libusb/os/poll_windows.c

   1 /*
   2  * poll_windows: poll compatibility wrapper for Windows
   3  * Copyright (C) 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 libusb 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 _O_RDONLY and once in _O_WRONLY 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 <fcntl.h>
  44 #include <stdio.h>
  45 #include <stdlib.h>
  46 #include <io.h>
  47
  48 #include <libusbi.h>
  49
  50 // Uncomment to debug the polling layer
  51 //#define DEBUG_POLL_WINDOWS
  52 #if defined(DEBUG_POLL_WINDOWS)
  53 #define poll_dbg usbi_dbg
  54 #else
  55 // MSVC6 cannot use a variadic argument and non MSVC
  56 // compilers produce warnings if parenthesis are ommitted.
  57 #if defined(_MSC_VER)
  58 #define poll_dbg
  59 #else
  60 #define poll_dbg(...)
  61 #endif
  62 #endif
  63
  64 #if defined(_PREFAST_)
  65 #pragma warning(disable:28719)
  66 #endif
  67
  68 #if defined(__CYGWIN__)
  69 // cygwin produces a warning unless these prototypes are defined
  70 extern int _close(int fd);
  71 extern int _snprintf(char *buffer, size_t count, const char *format, ...);
  72 extern int cygwin_attach_handle_to_fd(char *name, int fd, HANDLE handle, int bin, int access_mode);
  73 // _open_osfhandle() is not available on cygwin, but we can emulate
  74 // it for our needs with cygwin_attach_handle_to_fd()
  75 static inline int _open_osfhandle(intptr_t osfhandle, int flags)
  76 {
  77         int access_mode;
  78         switch (flags) {
  79         case _O_RDONLY:
  80                 access_mode = GENERIC_READ;
  81                 break;
  82         case _O_WRONLY:
  83                 access_mode = GENERIC_WRITE;
  84                 break;
  85         case _O_RDWR:
  86                 access_mode = GENERIC_READ|GENERIC_WRITE;
  87                 break;
  88         default:
  89                 usbi_err(NULL, "unsupported access mode");
  90                 return -1;
  91         }
  92         return cygwin_attach_handle_to_fd("/dev/null", -1, (HANDLE)osfhandle, -1, access_mode);
  93 }
  94 #endif
  95
  96 #define CHECK_INIT_POLLING do {if(!is_polling_set) init_polling();} while(0)
  97
  98 // public fd data
  99 const struct winfd INVALID_WINFD = {-1, INVALID_HANDLE_VALUE, NULL, RW_NONE};
 100 struct winfd poll_fd[MAX_FDS];
 101 // internal fd data
 102 struct {
 103         CRITICAL_SECTION mutex; // lock for fds
 104         // Additional variables for XP CancelIoEx partial emulation
 105         HANDLE original_handle;
 106         DWORD thread_id;
 107 } _poll_fd[MAX_FDS];
 108
 109 // globals
 110 BOOLEAN is_polling_set = FALSE;
 111 #if defined(DYNAMIC_FDS)
 112 HANDLE fd_update = INVALID_HANDLE_VALUE;        // event to notify poll of fd update
 113 HANDLE new_fd[MAX_FDS];         // overlapped event handles for fds created since last poll
 114 unsigned nb_new_fds = 0;        // nb new fds created since last poll
 115 usbi_mutex_t new_fd_mutex;      // mutex required for the above
 116 #endif
 117 LONG pipe_number = 0;
 118 static volatile LONG compat_spinlock = 0;
 119
 120 // CancelIoEx, available on Vista and later only, provides the ability to cancel
 121 // a single transfer (OVERLAPPED) when used. As it may not be part of any of the
 122 // platform headers, we hook into the Kernel32 system DLL directly to seek it.
