The right way to use start/stop AccessingSecurityScopedResource in swift-cpp interop

Question

Created Mar ’24

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Hi, so I have this case where I would like the user to pick a folder where they want to create a file/folder using UIDocumentPicker/Browser and I make the file using open() in cpp and use its fd to read/write to the file. Now, the first thing is I have to call startAccessingSecurityScopedResource() on the directory url, then I make the file, get its fd(file descriptor) and I leave this makefile() function.

Every startAccessingSecurityScopedResource() needs to be matched with a stopstartAccessingSecurityScopedResource().

So my question is do I 'have' to call stopAccessingSecurityScopedResource() 'just before' calling close() on the fd.

Or is it fine to call it after I have made the fd i.e., at the end of the makefile() function?

In the tests I did it seems that once the fd is opened, even if stopAccessingSecurityScopedResource() is called on it(the directory), I can continue to read/write from the fd until I close() the fd?

Answer 1

DTS Engineer OP

Apple

Mar ’24

Accepted Answer

Permissions are resolved when you call open, so doing this should be fine:

start accessing
fd = open
stop accessing
work with fd

It is possible for access to the file to be revoked out from under a file descriptor, but it’s very rare. On macOS, for example, you’ll see this if the user force unmounts the volume on which the file resides.

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