SE.LoadFile(...) fails to open ephemeris file despite successful swi_fopen override

[Langer75]

Hi Yanos,

I’m currently using SwissEphNet on a Linux-based .NET 8 project (Raspberry Pi), and encountering a persistent issue with loading Chiron (SE_CHIRON) using Swiss Ephemeris .se1 files.

I’ve successfully implemented a swi_fopen() override. The debug log confirms it is called correctly and returns the correct absolute path to seas_18.se1. The file:

• is located at /home/pi/ephe/seas_18.se1
• exists and is readable (File.Exists(...) == true)
• can be manually opened via FileStream without issue
• begins with SWISSEPH 1 in the header, matching known valid .se1 files

However, SE.LoadFile(fnamp) still returns null, and swe_calc(...) fails with the error:

SwissEph file 'seas_18.se1' not found in PATH '/home/pi/ephe'

All signs suggest that the file is rejected somewhere deeper in the native logic or interop layer — perhaps due to encoding, file handle treatment, or assumptions in the C-port mapping.

I’d be very grateful for any insight into what internal conditions LoadFile(...) checks beyond file existence, or whether this might be a known limitation in the current port.

Thanks in advance for your time and for maintaining this great library!

Best regards,
Andreas