/*
* poll_windows: poll compatibility wrapper for Windows
* Copyright © 2012-2013 RealVNC Ltd.
* Copyright © 2009-2010 Pete Batard <pete@akeo.ie>
* With contributions from Michael Plante, Orin Eman et al.
* Parts of poll implementation from libusb-win32, by Stephan Meyer et al.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
/*
* poll() and pipe() Windows compatibility layer for libusb 1.0
*
* The way this layer works is by using OVERLAPPED with async I/O transfers, as
* OVERLAPPED have an associated event which is flagged for I/O completion.
*
* For USB pollable async I/O, you would typically:
* - obtain a Windows HANDLE to a file or device that has been opened in
* OVERLAPPED mode
* - call usbi_create_fd with this handle to obtain a custom fd.
* Note that if you need simultaneous R/W access, you need to call create_fd
* twice, once in RW_READ and once in RW_WRITE mode to obtain 2 separate
* pollable fds
* - leave the core functions call the poll routine and flag POLLIN/POLLOUT
*
* The pipe pollable synchronous I/O works using the overlapped event associated
* with a fake pipe. The read/write functions are only meant to be used in that
* context.
*/
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include "libusbi.h"
// Uncomment to debug the polling layer
//#define DEBUG_POLL_WINDOWS
#if defined(DEBUG_POLL_WINDOWS)
#define poll_dbg usbi_dbg
#else
// MSVC++ < 2005 cannot use a variadic argument and non MSVC
// compilers produce warnings if parenthesis are ommitted.
#if defined(_MSC_VER) && (_MSC_VER < 1400)
#define poll_dbg
#else
#define poll_dbg(...)
#endif
#endif
#if defined(_PREFAST_)
#pragma warning(disable:28719)
#endif
#define CHECK_INIT_POLLING do {if(!is_polling_set) init_polling();} while(0)
// public fd data
const struct winfd INVALID_WINFD = {-1, INVALID_HANDLE_VALUE, NULL, NULL, NULL, RW_NONE};
struct winfd poll_fd[MAX_FDS];
// internal fd data
struct {
CRITICAL_SECTION mutex; // lock for fds
// Additional variables for XP CancelIoEx partial emulation
HANDLE original_handle;
DWORD thread_id;
} _poll_fd[MAX_FDS];
// globals
BOOLEAN is_polling_set = FALSE;
LONG pipe_number = 0;
static volatile LONG compat_spinlock = 0;
#if !defined(_WIN32_WCE)
// CancelIoEx, available on Vista and later only, provides the ability to cancel
// a single transfer (OVERLAPPED) when used. As it may not be part of any of the
// platform headers, we hook into the Kernel32 system DLL directly to seek it.
static BOOL (__stdcall *pCancelIoEx)(HANDLE, LPOVERLAPPED) = NULL;
#define Use_Duplicate_Handles (pCancelIoEx == NULL)
static inline void setup_cancel_io(void)
{
HMODULE hKernel32 = GetModuleHandleA("KERNEL32");
if (hKernel32 != NULL) {
pCancelIoEx = (BOOL (__stdcall *)(HANDLE,LPOVERLAPPED))
GetProcAddress(hKernel32, "CancelIoEx");
}
usbi_dbg("Will use CancelIo%s for I/O cancellation",
Use_Duplicate_Handles?"":"Ex");
}
static inline BOOL cancel_io(int _index)
{
if ((_index < 0) || (_index >= MAX_FDS)) {
return FALSE;
}
if ( (poll_fd[_index].fd < 0) || (poll_fd[_index].handle == INVALID_HANDLE_VALUE)
|| (poll_fd[_index].handle == 0) || (poll_fd[_index].overlapped == NULL) ) {
return TRUE;
}
if (poll_fd[_index].itransfer && poll_fd[_index].cancel_fn) {
