commit 07a9e548af0ed26d7354f3defaa8f18b2c5125f1
author tao.pei <tao.pei@ck-telecom.com> Fri Jul 17 17:18:41 2015 +0800
committer Narayan Kamath <narayan@google.com> Tue Jul 21 10:51:48 2015 +0100
tree bac808f24cd14d4bc55c885132a2966c487e6ac9
parent 4889c07b795dac023a90df36f1cc7cffce8dbe0d

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

media/mtp/MtpServer.cpp

diff --git a/media/mtp/MtpServer.cpp b/media/mtp/MtpServer.cpp
index 07199e3..3e0f239 100644
--- a/media/mtp/MtpServer.cpp
+++ b/media/mtp/MtpServer.cpp
@@ -214,10 +214,11 @@
             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;
                 }
@@ -787,15 +788,19 @@
 
     // then transfer the file
     int ret = ioctl(mFD, MTP_SEND_FILE_WITH_HEADER, (unsigned long)&mfr);
+    if (ret < 0) {
+        if (errno == ECANCELED) {
+            result = MTP_RESPONSE_TRANSACTION_CANCELLED;
+        } else {
+            result = MTP_RESPONSE_GENERAL_ERROR;
+        }
+    } else {
+        result = MTP_RESPONSE_OK;
+    }
+
     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;
-    }
-    return MTP_RESPONSE_OK;
+    return result;
 }
 
 MtpResponseCode MtpServer::doGetThumb() {
@@ -864,14 +869,15 @@
     // 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() {
@@ -985,6 +991,7 @@
     MtpResponseCode result = MTP_RESPONSE_OK;
     mode_t mask;
     int ret, initialData;
+    bool isCanceled = false;
 
     if (mSendObjectHandle == kInvalidObjectHandle) {
         ALOGE("Expected SendObjectInfo before SendObject");
@@ -1032,6 +1039,10 @@
             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);
         }
     }
@@ -1039,7 +1050,7 @@
 
     if (ret < 0) {
         unlink(mSendObjectFilePath);
-        if (errno == ECANCELED)
+        if (isCanceled)
             result = MTP_RESPONSE_TRANSACTION_CANCELLED;
         else
             result = MTP_RESPONSE_GENERAL_ERROR;
@@ -1208,6 +1219,7 @@
         length -= initialData;
     }
 
+    bool isCanceled = false;
     if (ret < 0) {
         ALOGE("failed to write initial data");
     } else {
@@ -1219,12 +1231,15 @@
 
             // 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;