diff options
| -rw-r--r-- | libusb/os/poll_windows.c | 282 |
1 files changed, 57 insertions, 225 deletions
diff --git a/libusb/os/poll_windows.c b/libusb/os/poll_windows.c index 234edcd..a7072b2 100644 --- a/libusb/os/poll_windows.c +++ b/libusb/os/poll_windows.c @@ -35,30 +35,9 @@ * pollable fds * - leave the core functions call the poll routine and flag POLLIN/POLLOUT * - * For pipe pollable synchronous I/O (read end polling only), you would: - * - create an anonymous pipe with usbi_pipe to obtain 2 fds (r & w) - * - use usbi_write / usbi_read to write to either end of the pipe - * - use poll to check for data to read - * Note that the usbi_read/usbi_write function actually perform - * asynchronous I/O internally, and could potentially be modified to support - * O_NON_BLOCK - * - * The way the polling on usbi_read works is by splitting all read I/O - * into a dual 1 byte/n-1 bytes asynchronous read operation. - * The 1 byte data (called the marker), is always armed for asynchronous - * readout, so that as soon as data becomes available, an OVERLAPPED event - * will be flagged, which poll can report. - * Then during the usbi_read routine itself, this 1 byte marker is copied - * to the buffer, along with the rest of the data. - * - * Note that, since most I/O is buffered, being notified when only the first - * byte of data is available is unlikely to delay read operations, since the - * rest of the data should be available in system buffers by the time read - * is called. - * - * Also note that if you don't use usbi_read to read inbound data, but - * use the OVERLAPPED directly (which is what we do in the USB async I/O - * functions), the marker is not used at all. + * 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 <fcntl.h> @@ -132,7 +111,7 @@ struct { BOOLEAN is_polling_set = FALSE; #if defined(DYNAMIC_FDS) HANDLE fd_update = INVALID_HANDLE_VALUE; // event to notify poll of fd update -HANDLE new_fd[MAX_FDS]; // overlapped event handlesm for fds created since last poll +HANDLE new_fd[MAX_FDS]; // overlapped event handles for fds created since last poll unsigned nb_new_fds = 0; // nb new fds created since last poll usbi_mutex_t new_fd_mutex; // mutex required for the above #endif @@ -303,67 +282,37 @@ void exit_polling(void) } /* - * sets the async I/O read on our 1 byte marker - * - * requires a valid index - */ -__inline void _init_read_marker(int index) -{ - // Cancel any read operation in progress - cancel_io(index); - // Setup a new async read on our marker - reset_overlapped(poll_fd[index].overlapped); - if (!ReadFile(poll_fd[index].handle, &_poll_fd[index].marker, 1, NULL, poll_fd[index].overlapped)) { - if(GetLastError() != ERROR_IO_PENDING) { - usbi_warn(NULL, "didn't get IO_PENDING!"); - reset_overlapped(poll_fd[index].overlapped); - } - } else { - // We got some sync I/O. We'll pretend it's async and set overlapped manually - poll_dbg("marker readout completed before exit!"); - if (!HasOverlappedIoCompleted(poll_fd[index].overlapped)) { - usbi_warn(NULL, "completed I/O still flagged as pending"); - poll_fd[index].overlapped->Internal = 0; - } - SetEvent(poll_fd[index].overlapped->hEvent); - poll_fd[index].overlapped->InternalHigh = 1; - } -} - -/* - * Create an async I/O anonymous pipe (that can be used for sync as well) + * Create a fake pipe. + * As libusb only uses pipes for signaling, all we need from a pipe is an + * event. To that extent, we only create wfd's and overlapped's as a means + * to access that event. */ int usbi_pipe(int filedes[2]) { int i, j; HANDLE handle[2]; - OVERLAPPED *overlapped0, *overlapped1; - char pipe_name[] = "\\\\.\\pipe\\libusb000000000000"; - LONG our_pipe_number; + OVERLAPPED* overlapped[2]; CHECK_INIT_POLLING; - overlapped0 = calloc(1, sizeof(OVERLAPPED)); - if (overlapped0 == NULL) { - return -1; - } - - overlapped1 = calloc(1, sizeof(OVERLAPPED)); - if (overlapped1 == NULL) { - free(overlapped0); + // We must use 2 separate overlapped, else we'll crash when trying to + // free the same overlapped twice on closure + overlapped[0] = calloc(1, sizeof(OVERLAPPED)); + if (overlapped[0] == NULL) { return -1; } + // The read end must have status pending for signaling to work in poll + overlapped[0]->Internal = STATUS_PENDING; - our_pipe_number = InterlockedIncrement(&pipe_number) - 1; // - 1 to mirror postfix operation inside _snprintf - if (our_pipe_number >= 0x10000) { - usbi_warn(NULL, "program assertion failed - more than 65536 pipes were used"); - our_pipe_number &= 0xFFFF; + overlapped[1] = calloc(1, sizeof(OVERLAPPED)); + if (overlapped[1] == NULL) { + goto out0; } - _snprintf(pipe_name, sizeof(pipe_name), "\\\\.