Processes & Concurrency

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Discover how the operating system manages multiple applications and processes simultaneously, ensuring smooth multitasking performance.

Concurrency Documentation

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Guideline 3.2.1(viii) - Business - Other Business Model Issues - Acceptable
The support URL provided in App Store Connect must direct to a support page with links to a loan services privacy policy. The support page must also reference the lender or lending license. The privacy policy provided in App Store Connect must include references to the lender. The verified email domains associated with your Apple Developer Program account must match domains for the submitting company or partnered financial institution.
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Concurrency Resources
Swift Concurrency Resources: DevForums tags: Concurrency The Swift Programming Language > Concurrency documentation Migrating to Swift 6 documentation WWDC 2022 Session 110351 Eliminate data races using Swift Concurrency — This ‘sailing on the sea of concurrency’ talk is a great introduction to the fundamentals. WWDC 2021 Session 10134 Explore structured concurrency in Swift — The table that starts rolling out at around 25:45 is really helpful. Swift Async Algorithms package Swift Concurrency Proposal Index DevForum post Why is flow control important? DevForums post Matt Massicotte’s blog Dispatch Resources: DevForums tags: Dispatch Dispatch documentation — Note that the Swift API and C API, while generally aligned, are different in many details. Make sure you select the right language at the top of the page. Dispatch man pages — While the standard Dispatch documentation is good, you can still find some great tidbits in the man pages. See Reading UNIX Manual Pages. Start by reading dispatch in section 3. WWDC 2015 Session 718 Building Responsive and Efficient Apps with GCD [1] WWDC 2017 Session 706 Modernizing Grand Central Dispatch Usage [1] Avoid Dispatch Global Concurrent Queues DevForums post Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" [1] These videos may or may not be available from Apple. If not, the URL should help you locate other sources of this info.
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Nov ’23
Why is flow control important?
One challenging aspect of Swift concurrency is flow control, aka backpressure. I was explaining this to someone today and thought it better to post that explanation here, for the benefit of all. If you have questions or comments, start a new thread in App & System Services > Processes & Concurrency and tag with Swift and Concurrency. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Why is flow control important? In Swift concurrency you often want to model data flows using AsyncSequence. However, that’s not without its challenges. A key issue is flow control, aka backpressure. Imagine you have a network connection with a requests property that returns an AsyncSequence of Request values. The core of your networking code might be a loop like this: func processRequests(connection: Connection) async throws { for try await request in connection.requests { let response = responseForRequest(request) try await connection.reply(with: response) } } Flow control is important in both the inbound and outbound cases. Let’s start with the inbound case. If the remote peer is generating requests very quickly, the network is fast, and responseForRequest(_:) is slow, it’s easy to fall foul of unbounded memory growth. For example, if you use AsyncStream to implement the requests property, its default buffering policy is .unbounded. So the code receiving requests from the connection will continue to receive them, buffering them in the async stream, without any bound. In the worst case scenario that might run your process out of memory. In a more typical scenario it might result in a huge memory spike. The outbound case is similar. Imagine that the remote peer keeps sending requests but stops receiving them. If the reply(with:) method isn’t implemented correctly, this might also result in unbounded memory growth. The solution to this problem is flow control. This flow control operates independently on the send and receive side: On the send side, the code sending responses should notice that the network connection has asserted flow control and stop sending responses until that flow control lifts. In an async method, like the reply(with:) example shown above, it can simply not return until the network connection has space to accept the reply. On the receive side, the code receiving requests from the connection should monitor how many are buffered. If that gets too big, it should stop receiving. That causes the requests to pile up in the connection itself. If the network connection implements flow control properly [1], this will propagate to the remote peer, which should stop generating requests. [1] TCP and QUIC both implement flow control. Use them! If you’re tempted to implement your own protocol directly on top of UDP, consider how it should handle flow control. Flow control and Network framework Network framework has built-in support for flow control. On the send side, it uses a ‘push’ model. When you call send(content:contentContext:isComplete:completion:) the connection buffers the message. However, it only calls the completion handler when it’s passed that message to the network for transmission [2]. If you send a message and don’t receive this completion callback, it’s time to stop sending more messages. On the receive side, Network framework uses a ‘pull’ model. The receiver calls a receive method, like receiveMessage(completion:), which calls a completion handler when there’s a message available. If you’ve already buffered too many messages, just stop calling this receive method. These techniques are readily adaptable to Swift concurrency using Swift’s CheckedContinuation type. That works for both send and receive, but there’s a wrinkle. If you want to model receive as an AsyncSequence, you can’t use AsyncStream. That’s because AsyncStream doesn’t support flow control. So, you’ll need to come up with your own AsyncSequence implementation [3]. [2] Note that this doesn’t mean that the data has made it to the remote peer, or has even been sent on the wire. Rather, it says that Network framework has successfully passed the data to the transport protocol implementation, which is then responsible for getting it to the remote peer. [3] There’s been a lot of discussion on Swift Evolution about providing such an implementation but none of that has come to fruition yet. Specifically: The Swift Async Algorithms package provides AsyncChannel, but my understanding is that this is not yet ready for prime time. I believe that the SwiftNIO folks have their own infrastructure for this. They’re driving this effort to build such support into Swift Async Algorithms. Avoid the need for flow control In some cases you can change your design to avoid the need for control. Imagine that your UI needs to show the state of a remote button. The network connection sends you a message every time the button is depressed or released. However, your UI only cares about the current state. If you forward every messages from the network to your UI, you have to worried about flow control. To eliminate that worry: Have your networking code translate the message to reflect the current state. Use AsyncStream with a buffering policy of .bufferingNewest(1). That way there’s only ever one value in the stream and, if the UI code is slow for some reason, while it might miss some transitions, it always knows about the latest state. 2024-12-13 Added a link to the MultiProducerSingleConsumerChannel PR. 2024-12-10 First posted.