// Cancel outstanding transfer via the specific callback
(*poll_fd[_index].cancel_fn)(poll_fd[_index].itransfer);
return TRUE;
}
if (pCancelIoEx != NULL) {
return (*pCancelIoEx)(poll_fd[_index].handle, poll_fd[_index].overlapped);
}
if (_poll_fd[_index].thread_id == GetCurrentThreadId()) {
return CancelIo(poll_fd[_index].handle);
}
usbi_warn(NULL, "Unable to cancel I/O that was started from another thread");
return FALSE;
}
#else
#define Use_Duplicate_Handles FALSE
static __inline void setup_cancel_io()
{
// No setup needed on WinCE
}
static __inline BOOL cancel_io(int _index)
{
if ((_index < 0) || (_index >= MAX_FDS)) {
return FALSE;
}
if ( (poll_fd[_index].fd < 0) || (poll_fd[_index].handle == INVALID_HANDLE_VALUE)
|| (poll_fd[_index].handle == 0) || (poll_fd[_index].overlapped == NULL) ) {
return TRUE;
}
if (poll_fd[_index].itransfer && poll_fd[_index].cancel_fn) {
// Cancel outstanding transfer via the specific callback
(*poll_fd[_index].cancel_fn)(poll_fd[_index].itransfer);
}
return TRUE;
}
#endif
// Init
void init_polling(void)
{
int i;
while (InterlockedExchange((LONG *)&compat_spinlock, 1) == 1) {
SleepEx(0, TRUE);
}
if (!is_polling_set) {
setup_cancel_io();
for (i=0; i<MAX_FDS; i++) {
poll_fd[i] = INVALID_WINFD;
_poll_fd[i].original_handle = INVALID_HANDLE_VALUE;
_poll_fd[i].thread_id = 0;
InitializeCriticalSection(&_poll_fd[i].mutex);
}
is_polling_set = TRUE;
}
InterlockedExchange((LONG *)&compat_spinlock, 0);
}
// Internal function to retrieve the table index (and lock the fd mutex)
static int _fd_to_index_and_lock(int fd)
{
int i;
if (fd < 0)
return -1;
for (i=0; i<MAX_FDS; i++) {
if (poll_fd[i].fd == fd) {
EnterCriticalSection(&_poll_fd[i].mutex);
// fd might have changed before we got to critical
if (poll_fd[i].fd != fd) {
LeaveCriticalSection(&_poll_fd[i].mutex);
continue;
}
return i;
}
}
return -1;
}
static OVERLAPPED *create_overlapped(void)
{
OVERLAPPED *overlapped = (OVERLAPPED*) calloc(1, sizeof(OVERLAPPED));
if (overlapped == NULL) {
return NULL;
}
overlapped->hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
if(overlapped->hEvent == NULL) {
free (overlapped);
return NULL;
}
return overlapped;
}
static void free_overlapped(OVERLAPPED *overlapped)
{
if (overlapped == NULL)
return;
if ( (overlapped->hEvent != 0)
&& (overlapped->hEvent != INVALID_HANDLE_VALUE) ) {
CloseHandle(overlapped->hEvent);
}
free(overlapped);
}
void exit_polling(void)
{
int i;
while (InterlockedExchange((LONG *)&compat_spinlock, 1) == 1) {
SleepEx(0, TRUE);
}
if (is_polling_set) {
is_polling_set = FALSE;
for (i=0; i<MAX_FDS; i++) {
// Cancel any async I/O (handle can be invalid)
cancel_io(i);
// If anything was pending on that I/O, it should be
// terminating, and we should be able to access the fd
// mutex lock before too long
EnterCriticalSection(&_poll_fd[i].mutex);
free_overlapped(poll_fd[i].overlapped);
if (Use_Duplicate_Handles) {
// Close duplicate handle
if (_poll_fd[i].original_handle != INVALID_HANDLE_VALUE) {
CloseHandle(poll_fd[i].handle);
}
}
poll_fd[i] = INVALID_WINFD;
LeaveCriticalSection(&_poll_fd[i].mutex);
DeleteCriticalSection(&_poll_fd[i].mutex);
}
}
InterlockedExchange((LONG *)&compat_spinlock, 0);
}
/*
* Create a fake pipe.
