1 /*
2  * Copyright (C) 2010 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #define LOG_TAG "MtpDataPacket"
18 
19 #include "MtpDataPacket.h"
20 
21 #include <algorithm>
22 #include <errno.h>
23 #include <fcntl.h>
24 #include <stdio.h>
25 #include <sys/types.h>
26 #include <usbhost/usbhost.h>
27 #include "MtpStringBuffer.h"
28 #include "IMtpHandle.h"
29 
30 namespace android {
31 
32 namespace {
33 // Reads the exact |count| bytes from |fd| to |buf|.
34 // Returns |count| if it succeed to read the bytes. Otherwise returns -1. If it reaches EOF, the
35 // function regards it as an error.
readExactBytes(int fd,void * buf,size_t count)36 ssize_t readExactBytes(int fd, void* buf, size_t count) {
37     if (count > SSIZE_MAX) {
38         return -1;
39     }
40     size_t read_count = 0;
41     while (read_count < count) {
42         int result = read(fd, static_cast<int8_t*>(buf) + read_count, count - read_count);
43         // Assume that EOF is error.
44         if (result <= 0) {
45             return -1;
46         }
47         read_count += result;
48     }
49     return read_count == count ? count : -1;
50 }
51 }  // namespace
52 
MtpDataPacket()53 MtpDataPacket::MtpDataPacket()
54     :   MtpPacket(MTP_BUFFER_SIZE),   // MAX_USBFS_BUFFER_SIZE
55         mOffset(MTP_CONTAINER_HEADER_SIZE)
56 {
57 }
58 
~MtpDataPacket()59 MtpDataPacket::~MtpDataPacket() {
60 }
61 
reset()62 void MtpDataPacket::reset() {
63     MtpPacket::reset();
64     mOffset = MTP_CONTAINER_HEADER_SIZE;
65 }
66 
setOperationCode(MtpOperationCode code)67 void MtpDataPacket::setOperationCode(MtpOperationCode code) {
68     MtpPacket::putUInt16(MTP_CONTAINER_CODE_OFFSET, code);
69 }
70 
setTransactionID(MtpTransactionID id)71 void MtpDataPacket::setTransactionID(MtpTransactionID id) {
72     MtpPacket::putUInt32(MTP_CONTAINER_TRANSACTION_ID_OFFSET, id);
73 }
74 
getUInt8(uint8_t & value)75 bool MtpDataPacket::getUInt8(uint8_t& value) {
76     if (mPacketSize - mOffset < sizeof(value))
77         return false;
78     value = mBuffer[mOffset++];
79     return true;
80 }
81 
getUInt16(uint16_t & value)82 bool MtpDataPacket::getUInt16(uint16_t& value) {
83     if (mPacketSize - mOffset < sizeof(value))
84         return false;
85     int offset = mOffset;
86     value = (uint16_t)mBuffer[offset] | ((uint16_t)mBuffer[offset + 1] << 8);
87     mOffset += sizeof(value);
88     return true;
89 }
90 
getUInt32(uint32_t & value)91 bool MtpDataPacket::getUInt32(uint32_t& value) {
92     if (mPacketSize - mOffset < sizeof(value))
93         return false;
94     int offset = mOffset;
95     value = (uint32_t)mBuffer[offset] | ((uint32_t)mBuffer[offset + 1] << 8) |
96            ((uint32_t)mBuffer[offset + 2] << 16)  | ((uint32_t)mBuffer[offset + 3] << 24);
97     mOffset += sizeof(value);
98     return true;
99 }
100 
getUInt64(uint64_t & value)101 bool MtpDataPacket::getUInt64(uint64_t& value) {
102     if (mPacketSize - mOffset < sizeof(value))
103         return false;
104     int offset = mOffset;
105     value = (uint64_t)mBuffer[offset] | ((uint64_t)mBuffer[offset + 1] << 8) |
106            ((uint64_t)mBuffer[offset + 2] << 16) | ((uint64_t)mBuffer[offset + 3] << 24) |
107            ((uint64_t)mBuffer[offset + 4] << 32) | ((uint64_t)mBuffer[offset + 5] << 40) |
108            ((uint64_t)mBuffer[offset + 6] << 48)  | ((uint64_t)mBuffer[offset + 7] << 56);
109     mOffset += sizeof(value);
110     return true;
111 }
112 
getUInt128(uint128_t & value)113 bool MtpDataPacket::getUInt128(uint128_t& value) {
114     return getUInt32(value[0]) && getUInt32(value[1]) && getUInt32(value[2]) && getUInt32(value[3]);
115 }
116 
getString(MtpStringBuffer & string)117 bool MtpDataPacket::getString(MtpStringBuffer& string)
118 {
119     return string.readFromPacket(this);
