import AudioCap's AudioRecordingPermission class

Package.swift

@@ -9,6 +9,11 @@ let package = Package(
         .macOS("14.2")
     ],
     targets: [
-        .executableTarget(name: "audiotee")
+        .executableTarget(
+            name: "audiotee",
+            swiftSettings: [
+                .define("ENABLE_TCC_SPI")
+            ]
+        )
     ]
 )

Sources/Permissions/AudioRecordingPermission.swift

@@ -0,0 +1,131 @@
+import OSLog
+import Observation
+import SwiftUI
+
+// Adapted with a huge debt of gratitude from https://github.com/insidegui/AudioCap/blob/main/AudioCap/ProcessTap/AudioRecordingPermission.swift
+
+/// Uses TCC SPI in order to check/request system audio recording permission.
+@Observable
+final class AudioRecordingPermission {
+  // private let logger = Logger(subsystem: kAppSubsystem, category: String(describing: AudioRecordingPermission.self))
+
+  enum Status: String {
+    case unknown
+    case denied
+    case authorized
+  }
+
+  private(set) var status: Status = .unknown
+
+  init() {
+    #if ENABLE_TCC_SPI
+      NotificationCenter.default.addObserver(
+        forName: NSApplication.didBecomeActiveNotification, object: nil, queue: .main
+      ) { [weak self] _ in
+        guard let self else { return }
+        self.updateStatus()
+      }
+
+      updateStatus()
+    #else
+      status = .authorized
+    #endif  // ENABLE_TCC_SPI
+  }
+
+  func request() {
+    #if ENABLE_TCC_SPI
+      // logger.debug(#function)
+
+      guard let request = Self.requestSPI else {
+        // logger.fault("Request SPI missing")
+        return
+      }
+
+      request("kTCCServiceAudioCapture" as CFString, nil) { [weak self] granted in
+        guard let self else { return }
+
+        // self.logger.info("Request finished with result: \(granted, privacy: .public)")
+
+        DispatchQueue.main.async {
+          if granted {
+            self.status = .authorized
+          } else {
+            self.status = .denied
+          }
+        }
+      }
+    #endif  // ENABLE_TCC_SPI
+  }
+
+  private func updateStatus() {
+    #if ENABLE_TCC_SPI
+      // logger.debug(#function)
+
+      guard let preflight = Self.preflightSPI else {
+        // logger.fault("Preflight SPI missing")
+        return
+      }
+
+      let result = preflight("kTCCServiceAudioCapture" as CFString, nil)
+
+      if result == 1 {
+        status = .denied
+      } else if result == 0 {
+        status = .authorized
+      } else {
+        status = .unknown
+      }
+    #endif  // ENABLE_TCC_SPI
+  }
+
+  #if ENABLE_TCC_SPI
+    private typealias PreflightFuncType = @convention(c) (CFString, CFDictionary?) -> Int
+    private typealias RequestFuncType = @convention(c) (
+      CFString, CFDictionary?, @escaping (Bool) -> Void
+    ) -> Void
+
+    /// `dlopen` handle to the TCC framework.
+    private static let apiHandle: UnsafeMutableRawPointer? = {
+      let tccPath = "/System/Library/PrivateFrameworks/TCC.framework/Versions/A/TCC"
+
+      guard let handle = dlopen(tccPath, RTLD_NOW) else {
+        assertionFailure("dlopen failed")
+        return nil
+      }
+
+      return handle
+    }()
+
+    /// `dlsym` function handle for `TCCAccessPreflight`.
+    private static let preflightSPI: PreflightFuncType? = {
+      guard let apiHandle else { return nil }
+
+      let fnName = "TCCAccessPreflight"
+
+      guard let funcSym = dlsym(apiHandle, fnName) else {
+        assertionFailure("Couldn't find symbol")
+        return nil
+      }
+
+      let fn = unsafeBitCast(funcSym, to: PreflightFuncType.self)
+
+      return fn
+    }()
+
+    /// `dlsym` function handle for `TCCAccessRequest`.
+    private static let requestSPI: RequestFuncType? = {
+      guard let apiHandle else { return nil }
+
+      let fnName = "TCCAccessRequest"
+
+      guard let funcSym = dlsym(apiHandle, fnName) else {
+        assertionFailure("Couldn't find symbol")
+        return nil
+      }
+
+      let fn = unsafeBitCast(funcSym, to: RequestFuncType.self)
+
+      return fn
+    }()
+  #endif  // ENABLE_TCC_SPI
+}