I was able to confirm with a customer of mine that calling copyfile with a source file that is a symbolic link on a NTFS partition always causes the error
NSPOSIXErrorDomain 12 Cannot allocate memory
They use NTFS drivers from Paragon.
They tried copying a symbolic link from NTFS to both APFS and NTFS with the same result. Is this an issue with macOS, or with the NTFS driver?
Copying regular files on the other hand always works. Copying manually from the Finder also seems to always work, both with regular files and symbolic links, so I'm wondering how the Finder does it.
Here is the sample app that they used to reproduce the issue. The first open panel allows to select the source directory and the second one the destination directory. The variable filename holds the name of the symbolic link to be copied from the source to the destination. Apparently it's not possible to select a symbolic link directly in NSOpenPanel, as it always resolves to the linked file.
@main
class AppDelegate: NSObject, NSApplicationDelegate {
func applicationDidFinishLaunching(_ notification: Notification) {
let openPanel = NSOpenPanel()
openPanel.canChooseDirectories = true
openPanel.canChooseFiles = false
openPanel.runModal()
let filename = "Modules"
let source = openPanel.urls[0].appendingPathComponent(filename)
openPanel.runModal()
let destination = openPanel.urls[0].appendingPathComponent(filename)
do {
let state = copyfile_state_alloc()
defer {
copyfile_state_free(state)
}
var bsize = UInt32(16_777_216)
if copyfile_state_set(state, UInt32(COPYFILE_STATE_BSIZE), &bsize) != 0 {
throw NSError(domain: NSPOSIXErrorDomain, code: Int(errno))
}
if copyfile_state_set(state, UInt32(COPYFILE_STATE_STATUS_CB), unsafeBitCast(copyfileCallback, to: UnsafeRawPointer.self)) != 0 || copyfile_state_set(state, UInt32(COPYFILE_STATE_STATUS_CTX), unsafeBitCast(self, to: UnsafeRawPointer.self)) != 0 || copyfile(source.path, destination.path, state, copyfile_flags_t(COPYFILE_NOFOLLOW)) != 0 {
throw NSError(domain: NSPOSIXErrorDomain, code: Int(errno))
}
} catch {
let error = error as NSError
let alert = NSAlert()
alert.messageText = "\(error.localizedDescription)\n\(error.domain) \(error.code)"
alert.runModal()
}
}
private let copyfileCallback: copyfile_callback_t = { what, stage, state, src, dst, ctx in
if what == COPYFILE_COPY_DATA {
if stage == COPYFILE_ERR {
return COPYFILE_QUIT
}
var size: off_t = 0
copyfile_state_get(state, UInt32(COPYFILE_STATE_COPIED), &size)
}
return COPYFILE_CONTINUE
}
}