120 }
121 
getAInt8()122 Int8List* MtpDataPacket::getAInt8() {
123     uint32_t count;
124     if (!getUInt32(count))
125         return NULL;
126     Int8List* result = new Int8List;
127     for (uint32_t i = 0; i < count; i++) {
128         int8_t value;
129         if (!getInt8(value)) {
130             delete result;
131             return NULL;
132         }
133         result->push_back(value);
134     }
135     return result;
136 }
137 
getAUInt8()138 UInt8List* MtpDataPacket::getAUInt8() {
139     uint32_t count;
140     if (!getUInt32(count))
141         return NULL;
142     UInt8List* result = new UInt8List;
143     for (uint32_t i = 0; i < count; i++) {
144         uint8_t value;
145         if (!getUInt8(value)) {
146             delete result;
147             return NULL;
148         }
149         result->push_back(value);
150     }
151     return result;
152 }
153 
getAInt16()154 Int16List* MtpDataPacket::getAInt16() {
155     uint32_t count;
156     if (!getUInt32(count))
157         return NULL;
158     Int16List* result = new Int16List;
159     for (uint32_t i = 0; i < count; i++) {
160         int16_t value;
161         if (!getInt16(value)) {
162             delete result;
163             return NULL;
164         }
165         result->push_back(value);
166     }
167     return result;
168 }
169 
getAUInt16()170 UInt16List* MtpDataPacket::getAUInt16() {
171     uint32_t count;
172     if (!getUInt32(count))
173         return NULL;
174     UInt16List* result = new UInt16List;
175     for (uint32_t i = 0; i < count; i++) {
176         uint16_t value;
177         if (!getUInt16(value)) {
178             delete result;
179             return NULL;
180         }
181         result->push_back(value);
182     }
183     return result;
184 }
185 
getAInt32()186 Int32List* MtpDataPacket::getAInt32() {
187     uint32_t count;
188     if (!getUInt32(count))
189         return NULL;
190     Int32List* result = new Int32List;
191     for (uint32_t i = 0; i < count; i++) {
192         int32_t value;
193         if (!getInt32(value)) {
194             delete result;
195             return NULL;
196         }
197         result->push_back(value);
198     }
199     return result;
200 }
201 
getAUInt32()202 UInt32List* MtpDataPacket::getAUInt32() {
203     uint32_t count;
204     if (!getUInt32(count))
205         return NULL;
206     UInt32List* result = new UInt32List;
207     for (uint32_t i = 0; i < count; i++) {
208         uint32_t value;
209         if (!getUInt32(value)) {
210             delete result;
211             return NULL;
212         }
213         result->push_back(value);
214     }
215     return result;
216 }
217 
getAInt64()218 Int64List* MtpDataPacket::getAInt64() {
219     uint32_t count;
220     if (!getUInt32(count))
221         return NULL;
222     Int64List* result = new Int64List;
223     for (uint32_t i = 0; i < count; i++) {
224         int64_t value;
225         if (!getInt64(value)) {
226             delete result;
227             return NULL;
228         }
229         result->push_back(value);
230     }
231     return result;
232 }
233 
getAUInt64()234 UInt64List* MtpDataPacket::getAUInt64() {
235     uint32_t count;
236     if (!getUInt32(count))
237         return NULL;
238     UInt64List* result = new UInt64List;
239     for (uint32_t i = 0; i < count; i++) {
240         uint64_t value;
241         if (!getUInt64(value)) {
242             delete result;
243             return NULL;
244         }
245         result->push_back(value);
246     }
247     return result;
248 }
249 
putInt8(int8_t value)250 void MtpDataPacket::putInt8(int8_t value) {
251     allocate(mOffset + 1);
252     mBuffer[mOffset++] = (uint8_t)value;
253     if (mPacketSize < mOffset)
254         mPacketSize = mOffset;