 123 static BOOL (__stdcall *pCancelIoEx)(HANDLE, LPOVERLAPPED) = NULL;
 124 #define CancelIoEx_Available (pCancelIoEx != NULL)
 125 __inline BOOL cancel_io(int index)
 126 {
 127         if ((index < 0) || (index >= MAX_FDS)) {
 128                 return FALSE;
 129         }
 130
 131         if ( (poll_fd[index].fd < 0) || (poll_fd[index].handle == INVALID_HANDLE_VALUE)
 132           || (poll_fd[index].handle == 0) || (poll_fd[index].overlapped == NULL) ) {
 133                 return TRUE;
 134         }
 135         if (CancelIoEx_Available) {
 136                 return (*pCancelIoEx)(poll_fd[index].handle, poll_fd[index].overlapped);
 137         }
 138         if (_poll_fd[index].thread_id == GetCurrentThreadId()) {
 139                 return CancelIo(poll_fd[index].handle);
 140         }
 141         usbi_warn(NULL, "Unable to cancel I/O that was started from another thread");
 142         return FALSE;
 143 }
 144
 145 // Init
 146 void init_polling(void)
 147 {
 148         int i;
 149
 150         while (InterlockedExchange((LONG *)&compat_spinlock, 1) == 1) {
 151                 SleepEx(0, TRUE);
 152         }
 153         if (!is_polling_set) {
 154                 pCancelIoEx = (BOOL (__stdcall *)(HANDLE,LPOVERLAPPED))
 155                         GetProcAddress(GetModuleHandle("KERNEL32"), "CancelIoEx");
 156                 usbi_dbg("Will use CancelIo%s for I/O cancellation",
 157                         CancelIoEx_Available?"Ex":"");
 158                 for (i=0; i<MAX_FDS; i++) {
 159                         poll_fd[i] = INVALID_WINFD;
 160                         _poll_fd[i].original_handle = INVALID_HANDLE_VALUE;
 161                         _poll_fd[i].thread_id = 0;
 162                         InitializeCriticalSection(&_poll_fd[i].mutex);
 163                 }
 164 #if defined(DYNAMIC_FDS)
 165                 // We need to create an update event so that poll is warned when there
 166                 // are new/deleted fds during a timeout wait operation
 167                 fd_update = CreateEvent(NULL, TRUE, FALSE, NULL);
 168                 if (fd_update == NULL) {
 169                         usbi_err(NULL, "unable to create update event");
 170                 }
 171                 usbi_mutex_init(&new_fd_mutex, NULL);
 172                 nb_new_fds = 0;
 173 #endif
 174                 is_polling_set = TRUE;
 175         }
 176         compat_spinlock = 0;
 177 }
 178
 179 // Internal function to retrieve the table index (and lock the fd mutex)
 180 int _fd_to_index_and_lock(int fd)
 181 {
 182         int i;
 183
 184         if (fd <= 0)
 185                 return -1;
 186
 187         for (i=0; i<MAX_FDS; i++) {
 188                 if (poll_fd[i].fd == fd) {
 189                         EnterCriticalSection(&_poll_fd[i].mutex);
 190                         // fd might have changed before we got to critical
 191                         if (poll_fd[i].fd != fd) {
 192                                 LeaveCriticalSection(&_poll_fd[i].mutex);
 193                                 continue;
 194                         }
 195                         return i;
 196                 }
 197         }
 198         return -1;
 199 }
 200
 201 OVERLAPPED *create_overlapped(void)
 202 {
 203         OVERLAPPED *overlapped = calloc(1, sizeof(OVERLAPPED));
 204         if (overlapped == NULL) {
 205                 return NULL;
 206         }
 207         overlapped->hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
 208         if(overlapped->hEvent == NULL) {
 209                 free (overlapped);
 210                 return NULL;
 211         }
 212         return overlapped;
 213 }
 214
 215 void free_overlapped(OVERLAPPED *overlapped)
 216 {
 217         if (overlapped == NULL)
 218                 return;
 219
 220         if ( (overlapped->hEvent != 0)
 221           && (overlapped->hEvent != INVALID_HANDLE_VALUE) ) {
 222                 CloseHandle(overlapped->hEvent);
 223         }
 224         free(overlapped);
 225 }
 226
 227 void reset_overlapped(OVERLAPPED *overlapped)
 228 {
 229         HANDLE event_handle;
 230         if (overlapped == NULL)
 231                 return;
 232
 233         event_handle = overlapped->hEvent;
 234         if (event_handle != NULL) {
 235                 ResetEvent(event_handle);
 236         }
 237         memset(overlapped, 0, sizeof(OVERLAPPED));
 238         overlapped->hEvent = event_handle;
 239 }
 240
 241 void exit_polling(void)
 242 {
 243         int i;
 244
 245         while (InterlockedExchange((LONG *)&compat_spinlock, 1) == 1) {
 246                 SleepEx(0, TRUE);
 247         }
 248         if (is_polling_set) {
 249                 is_polling_set = FALSE;
 250
 251                 for (i=0; i<MAX_FDS; i++) {
 252                         // Cancel any async I/O (handle can be invalid)
 253                         cancel_io(i);
