2 * Synchronous I/O functions for libusb
3 * Copyright © 2007-2008 Daniel Drake <dsd@gentoo.org>
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2.1 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
30 * @defgroup libusb_syncio Synchronous device I/O
32 * This page documents libusb's synchronous (blocking) API for USB device I/O.
33 * This interface is easy to use but has some limitations. More advanced users
34 * may wish to consider using the \ref libusb_asyncio "asynchronous I/O API" instead.
37 static void LIBUSB_CALL sync_transfer_cb(struct libusb_transfer *transfer)
39 int *completed = transfer->user_data;
41 usbi_dbg("actual_length=%d", transfer->actual_length);
42 /* caller interprets result and frees transfer */
45 static void sync_transfer_wait_for_completion(struct libusb_transfer *transfer)
47 int r, *completed = transfer->user_data;
48 struct libusb_context *ctx = HANDLE_CTX(transfer->dev_handle);
51 r = libusb_handle_events_completed(ctx, completed);
53 if (r == LIBUSB_ERROR_INTERRUPTED)
55 usbi_err(ctx, "libusb_handle_events failed: %s, cancelling transfer and retrying",
56 libusb_error_name(r));
57 libusb_cancel_transfer(transfer);
63 /** \ingroup libusb_syncio
64 * Perform a USB control transfer.
66 * The direction of the transfer is inferred from the bmRequestType field of
69 * The wValue, wIndex and wLength fields values should be given in host-endian
72 * \param dev_handle a handle for the device to communicate with
73 * \param bmRequestType the request type field for the setup packet
74 * \param bRequest the request field for the setup packet
75 * \param wValue the value field for the setup packet
76 * \param wIndex the index field for the setup packet
77 * \param data a suitably-sized data buffer for either input or output
78 * (depending on direction bits within bmRequestType)
79 * \param wLength the length field for the setup packet. The data buffer should
80 * be at least this size.
81 * \param timeout timeout (in millseconds) that this function should wait
82 * before giving up due to no response being received. For an unlimited
83 * timeout, use value 0.
84 * \returns on success, the number of bytes actually transferred
85 * \returns LIBUSB_ERROR_TIMEOUT if the transfer timed out
86 * \returns LIBUSB_ERROR_PIPE if the control request was not supported by the
88 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
89 * \returns LIBUSB_ERROR_BUSY if called from event handling context
90 * \returns LIBUSB_ERROR_INVALID_PARAM if the transfer size is larger than
91 * the operating system and/or hardware can support
92 * \returns another LIBUSB_ERROR code on other failures
94 int API_EXPORTED libusb_control_transfer(libusb_device_handle *dev_handle,
95 uint8_t bmRequestType, uint8_t bRequest, uint16_t wValue, uint16_t wIndex,
96 unsigned char *data, uint16_t wLength, unsigned int timeout)
98 struct libusb_transfer *transfer;
99 unsigned char *buffer;
103 if (usbi_handling_events(HANDLE_CTX(dev_handle)))
104 return LIBUSB_ERROR_BUSY;
106 transfer = libusb_alloc_transfer(0);
108 return LIBUSB_ERROR_NO_MEM;
110 buffer = (unsigned char*) malloc(LIBUSB_CONTROL_SETUP_SIZE + wLength);
112 libusb_free_transfer(transfer);
113 return LIBUSB_ERROR_NO_MEM;
116 libusb_fill_control_setup(buffer, bmRequestType, bRequest, wValue, wIndex,
118 if ((bmRequestType & LIBUSB_ENDPOINT_DIR_MASK) == LIBUSB_ENDPOINT_OUT)
119 memcpy(buffer + LIBUSB_CONTROL_SETUP_SIZE, data, wLength);
121 libusb_fill_control_transfer(transfer, dev_handle, buffer,
122 sync_transfer_cb, &completed, timeout);