255 }
256 
putUInt8(uint8_t value)257 void MtpDataPacket::putUInt8(uint8_t value) {
258     allocate(mOffset + 1);
259     mBuffer[mOffset++] = (uint8_t)value;
260     if (mPacketSize < mOffset)
261         mPacketSize = mOffset;
262 }
263 
putInt16(int16_t value)264 void MtpDataPacket::putInt16(int16_t value) {
265     allocate(mOffset + 2);
266     mBuffer[mOffset++] = (uint8_t)(value & 0xFF);
267     mBuffer[mOffset++] = (uint8_t)((value >> 8) & 0xFF);
268     if (mPacketSize < mOffset)
269         mPacketSize = mOffset;
270 }
271 
putUInt16(uint16_t value)272 void MtpDataPacket::putUInt16(uint16_t value) {
273     allocate(mOffset + 2);
274     mBuffer[mOffset++] = (uint8_t)(value & 0xFF);
275     mBuffer[mOffset++] = (uint8_t)((value >> 8) & 0xFF);
276     if (mPacketSize < mOffset)
277         mPacketSize = mOffset;
278 }
279 
putInt32(int32_t value)280 void MtpDataPacket::putInt32(int32_t value) {
281     allocate(mOffset + 4);
282     mBuffer[mOffset++] = (uint8_t)(value & 0xFF);
283     mBuffer[mOffset++] = (uint8_t)((value >> 8) & 0xFF);
284     mBuffer[mOffset++] = (uint8_t)((value >> 16) & 0xFF);
285     mBuffer[mOffset++] = (uint8_t)((value >> 24) & 0xFF);
286     if (mPacketSize < mOffset)
287         mPacketSize = mOffset;
288 }
289 
putUInt32(uint32_t value)290 void MtpDataPacket::putUInt32(uint32_t value) {
291     allocate(mOffset + 4);
292     mBuffer[mOffset++] = (uint8_t)(value & 0xFF);
293     mBuffer[mOffset++] = (uint8_t)((value >> 8) & 0xFF);
294     mBuffer[mOffset++] = (uint8_t)((value >> 16) & 0xFF);
295     mBuffer[mOffset++] = (uint8_t)((value >> 24) & 0xFF);
296     if (mPacketSize < mOffset)
297         mPacketSize = mOffset;
298 }
299 
putInt64(int64_t value)300 void MtpDataPacket::putInt64(int64_t value) {
301     allocate(mOffset + 8);
302     mBuffer[mOffset++] = (uint8_t)(value & 0xFF);
303     mBuffer[mOffset++] = (uint8_t)((value >> 8) & 0xFF);
304     mBuffer[mOffset++] = (uint8_t)((value >> 16) & 0xFF);
305     mBuffer[mOffset++] = (uint8_t)((value >> 24) & 0xFF);
306     mBuffer[mOffset++] = (uint8_t)((value >> 32) & 0xFF);
307     mBuffer[mOffset++] = (uint8_t)((value >> 40) & 0xFF);
308     mBuffer[mOffset++] = (uint8_t)((value >> 48) & 0xFF);
309     mBuffer[mOffset++] = (uint8_t)((value >> 56) & 0xFF);
310     if (mPacketSize < mOffset)
311         mPacketSize = mOffset;
312 }
313 
putUInt64(uint64_t value)314 void MtpDataPacket::putUInt64(uint64_t value) {
315     allocate(mOffset + 8);
316     mBuffer[mOffset++] = (uint8_t)(value & 0xFF);
317     mBuffer[mOffset++] = (uint8_t)((value >> 8) & 0xFF);
318     mBuffer[mOffset++] = (uint8_t)((value >> 16) & 0xFF);
319     mBuffer[mOffset++] = (uint8_t)((value >> 24) & 0xFF);
320     mBuffer[mOffset++] = (uint8_t)((value >> 32) & 0xFF);
321     mBuffer[mOffset++] = (uint8_t)((value >> 40) & 0xFF);
322     mBuffer[mOffset++] = (uint8_t)((value >> 48) & 0xFF);
323     mBuffer[mOffset++] = (uint8_t)((value >> 56) & 0xFF);
324     if (mPacketSize < mOffset)
325         mPacketSize = mOffset;
326 }
327 
putInt128(const int128_t & value)328 void MtpDataPacket::putInt128(const int128_t& value) {
329     putInt32(value[0]);
330     putInt32(value[1]);
331     putInt32(value[2]);
332     putInt32(value[3]);
333 }
334 
putUInt128(const uint128_t & value)335 void MtpDataPacket::putUInt128(const uint128_t& value) {
336     putUInt32(value[0]);
337     putUInt32(value[1]);
338     putUInt32(value[2]);
339     putUInt32(value[3]);
340 }
341 
putInt128(int64_t value)342 void MtpDataPacket::putInt128(int64_t value) {
343     putInt64(value);
344     putInt64(value < 0 ? -1 : 0);
345 }
346 
putUInt128(uint64_t value)347 void MtpDataPacket::putUInt128(uint64_t value) {
348     putUInt64(value);
349     putUInt64(0);
350 }
351 
