Use errno correctly.

After a failed write() or ioctl(), errno wasn't being checked until
after some other function calls that could also modify errno, thus
checking the wrong errno. Make sure to check it prior to doing anything
else that can modify it.

[Preconditions]
1.PC connects with phone(mtp).

[Procedures]
1.Copy a file from PC to phone.
2.Cancel the copying.
3.Recopy the file.

Change-Id: Id772fca7ccb96d3f43bd4beb210bedd8d3ac17fa

1 files changed, 29 insertions, 14 deletions

diff --git a/media/mtp/MtpServer.cpp b/media/mtp/MtpServer.cpp
index 6a334e6..3c91ffd 100644
--- a/media/mtp/MtpServer.cpp
+++ b/media/mtp/MtpServer.cpp
@@ -215,10 +215,11 @@ void MtpServer::run() {
             mResponse.setTransactionID(transaction);
             ALOGV("sending response %04X", mResponse.getResponseCode());
             ret = mResponse.write(fd);
+            const int savedErrno = errno;
             mResponse.dump();
             if (ret < 0) {
                 ALOGE("request write returned %d, errno: %d", ret, errno);
-                if (errno == ECANCELED) {
+                if (savedErrno == ECANCELED) {
                     // return to top of loop and wait for next command
                     continue;
                 }
@@ -793,15 +794,19 @@ MtpResponseCode MtpServer::doGetObject() {
 
     // then transfer the file
     int ret = ioctl(mFD, MTP_SEND_FILE_WITH_HEADER, (unsigned long)&mfr);
-    ALOGV("MTP_SEND_FILE_WITH_HEADER returned %d\n", ret);
-    close(mfr.fd);
     if (ret < 0) {
-        if (errno == ECANCELED)
-            return MTP_RESPONSE_TRANSACTION_CANCELLED;
-        else
-            return MTP_RESPONSE_GENERAL_ERROR;
+        if (errno == ECANCELED) {
+            result = MTP_RESPONSE_TRANSACTION_CANCELLED;
+        } else {
+            result = MTP_RESPONSE_GENERAL_ERROR;
+        }
+    } else {
+        result = MTP_RESPONSE_OK;
     }
-    return MTP_RESPONSE_OK;
+
+    ALOGV("MTP_SEND_FILE_WITH_HEADER returned %d\n", ret);
+    close(mfr.fd);
+    return result;
 }
 
 MtpResponseCode MtpServer::doGetThumb() {
@@ -870,14 +875,15 @@ MtpResponseCode MtpServer::doGetPartialObject(MtpOperationCode operation) {
     // transfer the file
     int ret = ioctl(mFD, MTP_SEND_FILE_WITH_HEADER, (unsigned long)&mfr);
     ALOGV("MTP_SEND_FILE_WITH_HEADER returned %d\n", ret);
-    close(mfr.fd);
+    result = MTP_RESPONSE_OK;
     if (ret < 0) {
         if (errno == ECANCELED)
-            return MTP_RESPONSE_TRANSACTION_CANCELLED;
+            result = MTP_RESPONSE_TRANSACTION_CANCELLED;
         else
-            return MTP_RESPONSE_GENERAL_ERROR;
+            result = MTP_RESPONSE_GENERAL_ERROR;
     }
-    return MTP_RESPONSE_OK;
+    close(mfr.fd);
+    return result;
 }
 
 MtpResponseCode MtpServer::doSendObjectInfo() {
@@ -991,6 +997,7 @@ MtpResponseCode MtpServer::doSendObject() {
     MtpResponseCode result = MTP_RESPONSE_OK;
     mode_t mask;
     int ret, initialData;
+    bool isCanceled = false;
 
     if (mSendObjectHandle == kInvalidObjectHandle) {
         ALOGE("Expected SendObjectInfo before SendObject");
@@ -1038,6 +1045,10 @@ MtpResponseCode MtpServer::doSendObject() {
             ALOGV("receiving %s\n", (const char *)mSendObjectFilePath);
             // transfer the file
             ret = ioctl(mFD, MTP_RECEIVE_FILE, (unsigned long)&mfr);
+            if ((ret < 0) && (errno == ECANCELED)) {
+                isCanceled = true;
+            }
+
             ALOGV("MTP_RECEIVE_FILE returned %d\n", ret);
         }
     }
@@ -1045,7 +1056,7 @@ MtpResponseCode MtpServer::doSendObject() {
 
     if (ret < 0) {
         unlink(mSendObjectFilePath);
-        if (errno == ECANCELED)
+        if (isCanceled)
             result = MTP_RESPONSE_TRANSACTION_CANCELLED;
         else
             result = MTP_RESPONSE_GENERAL_ERROR;
@@ -1214,6 +1225,7 @@ MtpResponseCode MtpServer::doSendPartialObject() {
         length -= initialData;
     }
 
+    bool isCanceled = false;
     if (ret < 0) {
         ALOGE("failed to write initial data");
     } else {
@@ -1225,12 +1237,15 @@ MtpResponseCode MtpServer::doSendPartialObject() {
 
             // transfer the file
             ret = ioctl(mFD, MTP_RECEIVE_FILE, (unsigned long)&mfr);
+            if ((ret < 0) && (errno == ECANCELED)) {
+                isCanceled = true;
+            }
             ALOGV("MTP_RECEIVE_FILE returned %d", ret);
         }
     }
     if (ret < 0) {
         mResponse.setParameter(1, 0);
-        if (errno == ECANCELED)
+        if (isCanceled)
             return MTP_RESPONSE_TRANSACTION_CANCELLED;
         else
             return MTP_RESPONSE_GENERAL_ERROR;