* As libusb only uses pipes for signaling, all we need from a pipe is an
* event. To that extent, we create a single wfd and overlapped as a means
* to access that event.
*/
int usbi_pipe(int filedes[2])
{
int i;
OVERLAPPED* overlapped;
CHECK_INIT_POLLING;
overlapped = create_overlapped();
if (overlapped == NULL) {
return -1;
}
// The overlapped must have status pending for signaling to work in poll
overlapped->Internal = STATUS_PENDING;
overlapped->InternalHigh = 0;
for (i=0; i<MAX_FDS; i++) {
if (poll_fd[i].fd < 0) {
EnterCriticalSection(&_poll_fd[i].mutex);
// fd might have been allocated before we got to critical
if (poll_fd[i].fd >= 0) {
LeaveCriticalSection(&_poll_fd[i].mutex);
continue;
}
// Use index as the unique fd number
poll_fd[i].fd = i;
// Read end of the "pipe"
filedes[0] = poll_fd[i].fd;
// We can use the same handle for both ends
filedes[1] = filedes[0];
poll_fd[i].handle = DUMMY_HANDLE;
poll_fd[i].overlapped = overlapped;
// There's no polling on the write end, so we just use READ for our needs
poll_fd[i].rw = RW_READ;
_poll_fd[i].original_handle = INVALID_HANDLE_VALUE;
LeaveCriticalSection(&_poll_fd[i].mutex);
return 0;
}
}
free_overlapped(overlapped);
return -1;
}
/*
* Create both an fd and an OVERLAPPED from an open Windows handle, so that
* it can be used with our polling function
* The handle MUST support overlapped transfers (usually requires CreateFile
* with FILE_FLAG_OVERLAPPED)
* Return a pollable file descriptor struct, or INVALID_WINFD on error
*
* Note that the fd returned by this function is a per-transfer fd, rather
* than a per-session fd and cannot be used for anything else but our
* custom functions (the fd itself points to the NUL: device)
* if you plan to do R/W on the same handle, you MUST create 2 fds: one for
* read and one for write. Using a single R/W fd is unsupported and will
* produce unexpected results
*/
struct winfd usbi_create_fd(HANDLE handle, int access_mode, struct usbi_transfer *itransfer, cancel_transfer *cancel_fn)
{
int i;
struct winfd wfd = INVALID_WINFD;
OVERLAPPED* overlapped = NULL;
CHECK_INIT_POLLING;
if ((handle == 0) || (handle == INVALID_HANDLE_VALUE)) {
return INVALID_WINFD;
}
wfd.itransfer = itransfer;
wfd.cancel_fn = cancel_fn;
if ((access_mode != RW_READ) && (access_mode != RW_WRITE)) {
usbi_warn(NULL, "only one of RW_READ or RW_WRITE are supported.\n"
"If you want to poll for R/W simultaneously, create multiple fds from the same handle.");
return INVALID_WINFD;
}
if (access_mode == RW_READ) {
wfd.rw = RW_READ;
} else {
wfd.rw = RW_WRITE;
}
overlapped = create_overlapped();
if(overlapped == NULL) {
return INVALID_WINFD;
}
for (i=0; i<MAX_FDS; i++) {
if (poll_fd[i].fd < 0) {
EnterCriticalSection(&_poll_fd[i].mutex);
// fd might have been removed before we got to critical
if (poll_fd[i].fd >= 0) {
LeaveCriticalSection(&_poll_fd[i].mutex);
continue;
}
// Use index as the unique fd number
wfd.fd = i;
// Attempt to emulate some of the CancelIoEx behaviour on platforms
// that don't have it
if (Use_Duplicate_Handles) {
