chore: import upstream snapshot with attribution

2026-07-13 12:25:30 +08:00
commit 680845cb1c
445 changed files with 103779 additions and 0 deletions
@@ -0,0 +1,112 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2025-2026 Apple Inc. and the Containerization project authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//===----------------------------------------------------------------------===//
+
+import Dispatch
+import Synchronization
+
+#if canImport(Musl)
+import Musl
+#elseif canImport(Glibc)
+import Glibc
+#elseif canImport(Darwin)
+import Darwin
+#endif
+
+/// Async friendly wrapper around `DispatchSourceSignal`. Provides an `AsyncStream`
+/// interface to get notified of received signals.
+public final class AsyncSignalHandler: Sendable {
+    /// An async stream that returns the signal that was caught, if ever.
+    public var signals: AsyncStream<Int32> {
+        let (stream, cont) = AsyncStream.makeStream(of: Int32.self)
+        self.state.withLock {
+            $0.conts.append(cont)
+        }
+        cont.onTermination = { @Sendable _ in
+            self.cancel()
+        }
+        return stream
+    }
+
+    /// Cancel every AsyncStream of signals, as well as the underlying
+    /// DispatchSignalSource's for each registered signal.
+    public func cancel() {
+        self.state.withLock {
+            if $0.conts.isEmpty {
+                return
+            }
+
+            for cont in $0.conts {
+                cont.finish()
+            }
+            for source in $0.sources {
+                source.cancel()
+            }
+            $0.conts.removeAll()
+            $0.sources.removeAll()
+        }
+    }
+
+    struct State: Sendable {
+        var conts: [AsyncStream<Int32>.Continuation] = []
+        // `sources` isn't used concurrently.
+        nonisolated(unsafe) var sources: [any DispatchSourceSignal] = []
+    }
+
+    // We keep a reference to the continuation object that is created for
+    // our AsyncStream and tell our signal handler to yield a value to it
+    // returning a value to the consumer
+    private func handler(_ sig: Int32) {
+        self.state.withLock {
+            for cont in $0.conts {
+                cont.yield(sig)
+            }
+        }
+    }
+
+    private let state: Mutex<State> = .init(State())
+
+    /// Create a new `AsyncSignalHandler` that catches all signals.
+    public static func catchAll() -> AsyncSignalHandler {
+        #if os(macOS)
+        let range = 1...31
+        #else
+        let range = 1...64
+        #endif
+        return create(notify: range.map { Int32($0) })
+    }
+
+    /// Create a new `AsyncSignalHandler` for the list of given signals `notify`.
+    /// The default signal handlers for these signals are removed and async handlers
+    /// added in their place. The async signal handlers that are installed simply
+    /// yield to a stream if and when a signal is caught.
+    public static func create(notify on: [Int32]) -> AsyncSignalHandler {
+        let out = AsyncSignalHandler()
+        var sources = [any DispatchSourceSignal]()
+        for sig in on {
+            signal(sig, SIG_IGN)
+            let source = DispatchSource.makeSignalSource(signal: sig)
+            source.setEventHandler {
+                out.handler(sig)
+            }
+            source.resume()
+            // Retain a reference to our signal sources so that they
+            // do not go out of scope.
+            sources.append(source)
+        }
+        out.state.withLock { $0.sources = sources }
+        return out
+    }
+}