 254                         // If anything was pending on that I/O, it should be
 255                         // terminating, and we should be able to access the fd
 256                         // mutex lock before too long
 257                         EnterCriticalSection(&_poll_fd[i].mutex);
 258                         if ( (poll_fd[i].fd > 0) && (poll_fd[i].handle != INVALID_HANDLE_VALUE) && (poll_fd[i].handle != 0)
 259                           && (GetFileType(poll_fd[i].handle) == FILE_TYPE_UNKNOWN) ) {
 260                                 _close(poll_fd[i].fd);
 261                         }
 262                         free_overlapped(poll_fd[i].overlapped);
 263                         if (!CancelIoEx_Available) {
 264                                 // Close duplicate handle
 265                                 if (_poll_fd[i].original_handle != INVALID_HANDLE_VALUE) {
 266                                         CloseHandle(poll_fd[i].handle);
 267                                 }
 268                         }
 269                         poll_fd[i] = INVALID_WINFD;
 270 #if defined(DYNAMIC_FDS)
 271                         usbi_mutex_destroy(&new_fd_mutex);
 272                         CloseHandle(fd_update);
 273                         fd_update = INVALID_HANDLE_VALUE;
 274 #endif
 275                         LeaveCriticalSection(&_poll_fd[i].mutex);
 276                         DeleteCriticalSection(&_poll_fd[i].mutex);
 277                 }
 278         }
 279         compat_spinlock = 0;
 280 }
 281
 282 /*
 283  * Create a fake pipe.
 284  * As libusb only uses pipes for signaling, all we need from a pipe is an
 285  * event. To that extent, we create a single wfd and overlapped as a means
 286  * to access that event.
 287  */
 288 int usbi_pipe(int filedes[2])
 289 {
 290         int i;
 291         HANDLE handle;
 292         OVERLAPPED* overlapped;
 293
 294         CHECK_INIT_POLLING;
 295
 296         overlapped = calloc(1, sizeof(OVERLAPPED));
 297         if (overlapped == NULL) {
 298                 return -1;
 299         }
 300         // The overlapped must have status pending for signaling to work in poll
 301         overlapped->Internal = STATUS_PENDING;
 302         overlapped->InternalHigh = 0;
 303
 304         // Read end of the "pipe"
 305         handle = CreateFileA("NUL", 0, 0, NULL, OPEN_EXISTING, 0, NULL);
 306         if (handle == INVALID_HANDLE_VALUE) {
 307                 usbi_err(NULL, "could not create pipe: errcode %d", (int)GetLastError());
 308                 goto out1;
 309         }
 310         filedes[0] = _open_osfhandle((intptr_t)handle, _O_RDONLY);
 311         // We can use the same handle for both ends
 312         filedes[1] = filedes[0];
 313         poll_dbg("pipe filedes = %d", filedes[0]);
 314
 315         // Note: manual reset must be true (second param) as the reset occurs in read
 316         overlapped->hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
 317         if(!overlapped->hEvent) {
 318                 goto out2;
 319         }
 320
 321         for (i=0; i<MAX_FDS; i++) {
 322                 if (poll_fd[i].fd < 0) {
 323                         EnterCriticalSection(&_poll_fd[i].mutex);
 324                         // fd might have been allocated before we got to critical
 325                         if (poll_fd[i].fd >= 0) {
 326                                 LeaveCriticalSection(&_poll_fd[i].mutex);
 327                                 continue;
 328                         }
 329
 330                         poll_fd[i].fd = filedes[0];
 331                         poll_fd[i].handle = handle;
 332                         poll_fd[i].overlapped = overlapped;
 333                         // There's no polling on the write end, so we just use READ for our needs
 334                         poll_fd[i].rw = RW_READ;
 335                         _poll_fd[i].original_handle = INVALID_HANDLE_VALUE;
 336                         LeaveCriticalSection(&_poll_fd[i].mutex);
 337                         return 0;
 338                 }
 339         }
 340
 341         CloseHandle(overlapped->hEvent);
 342 out2:
 343         CloseHandle(handle);
 344 out1:
 345         free(overlapped);
 346         return -1;
 347 }
 348
 349 /*
 350  * Create both an fd and an OVERLAPPED from an open Windows handle, so that
 351  * it can be used with our polling function
 352  * The handle MUST support overlapped transfers (usually requires CreateFile
 353  * with FILE_FLAG_OVERLAPPED)
 354  * Return a pollable file descriptor struct, or INVALID_WINFD on error
 355  *
 356  * Note that the fd returned by this function is a per-transfer fd, rather
 357  * than a per-session fd and cannot be used for anything else but our
 358  * custom functions (the fd itself points to the NUL: device)
 359  * if you plan to do R/W on the same handle, you MUST create 2 fds: one for