putAInt8(const int8_t * values,int count)352 void MtpDataPacket::putAInt8(const int8_t* values, int count) {
353     putUInt32(count);
354     for (int i = 0; i < count; i++)
355         putInt8(*values++);
356 }
357 
putAUInt8(const uint8_t * values,int count)358 void MtpDataPacket::putAUInt8(const uint8_t* values, int count) {
359     putUInt32(count);
360     for (int i = 0; i < count; i++)
361         putUInt8(*values++);
362 }
363 
putAInt16(const int16_t * values,int count)364 void MtpDataPacket::putAInt16(const int16_t* values, int count) {
365     putUInt32(count);
366     for (int i = 0; i < count; i++)
367         putInt16(*values++);
368 }
369 
putAUInt16(const uint16_t * values,int count)370 void MtpDataPacket::putAUInt16(const uint16_t* values, int count) {
371     putUInt32(count);
372     for (int i = 0; i < count; i++)
373         putUInt16(*values++);
374 }
375 
putAUInt16(const UInt16List * values)376 void MtpDataPacket::putAUInt16(const UInt16List* values) {
377     size_t count = (values ? values->size() : 0);
378     putUInt32(count);
379     for (size_t i = 0; i < count; i++)
380         putUInt16((*values)[i]);
381 }
382 
putAInt32(const int32_t * values,int count)383 void MtpDataPacket::putAInt32(const int32_t* values, int count) {
384     putUInt32(count);
385     for (int i = 0; i < count; i++)
386         putInt32(*values++);
387 }
388 
putAUInt32(const uint32_t * values,int count)389 void MtpDataPacket::putAUInt32(const uint32_t* values, int count) {
390     putUInt32(count);
391     for (int i = 0; i < count; i++)
392         putUInt32(*values++);
393 }
394 
putAUInt32(const UInt32List * list)395 void MtpDataPacket::putAUInt32(const UInt32List* list) {
396     if (!list) {
397         putEmptyArray();
398     } else {
399         size_t size = list->size();
400         putUInt32(size);
401         for (size_t i = 0; i < size; i++)
402             putUInt32((*list)[i]);
403     }
404 }
405 
putAInt64(const int64_t * values,int count)406 void MtpDataPacket::putAInt64(const int64_t* values, int count) {
407     putUInt32(count);
408     for (int i = 0; i < count; i++)
409         putInt64(*values++);
410 }
411 
putAUInt64(const uint64_t * values,int count)412 void MtpDataPacket::putAUInt64(const uint64_t* values, int count) {
413     putUInt32(count);
414     for (int i = 0; i < count; i++)
415         putUInt64(*values++);
416 }
417 
putString(const MtpStringBuffer & string)418 void MtpDataPacket::putString(const MtpStringBuffer& string) {
419     string.writeToPacket(this);
420 }
421 
putString(const char * s)422 void MtpDataPacket::putString(const char* s) {
423     MtpStringBuffer string(s);
424     string.writeToPacket(this);
425 }
426 
putString(const uint16_t * string)427 void MtpDataPacket::putString(const uint16_t* string) {
428     int count = 0;
429     for (int i = 0; i <= MTP_STRING_MAX_CHARACTER_NUMBER; i++) {
430         if (string[i])
431             count++;
432         else
433             break;
434     }
435     putUInt8(count > 0 ? count + 1 : 0);
436     for (int i = 0; i < count; i++)
437         putUInt16(string[i]);
438     // only terminate with zero if string is not empty
439     if (count > 0)
440         putUInt16(0);
441 }
442 
443 #ifdef MTP_DEVICE
read(IMtpHandle * h)444 int MtpDataPacket::read(IMtpHandle *h) {
445     int ret = h->read(mBuffer, MTP_BUFFER_SIZE);
446     if (ret < MTP_CONTAINER_HEADER_SIZE)
447         return -1;
448     mPacketSize = ret;
449     mOffset = MTP_CONTAINER_HEADER_SIZE;
450     return ret;
451 }
452 
write(IMtpHandle * h)453 int MtpDataPacket::write(IMtpHandle *h) {
454     MtpPacket::putUInt32(MTP_CONTAINER_LENGTH_OFFSET, mPacketSize);
455     MtpPacket::putUInt16(MTP_CONTAINER_TYPE_OFFSET, MTP_CONTAINER_TYPE_DATA);
456     int ret = h->write(mBuffer, mPacketSize);