\\pipe\\libusb%08x%04x", (unsigned)GetCurrentProcessId(), our_pipe_number); + // Not so important for the write end... + overlapped[1]->Internal = STATUS_PENDING; - // Read end of the pipe - handle[0] = CreateNamedPipeA(pipe_name, PIPE_ACCESS_INBOUND|FILE_FLAG_OVERLAPPED, - PIPE_TYPE_MESSAGE|PIPE_READMODE_MESSAGE, 1, 4096, 4096, 0, NULL); + // Read end of the "pipe" + handle[0] = CreateFileA("NUL", 0, 0, NULL, OPEN_EXISTING, 0, NULL); if (handle[0] == INVALID_HANDLE_VALUE) { usbi_err(NULL, "could not create pipe (read end): errcode %d", (int)GetLastError()); goto out1; @@ -371,9 +320,8 @@ int usbi_pipe(int filedes[2]) filedes[0] = _open_osfhandle((intptr_t)handle[0], _O_RDONLY); poll_dbg("filedes[0] = %d", filedes[0]); - // Write end of the pipe - handle[1] = CreateFileA(pipe_name, GENERIC_WRITE, 0, NULL, OPEN_EXISTING, - FILE_ATTRIBUTE_NORMAL|FILE_FLAG_OVERLAPPED, NULL); + // Write end of the "pipe" + handle[1] = CreateFileA("NUL", 0, 0, NULL, OPEN_EXISTING, 0, NULL); if (handle[1] == INVALID_HANDLE_VALUE) { usbi_err(NULL, "could not create pipe (write end): errcode %d", (int)GetLastError()); goto out2; @@ -381,15 +329,13 @@ int usbi_pipe(int filedes[2]) filedes[1] = _open_osfhandle((intptr_t)handle[1], _O_WRONLY); poll_dbg("filedes[1] = %d", filedes[1]); - // Create an OVERLAPPED for each end - overlapped0->hEvent = CreateEvent(NULL, TRUE, FALSE, NULL); - if(!overlapped0->hEvent) { + // Use the same event for both overlapped + // Note: manual reset must be true (second param) as the reset occurs in read + overlapped[0]->hEvent = CreateEvent(NULL, TRUE, FALSE, NULL); + if(!overlapped[0]->hEvent) { goto out3; } - overlapped1->hEvent = CreateEvent(NULL, TRUE, FALSE, NULL); - if(!overlapped1->hEvent) { - goto out4; - } + overlapped[1]->hEvent = overlapped[0]->hEvent; for (i=0, j=0; i<MAX_FDS; i++) { if (poll_fd[i].fd < 0) { @@ -402,14 +348,9 @@ int usbi_pipe(int filedes[2]) poll_fd[i].fd = filedes[j]; poll_fd[i].handle = handle[j]; - poll_fd[i].overlapped = (j==0)?overlapped0:overlapped1; + poll_fd[i].overlapped = overlapped[j]; poll_fd[i].rw = RW_READ+j; j++; - if (j==1) { - // Start a 1 byte nonblocking read operation - // so that we get read event notifications - _init_read_marker(i); - } LeaveCriticalSection(&_poll_fd[i].mutex); if (j>=2) { return 0; @@ -417,16 +358,15 @@ int usbi_pipe(int filedes[2]) } } - CloseHandle(overlapped1->hEvent); -out4: - CloseHandle(overlapped0->hEvent); + CloseHandle(overlapped[0]->hEvent); out3: CloseHandle(handle[1]); out2: CloseHandle(handle[0]); out1: - free(overlapped1); - free(overlapped0); + free(overlapped[1]); +out0: + free(overlapped[0]); return -1; } @@ -857,7 +797,7 @@ int usbi_close(int fd) if (CloseHandle(handle) == 0) { errno = EIO; } else { - r = 0; + r = 0; } LeaveCriticalSection(&_poll_fd[index].mutex); } @@ -865,27 +805,21 @@ int usbi_close(int fd) } /* - * synchronous write for custom poll (works on Windows file handles that - * have been opened with the FILE_FLAG_OVERLAPPED flag) - * - * Current restrictions: - * - binary mode only - * - no append mode + * synchronous write for fake "pipe" signaling */ ssize_t usbi_write(int fd, const void *buf, size_t count) { int index; - DWORD wr_count; - int r = -1; CHECK_INIT_POLLING; - index = _fd_to_index_and_lock(fd); - - if (count == 0) { - return 0; + 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) || (poll_fd[index].rw != RW_WRITE) ) { errno = EBADF; @@ -895,70 +829,26 @@ ssize_t usbi_write(int fd, const void *buf, size_t count) return -1; } - // For sync mode, we shouldn't get pending async write I/O - if (!HasOverlappedIoCompleted(poll_fd[index].overlapped)) { - usbi_warn(NULL, "usbi_write: previous write I/O was flagged