Add check before pthread_join

[pvyawaha]

Description of changes:
This change adds check so that pthread_join is called only when ota thread is created.

By submitting this pull request, I confirm that my contribution is made under the terms of the MIT license.

[aggarw13]

The set of bug improvements to the OTA demos (across different PRs since the previous release) would be good to add as a single CHANGELOG item point

[vikivivi]

• From the manpage of pthread_join. See possible errors code upon return.

RETURN VALUE
       On success, pthread_join() returns 0; on error, it returns an error number.

ERRORS
       EDEADLK
              A deadlock was detected (e.g., two threads tried to join with each other); or thread specifies the calling thread.

       EINVAL thread is not a joinable thread.

       EINVAL Another thread is already waiting to join with this thread.

       ESRCH  No thread with the ID thread could be found.

/**
 * @brief Start OTA demo.
 *
 * @return   EXIT_SUCCESS or EXIT_FAILURE.
 */
static int startOTADemo( void );

static int startOTADemo( void )
{
   ...
    if( returnStatus == EXIT_SUCCESS )
    {
        returnStatus = pthread_join( threadHandle, NULL );

        if( returnStatus != EXIT_SUCCESS )
        {
            LogError( ( "Failed to join thread"
                        ",error code = %d",
                        returnStatus ) );
        }
    }

    return returnStatus;
}

• Since startOTADemo() is documented to return either EXIT_SUCCESS or EXIT_FAILURE, we should not use error code of pthread_join() as the returned error code from startOTADemo(). In case someone uses the demo code startOTADemo() like this.

if( startOTADemo() != EXIT_FAILURE )   /* Error code of pthread_join will have the same as EXIT_SUCCESS */
{
   ....
}

• Proposed fix at the section of pthread_join().
  • Declare new variable returnJoin to LogError pthread_join() error code. Optional if just print failed to join thread.
  • On success of pthread_join() compare return 0. Just like all other pthread API in OTA demo. (I know EXIT_SUCCESS = 0 as well, but does not belong to the same list of error code)

    if( returnStatus == EXIT_SUCCESS )
    {
        if( ( returnJoin = pthread_join( threadHandle, NULL ) ) != 0 )
        {
            LogError( ( "Failed to join thread"
                        ",error code = %d",
                        returnJoin ) );
            returnStatus = EXIT_FAILURE;
        }
    }

    return returnStatus;

[pvyawaha]

* From the manpage of `pthread_join`. See possible errors code upon return.

RETURN VALUE
       On success, pthread_join() returns 0; on error, it returns an error number.

ERRORS
       EDEADLK
              A deadlock was detected (e.g., two threads tried to join with each other); or thread specifies the calling thread.

       EINVAL thread is not a joinable thread.

       EINVAL Another thread is already waiting to join with this thread.

       ESRCH  No thread with the ID thread could be found.

/**
 * @brief Start OTA demo.
 *
 * @return   EXIT_SUCCESS or EXIT_FAILURE.
 */
static int startOTADemo( void );

static int startOTADemo( void )
{
   ...
    if( returnStatus == EXIT_SUCCESS )
    {
        returnStatus = pthread_join( threadHandle, NULL );

        if( returnStatus != EXIT_SUCCESS )
        {
            LogError( ( "Failed to join thread"
                        ",error code = %d",
                        returnStatus ) );
        }
    }

    return returnStatus;
}

* Since `startOTADemo()` is documented to return either `EXIT_SUCCESS` or `EXIT_FAILURE`, we should not use error code of `pthread_join()` as the returned error code from `startOTADemo()`. In case someone uses the demo code `startOTADemo()` like this.

if( startOTADemo() != EXIT_FAILURE )   /* Error code of pthread_join will have the same as EXIT_SUCCESS */
{
   ....
}

* Proposed fix at the section of `pthread_join()`.
  
  * Declare new variable `returnJoin` to LogError `pthread_join()` error code. Optional if just print failed to join thread.
  * On success of `pthread_join()` compare return `0`. Just like all other pthread API in OTA demo. (I know EXIT_SUCCESS = 0 as well, but does not belong to the same list of error code)

    if( returnStatus == EXIT_SUCCESS )
    {
        if( ( returnJoin = pthread_join( threadHandle, NULL ) ) != 0 )
        {
            LogError( ( "Failed to join thread"
                        ",error code = %d",
                        returnJoin ) );
            returnStatus = EXIT_FAILURE;
        }
    }

    return returnStatus;

Added in commit
0ad0670

[vikivivi]

@pvyawaha Should I raise another issue or you simply make another commit ? You forget to switch LogError to use the new variable returnJoin. See my above proposed fix. There is no point to LogError returnStatus as it will be EXIT_SUCCESS.

diff --git a/demos/ota/ota_demo_core_http/ota_demo_core_http.c b/demos/ota/ota_demo_core_http/ota_demo_core_http.c
index 5e0a8359..2bbb3cdb 100644
--- a/demos/ota/ota_demo_core_http/ota_demo_core_http.c
+++ b/demos/ota/ota_demo_core_http/ota_demo_core_http.c
@@ -2091,13 +2091,13 @@ static int startOTADemo( void )
         returnJoin = pthread_join( threadHandle, NULL );
 
         if( returnJoin != 0 )
         {
             LogError( ( "Failed to join thread"
                         ",error code = %d",
-                        returnStatus ) );
+                        returnJoin ) );
 
             returnStatus = EXIT_FAILURE;
         }
     }
 
     return returnStatus;
diff --git a/demos/ota/ota_demo_core_mqtt/ota_demo_core_mqtt.c b/demos/ota/ota_demo_core_mqtt/ota_demo_core_mqtt.c
index 4d14ebd5..ed43dca9 100644
--- a/demos/ota/ota_demo_core_mqtt/ota_demo_core_mqtt.c
+++ b/demos/ota/ota_demo_core_mqtt/ota_demo_core_mqtt.c
@@ -1638,13 +1638,13 @@ static int startOTADemo( void )
         returnJoin = pthread_join( threadHandle, NULL );
 
         if( returnJoin != 0 )
         {
             LogError( ( "Failed to join thread"
                         ",error code = %d",
-                        returnStatus ) );
+                        returnJoin ) );
 
             returnStatus = EXIT_FAILURE;
         }
     }
 
     return returnStatus;

[pvyawaha]

Thank you for pointing it out, I will fix this.