Implement #311 - support RO SD images.

[vintagepc]

Description

Mount RO SD images appropriately and don't try to open/mmap them in write-mode.

Behaviour/ Breaking changes

N/A - adds functionality if SD file is RO, does not change existing behaviour with RW files.

Have you tested the changes?

Have not checked write commands to a locked SD card; MK3 firmware does not make any write attempts to the card IIRC.
Info message prints correctly if file is detected as RO.

Linked issues:

• Closes [FEATURE] Allow mounting SD images in R/O mode #311

[wavexx]

MK3 firmware does not make any write attempts to the card IIRC.

I was thinking that too, then I realized you can upload a file to the sd card using M28 / M29 and some other PRUSA code we can ignore.

I have no idea though if the FW actually handles write faults ...

[vintagepc]

Well then... sounds like you might be the one to find out 🤣

[codecov]

Codecov Report

Merging #312 (0746f16) into master (7b5d679) will increase coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #312      +/-   ##
==========================================
+ Coverage   89.02%   89.08%   +0.05%     
==========================================
  Files         140      140              
  Lines        6645     6659      +14     
==========================================
+ Hits         5916     5932      +16     
+ Misses        729      727       -2     

Impacted Files	Coverage Δ
parts/components/SDCard.h	100.00% <ø> (ø)
parts/components/SDCard.cpp	93.59% <100.00%> (+0.28%)	⬆️
utility/FatImage.cpp	92.68% <0.00%> (+2.43%)	⬆️

---

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 7b5d679...0746f16. Read the comment docs.