Thanks for the update! That's useful to know, I'll look out for any changes in future updates. there appears to be a breakdown in the logic which means that flag isn't getting set automatically I've also been seeing some other issues related to certain things I set in the FSKit API not showing up in statfs (mainly the volumeStatistics's blockSize and ioSize, FB21106711). I wonder if that's related, or maybe that's a completely separate issue.

Volume does not implement both maxFileSizeInBits and maxFileSize, while one of them must be implemented. Implementing this didn't seem to change the result. But I definitely do need to fix the sample FSKit project I've been copying as a base for all of these bug reports, then! Have you looked at what the actual block size of that device is and what FSBlockDeviceResource.blockSize is? Both physicalBlockSize and FSBlockDeviceResource.blockSize are 512 on the disk image. However, there are other issues. Your testing with a disk image, but the disk image block size is 0x200/512, NOT 0x1000/4096. If you’re looking at those values from the volume side, you may get 4096, but that's because the volume changed what stat returned, not because it's actually true. ... In your particular case, this also means that the stat value you're returning is 4x larger than the underlying FSResource size. That isn't necessarily "wrong", but that's because the VFS layer will basically believe "anything" you tell it, not because that's what you wanted to do. So, as context for where 4096 comes from, in my real extension I read the logical block size that the filesystem uses from a value stored on the superblock on disk. Most of the time that value is 4096 bytes, which is why I chose that value for the sample project. My assumption is that this value is supposed to be set to the logical block size that my file system uses? In which case that would be this larger value, not the physical block size on the device. I suppose a lot of my confusion lies from how FSBlockDeviceResource.blockSize is described as "The logical block size, the size of data blocks used by the file system," which I understand to mean that in my case, I should be able to set it to the value stored in the superblock (let's say that's 4096). But since I can't set that directly, I figured that setting the volume statistics' blockSize would report that higher value at the volume level in statfs then feed back to that value, but that didn't seem to happen since it remained at 512. Finally, on "f_ioSize", it's also possible that we're intentionally capping that size to 1MB. Hmm, but that would be a strange reason in this case, wouldn't it? In the sample project I set stats.ioSize = 524_288 which is half of the default value. So it should be within that limit, still, unless you mean that it's just always kept at 1 MB. Although I have seen the same behavior (ioSize always at 1MB even if set to a lower value) in my real project that does implement kernel offloaded IO, so it seems a bit confusing if that value can be "set" but doesn't actually do anything.

I think FSKit modules have to be sandboxed, but since you're not planning to be on the App Store and thus don't need to care about App Review, have you looked at the temporary exception entitlements (https://developer.apple.com/library/archive/documentation/Miscellaneous/Reference/EntitlementKeyReference/Chapters/AppSandboxTemporaryExceptionEntitlements.html)? You might find the file access ones useful.

By the way, it's usually best to make a reply instead of leaving a comment. Comments are easy to miss and usually don't create notifications. Do you know whether I can use com.apple.security.temporary-exception.files.absolute-path.read-write with /? I think it should work, although I haven't tried it myself. how do I log from the extension? If I use the standard logging framework, no logs arrive in the console app. Not sure exactly which "standard logging framework" you're referring to (there's a lot of them), but I've been able to use Swift's Logger API (from os.log, I think if you're in Obj-C you'd use os_log) from my extension and it acts like logging from a regular app. If you're trying that and it's not working, then are you logging on the debug or info levels? Those don't show up in Console's streaming view by default unless you enable them in the Action menu. The more severe levels do show up by default.

My issues might even be better solved with FSActivateOptionSyntax, but I don't know where to find the docs for it. Or how to propably use it. Yeah, that's probably meant to be used for your situation. I think you're supposed to be able to provide a path then you can get a security-scoped URL that you can use to access that specific path while sandboxed. I briefly looked at that a while ago but I don't think most of the Info.plist keys are documented right now. Most of the "documentation" right now is just scouring the forums or Apple's open-source FSKit extensions for examples (or, if you're lucky, replies to your feedbacks), which isn't too great. My (untested, could be wrong) assumption was that if you were to set something like <key>shortOptions</key> <string>abc:d:</string> Then on the command line you'd be able to pass options like -a or -b, while -c=arg and -d=arg both take additional arguments. I never needed it for my own extension though so I didn't look too hard, but the forums post you listed suggests that the ability to get a URL from them didn't work for that OP, so I don't know if it would actually work for you. That sounds like a bug but it looks like the OP of that thread disappeared so it's not too clear what happened there. If it doesn't work or you can't figure it out then you should probably file a bug and post it here; an Apple employee is more likely to be able to help you that way. In my experience the FSKit team has been pretty responsive to feedback when I also post about it on the forums, and even without posting. Or, just keep using the sandbox exception and call it a day. The only question remaining is: The test question. Tests... I should write some for my own module... Anyway, I think the better option is to try to separate out the logic for your file system into their own unit testable functions, then test those separately instead of trying to test it by mounting a whole volume with FSKit. Then you'd sidestep the issue around FSKit being weird when being automated. Your goal isn't really to test FSKit, it's to make sure your own file system logic is good, so I think for this kind of codebase that should be mostly sufficient. Unfortunately to do something like the analog of a "UI test" for a regular app (but I guess without the UI... an integration test?) I don't know how to automate it very well, but ideally your unit tests cover most of the things you do need to test.