 360  * read and one for write. Using a single R/W fd is unsupported and will
 361  * produce unexpected results
 362  */
 363 struct winfd usbi_create_fd(HANDLE handle, int access_mode)
 364 {
 365         int i, fd;
 366         struct winfd wfd = INVALID_WINFD;
 367         OVERLAPPED* overlapped = NULL;
 368
 369         CHECK_INIT_POLLING;
 370
 371         if ((handle == 0) || (handle == INVALID_HANDLE_VALUE)) {
 372                 return INVALID_WINFD;
 373         }
 374
 375         if ((access_mode != _O_RDONLY) && (access_mode != _O_WRONLY)) {
 376                 usbi_warn(NULL, "only one of _O_RDONLY or _O_WRONLY are supported.\n"
 377                         "If you want to poll for R/W simultaneously, create multiple fds from the same handle.");
 378                 return INVALID_WINFD;
 379         }
 380         if (access_mode == _O_RDONLY) {
 381                 wfd.rw = RW_READ;
 382         } else {
 383                 wfd.rw = RW_WRITE;
 384         }
 385
 386         // Ensure that we get a non system conflicting unique fd
 387         fd = _open_osfhandle((intptr_t)CreateFileA("NUL", 0, 0,
 388                 NULL, OPEN_EXISTING, 0, NULL), _O_RDWR);
 389         if (fd < 0) {
 390                 return INVALID_WINFD;
 391         }
 392
 393         overlapped = create_overlapped();
 394         if(overlapped == NULL) {
 395                 _close(fd);
 396                 return INVALID_WINFD;
 397         }
 398
 399         for (i=0; i<MAX_FDS; i++) {
 400                 if (poll_fd[i].fd < 0) {
 401                         EnterCriticalSection(&_poll_fd[i].mutex);
 402                         // fd might have been removed before we got to critical
 403                         if (poll_fd[i].fd >= 0) {
 404                                 LeaveCriticalSection(&_poll_fd[i].mutex);
 405                                 continue;
 406                         }
 407                         wfd.fd = fd;
 408                         // Attempt to emulate some of the CancelIoEx behaviour on platforms
 409                         // that don't have it
 410                         if (!CancelIoEx_Available) {
 411                                 _poll_fd[i].thread_id = GetCurrentThreadId();
 412                                 if (!DuplicateHandle(GetCurrentProcess(), handle, GetCurrentProcess(),
 413                                         &wfd.handle, 0, TRUE, DUPLICATE_SAME_ACCESS)) {
 414                                         usbi_warn(NULL, "could not duplicate handle for CancelIo - using original one");
 415                                         wfd.handle = handle;
 416                                         // Make sure we won't close the original handle on fd deletion then
 417                                         _poll_fd[i].original_handle = INVALID_HANDLE_VALUE;
 418                                 } else {
 419                                         _poll_fd[i].original_handle = handle;
 420                                 }
 421                         } else {
 422                                 wfd.handle = handle;
 423                         }
 424                         wfd.overlapped = overlapped;
 425                         memcpy(&poll_fd[i], &wfd, sizeof(struct winfd));
 426                         LeaveCriticalSection(&_poll_fd[i].mutex);
 427 #if defined(DYNAMIC_FDS)
 428                         usbi_mutex_lock(&new_fd_mutex);
 429                         new_fd[nb_new_fds++] = overlapped->hEvent;
 430                         usbi_mutex_unlock(&new_fd_mutex);
 431                         // Notify poll that fds have been updated
 432                         SetEvent(fd_update);
 433 #endif
 434                         return wfd;
 435                 }
 436         }
 437         free_overlapped(overlapped);
 438         _close(fd);
 439         return INVALID_WINFD;
 440 }
 441
 442 void _free_index(int index)
 443 {
 444         // Cancel any async IO (Don't care about the validity of our handles for this)
 445         cancel_io(index);
 446         // close fake handle for devices
 447         if ( (poll_fd[index].handle != INVALID_HANDLE_VALUE) && (poll_fd[index].handle != 0)
 448           && (GetFileType(poll_fd[index].handle) == FILE_TYPE_UNKNOWN) ) {
 449                 _close(poll_fd[index].fd);
 450         }
 451         // close the duplicate handle (if we have an actual duplicate)
 452         if (!CancelIoEx_Available) {
 453                 if (_poll_fd[index].original_handle != INVALID_HANDLE_VALUE) {
 454                         CloseHandle(poll_fd[index].handle);
 455                 }
 456                 _poll_fd[index].original_handle = INVALID_HANDLE_VALUE;
 457                 _poll_fd[index].thread_id = 0;
 458         }
 459         free_overlapped(poll_fd[index].overlapped);
 460         poll_fd[index] = INVALID_WINFD;
 461 }
 462
 463 /*
 464  * Release a pollable file descriptor.