457     return (ret < 0 ? ret : 0);
458 }
459 
writeData(IMtpHandle * h,void * data,uint32_t length)460 int MtpDataPacket::writeData(IMtpHandle *h, void* data, uint32_t length) {
461     allocate(length + MTP_CONTAINER_HEADER_SIZE);
462     memcpy(mBuffer + MTP_CONTAINER_HEADER_SIZE, data, length);
463     length += MTP_CONTAINER_HEADER_SIZE;
464     MtpPacket::putUInt32(MTP_CONTAINER_LENGTH_OFFSET, length);
465     MtpPacket::putUInt16(MTP_CONTAINER_TYPE_OFFSET, MTP_CONTAINER_TYPE_DATA);
466     int ret = h->write(mBuffer, length);
467     return (ret < 0 ? ret : 0);
468 }
469 
470 #endif // MTP_DEVICE
471 
472 #ifdef MTP_HOST
read(struct usb_request * request)473 int MtpDataPacket::read(struct usb_request *request) {
474     // first read the header
475     request->buffer = mBuffer;
476     request->buffer_length = mBufferSize;
477     int length = transfer(request);
478     if (length >= MTP_CONTAINER_HEADER_SIZE) {
479         // look at the length field to see if the data spans multiple packets
480         uint32_t totalLength = MtpPacket::getUInt32(MTP_CONTAINER_LENGTH_OFFSET);
481         allocate(totalLength);
482         while (totalLength > static_cast<uint32_t>(length)) {
483             request->buffer = mBuffer + length;
484             request->buffer_length = totalLength - length;
485             int ret = transfer(request);
486             if (ret >= 0)
487                 length += ret;
488             else {
489                 length = ret;
490                 break;
491             }
492         }
493     }
494     if (length >= 0)
495         mPacketSize = length;
496     return length;
497 }
498 
readData(struct usb_request * request,void * buffer,int length)499 int MtpDataPacket::readData(struct usb_request *request, void* buffer, int length) {
500     int read = 0;
501     while (read < length) {
502         request->buffer = (char *)buffer + read;
503         request->buffer_length = length - read;
504         int ret = transfer(request);
505         if (ret < 0) {
506             return ret;
507         }
508         read += ret;
509     }
510     return read;
511 }
512 
513 // Queue a read request.  Call readDataWait to wait for result
readDataAsync(struct usb_request * req)514 int MtpDataPacket::readDataAsync(struct usb_request *req) {
515     if (usb_request_queue(req)) {
516         ALOGE("usb_endpoint_queue failed, errno: %d", errno);
517         return -1;
518     }
519     return 0;
520 }
521 
522 // Wait for result of readDataAsync
readDataWait(struct usb_device * device)523 int MtpDataPacket::readDataWait(struct usb_device *device) {
524     struct usb_request *req = usb_request_wait(device, -1);
525     return (req ? req->actual_length : -1);
526 }
527 
readDataHeader(struct usb_request * request)528 int MtpDataPacket::readDataHeader(struct usb_request *request) {
529     request->buffer = mBuffer;
530     request->buffer_length = request->max_packet_size;
531     int length = transfer(request);
532     if (length >= 0)
533         mPacketSize = length;
534     return length;
535 }
536 
write(struct usb_request * request,UrbPacketDivisionMode divisionMode)537 int MtpDataPacket::write(struct usb_request *request, UrbPacketDivisionMode divisionMode) {
538     if (mPacketSize < MTP_CONTAINER_HEADER_SIZE || mPacketSize > MTP_BUFFER_SIZE) {
539         ALOGE("Illegal packet size.");
540         return -1;
541     }
542 
543     MtpPacket::putUInt32(MTP_CONTAINER_LENGTH_OFFSET, mPacketSize);
544     MtpPacket::putUInt16(MTP_CONTAINER_TYPE_OFFSET, MTP_CONTAINER_TYPE_DATA);
545 
546     size_t processedBytes = 0;
547     while (processedBytes < mPacketSize) {
548         const size_t write_size =
549                 processedBytes == 0 && divisionMode == FIRST_PACKET_ONLY_HEADER ?