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Background Task Scheduling (BGAppRefreshTask)
All the nuances of when and whether a background task runs aside, does launching the app cancel the currently scheduled refresh task? As an example, consider the following case: 8AM - user launches app. This launch schedules a background refresh for 12 hours later, at 8PM 12PM (noon) - user launches the app, views some content, then exits the app. Does the scheduled refresh for 8PM still exist, or does the launch at noon invalidate that task, since the refresh could conceivably be handled during that noon launch? Hopefully this is articulated clearly enough, but I'm trying to understand the specifics of background refresh behavior, since I don't want to run that refresh every time the app is opened. However, if opening the app invalidates scheduled refreshes, I will need to include logic that will reschedule the refresh accordingly.
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Async/Await and updating state
When using conformance to ObservableObject and then doing async work in a Task, you will get a warning courtesy of Combine if you then update an @Published or @State var from anywhere but the main thread. However, if you are using @Observable there is no such warning. Also, Thread.current is unavailable in asynchronous contexts, so says the warning. And I have read that in a sense you simply aren't concerned with what thread an async task is on. So for me, that begs a question. Is the lack of a warning, which when using Combine is rather important as ignoring it could lead to crashes, a pretty major bug that Apple seemingly should have addressed long ago? Or is it just not an issue to update state from another thread, because Xcode is doing that work for us behind the scenes too, just as it manages what thread the async task is running on when we don't specify? I see a lot of posts about this from around the initial release of Async/Await talking about using await MainActor.run {} at the point the state variable is updated, usually also complaining about the lack of a warning. But ow years later there is still no warning and I have to wonder if this is actually a non issue. On some ways similar to the fact that many of the early posts I have seen related to @Observable have examples of an @Observable ViewModel instantiated in the view as an @State variable, but in fact this is not needed as that is addressed behind the scenes for all properties of an @Observable type. At least, that is my understanding now, but I am learning Swift coming from a PowerShell background so I question my understanding a lot.
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Nov ’24
Launchd ran job quits early
Hey, I have a user script that I have set up to run daily with launchd, the launchd logs indicate that the script is started but it's almost immediately exited with status 0. The odd thing is that it doesn't say that the script was killed or stopped in anyway, even though that is what seems to happen. 2024-12-04 14:15:04.970214 (gui/501/com.me.test) <Notice>: internal event: WILL_SPAWN, code = 0 2024-12-04 14:15:04.970320 (gui/501/com.me.test) <Notice>: service state: spawn scheduled 2024-12-04 14:15:04.970325 (gui/501/com.me.test) <Notice>: service state: spawning 2024-12-04 14:15:04.970431 (gui/501/com.me.test) <Notice>: launching: xpc event 2024-12-04 14:15:04.972067 (gui/501/com.me.test [26446]) <Notice>: xpcproxy spawned with pid 26446 2024-12-04 14:15:04.972096 (gui/501/com.me.test [26446]) <Notice>: internal event: SPAWNED, code = 0 2024-12-04 14:15:04.972107 (gui/501/com.me.test [26446]) <Notice>: service state: xpcproxy 2024-12-04 14:15:04.972160 (gui/501/com.me.test [26446]) <Notice>: internal event: SOURCE_ATTACH, code = 0 2024-12-04 14:15:04.998157 (gui/501/com.me.test [26446]) <Notice>: service state: running 2024-12-04 14:15:04.998180 (gui/501/com.me.test [26446]) <Notice>: internal event: INIT, code = 0 2024-12-04 14:15:04.998199 (gui/501/com.me.test [26446]) <Notice>: Successfully spawned shell_wrapper.sh[26446] because xpc event 2024-12-04 14:15:05.217482 (gui/501/com.me.test [26446]) <Notice>: exited due to exit(0), ran for 246ms 2024-12-04 14:15:05.217494 (gui/501/com.me.test [26446]) <Notice>: service state: exited 2024-12-04 14:15:05.217502 (gui/501/com.me.test [26446]) <Notice>: internal event: EXITED, code = 0 2024-12-04 14:15:05.217506 (gui/501 [100003]) <Notice>: service inactive: com.me.test 2024-12-04 