 465  *
 466  * Note that the associated Windows handle is not closed by this call
 467  */
 468 void usbi_free_fd(int fd)
 469 {
 470         int index;
 471
 472         CHECK_INIT_POLLING;
 473
 474         index = _fd_to_index_and_lock(fd);
 475         if (index < 0) {
 476                 return;
 477         }
 478         _free_index(index);
 479         LeaveCriticalSection(&_poll_fd[index].mutex);
 480 }
 481
 482 /*
 483  * The functions below perform various conversions between fd, handle and OVERLAPPED
 484  */
 485 struct winfd fd_to_winfd(int fd)
 486 {
 487         int i;
 488         struct winfd wfd;
 489
 490         CHECK_INIT_POLLING;
 491
 492         if (fd <= 0)
 493                 return INVALID_WINFD;
 494
 495         for (i=0; i<MAX_FDS; i++) {
 496                 if (poll_fd[i].fd == fd) {
 497                         EnterCriticalSection(&_poll_fd[i].mutex);
 498                         // fd might have been deleted before we got to critical
 499                         if (poll_fd[i].fd != fd) {
 500                                 LeaveCriticalSection(&_poll_fd[i].mutex);
 501                                 continue;
 502                         }
 503                         memcpy(&wfd, &poll_fd[i], sizeof(struct winfd));
 504                         LeaveCriticalSection(&_poll_fd[i].mutex);
 505                         return wfd;
 506                 }
 507         }
 508         return INVALID_WINFD;
 509 }
 510
 511 struct winfd handle_to_winfd(HANDLE handle)
 512 {
 513         int i;
 514         struct winfd wfd;
 515
 516         CHECK_INIT_POLLING;
 517
 518         if ((handle == 0) || (handle == INVALID_HANDLE_VALUE))
 519                 return INVALID_WINFD;
 520
 521         for (i=0; i<MAX_FDS; i++) {
 522                 if (poll_fd[i].handle == handle) {
 523                         EnterCriticalSection(&_poll_fd[i].mutex);
 524                         // fd might have been deleted before we got to critical
 525                         if (poll_fd[i].handle != handle) {
 526                                 LeaveCriticalSection(&_poll_fd[i].mutex);
 527                                 continue;
 528                         }
 529                         memcpy(&wfd, &poll_fd[i], sizeof(struct winfd));
 530                         LeaveCriticalSection(&_poll_fd[i].mutex);
 531                         return wfd;
 532                 }
 533         }
 534         return INVALID_WINFD;
 535 }
 536
 537 struct winfd overlapped_to_winfd(OVERLAPPED* overlapped)
 538 {
 539         int i;
 540         struct winfd wfd;
 541
 542         CHECK_INIT_POLLING;
 543
 544         if (overlapped == NULL)
 545                 return INVALID_WINFD;
 546
 547         for (i=0; i<MAX_FDS; i++) {
 548                 if (poll_fd[i].overlapped == overlapped) {
 549                         EnterCriticalSection(&_poll_fd[i].mutex);
 550                         // fd might have been deleted before we got to critical
 551                         if (poll_fd[i].overlapped != overlapped) {
 552                                 LeaveCriticalSection(&_poll_fd[i].mutex);
 553                                 continue;
 554                         }
 555                         memcpy(&wfd, &poll_fd[i], sizeof(struct winfd));
 556                         LeaveCriticalSection(&_poll_fd[i].mutex);
 557                         return wfd;
 558                 }
 559         }
 560         return INVALID_WINFD;
 561 }
 562
 563 /*
 564  * POSIX poll equivalent, using Windows OVERLAPPED
 565  * Currently, this function only accepts one of POLLIN or POLLOUT per fd
 566  * (but you can create multiple fds from the same handle for read and write)
 567  */
 568 int usbi_poll(struct pollfd *fds, unsigned int nfds, int timeout)
 569 {
 570         unsigned i;
 571         int index, object_index, triggered;
 572         HANDLE *handles_to_wait_on;
 573         int *handle_to_index;
 574         DWORD nb_handles_to_wait_on = 0;
 575         DWORD ret;
 576
 577 #if defined(DYNAMIC_FDS)
 578         DWORD nb_extra_handles = 0;
 579         unsigned j;
 580
 581         // To address the possibility of missing new fds between the time the new
 582         // pollable fd set is assembled, and the ResetEvent() call below, an
 583         // additional new_fd[] HANDLE table is used for any new fd that was created
 584         // since the last call to poll (see below)
 585         ResetEvent(fd_update);
 586
 587         // At this stage, any new fd creation will be detected through the fd_update
 588         // event notification, and any previous creation that we may have missed
 589         // will be picked up through the existing new_fd[] table.
