libusb/os/poll_windows.c

   1 /*
   2  * poll_windows: poll compatibility wrapper for Windows
   3  * Copyright © 2009-2010 Pete Batard <pbatard@gmail.com>
   4  * With contributions from Michael Plante, Orin Eman et al.
   5  * Parts of poll implementation from libusb-win32, by Stephan Meyer et al.
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  *
  21  */
  22
  23 /*
  24  * poll() and pipe() Windows compatibility layer for libusbx 1.0
  25  *
  26  * The way this layer works is by using OVERLAPPED with async I/O transfers, as
  27  * OVERLAPPED have an associated event which is flagged for I/O completion.
  28  *
  29  * For USB pollable async I/O, you would typically:
  30  * - obtain a Windows HANDLE to a file or device that has been opened in
  31  *   OVERLAPPED mode
  32  * - call usbi_create_fd with this handle to obtain a custom fd.
  33  *   Note that if you need simultaneous R/W access, you need to call create_fd
  34  *   twice, once in RW_READ and once in RW_WRITE mode to obtain 2 separate
  35  *   pollable fds
  36  * - leave the core functions call the poll routine and flag POLLIN/POLLOUT
  37  *
  38  * The pipe pollable synchronous I/O works using the overlapped event associated
  39  * with a fake pipe. The read/write functions are only meant to be used in that
  40  * context.
  41  */
  42 #include <errno.h>
  43 #include <stdio.h>
  44 #include <stdlib.h>
  45
  46 #include <libusbi.h>
  47
  48 // Uncomment to debug the polling layer
  49 //#define DEBUG_POLL_WINDOWS
  50 #if defined(DEBUG_POLL_WINDOWS)
  51 #define poll_dbg usbi_dbg
  52 #else
  53 // MSVC++ < 2005 cannot use a variadic argument and non MSVC
  54 // compilers produce warnings if parenthesis are ommitted.
  55 #if defined(_MSC_VER) && _MSC_VER < 1400
  56 #define poll_dbg
  57 #else
  58 #define poll_dbg(...)
  59 #endif
  60 #endif
  61
  62 #if defined(_PREFAST_)
  63 #pragma warning(disable:28719)
  64 #endif
  65
  66 #if defined(_WIN32_WCE)
  67 #define usbi_sleep(ms) Sleep(ms)
  68 #else
  69 #define usbi_sleep(ms) SleepEx(ms, TRUE)
  70 #endif
  71
  72 #define CHECK_INIT_POLLING do {if(!is_polling_set) init_polling();} while(0)
  73
  74 // public fd data
  75 const struct winfd INVALID_WINFD = {-1, INVALID_HANDLE_VALUE, NULL, NULL, NULL, RW_NONE};
  76 struct winfd poll_fd[MAX_FDS];
  77 // internal fd data
  78 struct {
  79         CRITICAL_SECTION mutex; // lock for fds
  80         // Additional variables for XP CancelIoEx partial emulation
  81         HANDLE original_handle;
  82         DWORD thread_id;
  83 } _poll_fd[MAX_FDS];
  84
  85 // globals
  86 BOOLEAN is_polling_set = FALSE;
  87 LONG pipe_number = 0;
  88 static volatile LONG compat_spinlock = 0;
  89
  90 #if !defined(_WIN32_WCE)
  91 // CancelIoEx, available on Vista and later only, provides the ability to cancel
  92 // a single transfer (OVERLAPPED) when used. As it may not be part of any of the
  93 // platform headers, we hook into the Kernel32 system DLL directly to seek it.