14:15:05.217523 (gui/501/com.me.test [26446]) <Notice>: service state: not running In the script itself I log at the end to indicate that it finished successfully, when ran with launchd I never reach this point however. The script also do two network requests and make a pause for between 5-10 seconds with time.sleep(paus) (python script). However the launchd log indicates that the script finished in 246ms. Not sure what is going on, the script itself does not require any privileges above a normal user. I have tried running the script directly, and it works as expected. I have also tried evoking the script from launchd explicitly with: launchctl kickstart which starts the job but gives the same result as the scheduled job, except the log now says: `launching: non-ipc demand' instead. I have also tried to remove the networking requests and replace them by reading data from a file without any sleep, no difference in outcome though. I have generated the launchd plist file using Lingon.app and it's placed in ~/Library/LaunchAgents Not sure what more information I can provide, but need some suggestion on how I can proceed help solving this.
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Communicate with running app
I've written an app that uses On Idle (RunHandler) to prompt me to get up and stretch every 30 minutes. Is there anyway to query the running app to determine how long it's been since it last woke up and prompted me? Something like thru the apps properties by right clicking on the icon in the dock?
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What are Dispatch workloops?
I’ve been experimenting with Dispatch, and workloops in particular. I gather that they’re similar to serial queues, except that they reorder work items by QoS. I suspect there’s more to workloops than meets the eye, though; calling dispatch_set_target_queue on them has no effect, in spite of the <dispatch/workloop.h> saying that workloops “can be passed to all APIs accepting a dispatch queue, except for functions from the dispatch_sync() family”. Workloops keep showing up in odd places like Metal and Network.framework backtraces, and <dispatch/workloop.h> includes functionality for tying workloops to os_workgroups (?!). What exactly is a workloop beyond just a serial queue with priority ordering, and why can’t I set the target queue of one?
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Background Task Execution - Doesn't Seem Consistent
I have an app, that when enters the background schedules a task to run. The earliest possible time value is set, as is the completion handler when the task eventually runs. It seems to run pretty reliably for the 1st few interations and then (from looking at the streaming Console logs), doesn't seem to reach a high CP score to execute next time around. eg '......background.task:EDBC23' CurrentScore: 0.648418, ThresholdScore: 0.808034 DecisionToRun:0 looking at the previous entries before this, I can see the breakdown... {name: Application Policy, policyWeight: 50.000, response: {0, 0.35}} {name: Device Activity Policy, policyWeight: 5.000, response: {0, 0.50}} ], Decision: CP Score: 0.648418} and I understand certain elements are outside of our control; however, is there a preferred method to get a background task (which ultimately runs an API call) to trigger consistently? The silent-push method has come up a few times - but of course, if the user disables / doesn't consent to push notifications, that fails Any suggestions?
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macOS 14 XPC vs Foundation XPC
I'm looking into a newer XPC API available starting with macOS 14. Although it's declared as a low-level API I can't figure it how to specify code signing requirement using XPCListener and XPCSession. How do I connect it with xpc_listener_set_peer_code_signing_requirement and xpc_connection_set_peer_code_signing_requirement which require xpc_listener_t and xpc_connection_t respectively? Foundation XPC is declared as a high-level API and provides easy ways to specify code signing requirements on both ends of xpc. I'm confused with all these XPC APIs and their future: Newer really high-level XPCListener and XPCSession API (in low-level framework???) Low-level xpc_listener_t & xpc_connection_t -like API. Is it being replaced by newer XPCListener and XPCSession? How is it related to High-level Foundation XPC? Are NSXPCListener and NSXPCConnection going to be deprecated and replaced by XPCListener and XPCSession??