 590 #endif
 591
 592         CHECK_INIT_POLLING;
 593
 594         triggered = 0;
 595         handles_to_wait_on = malloc((nfds+1)*sizeof(HANDLE));   // +1 for fd_update
 596         handle_to_index = malloc(nfds*sizeof(int));
 597         if ((handles_to_wait_on == NULL) || (handle_to_index == NULL)) {
 598                 errno = ENOMEM;
 599                 triggered = -1;
 600                 goto poll_exit;
 601         }
 602
 603         for (i = 0; i < nfds; ++i) {
 604                 fds[i].revents = 0;
 605
 606                 // Only one of POLLIN or POLLOUT can be selected with this version of poll (not both)
 607                 if ((fds[i].events & ~POLLIN) && (!(fds[i].events & POLLOUT))) {
 608                         fds[i].revents |= POLLERR;
 609                         errno = EACCES;
 610                         usbi_warn(NULL, "unsupported set of events");
 611                         triggered = -1;
 612                         goto poll_exit;
 613                 }
 614
 615                 index = _fd_to_index_and_lock(fds[i].fd);
 616                 poll_dbg("fd[%d]=%d: (overlapped=%p) got events %04X", i, poll_fd[index].fd, poll_fd[index].overlapped, fds[i].events);
 617
 618                 if ( (index < 0) || (poll_fd[index].handle == INVALID_HANDLE_VALUE)
 619                   || (poll_fd[index].handle == 0) || (poll_fd[index].overlapped == NULL)) {
 620                         fds[i].revents |= POLLNVAL | POLLERR;
 621                         errno = EBADF;
 622                         if (index >= 0) {
 623                                 LeaveCriticalSection(&_poll_fd[index].mutex);
 624                         }
 625                         usbi_warn(NULL, "invalid fd");
 626                         triggered = -1;
 627                         goto poll_exit;
 628                 }
 629
 630                 // IN or OUT must match our fd direction
 631                 if ((fds[i].events & POLLIN) && (poll_fd[index].rw != RW_READ)) {
 632                         fds[i].revents |= POLLNVAL | POLLERR;
 633                         errno = EBADF;
 634                         usbi_warn(NULL, "attempted POLLIN on fd without READ access");
 635                         LeaveCriticalSection(&_poll_fd[index].mutex);
 636                         triggered = -1;
 637                         goto poll_exit;
 638                 }
 639
 640                 if ((fds[i].events & POLLOUT) && (poll_fd[index].rw != RW_WRITE)) {
 641                         fds[i].revents |= POLLNVAL | POLLERR;
 642                         errno = EBADF;
 643                         usbi_warn(NULL, "attempted POLLOUT on fd without WRITE access");
 644                         LeaveCriticalSection(&_poll_fd[index].mutex);
 645                         triggered = -1;
 646                         goto poll_exit;
 647                 }
 648
 649                 // The following macro only works if overlapped I/O was reported pending
 650                 if ( (HasOverlappedIoCompleted(poll_fd[index].overlapped))
 651                   || (HasOverlappedIoCompletedSync(poll_fd[index].overlapped)) ) {
 652                         poll_dbg("  completed");
 653                         // checks above should ensure this works:
 654                         fds[i].revents = fds[i].events;
 655                         triggered++;
 656                 } else {
 657                         handles_to_wait_on[nb_handles_to_wait_on] = poll_fd[index].overlapped->hEvent;
 658                         handle_to_index[nb_handles_to_wait_on] = i;
 659 #if defined(DYNAMIC_FDS)
 660                         // If this fd from the poll set is also part of the new_fd event handle table, remove it
 661                         usbi_mutex_lock(&new_fd_mutex);
 662                         for (j=0; j<nb_new_fds; j++) {
 663                                 if (handles_to_wait_on[nb_handles_to_wait_on] == new_fd[j]) {
 664                                         new_fd[j] = INVALID_HANDLE_VALUE;