  94 static BOOL (__stdcall *pCancelIoEx)(HANDLE, LPOVERLAPPED) = NULL;
  95 #define Use_Duplicate_Handles (pCancelIoEx == NULL)
  96
  97 static inline void setup_cancel_io(void)
  98 {
  99         pCancelIoEx = (BOOL (__stdcall *)(HANDLE,LPOVERLAPPED))
 100                 GetProcAddress(GetModuleHandleA("KERNEL32"), "CancelIoEx");
 101         usbi_dbg("Will use CancelIo%s for I/O cancellation",
 102                 Use_Duplicate_Handles?"":"Ex");
 103 }
 104
 105 static inline BOOL cancel_io(int _index)
 106 {
 107         if ((_index < 0) || (_index >= MAX_FDS)) {
 108                 return FALSE;
 109         }
 110
 111         if ( (poll_fd[_index].fd < 0) || (poll_fd[_index].handle == INVALID_HANDLE_VALUE)
 112           || (poll_fd[_index].handle == 0) || (poll_fd[_index].overlapped == NULL) ) {
 113                 return TRUE;
 114         }
 115         if (poll_fd[_index].itransfer && poll_fd[_index].cancel_fn) {
 116                 // Cancel outstanding transfer via the specific callback
 117                 (*poll_fd[_index].cancel_fn)(poll_fd[_index].itransfer);
 118                 return TRUE;
 119         }
 120         if (pCancelIoEx != NULL) {
 121                 return (*pCancelIoEx)(poll_fd[_index].handle, poll_fd[_index].overlapped);
 122         }
 123         if (_poll_fd[_index].thread_id == GetCurrentThreadId()) {
 124                 return CancelIo(poll_fd[_index].handle);
 125         }
 126         usbi_warn(NULL, "Unable to cancel I/O that was started from another thread");
 127         return FALSE;
 128 }
 129 #else
 130 #define Use_Duplicate_Handles FALSE
 131
 132 static __inline void setup_cancel_io()
 133 {
 134         // No setup needed on WinCE
 135 }
 136
 137 static __inline BOOL cancel_io(int _index)
 138 {
 139         if ((_index < 0) || (_index >= MAX_FDS)) {
 140                 return FALSE;
 141         }
 142         if ( (poll_fd[_index].fd < 0) || (poll_fd[_index].handle == INVALID_HANDLE_VALUE)
 143           || (poll_fd[_index].handle == 0) || (poll_fd[_index].overlapped == NULL) ) {
 144                 return TRUE;
 145         }
 146         if (poll_fd[_index].itransfer && poll_fd[_index].cancel_fn) {
 147                 // Cancel outstanding transfer via the specific callback
 148                 (*poll_fd[_index].cancel_fn)(poll_fd[_index].itransfer);
 149         }
 150         return TRUE;
 151 }
 152 #endif
 153
 154 // Init
 155 void init_polling(void)
 156 {
 157         int i;
 158
 159         while (InterlockedExchange((LONG *)&compat_spinlock, 1) == 1) {
 160                 usbi_sleep(0);
 161         }
 162         if (!is_polling_set) {
 163                 setup_cancel_io();
 164                 for (i=0; i<MAX_FDS; i++) {
 165                         poll_fd[i] = INVALID_WINFD;
 166                         _poll_fd[i].original_handle = INVALID_HANDLE_VALUE;
 167                         _poll_fd[i].thread_id = 0;
 168                         InitializeCriticalSection(&_poll_fd[i].mutex);
 169                 }
 170                 is_polling_set = TRUE;
 171         }
 172         InterlockedExchange((LONG *)&compat_spinlock, 0);
 173 }
 174
 175 // Internal function to retrieve the table index (and lock the fd mutex)
 176 static int _fd_to_index_and_lock(int fd)
 177 {
 178         int i;
 179
 180         if (fd < 0)
 181                 return -1;
 182
 183         for (i=0; i<MAX_FDS; i++) {
 184                 if (poll_fd[i].fd == fd) {
 185                         EnterCriticalSection(&_poll_fd[i].mutex);
 186                         // fd might have changed before we got to critical
 187                         if (poll_fd[i].fd != fd) {
 188                                 LeaveCriticalSection(&_poll_fd[i].mutex);
 189                                 continue;
 190                         }
 191                         return i;
 192                 }
 193         }
 194         return -1;
 195 }
 196
 197 static OVERLAPPED *create_overlapped(void)
 198 {
 199         OVERLAPPED *overlapped = (OVERLAPPED*) calloc(1, sizeof(OVERLAPPED));
 200         if (overlapped == NULL) {
 201                 return NULL;
 202         }
 203         overlapped->hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
 204         if(overlapped->hEvent == NULL) {
 205                 free (overlapped);
 206                 return NULL;
 207         }