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Nov ’24
Issue: API Call Delays (5-10 Minutes) on Real Device in tvOS 18 After Call Completes, Works Fine in Debug Mode and Simulator
I am encountering an issue when making an API call using URLSession with DispatchQueue.global(qos: .background).async on a real device running tvOS 18. The code works as expected on tvOS 17 and in the simulator for tvOS 18, but when I remove the debug mode, After the API call it takes few mintues or 5 to 10 min to load the data on the real device. Code: Here’s the code I am using for the API call: appconfig.getFeedURLData(feedUrl: feedUrl, timeOut: kRequestTimeOut, apiMethod: ApiMethod.POST.rawValue) { (result) in self.EpisodeItems = Utilities.sharedInstance.getEpisodeArray(data: result) } func getFeedURLData(feedUrl: String, timeOut: Int, apiMethod: String, completion: @escaping (_ result: Data?) -> ()) { guard let validUrl = URL(string: feedUrl) else { return } var request = URLRequest(url: validUrl, cachePolicy: .useProtocolCachePolicy, timeoutInterval: TimeInterval(timeOut)) let userPasswordString = "\(KappSecret):\(KappPassword)" let userPasswordData = userPasswordString.data(using: .utf8) let base64EncodedCredential = userPasswordData!.base64EncodedString(options: .lineLength64Characters) let authString = "Basic \(base64EncodedCredential)" let headers = [ "authorization": authString, "cache-control": "no-cache", "user-agent": "TN-CTV-\(kPlateForm)-\(kAppVersion)" ] request.addValue("application/json", forHTTPHeaderField: "Content-Type") request.httpMethod = apiMethod request.allHTTPHeaderFields = headers let response = URLSession.requestSynchronousData(request as URLRequest) if response.1 != nil { do { guard let parsedData = try JSONSerialization.jsonObject(with: response.1!, options: .mutableContainers) as? AnyObject else { print("Error parsing data") completion(nil) return } print(parsedData) completion(response.1) return } catch let error { print("Error: \(error.localizedDescription)") completion(response.1) return } } completion(response.1) } import Foundation public extension URLSession { public static func requestSynchronousData(_ request: URLRequest) -> (URLResponse?, Data?) { var data: Data? = nil var responseData: URLResponse? = nil let semaphore = DispatchSemaphore(value: 0) let task = URLSession.shared.dataTask(with: request) { taskData, response, error in data = taskData responseData = response if data == nil, let error = error { print(error) } semaphore.signal() } task.resume() _ = semaphore.wait(timeout: .distantFuture) return (responseData, data) } public static func requestSynchronousDataWithURLString(_ requestString: String) -> (URLResponse?, Data?) { guard let url = URL(string: requestString.checkValidUrl()) else { return (nil, nil) } let request = URLRequest(url: url) return URLSession.requestSynchronousData(request) } } Issue Description: Working scenario: The API call works fine on tvOS 17 and in the simulator for tvOS 18. Problem: When running on a real device with tvOS 18, the API call takes time[enter image description here] when debug mode is disabled, but works fine when debug mode is enabled, Data is loading after few minutes. Error message: Error Domain=WKErrorDomain Code=11 "Timed out while loading attributed string content" UserInfo={NSLocalizedDescription=Timed out while loading attributed string content} NSURLConnection finished with error - code -1001 nw_read_request_report [C4] Receive failed with error "Socket is not connected" Snapshot request 0x30089b3c0 complete with error: <NSError: 0x3009373f0; domain: BSActionErrorDomain; code: 1 ("response-not-possible")> tcp_input [C7.1.1.1:3] flags=[R] seq=817957096, ack=0, win=0 state=CLOSE_WAIT rcv_nxt=817957096, snd_una=275546887 Environment: Xcode version: 16.1 Real device: Model A1625 (32GB) tvOS version: 18.1 Debugging steps I’ve taken: I’ve verified that the issue does not occur in debug mode. I’ve confirmed that the API call works fine on tvOS 17 and in the simulator (tvOS 18). The error suggests a network timeout (-1001) and a socket connection issue ("Socket is not connected"). Questions: Is this a known issue with tvOS 18 on real devices? Are there any specific settings or configurations in tvOS 18 that could be causing the timeout error in non-debug mode? Could this be related to how URLSession or networking behaves differently in release mode? I would appreciate any help or insights into this issue!