 665                                         break;
 666                                 }
 667                         }
 668                         usbi_mutex_unlock(&new_fd_mutex);
 669 #endif
 670                         nb_handles_to_wait_on++;
 671                 }
 672                 LeaveCriticalSection(&_poll_fd[index].mutex);
 673         }
 674 #if defined(DYNAMIC_FDS)
 675         // At this stage, new_fd[] should only contain events from fds that
 676         // have been added since the last call to poll, but are not (yet) part
 677         // of the pollable fd set. Typically, these would be from fds that have
 678         // been created between the construction of the fd set and the calling
 679         // of poll.
 680         // Event if we won't be able to return usable poll data on these events,
 681         // make sure we monitor them to return an EINTR code
 682         usbi_mutex_lock(&new_fd_mutex); // We could probably do without
 683         for (i=0; i<nb_new_fds; i++) {
 684                 if (new_fd[i] != INVALID_HANDLE_VALUE) {
 685                         handles_to_wait_on[nb_handles_to_wait_on++] = new_fd[i];
 686                         nb_extra_handles++;
 687                 }
 688         }
 689         usbi_mutex_unlock(&new_fd_mutex);
 690         poll_dbg("dynamic_fds: added %d extra handles", nb_extra_handles);
 691 #endif
 692
 693         // If nothing was triggered, wait on all fds that require it
 694         if ((timeout != 0) && (triggered == 0) && (nb_handles_to_wait_on != 0)) {
 695 #if defined(DYNAMIC_FDS)
 696                 // Register for fd update notifications
 697                 handles_to_wait_on[nb_handles_to_wait_on++] = fd_update;
 698                 nb_extra_handles++;
 699 #endif
 700                 if (timeout < 0) {
 701                         poll_dbg("starting infinite wait for %d handles...", (int)nb_handles_to_wait_on);
 702                 } else {
 703                         poll_dbg("starting %d ms wait for %d handles...", timeout, (int)nb_handles_to_wait_on);
 704                 }
 705                 ret = WaitForMultipleObjects(nb_handles_to_wait_on, handles_to_wait_on,
 706                         FALSE, (timeout<0)?INFINITE:(DWORD)timeout);
 707                 object_index = ret-WAIT_OBJECT_0;
 708                 if ((object_index >= 0) && ((DWORD)object_index < nb_handles_to_wait_on)) {
 709 #if defined(DYNAMIC_FDS)
 710                         if ((DWORD)object_index >= (nb_handles_to_wait_on-nb_extra_handles)) {
 711                                 // Detected fd update => flag a poll interruption
 712                                 if ((DWORD)object_index == (nb_handles_to_wait_on-1))
 713                                         poll_dbg("  dynamic_fds: fd_update event");
 714                                 else
 715                                         poll_dbg("  dynamic_fds: new fd I/O event");
 716                                 errno = EINTR;
 717                                 triggered = -1;
 718                                 goto poll_exit;
 719                         }
 720 #endif
 721                         poll_dbg("  completed after wait");
 722                         i = handle_to_index[object_index];
 723                         index = _fd_to_index_and_lock(fds[i].fd);
 724                         fds[i].revents = fds[i].events;
 725                         triggered++;
 726                         if (index >= 0) {
 727                                 LeaveCriticalSection(&_poll_fd[index].mutex);
 728                         }
 729                 } else if (ret == WAIT_TIMEOUT) {
 730                         poll_dbg("  timed out");
 731                         triggered = 0;  // 0 = timeout
 732                 } else {
 733                         errno = EIO;
 734                         triggered = -1; // error
 735                 }
 736         }
 737
 738 poll_exit:
 739         if (handles_to_wait_on != NULL) {
 740                 free(handles_to_wait_on);
 741         }