 208         return overlapped;
 209 }
 210
 211 static void free_overlapped(OVERLAPPED *overlapped)
 212 {
 213         if (overlapped == NULL)
 214                 return;
 215
 216         if ( (overlapped->hEvent != 0)
 217           && (overlapped->hEvent != INVALID_HANDLE_VALUE) ) {
 218                 CloseHandle(overlapped->hEvent);
 219         }
 220         free(overlapped);
 221 }
 222
 223 void exit_polling(void)
 224 {
 225         int i;
 226
 227         while (InterlockedExchange((LONG *)&compat_spinlock, 1) == 1) {
 228                 usbi_sleep(0);
 229         }
 230         if (is_polling_set) {
 231                 is_polling_set = FALSE;
 232
 233                 for (i=0; i<MAX_FDS; i++) {
 234                         // Cancel any async I/O (handle can be invalid)
 235                         cancel_io(i);
 236                         // If anything was pending on that I/O, it should be
 237                         // terminating, and we should be able to access the fd
 238                         // mutex lock before too long
 239                         EnterCriticalSection(&_poll_fd[i].mutex);
 240                         free_overlapped(poll_fd[i].overlapped);
 241                         if (Use_Duplicate_Handles) {
 242                                 // Close duplicate handle
 243                                 if (_poll_fd[i].original_handle != INVALID_HANDLE_VALUE) {
 244                                         CloseHandle(poll_fd[i].handle);
 245                                 }
 246                         }
 247                         poll_fd[i] = INVALID_WINFD;
 248                         LeaveCriticalSection(&_poll_fd[i].mutex);
 249                         DeleteCriticalSection(&_poll_fd[i].mutex);
 250                 }
 251         }
 252         InterlockedExchange((LONG *)&compat_spinlock, 0);
 253 }
 254
 255 /*
 256  * Create a fake pipe.
 257  * As libusbx only uses pipes for signaling, all we need from a pipe is an
 258  * event. To that extent, we create a single wfd and overlapped as a means
 259  * to access that event.
 260  */
 261 int usbi_pipe(int filedes[2])
 262 {
 263         int i;
 264         OVERLAPPED* overlapped;
 265
 266         CHECK_INIT_POLLING;
 267
 268         overlapped = create_overlapped();
 269
 270         if (overlapped == NULL) {
 271                 return -1;
 272         }
 273         // The overlapped must have status pending for signaling to work in poll
 274         overlapped->Internal = STATUS_PENDING;
 275         overlapped->InternalHigh = 0;
 276
 277         for (i=0; i<MAX_FDS; i++) {
 278                 if (poll_fd[i].fd < 0) {
 279                         EnterCriticalSection(&_poll_fd[i].mutex);
 280                         // fd might have been allocated before we got to critical
 281                         if (poll_fd[i].fd >= 0) {
 282                                 LeaveCriticalSection(&_poll_fd[i].mutex);
 283                                 continue;
 284                         }
 285
 286                         // Use index as the unique fd number
 287                         poll_fd[i].fd = i;
 288                         // Read end of the "pipe"
 289                         filedes[0] = poll_fd[i].fd;
 290                         // We can use the same handle for both ends
 291                         filedes[1] = filedes[0];
 292
 293                         poll_fd[i].handle = DUMMY_HANDLE;
 294                         poll_fd[i].overlapped = overlapped;
 295                         // There's no polling on the write end, so we just use READ for our needs
 296                         poll_fd[i].rw = RW_READ;
 297                         _poll_fd[i].original_handle = INVALID_HANDLE_VALUE;
 298                         LeaveCriticalSection(&_poll_fd[i].mutex);
 299                         return 0;
 300                 }
 301         }
 302         free_overlapped(overlapped);
 303         return -1;
 304 }
 305
 306 /*
 307  * Create both an fd and an OVERLAPPED from an open Windows handle, so that
 308  * it can be used with our polling function
 309  * The handle MUST support overlapped transfers (usually requires CreateFile
 310  * with FILE_FLAG_OVERLAPPED)
 311  * Return a pollable file descriptor struct, or INVALID_WINFD on error
 312  *
 313  * Note that the fd returned by this function is a per-transfer fd, rather