pending!"); - cancel_io(index); - } - - poll_dbg("writing %d bytes to fd=%d", count, poll_fd[index].fd); - - reset_overlapped(poll_fd[index].overlapped); - if (!WriteFile(poll_fd[index].handle, buf, (DWORD)count, &wr_count, poll_fd[index].overlapped)) { - if(GetLastError() == ERROR_IO_PENDING) { - // I/O started but is not completed => wait till completion - switch(WaitForSingleObject(poll_fd[index].overlapped->hEvent, INFINITE)) - { - case WAIT_OBJECT_0: - if (GetOverlappedResult(poll_fd[index].handle, - poll_fd[index].overlapped, &wr_count, FALSE)) { - r = 0; - goto out; - } else { - usbi_warn(NULL, "GetOverlappedResult failed with error %d", (int)GetLastError()); - errno = EIO; - goto out; - } - default: - errno = EIO; - goto out; - } - } else { - // I/O started and failed - usbi_warn(NULL, "WriteFile failed with error %d", (int)GetLastError()); - errno = EIO; - goto out; - } - } - - // I/O started and completed synchronously - r = 0; + poll_dbg("Set pipe event"); + SetEvent(poll_fd[index].overlapped->hEvent); -out: - if (r) { - reset_overlapped(poll_fd[index].overlapped); - LeaveCriticalSection(&_poll_fd[index].mutex); - return -1; - } else { - LeaveCriticalSection(&_poll_fd[index].mutex); - return (ssize_t)wr_count; - } + LeaveCriticalSection(&_poll_fd[index].mutex); + return sizeof(unsigned char); } /* - * synchronous read for custom poll (works on Windows file handles that - * have been opened with the FILE_FLAG_OVERLAPPED flag) + * synchronous read for fake "pipe" signaling */ ssize_t usbi_read(int fd, void *buf, size_t count) { int index; - DWORD rd_count; - int r = -1; + ssize_t r = -1; CHECK_INIT_POLLING; - if (count == 0) { - return 0; + if (count != sizeof(unsigned char)) { + usbi_err(NULL, "this function should only used for signaling"); + return -1; } index = _fd_to_index_and_lock(fd); @@ -973,76 +863,18 @@ ssize_t usbi_read(int fd, void *buf, size_t count) goto out; } - - // still waiting for completion => force completion - if (!HasOverlappedIoCompleted(poll_fd[index].overlapped)) { - if (WaitForSingleObject(poll_fd[index].overlapped->hEvent, INFINITE) != WAIT_OBJECT_0) { - usbi_warn(NULL, "waiting for marker failed: %d", (int)GetLastError()); - errno = EIO; - goto out; - } - } - - // Find out if we've read the first byte - if (!GetOverlappedResult(poll_fd[index].handle, poll_fd[index].overlapped, &rd_count, FALSE)) { - if (GetLastError() != ERROR_MORE_DATA) { - usbi_warn(NULL, "readout of marker failed: %d", (int)GetLastError()); - errno = EIO; - goto out; - } else { - usbi_warn(NULL, "readout of marker reported more data"); - } - } - - poll_dbg("count = %d, rd_count(marker) = %d", count, (int)rd_count); - - // We should have our marker by now - if (rd_count != 1) { - usbi_warn(NULL, "unexpected number of bytes for marker (%d)", (int)rd_count); + 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; } - ((BYTE*)buf)[0] = _poll_fd[index].marker; - - // Read supplementary bytes if needed (blocking) - if (count > 1) { - reset_overlapped(poll_fd[index].overlapped); - if (!ReadFile(poll_fd[index].handle, (char*)buf+1, (DWORD)(count-1), &rd_count, poll_fd[index].overlapped)) { - if(GetLastError() == ERROR_IO_PENDING) { - if (!GetOverlappedResult(poll_fd[index].handle, poll_fd[index].overlapped, &rd_count, TRUE)) { - if (GetLastError() == ERROR_MORE_DATA) { - usbi_warn(NULL, "could not fetch all data"); - } - usbi_warn(NULL, "readout of supplementary data failed: %d", (int)GetLastError()); - errno = EIO; - goto out; - } - } else { - usbi_warn(NULL, "could not start blocking read of supplementary: %d", (int)GetLastError()); - errno = EIO; - goto out; - } - } - // If ReadFile completed synchronously, we're fine too + poll_dbg("Cleared pipe event"); + ResetEvent(poll_fd[index].overlapped->hEvent); - poll_dbg("rd_count(supplementary ) = %d", (int)rd_count); - - if ((rd_count+1) != count) { - poll_dbg("wanted %d-1, got %d", count, (int)rd_count); - errno = EIO; - goto out; - } - } - - r = 0; + r = sizeof(unsigned char); out: - // Setup pending read I/O for the marker - _init_read_marker(index); LeaveCriticalSection(&_poll_fd[index].mutex); - if (r) - return -1; - else - return count; -}
\ No newline at end of file + return r; +} |