 742         if (handle_to_index != NULL) {
 743                 free(handle_to_index);
 744         }
 745 #if defined(DYNAMIC_FDS)
 746         usbi_mutex_lock(&new_fd_mutex);
 747         nb_new_fds = 0;
 748         usbi_mutex_unlock(&new_fd_mutex);
 749 #endif
 750         return triggered;
 751 }
 752
 753 /*
 754  * close a fake pipe fd
 755  */
 756 int usbi_close(int fd)
 757 {
 758         int index;
 759         int r = -1;
 760
 761         CHECK_INIT_POLLING;
 762
 763         index = _fd_to_index_and_lock(fd);
 764
 765         if (index < 0) {
 766                 errno = EBADF;
 767         } else {
 768                 if (poll_fd[index].overlapped != NULL) {
 769                         // Must be a different event for each end of the pipe
 770                         CloseHandle(poll_fd[index].overlapped->hEvent);
 771                         free(poll_fd[index].overlapped);
 772                 }
 773                 if (CloseHandle(poll_fd[index].handle) == 0) {
 774                         errno = EIO;
 775                 } else {
 776                         r = 0;
 777                 }
 778                 poll_fd[index] = INVALID_WINFD;
 779                 LeaveCriticalSection(&_poll_fd[index].mutex);
 780         }
 781         return r;
 782 }
 783
 784 /*
 785  * synchronous write for fake "pipe" signaling
 786  */
 787 ssize_t usbi_write(int fd, const void *buf, size_t count)
 788 {
 789         int index;
 790
 791         CHECK_INIT_POLLING;
 792
 793         if (count != sizeof(unsigned char)) {
 794                 usbi_err(NULL, "this function should only used for signaling");
 795                 return -1;
 796         }
 797
 798         index = _fd_to_index_and_lock(fd);
 799
 800         if ( (index < 0) || (poll_fd[index].overlapped == NULL) ) {
 801                 errno = EBADF;
 802                 if (index >= 0) {
 803                         LeaveCriticalSection(&_poll_fd[index].mutex);
 804                 }
 805                 return -1;
 806         }
 807
 808         poll_dbg("set pipe event (fd = %d, thread = %08X)", index, GetCurrentThreadId());
 809         SetEvent(poll_fd[index].overlapped->hEvent);
 810         poll_fd[index].overlapped->Internal = STATUS_WAIT_0;
 811         // If two threads write on the pipe at the same time, we need to
 812         // process two separate reads => use the overlapped as a counter
 813         poll_fd[index].overlapped->InternalHigh++;
 814
 815         LeaveCriticalSection(&_poll_fd[index].mutex);
 816         return sizeof(unsigned char);
 817 }
 818
 819 /*
 820  * synchronous read for fake "pipe" signaling
 821  */
 822 ssize_t usbi_read(int fd, void *buf, size_t count)
 823 {
 824         int index;
 825         ssize_t r = -1;
 826
 827         CHECK_INIT_POLLING;
 828
 829         if (count != sizeof(unsigned char)) {
 830                 usbi_err(NULL, "this function should only used for signaling");
 831                 return -1;
 832         }
 833
 834         index = _fd_to_index_and_lock(fd);
 835
 836         if (index < 0) {
 837                 errno = EBADF;
 838                 return -1;
 839         }
 840
 841         if (WaitForSingleObject(poll_fd[index].overlapped->hEvent, INFINITE) != WAIT_OBJECT_0) {
 842                 usbi_warn(NULL, "waiting for event failed: %d", (int)GetLastError());
 843                 errno = EIO;
 844                 goto out;
 845         }
 846
 847         poll_dbg("clr pipe event (fd = %d, thread = %08X)", index, GetCurrentThreadId());
 848         poll_fd[index].overlapped->InternalHigh--;
 849         // Don't reset unless we don't have any more events to process
 850         if (poll_fd[index].overlapped->InternalHigh <= 0) {
 851                 ResetEvent(poll_fd[index].overlapped->hEvent);
 852                 poll_fd[index].overlapped->Internal = STATUS_PENDING;
 853         }
 854
 855         r = sizeof(unsigned char);
 856
 857 out:
 858         LeaveCriticalSection(&_poll_fd[index].mutex);
 859         return r;
 860 }