 314  * than a per-session fd and cannot be used for anything else but our
 315  * custom functions (the fd itself points to the NUL: device)
 316  * if you plan to do R/W on the same handle, you MUST create 2 fds: one for
 317  * read and one for write. Using a single R/W fd is unsupported and will
 318  * produce unexpected results
 319  */
 320 struct winfd usbi_create_fd(HANDLE handle, int access_mode, struct usbi_transfer *itransfer, cancel_transfer *cancel_fn)
 321 {
 322         int i;
 323         struct winfd wfd = INVALID_WINFD;
 324         OVERLAPPED* overlapped = NULL;
 325
 326         CHECK_INIT_POLLING;
 327
 328         if ((handle == 0) || (handle == INVALID_HANDLE_VALUE)) {
 329                 return INVALID_WINFD;
 330         }
 331
 332         wfd.itransfer = itransfer;
 333         wfd.cancel_fn = cancel_fn;
 334
 335         if ((access_mode != RW_READ) && (access_mode != RW_WRITE)) {
 336                 usbi_warn(NULL, "only one of RW_READ or RW_WRITE are supported.\n"
 337                         "If you want to poll for R/W simultaneously, create multiple fds from the same handle.");
 338                 return INVALID_WINFD;
 339         }
 340         if (access_mode == RW_READ) {
 341                 wfd.rw = RW_READ;
 342         } else {
 343                 wfd.rw = RW_WRITE;
 344         }
 345
 346         overlapped = create_overlapped();
 347         if(overlapped == NULL) {
 348                 return INVALID_WINFD;
 349         }
 350
 351         for (i=0; i<MAX_FDS; i++) {
 352                 if (poll_fd[i].fd < 0) {
 353                         EnterCriticalSection(&_poll_fd[i].mutex);
 354                         // fd might have been removed before we got to critical
 355                         if (poll_fd[i].fd >= 0) {
 356                                 LeaveCriticalSection(&_poll_fd[i].mutex);
 357                                 continue;
 358                         }
 359                         // Use index as the unique fd number
 360                         wfd.fd = i;
 361                         // Attempt to emulate some of the CancelIoEx behaviour on platforms
 362                         // that don't have it
 363                         if (Use_Duplicate_Handles) {
 364                                 _poll_fd[i].thread_id = GetCurrentThreadId();
 365                                 if (!DuplicateHandle(GetCurrentProcess(), handle, GetCurrentProcess(),
 366                                         &wfd.handle, 0, TRUE, DUPLICATE_SAME_ACCESS)) {
 367                                         usbi_dbg("could not duplicate handle for CancelIo - using original one");
 368                                         wfd.handle = handle;
 369                                         // Make sure we won't close the original handle on fd deletion then
 370                                         _poll_fd[i].original_handle = INVALID_HANDLE_VALUE;
 371                                 } else {
 372                                         _poll_fd[i].original_handle = handle;
 373                                 }
 374                         } else {
 375                                 wfd.handle = handle;
 376                         }
 377                         wfd.overlapped = overlapped;
 378                         memcpy(&poll_fd[i], &wfd, sizeof(struct winfd));
 379                         LeaveCriticalSection(&_poll_fd[i].mutex);
 380                         return wfd;
 381                 }
 382         }
 383         free_overlapped(overlapped);
 384         return INVALID_WINFD;
 385 }
 386
 387 static void _free_index(int _index)
 388 {
 389         // Cancel any async IO (Don't care about the validity of our handles for this)
 390         cancel_io(_index);
 391         // close the duplicate handle (if we have an actual duplicate)
 392         if (Use_Duplicate_Handles) {
 393                 if (_poll_fd[_index].original_handle != INVALID_HANDLE_VALUE) {
 394                         CloseHandle(poll_fd[_index].handle);
 395                 }
 396                 _poll_fd[_index].original_handle = INVALID_HANDLE_VALUE;
 397                 _poll_fd[_index].thread_id = 0;
 398         }
 399         free_overlapped(poll_fd[_index].overlapped);
 400         poll_fd[_index] = INVALID_WINFD;
 401 }
 402
 403 /*
 404  * Release a pollable file descriptor.