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Nov ’24
One-time privilege escalation in non-sandboxed apps
Hi, we are in the process of exploring how to create an installer for our array of apps. We have come to the conclusion that regular .pkg installers produced by pkgbuild and productbuild are unfulfilling of our expectations. [1] Regardless, our installer needs to place files at privileged locations (/Library/Application Support) so we are looking into how to best solve this problem, with the user having the largest clarity on what they are about to do (so no shady "wants to make changes" dialogs) the least steps to do to install these files in the right place (so no targeted NSSavePanel-s) Now, we have done our light reading via some nicely collected posts on the topic (https://forums.developer.apple.com/forums/thread/708765 for example) and the single missing option in the list of privilege escalation models seems to be a one-time privilege escalation from a GUI app. Our reasons for declaring so: AuthorizationExecuteWithPrivileges is long deprecated and we are trying to build a futureproof solution NSAppleScript is just putting up a shady ("wants to make changes") dialog when trying something like this: $ osascript -e "set filePath to \"/Library/Application Support\"" -e "do shell script \"touch \" & the quoted form of filePath & \"/yyy.txt\" with administrator privileges" Is there another way to request a one-time authorization from the admin to perform such a simple operation as copying a file to a protected location? I know it's possible to externalize and internalize Authorization Rights, but they are just an interface to create extra rights and use them as barriers, because they don't actually pass the required right to further operations based on this documentation. Using SMAppService to register a daemon, which has to be manually allowed by the user adds a lot to the complexity of this installation process, and is something we would like to avoid if possible. (And it's also not the right security model if we want to be honest - we don't want ongoing administrator rights and a daemon) Is there something we haven't taken into consideration? [1] preinstall scripts run after the choices are presented during installation and we would need advanced logic (not the limited JavaScript system/files API provided by Installer JS) - plus, the GUI is obviously very limited in a .pkg :(
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Nov ’24
BSD Privilege Escalation on macOS
This week I’m handling a DTS incident from a developer who wants to escalate privileges in their app. This is a tricky problem. Over the years I’ve explained aspects of this both here on DevForums and in numerous DTS incidents. Rather than do that again, I figured I’d collect my thoughts into one place and share them here. If you have questions or comments, please start a new thread with an appropriate tag (Service Management or XPC are the most likely candidates here) in the App & System Services > Core OS topic area. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" BSD Privilege Escalation on macOS macOS has multiple privilege models. Some of these were inherited from its ancestor platforms. For example, Mach messages has a capability-based privilege model. Others were introduced by Apple to address specific user scenarios. For example, macOS 10.14 and later have mandatory access control (MAC), as discussed in On File System Permissions. One of the most important privilege models is the one inherited from BSD. This is the classic users and groups model. Many subsystems within macOS, especially those with a BSD heritage, use this model. For example, a packet tracing tool must open a BPF device, /dev/bpf*, and that requires root privileges. Specifically, the process that calls open must have an effective user ID of 0, that is, the root user. That process is said to be running as root, and escalating BSD privileges is the act of getting code to run as root. IMPORTANT Escalating privileges does not bypass all privilege restrictions. For example, MAC applies to all processes, including those running as root. Indeed, running as root can make things harder because TCC will not display UI when a launchd daemon trips over a MAC restriction. Escalating privileges on macOS is not straightforward. There are many different ways to do this, each with its own pros and cons. The best approach depends on your specific circumstances. Note If you find operations where a root privilege restriction doesn’t make sense, feel free to file a bug requesting that it be lifted. This is not without precedent. For example, in macOS 10.2 (yes, back in 2002!) we made it possible to implement ICMP (ping) without root privileges. And in macOS 10.14 we removed the restriction on binding to low-number ports (r. 17427890). Nice! Decide on One-Shot vs Ongoing Privileges To start, decide whether you want one-shot or ongoing privileges. For one-shot privileges, the user authorises the operation, you perform it, and that’s that. For example, if you’re creating an un-installer for your product, one-shot privileges make sense because, once it’s done, your code is no longer present on the user’s system. In contrast, for ongoing privileges the user authorises the installation of a launchd daemon. This code always runs as root and thus can perform privileged operations at any time. Folks often ask for one-shot privileges but really need ongoing privileges. A classic example of this is a custom installer. In many cases installation isn’t a one-shot operation. Rather, the installer includes a software update mechanism that needs ongoing privileges. If that’s the case, there’s no point dealing with one-shot privileges at all. Just get ongoing privileges and treat your initial operation as a special case within that. Keep in mind that you can convert one-shot privileges to ongoing privileges by installing a launchd daemon. Just Because You Can, Doesn’t Mean You Should Ongoing privileges represent an obvious security risk. Your daemon can perform an operation, but how does it know whether it should perform that operation? There are two common ways to authorise operations: Authorise the user Authorise the client To authorise the user, use Authorization Services. For a specific example of this, look at the EvenBetterAuthorizationSample sample code. Note This sample hasn’t been updated in a while (sorry!) and it’s ironic that one of the things it