COPYFILE with Swift ?

The third parameter to copyfile is a copy state ‘object’ (copyfile_state_t). To implement COPY_QUIT, you’ll need to allocate one of these (copyfile_state_alloc), configure it (copyfile_state_set), pass it in to the copyfile call, and then deallocate it when you’re done (copyfile_state_free).

Once you have a copy state object, the specific state you need to set is COPYFILE_STATE_STATUS_CB. This takes a C function pointer (of type copyfile_callback_t) as a parameter.

Getting this all right is going to be tricky. It would be tricky even from a C-based language, and Swift doesn’t make it any easier.

---

The first thing I’d do is wrap the copyfile function so that it takes URL parameters directly:

Code Block  
private func copyfileQ(_ from: URL, _ to: URL, _ state: copyfile_state_t?, _ flags: copyfile_flags_t) -> Int32 {
    return from.withUnsafeFileSystemRepresentation { fromPtr -> Int32 in
        to.withUnsafeFileSystemRepresentation { toPtr -> Int32 in
            copyfile(fromPtr, toPtr, state, flags)
        }
    }
}

You can then call it like so:

Code Block  
let success = copyfileQ(self.sourceURL, self.destinationURL, nil, copyfile_flags_t(COPYFILE_DATA)) >= 0
guard success else {
    throw NSError(domain: NSPOSIXErrorDomain, code: Int(errno), userInfo: nil)
}

Now you have to deal with the copy state object. You can allocate this like so:

Code Block  
let state = copyfile_state_alloc()
defer {
    copyfile_state_free(state)
}

Note that this uses a defer statement to guarantee that it gets deallocated. Then pass it in to copyfile like so:

Code Block  
let success = copyfileQ(self.sourceURL, self.destinationURL, state, copyfile_flags_t(COPYFILE_DATA)) >= 0

Now you need to set up the callback. This is where things get tricky. The problem is that the type of the third parameter to copyfile_state_set depends on the selector you pass it. For example:

• For COPYFILE_STATE_STATUS_CB, it is a C function pointer of type copyfile_callback_t.

• For COPYFILE_STATE_STATUS_CTX, it is a C void * parameter.

These two cases have to be handled differently. For COPYFILE_STATE_STATUS_CTX, the desired parameter is an object (self) and thus you can use the standard Unmanaged tricks.

Code Block  
let context = Unmanaged.passUnretained(self)
copyfile_state_set(state, UInt32(COPYFILE_STATE_STATUS_CTX), context.toOpaque())

For COPYFILE_STATE_STATUS_CB, the desired parameter is a C function pointer, and that requires an ugly unsafeBitCast(…).

Code Block  
let callback: copyfile_callback_t = { what, stage, state, src, dst, context in
copyfile_state_set(state, UInt32(COPYFILE_STATE_STATUS_CB), unsafeBitCast(callback, to: UnsafeRawPointer.self))

Putting this all together, you’ll find pasted in below the source for a command-line tool that copies from a source to a destination. If the source looks like this:

Code Block  
$ find /Users/quinn/Test/source
/Users/quinn/Test/source
/Users/quinn/Test/source/.DS_Store
/Users/quinn/Test/source/f1.txt
/Users/quinn/Test/source/nested
/Users/quinn/Test/source/nested/.DS_Store
/Users/quinn/Test/source/nested/f2.txt

it prints:

Code Block  
what: 2
stage: 1
state: 0x000000010183e680
src: /Users/quinn/Test/source
dst: /Users/quinn/Test/destination/source
what: 2
stage: 2
state: 0x000000010183e680
src: /Users/quinn/Test/source
dst: /Users/quinn/Test/destination/source
what: 1
stage: 1
state: 0x000000010050aa30
src: /Users/quinn/Test/source/.DS_Store
dst: /Users/quinn/Test/destination/source/.DS_Store
what: 4
stage: 4
state: 0x000000010050aa30
src: /Users/quinn/Test/source/.DS_Store
dst: /Users/quinn/Test/destination/source/.DS_Store
what: 1
stage: 2
state: 0x000000010050aa30
src: /Users/quinn/Test/source/.DS_Store
dst: /Users/quinn/Test/destination/source/.DS_Store
what: 1
stage: 1
state: 0x00000001006186e0
src: /Users/quinn/Test/source/f1.txt
dst: /Users/quinn/Test/destination/source/f1.txt
what: 4
stage: 4
state: 0x00000001006186e0
src: /Users/quinn/Test/source/f1.txt
dst: /Users/quinn/Test/destination/source/f1.txt
what: 1
stage: 2
state: 0x00000001006186e0
src: /Users/quinn/Test/source/f1.txt
dst: /Users/quinn/Test/destination/source/f1.txt
what: 2
stage: 1
state: 0x000000010183e680
src: /Users/quinn/Test/source/nested
dst: /Users/quinn/Test/destination/source/nested
what: 2
stage: 2
state: 0x000000010183e680
src: /Users/quinn/Test/source/nested
dst: /Users/quinn/Test/destination/source/nested
what: 1
stage: 1
state: 0x0000000101839d00
src: /Users/quinn/Test/source/nested/.DS_Store
dst: /Users/quinn/Test/destination/source/nested/.DS_Store
what: 4
stage: 4
state: 0x0000000101839d00
src: /Users/quinn/Test/source/nested/.DS_Store
dst: /Users/quinn/Test/destination/source/nested/.DS_Store
what: 1
stage: 2
state: 0x0000000101839d00
src: /Users/quinn/Test/source/nested/.DS_Store
dst: /Users/quinn/Test/destination/source/nested/.DS_Store
what: 1
stage: 1
state: 0x0000000101900540
src: /Users/quinn/Test/source/nested/f2.txt
dst: /Users/quinn/Test/destination/source/nested/f2.txt
what: 4
stage: 4
state: 0x0000000101900540
src: /Users/quinn/Test/source/nested/f2.txt
dst: /Users/quinn/Test/destination/source/nested/f2.txt
what: 1
stage: 2
state: 0x0000000101900540
src: /Users/quinn/Test/source/nested/f2.txt
dst: /Users/quinn/Test/destination/source/nested/f2.txt
what: 3
stage: 1
state: 0x0000000100736830
src: /Users/quinn/Test/source/nested
dst: /Users/quinn/Test/destination/source/nested
what: 3
stage: 2
state: 0x0000000100736830
src: /Users/quinn/Test/source/nested
dst: /Users/quinn/Test/destination/source/nested
what: 3
stage: 1
state: 0x0000000100736830
src: /Users/quinn/Test/source
dst: /Users/quinn/Test/destination/source
what: 3
stage: 2
state: 0x0000000100736830
src: /Users/quinn/Test/source
dst: /Users/quinn/Test/destination/source
callbackCount: 20