 405  *
 406  * Note that the associated Windows handle is not closed by this call
 407  */
 408 void usbi_free_fd(int fd)
 409 {
 410         int _index;
 411
 412         CHECK_INIT_POLLING;
 413
 414         _index = _fd_to_index_and_lock(fd);
 415         if (_index < 0) {
 416                 return;
 417         }
 418         _free_index(_index);
 419         LeaveCriticalSection(&_poll_fd[_index].mutex);
 420 }
 421
 422 /*
 423  * The functions below perform various conversions between fd, handle and OVERLAPPED
 424  */
 425 struct winfd fd_to_winfd(int fd)
 426 {
 427         int i;
 428         struct winfd wfd;
 429
 430         CHECK_INIT_POLLING;
 431
 432         if (fd <= 0)
 433                 return INVALID_WINFD;
 434
 435         for (i=0; i<MAX_FDS; i++) {
 436                 if (poll_fd[i].fd == fd) {
 437                         EnterCriticalSection(&_poll_fd[i].mutex);
 438                         // fd might have been deleted before we got to critical
 439                         if (poll_fd[i].fd != fd) {
 440                                 LeaveCriticalSection(&_poll_fd[i].mutex);
 441                                 continue;
 442                         }
 443                         memcpy(&wfd, &poll_fd[i], sizeof(struct winfd));
 444                         LeaveCriticalSection(&_poll_fd[i].mutex);
 445                         return wfd;
 446                 }
 447         }
 448         return INVALID_WINFD;
 449 }
 450
 451 struct winfd handle_to_winfd(HANDLE handle)
 452 {
 453         int i;
 454         struct winfd wfd;
 455
 456         CHECK_INIT_POLLING;
 457
 458         if ((handle == 0) || (handle == INVALID_HANDLE_VALUE))
 459                 return INVALID_WINFD;
 460
 461         for (i=0; i<MAX_FDS; i++) {
 462                 if (poll_fd[i].handle == handle) {
 463                         EnterCriticalSection(&_poll_fd[i].mutex);
 464                         // fd might have been deleted before we got to critical
 465                         if (poll_fd[i].handle != handle) {
 466                                 LeaveCriticalSection(&_poll_fd[i].mutex);
 467                                 continue;
 468                         }
 469                         memcpy(&wfd, &poll_fd[i], sizeof(struct winfd));
 470                         LeaveCriticalSection(&_poll_fd[i].mutex);
 471                         return wfd;
 472                 }
 473         }
 474         return INVALID_WINFD;
 475 }
 476
 477 struct winfd overlapped_to_winfd(OVERLAPPED* overlapped)
 478 {
 479         int i;
 480         struct winfd wfd;
 481
 482         CHECK_INIT_POLLING;
 483
 484         if (overlapped == NULL)
 485                 return INVALID_WINFD;
 486
 487         for (i=0; i<MAX_FDS; i++) {
 488                 if (poll_fd[i].overlapped == overlapped) {
 489                         EnterCriticalSection(&_poll_fd[i].mutex);
 490                         // fd might have been deleted before we got to critical
 491                         if (poll_fd[i].overlapped != overlapped) {
 492                                 LeaveCriticalSection(&_poll_fd[i].mutex);
 493                                 continue;
 494                         }
 495                         memcpy(&wfd, &poll_fd[i], sizeof(struct winfd));
 496                         LeaveCriticalSection(&_poll_fd[i].mutex);
 497                         return wfd;
 498                 }
 499         }
 500         return INVALID_WINFD;
 501 }
 502
 503 /*
 504  * POSIX poll equivalent, using Windows OVERLAPPED
 505  * Currently, this function only accepts one of POLLIN or POLLOUT per fd
 506  * (but you can create multiple fds from the same handle for read and write)
 507  */
 508 int usbi_poll(struct pollfd *fds, unsigned int nfds, int timeout)
 509 {
 510         unsigned i;
 511         int _index, object_index, triggered;
 512         HANDLE *handles_to_wait_on;
 513         int *handle_to_index;
 514         DWORD nb_handles_to_wait_on = 0;
 515         DWORD ret;
 516
 517         CHECK_INIT_POLLING;
 518
 519         triggered = 0;
 520         handles_to_wait_on = (HANDLE*) calloc(nfds+1, sizeof(HANDLE));  // +1 for fd_update
 521         handle_to_index = (int*) calloc(nfds, sizeof(int));
 522         if ((handles_to_wait_on == NULL) || (handle_to_index == NULL)) {
