commit 5410756e75fb7567540f13d3813f42f4ac3838a0
author Jerry Zhang <zhangjerry@google.com> Mon May 15 11:54:19 2017 -0700
committer Jerry Zhang <zhangjerry@google.com> Mon May 15 13:21:46 2017 -0700
tree 9c43426b3e7ec072dff9a54b795757566f389673
parent 77994d70fe8d4805126361bbd0afbcac1cd1d2f0

Fix file transfer corner cases.

Fix zero packet read/write in corner cases
with initial read/writes. This affects transfers
of 16372 bytes to the device and transfers of
1012 bytes (or packet size - 12) from the device.

Test: Transfer various length files
Bug: 37175601
Change-Id: Ic1281e8757d1a33d78c66d2c57319b5ee38d6a46

media/mtp/MtpServer.cpp

diff --git a/media/mtp/MtpServer.cpp b/media/mtp/MtpServer.cpp
index 88dabff..5c33265 100644
--- a/media/mtp/MtpServer.cpp
+++ b/media/mtp/MtpServer.cpp
@@ -1052,23 +1052,22 @@
         ALOGE("failed to write initial data");
         result = MTP_RESPONSE_GENERAL_ERROR;
     } else {
-        if (mSendObjectFileSize - initialData > 0) {
-            mfr.offset = initialData;
-            if (mSendObjectFileSize == 0xFFFFFFFF) {
-                // tell driver to read until it receives a short packet
-                mfr.length = 0xFFFFFFFF;
-            } else {
-                mfr.length = mSendObjectFileSize - initialData;
-            }
+        mfr.offset = initialData;
+        if (mSendObjectFileSize == 0xFFFFFFFF) {
+            // tell driver to read until it receives a short packet
+            mfr.length = 0xFFFFFFFF;
+        } else {
+            mfr.length = mSendObjectFileSize - initialData;
+        }
 
-            mfr.command = 0;
-            mfr.transaction_id = 0;
+        mfr.command = 0;
+        mfr.transaction_id = 0;
 
-            // transfer the file
-            ret = sHandle->receiveFile(mfr);
-            if ((ret < 0) && (errno == ECANCELED)) {
-                isCanceled = true;
-            }
+        // transfer the file
+        ret = sHandle->receiveFile(mfr, mfr.length == 0 &&
+                initialData == MTP_BUFFER_SIZE - MTP_CONTAINER_HEADER_SIZE);
+        if ((ret < 0) && (errno == ECANCELED)) {
+            isCanceled = true;
         }
     }
     struct stat sstat;
@@ -1256,19 +1255,18 @@
     if (ret < 0) {
         ALOGE("failed to write initial data");
     } else {
-        if (length > 0) {
-            mtp_file_range  mfr;
-            mfr.fd = edit->mFD;
-            mfr.offset = offset;
-            mfr.length = length;
-            mfr.command = 0;
-            mfr.transaction_id = 0;
+        mtp_file_range  mfr;
+        mfr.fd = edit->mFD;
+        mfr.offset = offset;
+        mfr.length = length;
+        mfr.command = 0;
+        mfr.transaction_id = 0;
 
-            // transfer the file
-            ret = sHandle->receiveFile(mfr);
-            if ((ret < 0) && (errno == ECANCELED)) {
-                isCanceled = true;
-            }
+        // transfer the file
+        ret = sHandle->receiveFile(mfr, mfr.length == 0 &&
+                initialData == MTP_BUFFER_SIZE - MTP_CONTAINER_HEADER_SIZE);
+        if ((ret < 0) && (errno == ECANCELED)) {
+            isCanceled = true;
         }
     }
     if (ret < 0) {