imdocker: Coverity-detected issues

[rgerhards]

unfortunately, Coverity scan can only be run "after the fact" and not as part of CI. So it now reports problem with imdocker, which has recently merged:

** CID 202689:  Control flow issues  (DEADCODE)
/contrib/imdocker/imdocker.c: 800 in dockerContainerInfoNew()


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*** CID 202689:  Control flow issues  (DEADCODE)
/contrib/imdocker/imdocker.c: 800 in dockerContainerInfoNew()
794             docker_container_info_t* pThis = calloc(1, sizeof(docker_container_info_t));
795             CHKmalloc(pThis);
796             *ppThis = pThis;
797     
798     finalize_it:
799             if (iRet != RS_RET_OK && pThis) {
>>>     CID 202689:  Control flow issues  (DEADCODE)
>>>     Execution cannot reach this statement: "dockerContainerInfoDestruct...".
800                     dockerContainerInfoDestruct(pThis);
801             }
802             RETiRet;
803     }
804     
805     static void

** CID 202688:  Null pointer dereferences  (REVERSE_INULL)
/contrib/imdocker/imdocker.c: 1381 in imdocker_container_logs_curlCB()


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*** CID 202688:  Null pointer dereferences  (REVERSE_INULL)
/contrib/imdocker/imdocker.c: 1381 in imdocker_container_logs_curlCB()
1375                    pDataBuf->bytes_remaining = 0;
1376                    write_size = realsize;
1377                    pread = pdata;
1378            }
1379     
1380            /* allocate the expected payload size */
>>>     CID 202688:  Null pointer dereferences  (REVERSE_INULL)
>>>     Null-checking "pDataBuf" suggests that it may be null, but it has already been dereferenced on all paths leading to the check.
1381            if (pDataBuf) {
1382                    CHKiRet(dockerContLogsBufWrite(pDataBuf, pread, write_size));
1383                    if (pDataBuf->bytes_remaining == 0) {
1384                            DBGPRINTF("%s() - write size is same as payload_size\n", __FUNCTION__);
1385                            /* NOTE: We do see if a log line gets extended beyond 16K
1386                             * if (mem->data[mem->len-1] == imdocker_eol_char)

@n2yen can you have a look? I can enable full access to coverity, which usually is pretty helpful. Just request it. rsyslog homepage on Coverity: https://scan.coverity.com/projects/rsyslog-rsyslog