 523                 errno = ENOMEM;
 524                 triggered = -1;
 525                 goto poll_exit;
 526         }
 527
 528         for (i = 0; i < nfds; ++i) {
 529                 fds[i].revents = 0;
 530
 531                 // Only one of POLLIN or POLLOUT can be selected with this version of poll (not both)
 532                 if ((fds[i].events & ~POLLIN) && (!(fds[i].events & POLLOUT))) {
 533                         fds[i].revents |= POLLERR;
 534                         errno = EACCES;
 535                         usbi_warn(NULL, "unsupported set of events");
 536                         triggered = -1;
 537                         goto poll_exit;
 538                 }
 539
 540                 _index = _fd_to_index_and_lock(fds[i].fd);
 541                 poll_dbg("fd[%d]=%d: (overlapped=%p) got events %04X", i, poll_fd[_index].fd, poll_fd[_index].overlapped, fds[i].events);
 542
 543                 if ( (_index < 0) || (poll_fd[_index].handle == INVALID_HANDLE_VALUE)
 544                   || (poll_fd[_index].handle == 0) || (poll_fd[_index].overlapped == NULL)) {
 545                         fds[i].revents |= POLLNVAL | POLLERR;
 546                         errno = EBADF;
 547                         if (_index >= 0) {
 548                                 LeaveCriticalSection(&_poll_fd[_index].mutex);
 549                         }
 550                         usbi_warn(NULL, "invalid fd");
 551                         triggered = -1;
 552                         goto poll_exit;
 553                 }
 554
 555                 // IN or OUT must match our fd direction
 556                 if ((fds[i].events & POLLIN) && (poll_fd[_index].rw != RW_READ)) {
 557                         fds[i].revents |= POLLNVAL | POLLERR;
 558                         errno = EBADF;
 559                         usbi_warn(NULL, "attempted POLLIN on fd without READ access");
 560                         LeaveCriticalSection(&_poll_fd[_index].mutex);
 561                         triggered = -1;
 562                         goto poll_exit;
 563                 }
 564
 565                 if ((fds[i].events & POLLOUT) && (poll_fd[_index].rw != RW_WRITE)) {
 566                         fds[i].revents |= POLLNVAL | POLLERR;
 567                         errno = EBADF;
 568                         usbi_warn(NULL, "attempted POLLOUT on fd without WRITE access");
 569                         LeaveCriticalSection(&_poll_fd[_index].mutex);
 570                         triggered = -1;
 571                         goto poll_exit;
 572                 }
 573
 574                 // The following macro only works if overlapped I/O was reported pending
 575                 if ( (HasOverlappedIoCompleted(poll_fd[_index].overlapped))
 576                   || (HasOverlappedIoCompletedSync(poll_fd[_index].overlapped)) ) {
 577                         poll_dbg("  completed");
 578                         // checks above should ensure this works:
 579                         fds[i].revents = fds[i].events;
 580                         triggered++;
 581                 } else {
 582                         handles_to_wait_on[nb_handles_to_wait_on] = poll_fd[_index].overlapped->hEvent;
 583                         handle_to_index[nb_handles_to_wait_on] = i;
 584                         nb_handles_to_wait_on++;
 585                 }
 586                 LeaveCriticalSection(&_poll_fd[_index].mutex);
 587         }
 588
 589         // If nothing was triggered, wait on all fds that require it
 590         if ((timeout != 0) && (triggered == 0) && (nb_handles_to_wait_on != 0)) {
 591                 if (timeout < 0) {
 592                         poll_dbg("starting infinite wait for %d handles...", (int)nb_handles_to_wait_on);
 593                 } else {
 594                         poll_dbg("starting %d ms wait for %d handles...", timeout, (int)nb_handles_to_wait_on);
 595                 }
 596                 ret = WaitForMultipleObjects(nb_handles_to_wait_on, handles_to_wait_on,
 597                         FALSE, (timeout<0)?INFINITE:(DWORD)timeout);
 598                 object_index = ret-WAIT_OBJECT_0;
 599                 if ((object_index >= 0) && ((DWORD)object_index < nb_handles_to_wait_on)) {
 600                         poll_dbg("  completed after wait");
 601                         i = handle_to_index[object_index];
