Upload error for empty blob on MQTT

[opekhovskiy-zf]

Development Machine, OS, Compiler (and Other Relevant Toolchain Info)

Ubuntu 22.04.1 LTS
gcc (Ubuntu 11.2.0-19ubuntu1) 11.2.0

SDK Version

1.9.1
Commit SHA: 3fd808b
Release 2022-09-19

Protocol

MQTT

Describe the Bug

Sending zero size blob with IoTHubDeviceClient_UploadMultipleBlocksToBlobAsync function leads to
underfined behavior in most cases causing FILE_UPLOAD_ERROR.
The main reason is that variable httpResponse defined in IoTHubClient_LL_UploadMultipleBlocksToBlob_Impl
left uninitialized after the call of Blob_UploadMultipleBlocksFromSasUri.
This is because when source == NULL || size == 0 (which is our case) variable httpStatus
(which is the pointer to the outer httpResponse) is never used.
The patch 01-empty-blob-http-status-fix.patch just adds *httpStatus = 200.

Here is how call stack looks in this case:
InvokeUserCallbackAndSendBlobs blob.c:209
Blob_UploadMultipleBlocksFromSasUri blob.c:347
IoTHubClient_LL_UploadMultipleBlocksToBlob_Impl iothub_client_ll_uploadtoblob.c:742
IoTHubClientCore_LL_UploadMultipleBlocksToBlobEx iothub_client_core_ll.c:2770
uploadMultipleBlock_thread iothub_client_core.c:2437
ThreadWrapper threadapi_pthreads.c:35
start_thread 0x00007ffff6aefb43
clone3 0x00007ffff6b81a00

MCVE

Please use example attached
azure_empty_blob_test.zip

Console Logs

$ ./test
Test started!
SDK version: 1.9.1
-> 22:18:07 CONNECT | VER: 4 | KEEPALIVE: 120 | FLAGS: 192 | USERNAME: ares-iot-odc.azure-devices.net/7C9763504107/?api-version=2020-09-30&DeviceClientType=iothubclient%2f1.9.1%20(native%3b%20Linux%3b%20x86_64) | PWD: XXXX | CLEAN: 0
<- 22:18:07 CONNACK | SESSION_PRESENT: true | RETURN_CODE: 0x0
IOTHUB_CLIENT_CONNECTION_AUTHENTICATED: IOTHUB_CLIENT_CONNECTION_OK
-> 22:18:07 SUBSCRIBE | PACKET_ID: 2 | TOPIC_NAME: devices/7C9763504107/messages/devicebound/# | QOS: 1 | TOPIC_NAME: $iothub/twin/res/# | QOS: 0
Async upload empty1.txt for Blob #1
<- 22:18:07 SUBACK | PACKET_ID: 2 | RETURN_CODE: 1 | RETURN_CODE: 0
-> 22:18:07 PUBLISH | IS_DUP: false | RETAIN: 0 | QOS: DELIVER_AT_MOST_ONCE | TOPIC_NAME: $iothub/twin/GET/?$rid=3
<- 22:18:07 PUBLISH | IS_DUP: false | RETAIN: 0 | QOS: DELIVER_AT_MOST_ONCE | TOPIC_NAME: $iothub/twin/res/200/?$rid=3 | PAYLOAD_LEN: 2888
-> 22:18:07 SUBSCRIBE | PACKET_ID: 4 | TOPIC_NAME: $iothub/twin/PATCH/properties/desired/# | QOS: 0
<- 22:18:07 SUBACK | PACKET_ID: 4 | RETURN_CODE: 0
Sending Blob #1
Blob send OK
Async upload empty2.txt for Blob #2
Sending Blob #2
Blob send Error: FILE_UPLOAD_ERROR
Async upload empty3.txt for Blob #3
Sending Blob #3
Blob send Error: FILE_UPLOAD_ERROR
Async upload empty4.txt for Blob #4
Sending Blob #4
Blob send Error: FILE_UPLOAD_ERROR
Async upload empty5.txt for Blob #5
Sending Blob #5
Blob send Error: FILE_UPLOAD_ERROR
Async upload empty6.txt for Blob #6
Sending Blob #6
Blob send Error: FILE_UPLOAD_ERROR
Async upload empty7.txt for Blob #7
Sending Blob #7
Blob send Error: FILE_UPLOAD_ERROR
Async upload empty8.txt for Blob #8
Sending Blob #8
Blob send Error: FILE_UPLOAD_ERROR
Async upload empty9.txt for Blob #9
Sending Blob #9
Blob send Error: FILE_UPLOAD_ERROR
Async upload empty10.txt for Blob #10
-> 22:18:11 UNSUBSCRIBE | PACKET_ID: 5 | TOPIC_NAME: devices/7C9763504107/messages/devicebound/#
Sending Blob #10
Blob send Error: FILE_UPLOAD_ERROR
-> 22:18:11 DISCONNECT
Test finished!

[ericwolz]

#2393

[ericwolz]

Thanks for the submission. This issue has been resolved.