Thanks! That clears my confusion up. Right now I'll just be focusing on the layers relevant to an FSKit module. I wasn't even really thinking of the case where reported total bytes != physical total bytes, but that example makes sense. As a real-world example, copy-on-write (COW) file systems like APFS work by pushing "all" changes out as writes which are then applied, but that also means that it's possible to put the file system into a state where it can no longer be modified. Modification would require free space, so if all the space is gone modification becomes impossible... and that INCLUDES deleting files. The simplest solution to this is exactly what APFS does— set aside enough space that you'll "always" be able to delete files, then increase your used count so that the volume is "full" before you ACTUALLY run out of "all" space. Huh. Out of curiosity, did APFS always do that to prevent that issue? I vaguely remember seeing an issue like that at a user level years ago (although, I don't really have any evidence to really prove that that was the specific issue that happened, so maybe not). In any case, going back to the original issue, I wonder if that's related, or maybe that's a completely separate issue. I think we can file this under "completely separate."

Makes sense, so seems like what I saw back then [1] almost certainly wasn't at the APFS layer, then. one follow-up comment for the "haters" out there: Ha, well I would hope that someone looking at an FSKit-related question on the forums would know enough about file systems to understand why that would make sense, though I suppose you never know ;) COW is definitely saving me more space on my machine than whatever is reserved for that purpose. [1] If you're curious it was an old Apple Watch I had that got stuck in a boot loop after restarting it to try to fix some "crashy app" behavior, and IIRC there were low storage alerts shortly before that happened. Definitely way after the iOS 8 days.

Can you confirm that this is happening in macOS 15.7.3 (24G416) in upload a new sysdiagnose if it is? It is, unfortunately, still happening in a macOS 15.7.3 (24G416) VM I'm testing in. I attached a new sysdiagnose to FB21305906. I don't know what (if any) user interface you've implemented, but having some kind of "app experience" running while your volume is mounted would be the most direct way to prevent these issues. Hmm, ok. So presumably if I just wait for a "fix" I might be waiting for a while. Right now my own UI is just a guide to enable the file system extension, so there's essentially no reason at the moment for users to keep the app itself open after that point. It's pretty much just in an app because it's necessary for distribution. Maybe I could have some GUI-less mode of the app open whenever the extension mounts something and then kill that instance on unmount? But between sandboxing and App Review complications I don't know if that's actually feasible.

[quote='869273022, JohnC2, /thread/809952?answerId=869273022#869273022, /profile/JohnC2'] Are there any examples of Apple designed apps that behave in this manner? I can't seem to find any. [/quote] I don't know if most of the password entry fields in Apple apps even have a reveal password button for sighted users (I could not find one on a random one I checked), but Apple's Passwords app allows you to reveal passwords, including when using VoiceOver, and reads the password aloud when using VoiceOver. [quote='869273022, JohnC2, /thread/809952?answerId=869273022#869273022, /profile/JohnC2'] These types of buttons in general to me seem to defeat the purpose of "secure text entry". [/quote] That seems more like an argument against the reveal password button in general than an argument against showing it to a VoiceOver user. Which is certainly an opinion you can have, but it's not really accessibility-specific. I'd agree with both your accessibility team and the above engineer that it's worth having the option there in the screen reader case, if you're going to have it there at all. If a VoiceOver user clicks that button, they would probably expect it to be read aloud. Keep in mind that someone may be using e.g. headphones or simply be alone and consider it worth any "risk."

[quote='810660021, SamanthaValverde, /thread/810660, /profile/SamanthaValverde'] App status: Ready for Review (unchanged for 2 weeks) [/quote] That means you only made a draft submission and haven’t submitted your app If it’s submitted it should say “Waiting for Review” or “In Review” edit: also, for your actual question, my experience is usually that I’m waiting for review for about a day at most and in review for about 1-2 hours However, I did recently have to wait about 3 days for the review to start, although that wait did include the weekend and I assume there were also more submissions than usual due to the age rating emails they sent out