[frederik]

Hi, first of all, I would like to thank you for an excellent product, but there is one issue which began since release of Android Oreo 8.1 on my tablet and is related to the I/O operations with SD card. I have been observing the situation for a long time now. Reading/writing to the SD card by Magic DOSBox is very slow and often corrupted or no data are read. Almost all applications from Google store were affected by this problem, but the developers already fixed their apps in their later releases (Mapy.cz, Total Commander etc.) but newer releases of Magic DOSBox did not fix it. Basically, if I run the game from SD card and in the game try to save the game state on the SD card, I am unable to load the saved game back, I am receiving the error message “Cannot read the file” or “The read file is corrupted”. It interesting if I dismount the SD card and again re-mount, Magic DOSBox can suddenly read the saved game from the SD card. Do you know where might be the problem please?

[admin]

Hi, thanks for report. This is new to me. I did not notice any specific changes to sdcard on android 8.1. I dont have device with android 8.1, but i can test it in emulator. I now worked a lot on storages support from android 11 and version is not yet out. But this is different.

Do you mean to have data on sdcard on public location or in /android/data/bruenor.magicbox ?

Hm, but wait, there is no way how magic dosbox can save state on sdcard? Only new (still unreleased) version can do it. With save state you mean “Save State” from general settings menu, or the way how game saves self?

[frederik]

Hi, thanks for a quick respond. I mean the procedure saving/loading in game doesn’t work without problems since Oreo 8.1 (a lot of DOS games offer saving/loading possibility). The problem is that loading the saved game back throws an error that the file is corrupted, or cannot be read. I know that Magic DOSBox offers also “Save State” option, but this is something else.

[admin]

Hi,

Ah allright. To be sure, your games are on removable sdcard? If yes, they are in public folder in private? If in public then did you granted sdcard permissions in global setting

[frederik]

Hi, yes, all of my games are stored on SD card which is formatted as portable. And yes, I granted permissions to the Magic DOSBox to be able to access the game folder on SD card in the global settings. If I did not do this, I think I cannot even start the game from SD card. I am able to run the game, but as I mentioned only if the game wants to store some file in its folder on SD card and again recover the file from the folder, it fails with “The read file is corrupted” message and the game crashes. All games are affected. I originally thought that maybe new Android version would fix it, but I see that Magic DOSbox problem with the SD card handling in every Android version since Oreo on my hardware (2 of my tablets).

[frederik]

I think it could be something with read/write permissions which were changed in Oreo 8. See here: https://stackoverflow.com/questions/55687903/file-read-and-write-in-android-8-1-and-above
?

[admin]

I check permissions in runtime. The post on stackoverflow is about internal storage, not sdcard. This is different access. But I have huawei phone with android 9. I will try it. Or is it related to android 8.1 only?

Btw, internal storage works fine? I mean, for example /storage/emulated/0/Games

What comes on my mind is that sdcard permission granted in global settings is lost after restart or so and should be re-granted. This I dont check in runtime.

[Author]

Posts