demonstrates, opening a low-number port, no longer requires root privileges. However, the core concepts demonstrated by the sample are still valid. The packet trace example from above is a situation where authorising the user with Authorization Services makes perfect sense. By default you might want your privileged helper tool to allow any user to run a packet trace. However, your code might be running on a Mac in a managed environment, where the site admin wants to restrict this to just admin users, or just a specific group of users. A custom authorisation right gives the site admin the flexibility to configure authorisation exactly as they want. Authorising the client is a relatively new idea. It assumes that some process is using XPC to request that the daemon perform a privileged operation. In that case, the daemon can use XPC facilities to ensure that only certain processes can make such a request. Doing this securely is a challenge. For specific API advice, see this post. WARNING This authorisation is based on the code signature of the process’s main executable. If the process loads plug-ins [1], the daemon can’t tell the difference between a request coming from the main executable and a request coming from a plug-in. [1] I’m talking in-process plug-ins here. Plug-ins that run in their own process, such as those managed by ExtensionKit, aren’t a concern. Choose an Approach There are (at least) seven different ways to run with root privileges on macOS: A setuid-root executable The sudo command AppleScript’s do shell script command, passing true to the administrator privileges parameter The AuthorizationExecuteWithPrivileges routine, deprecated since macOS 10.7 The SMJobSubmit routine targeting the kSMDomainSystemLaunchd domain, deprecated since macOS 10.10 The SMJobBless routine, deprecated since macOS 13 An installer package (.pkg) The SMAppService class, a much-needed enhancement to the Service Management framework introduced in macOS 13 Note There’s one additional approach: The privileged file operation feature in NSWorkspace. I’ve not listed it here because it doesn’t let you run arbitrary code with root privileges. It does, however, have one critical benefit: It’s supported in sandboxed apps. See this post for a bunch of hints and tips. To choose between them: Do not use a setuid-root executable. Ever. It’s that simple! Doing that is creating a security vulnerability looking for an attacker to exploit it. If you’re working interactively on the command line, use sudo. IMPORTANT sudo is not appropriate to use as an API. While it may be possible to make this work under some circumstances, by the time you’re done you’ll have code that’s way more complicated than the alternatives. If you’re building an ad hoc solution to distribute to a limited audience, and you need one-shot privileges, use either AuthorizationExecuteWithPrivileges or AppleScript. While AuthorizationExecuteWithPrivileges still works, it’s been deprecated for many years. Do not use it in a widely distributed product. The AppleScript approach works great from AppleScript, but you can also use it from native code using NSAppleScript. See the code snippet later in this post. If you need one-shot privileges in a widely distributed product, consider using SMJobSubmit. While this is officially deprecated, it’s used by the very popular Sparkle update framework, and thus it’s unlikely to break without warning. If you only need escalated privileges to install your product, consider using an installer package. That’s by far the easiest solution to this problem. Keep in mind that an installer package can install a launchd daemon and thereby gain ongoing privileges. If you need ongoing privileges but don’t want to ship an installer package, use SMAppService. If you need to deploy to older systems, use SMJobBless. For instructions on using SMAppService, see Updating helper executables from earlier versions of macOS. For a comprehensive example of how to use SMJobBless, see the EvenBetterAuthorizationSample sample code. For the simplest possible example, see the SMJobBless sample code. That has a Python script to help you debug your setup. Unfortunately this hasn’t been updated in a while; see this thread for more. Hints and Tips I’m sure I’ll think of more of these as time goes by but, for the moment, let’s start with the big one… Do not run GUI code as root. In some cases you can make this work but it’s not supported. Moreover, it’s not safe. The GUI frameworks are huge, and thus have a huge attack surface. If you run GUI code as root, you are opening yourself up to security vulnerabilities. Appendix: Running an AppleScript from Native Code Below is an example of running a shell script with elevated privileges using NSAppleScript. WARNING This is not meant to be the final word in privilege escalation. Before using this, work through the steps above to see if it’s the right option for you. Hint It probably isn’t! let url: URL = … file URL for the script to execute … let script = NSAppleScript(source: """ on open (filePath) if class of filePath is not text then error "Expected a single file path argument." end if set shellScript to "exec " & quoted form of filePath do shell script shellScript with administrator privileges end open """)! // Create the Apple event. let event = NSAppleEventDescriptor( eventClass: AEEventClass(kCoreEventClass), eventID: AEEventID(kAEOpenDocuments), targetDescriptor: nil, returnID: AEReturnID(kAutoGenerateReturnID), transactionID: AETransactionID(kAnyTransactionID) ) // Set up the direct object parameter to be a single string holding the // path to our script. let parameters = NSAppleEventDescriptor(string: url.path) event.setDescriptor(parameters, forKeyword: AEKeyword(keyDirectObject)) // The `as NSAppleEventDescriptor?` is required due to a bug in the // nullability annotation on this method’s result (r. 38702068). var error: NSDictionary? = nil guard let result = script.executeAppleEvent(event, error: &error) as NSAppleEventDescriptor? else { let code = (error?[NSAppleScript.errorNumber] as? Int) ?? 1 let message = (error?[NSAppleScript.errorMessage] as? String) ?? "-" throw NSError(domain: "ShellScript", code: code, userInfo: nil) } let scriptResult = result.stringValue ?? "" Revision History 2024-11-15 Added info about SMJobSubmit. Made other minor editorial changes. 2024-07-29 Added a reference to the NSWorkspace privileged file operation feature. Made other minor editorial changes. 2022-06-22 First posted.