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

---

Code Block  
import Foundation
private func copyfileQ(_ from: URL, _ to: URL, _ state: copyfile_state_t?, _ flags: copyfile_flags_t) -> Int32 {
    return from.withUnsafeFileSystemRepresentation { fromPtr -> Int32 in
        to.withUnsafeFileSystemRepresentation { toPtr -> Int32 in
            copyfile(fromPtr, toPtr, state, flags)
        }
    }
}
class Copier {
    init(from sourceURL: URL, to destinationURL: URL) {
        self.sourceURL = sourceURL
        self.destinationURL = destinationURL
    }
    let sourceURL: URL
    let destinationURL: URL
    func run() throws {
        // Allocate our state, arranging to deallocate it when we return.
        let state = copyfile_state_alloc()
        defer {
            copyfile_state_free(state)
        }
    
        // Create a C function point that calls our `callback(…)` method.  Note
        // that we can’t use `self` here because this is a C function pointer.
        // Rather, we have to recover `self` (here called `obj`) from the
        // `context` parameter.
    
        let callback: copyfile_callback_t = { what, stage, state, src, dst, context in
            let obj = Unmanaged<Copier>.fromOpaque(context!).takeUnretainedValue()
            return obj.callback(what: what, stage: stage, state: state!, src: src, dst: dst)
        }
    
        // Apply that to the state.  Note the use of `unsafeBitCast(…)` here.
        // This is the best of a bad set of options for converting a C function
        // pointer to a C `void *`.
    
        copyfile_state_set(state, UInt32(COPYFILE_STATE_STATUS_CB), unsafeBitCast(callback, to: UnsafeRawPointer.self))
        // We pass an unretained reference because the reference only needs to
        // persist as long as `state`, and we deallocate `state` before we return
        // from this function.
    
        let context = Unmanaged.passUnretained(self)
        copyfile_state_set(state, UInt32(COPYFILE_STATE_STATUS_CTX), context.toOpaque())
    
        // We’re all set up, so let’s call `copyfile`.
    
        let success = copyfileQ(self.sourceURL, self.destinationURL, state, copyfile_flags_t(COPYFILE_DATA | COPYFILE_RECURSIVE)) >= 0
        guard success else {
            throw NSError(domain: NSPOSIXErrorDomain, code: Int(errno), userInfo: nil)
        }
        print("callbackCount: \(self.callbackCount)")
    }
    var callbackCount = 0
    private func callback(what: Int32, stage: Int32, state: copyfile_state_t, src: UnsafePointer<CChar>?, dst: UnsafePointer<CChar>?) -> Int32 {
        print("what: \(what)")
        print("stage: \(stage)")
        print("state: \(state)")
        print("src: \(src.flatMap { String(cString: $0) } ?? "nil")")
        print("dst: \(dst.flatMap { String(cString: $0) } ?? "nil")")
        print()
        // Increment the callback count to prove that `self` is functioning.
        self.callbackCount += 1
        return COPYFILE_CONTINUE
    }
}
func main() {
    let src = URL(fileURLWithPath: "/Users/quinn/Test/source")
    let dst = URL(fileURLWithPath: "/Users/quinn/Test/destination")
    let copier = Copier(from: src, to: dst)
    try! copier.run()
}
main()
exit(EXIT_SUCCESS)

Thanks soo much, shall give it a try.

Do I need "exit(EXIT_SUCCESS)" ? Also if I use COPYFILE_QUIT this will be in the callback ?

Found an example of copyfile ... https://github.com/rustle/RSTLCopyOperation/blob/master/Copy/RSTLCopyOperation.m

Within the callback which I set up ok, having trouble specifically within the NSLog is %@ and %s no idea how it gets the total ?

case COPYFILE_COPY_DATA:
    switch (stage) {
    case COPYFILE_PROGRESS:
    {
        off_t copiedBytes;
        const int returnCode = copyfile_state_get(state, COPYFILE_STATE_COPIED, &copiedBytes);
        if (returnCode == 0)
        {
        NSLog(@"Copied %@ of %s so far", [NSByteCountFormatter stringFromByteCount:copiedBytes countStyle:NSByteCountFormatterCountStyleFile], fromPath);
        }

I tried in the callback "if isCancelled { return COPYQUIT }" which seems to work ok, however shows an error "error processing data: Invalid argument", but does carry on. Should I ignore this ? It's not the error thrown as specified, only happens when interrupting the flow.

Something went wrong to my account. Please help me fix the things that need to be fix