550                         MTP_CONTAINER_HEADER_SIZE : mPacketSize - processedBytes;
551         request->buffer = mBuffer + processedBytes;
552         request->buffer_length = write_size;
553         const int result = transfer(request);
554         if (result < 0) {
555             ALOGE("Failed to write bytes to the device.");
556             return -1;
557         }
558         processedBytes += result;
559     }
560 
561     return processedBytes == mPacketSize ? processedBytes : -1;
562 }
563 
write(struct usb_request * request,UrbPacketDivisionMode divisionMode,int fd,size_t payloadSize)564 int MtpDataPacket::write(struct usb_request *request,
565                          UrbPacketDivisionMode divisionMode,
566                          int fd,
567                          size_t payloadSize) {
568     // Obtain the greatest multiple of minimum packet size that is not greater than
569     // MTP_BUFFER_SIZE.
570     if (request->max_packet_size <= 0) {
571         ALOGE("Cannot determine bulk transfer size due to illegal max packet size %d.",
572               request->max_packet_size);
573         return -1;
574     }
575     const size_t maxBulkTransferSize =
576             MTP_BUFFER_SIZE - (MTP_BUFFER_SIZE % request->max_packet_size);
577     const size_t containerLength = payloadSize + MTP_CONTAINER_HEADER_SIZE;
578     size_t processedBytes = 0;
579     bool readError = false;
580 
581     // Bind the packet with given request.
582     request->buffer = mBuffer;
583     allocate(maxBulkTransferSize);
584 
585     while (processedBytes < containerLength) {
586         size_t bulkTransferSize = 0;
587 
588         // prepare header.
589         const bool headerSent = processedBytes != 0;
590         if (!headerSent) {
591             MtpPacket::putUInt32(MTP_CONTAINER_LENGTH_OFFSET, containerLength);
592             MtpPacket::putUInt16(MTP_CONTAINER_TYPE_OFFSET, MTP_CONTAINER_TYPE_DATA);
593             bulkTransferSize += MTP_CONTAINER_HEADER_SIZE;
594         }
595 
596         // Prepare payload.
597         if (headerSent || divisionMode == FIRST_PACKET_HAS_PAYLOAD) {
598             const size_t processedPayloadBytes =
599                     headerSent ? processedBytes - MTP_CONTAINER_HEADER_SIZE : 0;
600             const size_t maxRead = payloadSize - processedPayloadBytes;
601             const size_t maxWrite = maxBulkTransferSize - bulkTransferSize;
602             const size_t bulkTransferPayloadSize = std::min(maxRead, maxWrite);
603             // prepare payload.
604             if (!readError) {
605                 const ssize_t result = readExactBytes(
606                         fd,
607                         mBuffer + bulkTransferSize,
608                         bulkTransferPayloadSize);
609                 if (result < 0) {
610                     ALOGE("Found an error while reading data from FD. Send 0 data instead.");
611                     readError = true;
612                 }
613             }
614             if (readError) {
615                 memset(mBuffer + bulkTransferSize, 0, bulkTransferPayloadSize);
616             }
617             bulkTransferSize += bulkTransferPayloadSize;
618         }
619 
620         // Bulk transfer.
621         mPacketSize = bulkTransferSize;
622         request->buffer_length = bulkTransferSize;
623         const int result = transfer(request);
624         if (result != static_cast<ssize_t>(bulkTransferSize)) {
625             // Cannot recover writing error.
626             ALOGE("Found an error while write data to MtpDevice.");
627             return -1;
628         }
629 
630         // Update variables.
631         processedBytes += bulkTransferSize;
632     }
633 
634     return readError ? -1 : processedBytes;
635 }
636 
637 #endif // MTP_HOST
638 
getData(int * outLength) const639 void* MtpDataPacket::getData(int* outLength) const {
640     int length = mPacketSize - MTP_CONTAINER_HEADER_SIZE;
641     if (length > 0) {
642         void* result = malloc(length);
643         if (result) {
644             memcpy(result, mBuffer + MTP_CONTAINER_HEADER_SIZE, length);
645             *outLength = length;
646             return result;
647         }
648     }
649     *outLength = 0;
650     return NULL;
651 }
652 
653 }  // namespace android
654