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2.7k
Jun ’22
Can we disable KeepAlive temporarily for launchctl?
I have a process [command line cpp application] which i want to run always such as it should relaunch after a crash, after device startup etc. I created a launchd Property List File with KeepAlive true and placed under /Library/LaunchDaemons. Problem Statements: I have a bash script to start and stop this process. start using: launchctl bootstrap. stop involve these two steps: send SIGTERM signal and wait untill process stops after doing some cleanups launchctl bootout [It doesn't sends SIGTERM] during steps 1 - Process is getting stop, but also getting immediate relaunch by launchctl during step 2 - it getting stop again. is there a proper way so that we can disable KeepAlive temporarily so that process will not launch during step 1? or suggest other ways to handle this?
3
0
256
Nov ’24
Background Tasks runs foreground
Hello everyone! I'm having a problem with background tasks running in the foreground. When a user enters the app, a background task is triggered. I've written some code to check if the app is in the foreground and to prevent the task from running, but it doesn't always work. Sometimes the task runs in the background as expected, but other times it runs in the foreground, as I mentioned earlier. Could it be that I'm doing something wrong? Any suggestions would be appreciated. here is code: class BackgroundTaskService { @Environment(\.scenePhase) var scenePhase static let shared = BackgroundTaskService() private init() {} // MARK: - create task func createCheckTask() { let identifier = TaskIdentifier.check BGTaskScheduler.shared.getPendingTaskRequests { requests in if requests.contains(where: { $0.identifier == identifier.rawValue }) { return } self.createByInterval(identifier: identifier.rawValue, interval: identifier.interval) } } private func createByInterval(identifier: String, interval: TimeInterval) { let request = BGProcessingTaskRequest(identifier: identifier) request.earliestBeginDate = Date(timeIntervalSinceNow: interval) scheduleTask(request: request) } // MARK: submit task private func scheduleTask(request: BGProcessingTaskRequest) { do { try BGTaskScheduler.shared.submit(request) } catch { // some actions with error } } // MARK: background actions func checkTask(task: BGProcessingTask) { let today = Calendar.current.startOfDay(for: Date()) let lastExecutionDate = UserDefaults.standard.object(forKey: "lastCheckExecutionDate") as? Date ?? Date.distantPast let notRunnedToday = !Calendar.current.isDate(today, inSameDayAs: lastExecutionDate) guard notRunnedToday else { task.setTaskCompleted(success: true) createCheckTask() return } if scenePhase == .background { TaskActionStore.shared.getAction(for: task.identifier)?() } task.setTaskCompleted(success: true) UserDefaults.standard.set(today, forKey: "lastCheckExecutionDate") createCheckTask() } } And in AppDelegate: BGTaskScheduler.shared.register(forTaskWithIdentifier: "check", using: nil) { task in guard let task = task as? BGProcessingTask else { return } BackgroundTaskService.shared.checkNodeTask(task: task) } BackgroundTaskService.shared.createCheckTask()
1
0
267
Nov ’24
SMAppService re-register after app upgrade
I was experimenting with Service Management API and Xcode project from https://developer.apple.com/documentation/servicemanagement/updating-your-app-package-installer-to-use-the-new-service-management-api and faced some issues with the API. I replaced agent with XPC service and tried to re-register it. Use case is a new app package installation with a newer service binary. In order to get the running service restarted with the new binary it's required to unregister old version and register new one. Otherwise the old version would be still running after app upgrade. The problem is that register fails with "Operation not permitted" error after running unregister which seems to work fine. Experiments with some delays (500ms) between unregister and register seem to help but it's a not a good solution to work around the problem. I'm using open func unregister() async throws with description: The completion handler will be invoked after the running process has been killed if successful or will be invoked whenever an error occurs. After the completion handler has been invoked it is safe to re-register the service. Sample output with no 500ms sleep between unregister and register calls: /Library/Application\ Support/YourDeveloperName/SMAppServiceSampleCode.app/Contents/MacOS/SMAppServiceSampleCode unregister &amp;&amp; /Library/Application\ Support/YourDeveloperName/SMAppServiceSampleCode.app/Contents/MacOS/SMAppServiceSampleCode