_poll_fd[i].thread_id = GetCurrentThreadId();
if (!DuplicateHandle(GetCurrentProcess(), handle, GetCurrentProcess(),
&wfd.handle, 0, TRUE, DUPLICATE_SAME_ACCESS)) {
usbi_dbg("could not duplicate handle for CancelIo - using original one");
wfd.handle = handle;
// Make sure we won't close the original handle on fd deletion then
_poll_fd[i].original_handle = INVALID_HANDLE_VALUE;
} else {
_poll_fd[i].original_handle = handle;
}
} else {
wfd.handle = handle;
}
wfd.overlapped = overlapped;
memcpy(&poll_fd[i], &wfd, sizeof(struct winfd));
LeaveCriticalSection(&_poll_fd[i].mutex);
return wfd;
}
}
free_overlapped(overlapped);
return INVALID_WINFD;
}
static void _free_index(int _index)
{
// Cancel any async IO (Don't care about the validity of our handles for this)
cancel_io(_index);
// close the duplicate handle (if we have an actual duplicate)
if (Use_Duplicate_Handles) {
if (_poll_fd[_index].original_handle != INVALID_HANDLE_VALUE) {
CloseHandle(poll_fd[_index].handle);
}
_poll_fd[_index].original_handle = INVALID_HANDLE_VALUE;
_poll_fd[_index].thread_id = 0;
}
free_overlapped(poll_fd[_index].overlapped);
poll_fd[_index] = INVALID_WINFD;
}
/*
* Release a pollable file descriptor.
*
* Note that the associated Windows handle is not closed by this call
*/
void usbi_free_fd(struct winfd *wfd)
{
int _index;
CHECK_INIT_POLLING;
_index = _fd_to_index_and_lock(wfd->fd);
if (_index < 0) {
return;
}
_free_index(_index);
*wfd = INVALID_WINFD;
LeaveCriticalSection(&_poll_fd[_index].mutex);
}
/*
* The functions below perform various conversions between fd, handle and OVERLAPPED
*/
struct winfd fd_to_winfd(int fd)
{
int i;
struct winfd wfd;
CHECK_INIT_POLLING;
if (fd < 0)
return INVALID_WINFD;
for (i=0; i<MAX_FDS; i++) {
if (poll_fd[i].fd == fd) {
EnterCriticalSection(&_poll_fd[i].mutex);
// fd might have been deleted before we got to critical
if (poll_fd[i].fd != fd) {
LeaveCriticalSection(&_poll_fd[i].mutex);
continue;
}
memcpy(&wfd, &poll_fd[i], sizeof(struct winfd));
LeaveCriticalSection(&_poll_fd[i].mutex);
return wfd;
}
}
return INVALID_WINFD;
}
struct winfd handle_to_winfd(HANDLE handle)
{
int i;
struct winfd wfd;
CHECK_INIT_POLLING;
if ((handle == 0) || (handle == INVALID_HANDLE_VALUE))
return INVALID_WINFD;
for (i=0; i<MAX_FDS; i++) {
if (poll_fd[i].handle == handle) {
EnterCriticalSection(&_poll_fd[i].mutex);
// fd might have been deleted before we got to critical
if (poll_fd[i].handle != handle) {
LeaveCriticalSection(&_poll_fd[i].mutex);
continue;
}
memcpy(&wfd, &poll_fd[i], sizeof(struct winfd));
LeaveCriticalSection(&_poll_fd[i].mutex);
return wfd;
}
}
return INVALID_WINFD;
}
struct winfd overlapped_to_winfd(OVERLAPPED* overlapped)
{
int i;
struct winfd wfd;
CHECK_INIT_POLLING;
if (overlapped == NULL)
return INVALID_WINFD;
for (i=0; i<MAX_FDS; i++) {
if (poll_fd[i].overlapped == overlapped) {
EnterCriticalSection(&_poll_fd[i].mutex);
// fd might have been deleted before we got to critical
if (poll_fd[i].overlapped != overlapped) {
LeaveCriticalSection(&_poll_fd[i].mutex);
