[WIP, DNM] Enable exit tests on Android API level 28 and newer.

Package.swift

@@ -363,6 +363,19 @@ extension BuildSettingCondition {
   }
 }
 
+/// A constant set of platforms including Android when the compiler is 6.3 or
+/// newer.
+///
+/// This constant is used to conditionally enable features on Android only on
+/// newer compilers.
+nonisolated(unsafe) var androidIfCompiler6_3: some Collection<Platform> {
+#if compiler(>=6.3)
+  CollectionOfOne(.android)
+#else
+  EmptyCollection()
+#endif
+}
+
 extension Array where Element == PackageDescription.SwiftSetting {
   /// Settings intended to be applied to every Swift target in this package.
   /// Analogous to project-level build settings in an Xcode project.
@@ -398,8 +411,8 @@ extension Array where Element == PackageDescription.SwiftSetting {
 
       .define("SWT_TARGET_OS_APPLE", .whenApple()),
 
-      .define("SWT_NO_EXIT_TESTS", .whenEmbedded(or: .when(platforms: [.iOS, .watchOS, .tvOS, .visionOS, .wasi, .android]))),
-      .define("SWT_NO_PROCESS_SPAWNING", .whenEmbedded(or: .when(platforms: [.iOS, .watchOS, .tvOS, .visionOS, .wasi, .android]))),
+      .define("SWT_NO_EXIT_TESTS", .whenEmbedded(or: .when(platforms: [.iOS, .watchOS, .tvOS, .visionOS, .wasi] + androidIfCompiler6_3))),
+      .define("SWT_NO_PROCESS_SPAWNING", .whenEmbedded(or: .when(platforms: [.iOS, .watchOS, .tvOS, .visionOS, .wasi] + androidIfCompiler6_3))),
       .define("SWT_NO_SNAPSHOT_TYPES", .whenEmbedded(or: .whenApple(false))),
       .define("SWT_NO_DYNAMIC_LINKING", .whenEmbedded(or: .when(platforms: [.wasi]))),
       .define("SWT_NO_PIPES", .whenEmbedded(or: .when(platforms: [.wasi]))),
@@ -457,8 +470,8 @@ extension Array where Element == PackageDescription.CXXSetting {
     var result = Self()
 
     result += [
-      .define("SWT_NO_EXIT_TESTS", .whenEmbedded(or: .when(platforms: [.iOS, .watchOS, .tvOS, .visionOS, .wasi, .android]))),
-      .define("SWT_NO_PROCESS_SPAWNING", .whenEmbedded(or: .when(platforms: [.iOS, .watchOS, .tvOS, .visionOS, .wasi, .android]))),
+      .define("SWT_NO_EXIT_TESTS", .whenEmbedded(or: .when(platforms: [.iOS, .watchOS, .tvOS, .visionOS, .wasi]))),
+      .define("SWT_NO_PROCESS_SPAWNING", .whenEmbedded(or: .when(platforms: [.iOS, .watchOS, .tvOS, .visionOS, .wasi]))),
       .define("SWT_NO_SNAPSHOT_TYPES", .whenEmbedded(or: .whenApple(false))),
       .define("SWT_NO_DYNAMIC_LINKING", .whenEmbedded(or: .when(platforms: [.wasi]))),
       .define("SWT_NO_PIPES", .whenEmbedded(or: .when(platforms: [.wasi]))),

