 rv = SCARD_E_INVALID_PARAMETER;

3266 goto end;

3267 }

3268 *(char **)mszReaders = buf;

3269 }

3270 else

3271 {

3272 buf = mszReaders;

3273

3274 /* not enough place to store the reader names */

3275 if ((NULL != mszReaders) && (*pcchReaders < dwReadersLen))

3276 {

3277 rv = SCARD_E_INSUFFICIENT_BUFFER;

3278 goto end;

3279 }

3280 }

3281

3282 if (mszReaders == NULL) /* text array not allocated */

3283 goto end;

3284

3285 for (i = 0; i < PCSCLITE_MAX_READERS_CONTEXTS; i++)

3286 {

3287 if ((readerStates[i])->readerID != 0)

3288 {

3289 /*

3290 * Build the multi-string

3291 */

3292 strcpy(buf, (readerStates[i])->readerName);

3293 buf += strlen((readerStates[i])->readerName)+1;

3294 }

3295 }

3296 *buf = '/0'; /* Add the last null */

3297

3298 end:

3299 /* set the reader names length */

3300 *pcchReaders = dwReadersLen;

3301

3302 (void)SYS_MutexUnLock(psContextMap[dwContextIndex].mMutex);

3303

3304 PROFILE_END(rv)

3305

3306 return rv;

3307 }

上面又出现了

3227 dwContextIndex = SCardGetContextIndice(hContext);

3228 if (dwContextIndex == -1)

3229 return SCARD_E_INVALID_HANDLE;

3230

3231 (void)SYS_MutexLock(psContextMap[dwContextIndex].mMutex);

3232

3233 /* check the context is still opened */

3234 dwContextIndex = SCardGetContextIndice(hContext);

3235 if (dwContextIndex == -1)

3236 /* the context is now invalid

3237 * -> another thread may have called SCardReleaseContext

3238 * -> so the mMutex has been unlocked */

3239 return SCARD_E_INVALID_HANDLE;

已经解释过了。以后这样的片段不再解释了。

3242 for (i = 0; i < PCSCLITE_MAX_READERS_CONTEXTS; i++)

3243 if ((readerStates[i])->readerID != 0)

3244 dwReadersLen += strlen((readerStates[i])->readerName) + 1;

这里出现了readerStates这个在哪里初始化过？

依然记得，在前面的SCardEstablishContextTH

411 for (i = 0; i < PCSCLITE_MAX_READERS_CONTEXTS; i++)

412 {

413 readerStates[i] =

414 (PREADER_STATE)SYS_PublicMemoryMap(sizeof(READER_STATE),

415 mapAddr, (i * pageSize));

416 if (readerStates[i] == NULL)

417 {

418 Log2(PCSC_LOG_CRITICAL, "Cannot public memory map: %s",

419 strerror(errno));

420 (void)SYS_CloseFile(mapAddr); /* Close the memory map file */

421 return SCARD_F_INTERNAL_ERROR;

422 }

423 }

I got it.

这里初始化过了。

通过共享内存，动态获得了系统中读卡器的状态。

看看 READER_STATE的定义,再看一次

typedef struct pubReaderStatesList

{

int32_t readerID;

char readerName[MAX_READERNAME];

uint32_t readerState;

int32_t readerSharing;

UCHAR cardAtr[MAX_ATR_SIZE];

uint32_t cardAtrLength;

uint32_t cardProtocol;

}

READER_STATE, *PREADER_STATE;

这里有 readerName，太好了。

这样的话， SCardListReaders只要收集 READER_STATE数组提供的 readerName，就实现了获取读卡器列表。

3285~3294行，从共享内存中获得了读卡器列表

3285 for (i = 0; i < PCSCLITE_MAX_READERS_CONTEXTS; i++)

3286 {

3287 if ((readerStates[i])->readerID != 0)

3288 {

3289 /*

3290 * Build the multi-string

3291 */

3292 strcpy(buf, (readerStates[i])->readerName);

3293 buf += strlen((readerStates[i])->readerName)+1;

3294 }

3295 }

3296 *buf = '/0'; /* Add the last null */

特别又列了一次这个片段，是为了说明读卡器列表字符串的格式是：每个读卡器名字都是以'/０'作为间隔，字符串的最后是两个'/0'。和读卡器组列表字符串的格式(已经提过)一样。

而且读卡器列表的内存分配方式也分为是SCardListReaders分配，还是APPLICATION自己分配两种。

回到testpcsc.c 146行

146 if (SCARD_E_NO_READERS_AVAILABLE == rv)

147 {

148 printf("Testing SCardGetStatusChange /n");

149 printf("Please insert a working reader/t: ");

150 (void)fflush(stdout);

151 rgReaderStates[0].szReader = "////?PnP?//Notification";

152 rgReaderStates[0].dwCurrentState = SCARD_STATE_EMPTY;

153

154 rv = SCardGetStatusChange(hContext, INFINITE, rgReaderStates, 1);

155 test_rv(rv, hContext, PANIC);

156 }

如果144行SCardListReaders没有找到任何读卡器，则146判断成立，

提示插入读卡器，

"////?PnP?//Notification"还有SCardGetStatusChange都是做些什么的？

别着急，慢慢说。