continue;
}
memcpy(&wfd, &poll_fd[i], sizeof(struct winfd));
LeaveCriticalSection(&_poll_fd[i].mutex);
return wfd;
}
}
return INVALID_WINFD;
}
/*
* POSIX poll equivalent, using Windows OVERLAPPED
* Currently, this function only accepts one of POLLIN or POLLOUT per fd
* (but you can create multiple fds from the same handle for read and write)
*/
int usbi_poll(struct pollfd *fds, unsigned int nfds, int timeout)
{
unsigned i;
int _index, object_index, triggered;
HANDLE *handles_to_wait_on;
int *handle_to_index;
DWORD nb_handles_to_wait_on = 0;
DWORD ret;
CHECK_INIT_POLLING;
triggered = 0;
handles_to_wait_on = (HANDLE*) calloc(nfds+1, sizeof(HANDLE)); // +1 for fd_update
handle_to_index = (int*) calloc(nfds, sizeof(int));
if ((handles_to_wait_on == NULL) || (handle_to_index == NULL)) {
errno = ENOMEM;
triggered = -1;
goto poll_exit;
}
for (i = 0; i < nfds; ++i) {
fds[i].revents = 0;
// Only one of POLLIN or POLLOUT can be selected with this version of poll (not both)
if ((fds[i].events & ~POLLIN) && (!(fds[i].events & POLLOUT))) {
fds[i].revents |= POLLERR;
errno = EACCES;
usbi_warn(NULL, "unsupported set of events");
triggered = -1;
goto poll_exit;
}
_index = _fd_to_index_and_lock(fds[i].fd);
poll_dbg("fd[%d]=%d: (overlapped=%p) got events %04X", i, poll_fd[_index].fd, poll_fd[_index].overlapped, fds[i].events);
if ( (_index < 0) || (poll_fd[_index].handle == INVALID_HANDLE_VALUE)
|| (poll_fd[_index].handle == 0) || (poll_fd[_index].overlapped == NULL)) {
fds[i].revents |= POLLNVAL | POLLERR;
errno = EBADF;
if (_index >= 0) {
LeaveCriticalSection(&_poll_fd[_index].mutex);
}
usbi_warn(NULL, "invalid fd");
triggered = -1;
goto poll_exit;
}
// IN or OUT must match our fd direction
if ((fds[i].events & POLLIN) && (poll_fd[_index].rw != RW_READ)) {
fds[i].revents |= POLLNVAL | POLLERR;
errno = EBADF;
usbi_warn(NULL, "attempted POLLIN on fd without READ access");
LeaveCriticalSection(&_poll_fd[_index].mutex);
triggered = -1;
goto poll_exit;
}
if ((fds[i].events & POLLOUT) && (poll_fd[_index].rw != RW_WRITE)) {
fds[i].revents |= POLLNVAL | POLLERR;
errno = EBADF;
usbi_warn(NULL, "attempted POLLOUT on fd without WRITE access");
LeaveCriticalSection(&_poll_fd[_index].mutex);
triggered = -1;
goto poll_exit;
}
// The following macro only works if overlapped I/O was reported pending
if ( (HasOverlappedIoCompleted(poll_fd[_index].overlapped))
|| (HasOverlappedIoCompletedSync(poll_fd[_index].overlapped)) ) {
poll_dbg(" completed");
// checks above should ensure this works:
fds[i].revents = fds[i].events;
triggered++;
} else {
handles_to_wait_on[nb_handles_to_wait_on] = poll_fd[_index].overlapped->hEvent;
handle_to_index[nb_handles_to_wait_on] = i;
nb_handles_to_wait_on++;
}
LeaveCriticalSection(&_poll_fd[_index].mutex);
}
// If nothing was triggered, wait on all fds that require it
if ((timeout != 0) && (triggered == 0) && (nb_handles_to_wait_on != 0)) {
if (timeout < 0) {
poll_dbg("starting infinite wait for %d handles...", (int)nb_handles_to_wait_on);
} else {