Sources/Overlays/_Testing_Foundation/Attachments/Attachment+URL.swift

@@ -160,6 +160,13 @@ private let _archiverPath: String? = {
 /// an archive (currently of `.zip` format, although this is subject to change.)
 private func _compressContentsOfDirectory(at directoryURL: URL) async throws -> Data {
 #if !SWT_NO_PROCESS_SPAWNING
+#if os(Android)
+  guard #available(Android 28, *) else {
+    // API level 28 corresponds to Android 9 Pie.
+    throw CocoaError(.featureUnsupported, userInfo: [NSLocalizedDescriptionKey: "Attaching directories to tests requires Android 9 (API level 28) or newer."])
+  }
+#endif
+
   let temporaryName = "\(UUID().uuidString).zip"
   let temporaryURL = FileManager.default.temporaryDirectory.appendingPathComponent(temporaryName)
   defer {
@@ -180,20 +187,22 @@ private func _compressContentsOfDirectory(at directoryURL: URL) async throws ->
   // OpenBSD's tar(1) does not support writing PKZIP archives, and /usr/bin/zip
   // tool is an optional install, so we check if it's present before trying to
   // execute it.
-#if os(Linux) || os(OpenBSD)
+  //
+  // TODO: figure out whether tar or zip is available on Android and where it's stored
+#if os(Linux) || os(OpenBSD) || os(Android)
   let archiverPath = "/bin/sh"
-#if os(Linux)
+#if os(Linux) || os(Android)
   let trueArchiverPath = "/usr/bin/zip"
 #else
   let trueArchiverPath = "/usr/local/bin/zip"
+#endif
   var isDirectory = false
   if !FileManager.default.fileExists(atPath: trueArchiverPath, isDirectory: &isDirectory) || isDirectory {
     throw CocoaError(.fileNoSuchFile, userInfo: [
       NSLocalizedDescriptionKey: "The 'zip' package is not installed.",
       NSFilePathErrorKey: trueArchiverPath
     ])
   }
-#endif
 #elseif SWT_TARGET_OS_APPLE || os(FreeBSD)
   let archiverPath = "/usr/bin/tar"
 #elseif os(Windows)
@@ -211,7 +220,7 @@ private func _compressContentsOfDirectory(at directoryURL: URL) async throws ->
   let sourcePath = directoryURL.path
   let destinationPath = temporaryURL.path
   let arguments = {
-#if os(Linux) || os(OpenBSD)
+#if os(Linux) || os(OpenBSD) || os(Android)
     // The zip command constructs relative paths from the current working
     // directory rather than from command-line arguments.
     ["-c", #"cd "$0" && "$1" "$2" --recurse-paths ."#, sourcePath, trueArchiverPath, destinationPath]

Sources/Testing/ExitTests/ExitStatus.swift

@@ -23,7 +23,10 @@ private import _TestingInternals
 ///   @Available(Swift, introduced: 6.2)
 ///   @Available(Xcode, introduced: 26.0)
 /// }
-#if SWT_NO_PROCESS_SPAWNING
+#if !SWT_NO_PROCESS_SPAWNING
+@available(Android 28, *)
+#else
+@_unavailableInEmbedded
 @available(*, unavailable, message: "Exit tests are not available on this platform.")
 #endif
 public enum ExitStatus: Sendable {
@@ -90,7 +93,10 @@ public enum ExitStatus: Sendable {
 
 // MARK: - Equatable
 
-#if SWT_NO_PROCESS_SPAWNING
+#if !SWT_NO_PROCESS_SPAWNING
+@available(Android 28, *)
+#else
+@_unavailableInEmbedded
 @available(*, unavailable, message: "Exit tests are not available on this platform.")
 #endif
 extension ExitStatus: Equatable {}
@@ -109,7 +115,10 @@ private let _sigabbrev_np = symbol(named: "sigabbrev_np").map {
 }
 #endif
 
-#if SWT_NO_PROCESS_SPAWNING
+#if !SWT_NO_PROCESS_SPAWNING
+@available(Android 28, *)
+#else
+@_unavailableInEmbedded
 @available(*, unavailable, message: "Exit tests are not available on this platform.")
 #endif
 extension ExitStatus: CustomStringConvertible {

Sources/Testing/ExitTests/ExitTest.CapturedValue.swift

@@ -11,7 +11,9 @@
 private import _TestingInternals
 
 @_spi(ForToolsIntegrationOnly)
-#if SWT_NO_EXIT_TESTS
+#if !SWT_NO_EXIT_TESTS
+@available(Android 28, *)
+#else
 @_unavailableInEmbedded
 @available(*, unavailable, message: "Exit tests are not available on this platform.")
 #endif

Sources/Testing/ExitTests/ExitTest.Condition.swift

@@ -10,7 +10,9 @@
 
 private import _TestingInternals
 
-#if SWT_NO_EXIT_TESTS
+#if !SWT_NO_EXIT_TESTS
+@available(Android 28, *)
+#else
 @_unavailableInEmbedded
 @available(*, unavailable, message: "Exit tests are not available on this platform.")
 #endif
@@ -58,7 +60,9 @@ extension ExitTest {
 
 // MARK: -
 
-#if SWT_NO_EXIT_TESTS
+#if !SWT_NO_EXIT_TESTS
+@available(Android 28, *)
+#else
 @_unavailableInEmbedded
 @available(*, unavailable, message: "Exit tests are not available on this platform.")
 #endif
@@ -178,7 +182,9 @@ extension ExitTest.Condition {
 
