Fix os.OpenFile mode and permission

[k1LoW]

No description provided.

[codecov]

Codecov Report

Merging #191 into master will decrease coverage by 0.90%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #191      +/-   ##
==========================================
- Coverage   67.93%   67.03%   -0.91%     
==========================================
  Files          19       19              
  Lines        3206     3206              
==========================================
- Hits         2178     2149      -29     
- Misses        803      837      +34     
+ Partials      225      220       -5     

Impacted Files	Coverage Δ
datasource/datasource.go	21.26% <0.00%> (-13.13%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 4f4bdc3...999dab2. Read the comment docs.