`klayoutrc` parse issue silently replaces config file

[martinjankoehler]

I've saved an invalid config option,
which led to a parsing error:

ERROR: Problem reading config file /Users/martin/.klayout/klayoutrc: XML parser error: error occurred while parsing element in line 1815, column 22

• EXPECTED:
  • I expected the program to either quit,
  • or (preferrably) create a backup of the problematic klayoutrc, e.g. ~/.klayout/klayoutrc_2025-02-25_13h58m_003234.bak
• OBTAINED:
  • file was silently replaced with a default file (e.g. I now lost a lot of settings)

[klayoutmatthias]

Hi Martin,

I was this can happen if you close two instances at the same time and both write to the same file. A backup could suffer from the same effect if two processes try to copy away a file to the same backup. Maybe the only true solution is making the file write atomic by employing a system semaphore (at least for processes on the same host).

Matthias

[martinjankoehler]

Hi Matthias,

It really was only one instance!
Really only the XML parsing error itself triggered this: #2285

Best,
Martin

[klayoutmatthias]

I have implemented backup files - up to ten backups are kept, named "klayoutrc.1" (most recent) to "klayoutrc.10" (oldest). I hope, this mitigates that problem.

Matthias