123 transfer->flags = LIBUSB_TRANSFER_FREE_BUFFER;
124 r = libusb_submit_transfer(transfer);
126 libusb_free_transfer(transfer);
130 sync_transfer_wait_for_completion(transfer);
132 if ((bmRequestType & LIBUSB_ENDPOINT_DIR_MASK) == LIBUSB_ENDPOINT_IN)
133 memcpy(data, libusb_control_transfer_get_data(transfer),
134 transfer->actual_length);
136 switch (transfer->status) {
137 case LIBUSB_TRANSFER_COMPLETED:
138 r = transfer->actual_length;
140 case LIBUSB_TRANSFER_TIMED_OUT:
141 r = LIBUSB_ERROR_TIMEOUT;
143 case LIBUSB_TRANSFER_STALL:
144 r = LIBUSB_ERROR_PIPE;
146 case LIBUSB_TRANSFER_NO_DEVICE:
147 r = LIBUSB_ERROR_NO_DEVICE;
149 case LIBUSB_TRANSFER_OVERFLOW:
150 r = LIBUSB_ERROR_OVERFLOW;
152 case LIBUSB_TRANSFER_ERROR:
153 case LIBUSB_TRANSFER_CANCELLED:
157 usbi_warn(HANDLE_CTX(dev_handle),
158 "unrecognised status code %d", transfer->status);
159 r = LIBUSB_ERROR_OTHER;
162 libusb_free_transfer(transfer);
166 static int do_sync_bulk_transfer(struct libusb_device_handle *dev_handle,
167 unsigned char endpoint, unsigned char *buffer, int length,
168 int *transferred, unsigned int timeout, unsigned char type)
170 struct libusb_transfer *transfer;
174 if (usbi_handling_events(HANDLE_CTX(dev_handle)))
175 return LIBUSB_ERROR_BUSY;
177 transfer = libusb_alloc_transfer(0);
179 return LIBUSB_ERROR_NO_MEM;
181 libusb_fill_bulk_transfer(transfer, dev_handle, endpoint, buffer, length,
182 sync_transfer_cb, &completed, timeout);
183 transfer->type = type;
185 r = libusb_submit_transfer(transfer);
187 libusb_free_transfer(transfer);
191 sync_transfer_wait_for_completion(transfer);
194 *transferred = transfer->actual_length;
196 switch (transfer->status) {
197 case LIBUSB_TRANSFER_COMPLETED:
200 case LIBUSB_TRANSFER_TIMED_OUT:
201 r = LIBUSB_ERROR_TIMEOUT;
203 case LIBUSB_TRANSFER_STALL:
204 r = LIBUSB_ERROR_PIPE;
206 case LIBUSB_TRANSFER_OVERFLOW:
207 r = LIBUSB_ERROR_OVERFLOW;
209 case LIBUSB_TRANSFER_NO_DEVICE:
210 r = LIBUSB_ERROR_NO_DEVICE;
212 case LIBUSB_TRANSFER_ERROR:
213 case LIBUSB_TRANSFER_CANCELLED:
217 usbi_warn(HANDLE_CTX(dev_handle),
218 "unrecognised status code %d", transfer->status);
219 r = LIBUSB_ERROR_OTHER;
222 libusb_free_transfer(transfer);
226 /** \ingroup libusb_syncio
227 * Perform a USB bulk transfer. The direction of the transfer is inferred from
228 * the direction bits of the endpoint address.
230 * For bulk reads, the <tt>length</tt> field indicates the maximum length of
231 * data you are expecting to receive. If less data arrives than expected,
232 * this function will return that data, so be sure to check the
233 * <tt>transferred</tt> output parameter.
235 * You should also check the <tt>transferred</tt> parameter for bulk writes.
236 * Not all of the data may have been written.
238 * Also check <tt>transferred</tt> when dealing with a timeout error code.
239 * libusb may have to split your transfer into a number of chunks to satisfy
240 * underlying O/S requirements, meaning that the timeout may expire after
241 * the first few chunks have completed. libusb is careful not to lose any data
242 * that may have been transferred; do not assume that timeout conditions
243 * indicate a complete lack of I/O.
245 * \param dev_handle a handle for the device to communicate with
246 * \param endpoint the address of a valid endpoint to communicate with
247 * \param data a suitably-sized data buffer for either input or output
248 * (depending on endpoint)
249 * \param length for bulk writes, the number of bytes from data to be sent. for
250 * bulk reads, the maximum number of bytes to receive into the data buffer.
