indi_pegasus_upb crashes if project compiled with _GLIBCXX_ASSERTIONS

[wgauvin]

Describe the bug
When the project is compiled with _GLIBCXX_ASSERTIONS in the CXXFLAGS then indi_pegasus_upb crashes during the getSensorData step. When in debug logs it is clear that the getSensorData("PA") does the communication with my UPBv2 as response comes back. However, the driver doesn't complete and the program aborts() (sig = 6).

The occurs in ArchLinux distros (main ArchLinux as well as Manjaro ARM) as the default CXXFLAGS for packages includes _GLIBCXX_ASSERTIONS. I have done local builds removing that flag and the driver doesn't crash.

When the _GLIBCXX_DEBUG is also included, the details state that there is an assertion of trying to index a position 0 when the size of the vector is 0.

I've tracked this down to 2 parts within the pegasus_ubp.cpp, in getSensorData and sensorUpdated there is no check to see if the lastSensorData has been set or not. Also this issue also exists in getStepperData (found by first doing a local fix for sensorUpdated.

To Reproduce
Exact steps to reproduce the behavior.

1. Build project with CXXFLAGS including _GLIBCXX_ASSERTIONS set (also include _GLIBCXX_DEBUG for details)
2. run ./indiserver -vvv ./indi_pegasus_upb
3. Enable INDI debugging

indi_setprop "Pegasus UPB.DEBUG.ENABLE=On"
indi_setprop "Pegasus UPB.DEBUG_LEVEL.DBG_DEBUG=On"
indi_setprop "Pegasus UPB.LOGGING_LEVEL.LOG_DEBUG=On"
indi_setprop "Pegasus UPB.LOG_OUTPUT.FILE_DEBUG=On"

5. Try to have INDI server to connect to the UPBv2

indi_setprop "Pegasus UPB.CONNECTION.CONNECT=On"

Expected behavior
The expected behavior is that indiserver will connect to the device. However, when compiled with _GLIBCXX_ASSERTIONS the program aborts.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: ArchLinux
• Version: Linux deepthought 5.17.9-arch1-1 Make core compile #1 SMP PREEMPT Wed, 18 May 2022 17:30:11 +0000 x86_64 GNU/Linux

Log Files
Make sure to enable logging and include log files https://indilib.org/support/logs-submission.html
indi_pegasus_upb_fixed.log
indi_pegasus_upb_invalid.log

In the invalid log, on line 335 you can see the assertion has failed
In the valid log, line 427 is the response of the "PA" call and what follows is that it processes correctly

[wgauvin]

I am happy to do a pull request to fix this as I have a hack to work around it.

[knro]

Thank you for the report. Sure please send a PR if ready.

[wgauvin]

PR is #1663