 602                         _index = _fd_to_index_and_lock(fds[i].fd);
 603                         fds[i].revents = fds[i].events;
 604                         triggered++;
 605                         if (_index >= 0) {
 606                                 LeaveCriticalSection(&_poll_fd[_index].mutex);
 607                         }
 608                 } else if (ret == WAIT_TIMEOUT) {
 609                         poll_dbg("  timed out");
 610                         triggered = 0;  // 0 = timeout
 611                 } else {
 612                         errno = EIO;
 613                         triggered = -1; // error
 614                 }
 615         }
 616
 617 poll_exit:
 618         if (handles_to_wait_on != NULL) {
 619                 free(handles_to_wait_on);
 620         }
 621         if (handle_to_index != NULL) {
 622                 free(handle_to_index);
 623         }
 624         return triggered;
 625 }
 626
 627 /*
 628  * close a fake pipe fd
 629  */
 630 int usbi_close(int fd)
 631 {
 632         int _index;
 633         int r = -1;
 634
 635         CHECK_INIT_POLLING;
 636
 637         _index = _fd_to_index_and_lock(fd);
 638
 639         if (_index < 0) {
 640                 errno = EBADF;
 641         } else {
 642                 free_overlapped(poll_fd[_index].overlapped);
 643                 poll_fd[_index] = INVALID_WINFD;
 644                 LeaveCriticalSection(&_poll_fd[_index].mutex);
 645         }
 646         return r;
 647 }
 648
 649 /*
 650  * synchronous write for fake "pipe" signaling
 651  */
 652 ssize_t usbi_write(int fd, const void *buf, size_t count)
 653 {
 654         int _index;
 655         UNUSED(buf);
 656
 657         CHECK_INIT_POLLING;
 658
 659         if (count != sizeof(unsigned char)) {
 660                 usbi_err(NULL, "this function should only used for signaling");
 661                 return -1;
 662         }
 663
 664         _index = _fd_to_index_and_lock(fd);
 665
 666         if ( (_index < 0) || (poll_fd[_index].overlapped == NULL) ) {
 667                 errno = EBADF;
 668                 if (_index >= 0) {
 669                         LeaveCriticalSection(&_poll_fd[_index].mutex);
 670                 }
 671                 return -1;
 672         }
 673
 674         poll_dbg("set pipe event (fd = %d, thread = %08X)", _index, GetCurrentThreadId());
 675         SetEvent(poll_fd[_index].overlapped->hEvent);
 676         poll_fd[_index].overlapped->Internal = STATUS_WAIT_0;
 677         // If two threads write on the pipe at the same time, we need to
 678         // process two separate reads => use the overlapped as a counter
 679         poll_fd[_index].overlapped->InternalHigh++;
 680
 681         LeaveCriticalSection(&_poll_fd[_index].mutex);
 682         return sizeof(unsigned char);
 683 }
 684
 685 /*
 686  * synchronous read for fake "pipe" signaling
 687  */
 688 ssize_t usbi_read(int fd, void *buf, size_t count)
 689 {
 690         int _index;
 691         ssize_t r = -1;
 692         UNUSED(buf);
 693
 694         CHECK_INIT_POLLING;
 695
 696         if (count != sizeof(unsigned char)) {
 697                 usbi_err(NULL, "this function should only used for signaling");
 698                 return -1;
 699         }
 700
 701         _index = _fd_to_index_and_lock(fd);
 702
 703         if (_index < 0) {
 704                 errno = EBADF;
 705                 return -1;
 706         }
 707
 708         if (WaitForSingleObject(poll_fd[_index].overlapped->hEvent, INFINITE) != WAIT_OBJECT_0) {
 709                 usbi_warn(NULL, "waiting for event failed: %d", (int)GetLastError());
 710                 errno = EIO;
 711                 goto out;
 712         }
 713
 714         poll_dbg("clr pipe event (fd = %d, thread = %08X)", _index, GetCurrentThreadId());
 715         poll_fd[_index].overlapped->InternalHigh--;
 716         // Don't reset unless we don't have any more events to process
 717         if (poll_fd[_index].overlapped->InternalHigh <= 0) {
 718                 ResetEvent(poll_fd[_index].overlapped->hEvent);
 719                 poll_fd[_index].overlapped->Internal = STATUS_PENDING;
 720         }
 721
 722         r = sizeof(unsigned char);
 723
 724 out:
 725         LeaveCriticalSection(&_poll_fd[_index].mutex);
 726         return r;
 727 }