251 * \param transferred output location for the number of bytes actually
252 * transferred. Since version 1.0.21 (\ref LIBUSB_API_VERSION >= 0x01000105),
253 * it is legal to pass a NULL pointer if you do not wish to receive this
255 * \param timeout timeout (in millseconds) that this function should wait
256 * before giving up due to no response being received. For an unlimited
257 * timeout, use value 0.
259 * \returns 0 on success (and populates <tt>transferred</tt>)
260 * \returns LIBUSB_ERROR_TIMEOUT if the transfer timed out (and populates
261 * <tt>transferred</tt>)
262 * \returns LIBUSB_ERROR_PIPE if the endpoint halted
263 * \returns LIBUSB_ERROR_OVERFLOW if the device offered more data, see
264 * \ref libusb_packetoverflow
265 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
266 * \returns LIBUSB_ERROR_BUSY if called from event handling context
267 * \returns another LIBUSB_ERROR code on other failures
269 int API_EXPORTED libusb_bulk_transfer(struct libusb_device_handle *dev_handle,
270 unsigned char endpoint, unsigned char *data, int length, int *transferred,
271 unsigned int timeout)
273 return do_sync_bulk_transfer(dev_handle, endpoint, data, length,
274 transferred, timeout, LIBUSB_TRANSFER_TYPE_BULK);
277 /** \ingroup libusb_syncio
278 * Perform a USB interrupt transfer. The direction of the transfer is inferred
279 * from the direction bits of the endpoint address.
281 * For interrupt reads, the <tt>length</tt> field indicates the maximum length
282 * of data you are expecting to receive. If less data arrives than expected,
283 * this function will return that data, so be sure to check the
284 * <tt>transferred</tt> output parameter.
286 * You should also check the <tt>transferred</tt> parameter for interrupt
287 * writes. Not all of the data may have been written.
289 * Also check <tt>transferred</tt> when dealing with a timeout error code.
290 * libusb may have to split your transfer into a number of chunks to satisfy
291 * underlying O/S requirements, meaning that the timeout may expire after
292 * the first few chunks have completed. libusb is careful not to lose any data
293 * that may have been transferred; do not assume that timeout conditions
294 * indicate a complete lack of I/O.
296 * The default endpoint bInterval value is used as the polling interval.
298 * \param dev_handle a handle for the device to communicate with
299 * \param endpoint the address of a valid endpoint to communicate with
300 * \param data a suitably-sized data buffer for either input or output
301 * (depending on endpoint)
302 * \param length for bulk writes, the number of bytes from data to be sent. for
303 * bulk reads, the maximum number of bytes to receive into the data buffer.
304 * \param transferred output location for the number of bytes actually
305 * transferred. Since version 1.0.21 (\ref LIBUSB_API_VERSION >= 0x01000105),
306 * it is legal to pass a NULL pointer if you do not wish to receive this
308 * \param timeout timeout (in millseconds) that this function should wait
309 * before giving up due to no response being received. For an unlimited
310 * timeout, use value 0.
312 * \returns 0 on success (and populates <tt>transferred</tt>)
313 * \returns LIBUSB_ERROR_TIMEOUT if the transfer timed out
314 * \returns LIBUSB_ERROR_PIPE if the endpoint halted
315 * \returns LIBUSB_ERROR_OVERFLOW if the device offered more data, see
316 * \ref libusb_packetoverflow
317 * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
318 * \returns LIBUSB_ERROR_BUSY if called from event handling context
319 * \returns another LIBUSB_ERROR code on other error
321 int API_EXPORTED libusb_interrupt_transfer(
322 struct libusb_device_handle *dev_handle, unsigned char endpoint,
323 unsigned char *data, int length, int *transferred, unsigned int timeout)
325 return do_sync_bulk_transfer(dev_handle, endpoint, data, length,
326 transferred, timeout, LIBUSB_TRANSFER_TYPE_INTERRUPT);