poll_dbg("starting %d ms wait for %d handles...", timeout, (int)nb_handles_to_wait_on);
}
ret = WaitForMultipleObjects(nb_handles_to_wait_on, handles_to_wait_on,
FALSE, (timeout<0)?INFINITE:(DWORD)timeout);
object_index = ret-WAIT_OBJECT_0;
if ((object_index >= 0) && ((DWORD)object_index < nb_handles_to_wait_on)) {
poll_dbg(" completed after wait");
i = handle_to_index[object_index];
_index = _fd_to_index_and_lock(fds[i].fd);
fds[i].revents = fds[i].events;
triggered++;
if (_index >= 0) {
LeaveCriticalSection(&_poll_fd[_index].mutex);
}
} else if (ret == WAIT_TIMEOUT) {
poll_dbg(" timed out");
triggered = 0; // 0 = timeout
} else {
errno = EIO;
triggered = -1; // error
}
}
poll_exit:
if (handles_to_wait_on != NULL) {
free(handles_to_wait_on);
}
if (handle_to_index != NULL) {
free(handle_to_index);
}
return triggered;
}
/*
* close a fake pipe fd
*/
int usbi_close(int fd)
{
int _index;
int r = -1;
CHECK_INIT_POLLING;
_index = _fd_to_index_and_lock(fd);
if (_index < 0) {
errno = EBADF;
} else {
free_overlapped(poll_fd[_index].overlapped);
poll_fd[_index] = INVALID_WINFD;
LeaveCriticalSection(&_poll_fd[_index].mutex);
}
return r;
}
/*
* synchronous write for fake "pipe" signaling
*/
ssize_t usbi_write(int fd, const void *buf, size_t count)
{
int _index;
UNUSED(buf);
CHECK_INIT_POLLING;
if (count != sizeof(unsigned char)) {
usbi_err(NULL, "this function should only used for signaling");
return -1;
}
_index = _fd_to_index_and_lock(fd);
if ( (_index < 0) || (poll_fd[_index].overlapped == NULL) ) {
errno = EBADF;
if (_index >= 0) {
LeaveCriticalSection(&_poll_fd[_index].mutex);
}
return -1;
}
poll_dbg("set pipe event (fd = %d, thread = %08X)", _index, GetCurrentThreadId());
SetEvent(poll_fd[_index].overlapped->hEvent);
poll_fd[_index].overlapped->Internal = STATUS_WAIT_0;
// If two threads write on the pipe at the same time, we need to
// process two separate reads => use the overlapped as a counter
poll_fd[_index].overlapped->InternalHigh++;
LeaveCriticalSection(&_poll_fd[_index].mutex);
return sizeof(unsigned char);
}
/*
* synchronous read for fake "pipe" signaling
*/
ssize_t usbi_read(int fd, void *buf, size_t count)
{
int _index;
ssize_t r = -1;
UNUSED(buf);
CHECK_INIT_POLLING;
if (count != sizeof(unsigned char)) {
usbi_err(NULL, "this function should only used for signaling");
return -1;
}
_index = _fd_to_index_and_lock(fd);
if (_index < 0) {
errno = EBADF;
return -1;
}
if (WaitForSingleObject(poll_fd[_index].overlapped->hEvent, INFINITE) != WAIT_OBJECT_0) {
usbi_warn(NULL, "waiting for event failed: %d", (int)GetLastError());
errno = EIO;
goto out;
}
poll_dbg("clr pipe event (fd = %d, thread = %08X)", _index, GetCurrentThreadId());
poll_fd[_index].overlapped->InternalHigh--;
// Don't reset unless we don't have any more events to process
if (poll_fd[_index].overlapped->InternalHigh <= 0) {
ResetEvent(poll_fd[_index].overlapped->hEvent);
poll_fd[_index].overlapped->Internal = STATUS_PENDING;
}
r = sizeof(unsigned char);
out:
LeaveCriticalSection(&_poll_fd[_index].mutex);
return r;
}