register Successfully unregistered LaunchDaemon(com.xpc.example.service.plist) Unable to register LaunchDaemon(com.xpc.example.service.plist): Error Domain=SMAppServiceErrorDomain Code=1 "Operation not permitted" UserInfo={NSLocalizedFailureReason=Operation not permitted} In fact it doesn't seem to be safe to re-register. Any explanation would much appreciated! ===================================================== Side issue #2: I tried to add a similar helper executable as in the original project with register/unregister and put it inside the same app bundle but at a different location like Contents/Helpers/ folder instead of Contents/MacOS. And it always fails with this error: Error Domain=SMAppServiceErrorDomain Code=3 "Codesigning failure loading plist: com.okta.service.osquery code: -67028" UserInfo={NSLocalizedFailureReason=Codesigning failure loading plist: com.okta.service.osquery code: -67028} When I moved the helper binary to Contents/MacOS/ folder along with the main app executable it starts working fine again. Other folders like Resources/XPCServices also don't work. Is it a hard requirement for an executable to be located inside main Contents/MacOS folder in order to be able to call SMAppService register/unregister APIs? I haven't found any documentation regarding this requirement. Thanks, Pavel
4
0
323
Nov ’24
Creating a custom Application Launcher
Hi, I want to create a custom application launcher, so I'd like the app to be able to just list the apps installed and launch them when touched. My idea is to have a Minimalist UI in order to enhance productivity. Is it possible? I see there is already one App doing it https://apps.apple.com/us/app/dumb-phone/id6504743503 I want to do something similar, so how does the App in the link obtains the Apps installed on the device?
1
0
197
Nov ’24
LaunchDaemon not loading after Sonoma update
I updated my computer to Sonoma, and now my LaunchDaemon will not load. I have the following setup : File in /Library/LaunchDaemons/com.startup.plist like this : <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>Label</key> <string>com.startup</string> <key>ProgramArguments</key> <array> <string>/usr/local/bin/bash</string> <string>/Library/Scripts/Startup/startup.sh</string> </array> <key>RunAtLoad</key> <true/> <key>StandardErrorPath</key> <string>/tmp/com.startup.stderr</string> <key>StandardOutPath</key> <string>/tmp/com.startup.stdout</string> </dict> </plist> File in File in /Library/Scripts/Startup/startup.sh #!/bin/zsh PATH=/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Users:/Users/root:/Users/root/Scripts:/Library/Scripts:/Library/Scripts/Startup #Load modules for Fuse /Library/Filesystems/macfuse.fs/Contents/Resources/load_macfuse /usr/sbin/sysctl -w vfs.generic.macfuse.tunables.allow_other=1 #Connect to XXXXXX_net /bin/sleep 28 myip=0 while [ $myip = 0 ] do /bin/sleep 3 myip=$(ifconfig -l | xargs -n1 ipconfig getifaddr) done /usr/local/bin/sshfs XXXX@XXXXXX.net: /Volumes/XXXXXX.net -o local,auto_cache,reconnect,ServerAliveInterval=15,ServerAliveCountMax=3,ConnectTimeout=5,daemon_timeout=60,iosize=2097152,volname=XXXXXX.net,allow_other,defer_permissions,async_read,Ciphers=aes128-gcm@openssh.com,Cipher=aes128-gcm@openssh.com,compression=no And then we need some commands to be run as root user during boot : /private/etc/sudoers.d/startup-script-nopasswd username ALL = (root) NOPASSWD: /usr/sbin/sysctl username ALL = (root) NOPASSWD: /usr/local/bin/sshfs As of now, I cant even get the /Library/LaunchDaemons/com.startup.plist to run after i updated the macOS to Sonoma ….
3
0
364
Nov ’24
The source editor extension can't connect xpc service
I created a macOS app, added an XPC service target, and also added a source editor extension. in The source editor extension‘s perform function. It doesn't work - (void)performCommandWithInvocation:(XCSourceEditorCommandInvocation *)invocation completionHandler:(void (^)(NSError * _Nullable nilOrError))completionHandler { self.xpcConnect = [[NSXPCConnection alloc] initWithServiceName:@"test.TestNewXPCApp.NewXPC"]; NSXPCInterface *interface = [NSXPCInterface interfaceWithProtocol:@protocol(NewXPCProtocol)]; self.xpcConnect.remoteObjectInterface = interface; [self.xpcConnect resume]; [[self.xpcConnect remoteObjectProxy] performCalculationWithNumber:@231 andNumber:@119 withReply:^(NSNumber *reply) { // We have received a response. NSLog(@"ui success%@", reply); }]; But In ViewControler.m, executing the same code , it can work. So why is it possible to connect to the XPC service from within the macOS app, but not from the source editor extension?
1
0
214
Nov ’24