 // MARK: - CustomStringConvertible
 
-#if SWT_NO_EXIT_TESTS
+#if !SWT_NO_EXIT_TESTS
+@available(Android 28, *)
+#else
 @_unavailableInEmbedded
 @available(*, unavailable, message: "Exit tests are not available on this platform.")
 #endif
@@ -201,7 +207,9 @@ extension ExitTest.Condition: CustomStringConvertible {
 
 // MARK: - Comparison
 
-#if SWT_NO_EXIT_TESTS
+#if !SWT_NO_EXIT_TESTS
+@available(Android 28, *)
+#else
 @_unavailableInEmbedded
 @available(*, unavailable, message: "Exit tests are not available on this platform.")
 #endif

Sources/Testing/ExitTests/ExitTest.Result.swift

@@ -8,7 +8,9 @@
 // See https://swift.org/CONTRIBUTORS.txt for Swift project authors
 //
 
-#if SWT_NO_EXIT_TESTS
+#if !SWT_NO_EXIT_TESTS
+@available(Android 28, *)
+#else
 @_unavailableInEmbedded
 @available(*, unavailable, message: "Exit tests are not available on this platform.")
 #endif

Sources/Testing/ExitTests/ExitTest.swift

@@ -34,7 +34,9 @@ private import _TestingInternals
 ///   @Available(Swift, introduced: 6.2)
 ///   @Available(Xcode, introduced: 26.0)
 /// }
-#if SWT_NO_EXIT_TESTS
+#if !SWT_NO_EXIT_TESTS
+@available(Android 28, *)
+#else
 @_unavailableInEmbedded
 @available(*, unavailable, message: "Exit tests are not available on this platform.")
 #endif
@@ -223,6 +225,21 @@ extension ExitTest {
     // as I can tell, special-case RLIMIT_CORE=1.
     var rl = rlimit(rlim_cur: 0, rlim_max: 0)
     _ = setrlimit(RLIMIT_CORE, &rl)
+#elseif os(Android)
+    // Android inherits the RLIMIT_CORE=1 special case from Linux.
+    // SEE: https://android.googlesource.com/kernel/common/+/refs/heads/android-mainline/fs/coredump.c#978
+    var rl = rlimit(rlim_cur: 1, rlim_max: 1)
+    _ = setrlimit(RLIMIT_CORE, &rl)
+
+    // In addition, Android installs signal handlers in native processes that
+    // cause the system to generate "tombstone" files. Suppress those too by
+    // resetting all signal handlers to SIG_DFL. debuggerd_register_handlers()
+    // is not exported, so we must manually walk all the signals it handles.
+    // SEE: https://android.googlesource.com/platform/system/core/+/main/debuggerd/include/debuggerd/handler.h#81
+    let BIONIC_SIGNAL_DEBUGGER = __SIGRTMIN + 3
+    for sig in [SIGABRT, SIGBUS, SIGFPE, SIGILL, SIGSEGV, SIGSTKFLT, SIGSYS, SIGTRAP, BIONIC_SIGNAL_DEBUGGER] {
+      _ = signal(sig, swt_SIG_DFL())
+    }
 #elseif os(Windows)
     // On Windows, similarly disable Windows Error Reporting and the Windows
     // Error Reporting UI. Note we expect to be the first component to call
@@ -662,7 +679,7 @@ extension ExitTest {
     Environment.setVariable(nil, named: name)
 
     var fd: CInt?
-#if SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD)
+#if SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD) || os(Android)
     fd = CInt(environmentVariable)
 #elseif os(Windows)
     if let handle = UInt(environmentVariable).flatMap(HANDLE.init(bitPattern:)) {
@@ -699,7 +716,7 @@ extension ExitTest {
   ///   back to a (new) file handle with `_makeFileHandle()`, or `nil` if the
   ///   file handle could not be converted to a string.
   private static func _makeEnvironmentVariable(for fileHandle: borrowing FileHandle) -> String? {
-#if SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD)
+#if SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD) || os(Android)
     return fileHandle.withUnsafePOSIXFileDescriptor { fd in
       fd.map(String.init(describing:))
     }

Sources/Testing/ExitTests/SpawnProcess.swift

@@ -17,7 +17,7 @@ internal import _TestingInternals
 
 /// A platform-specific value identifying a process running on the current
 /// system.
-#if SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD)
+#if SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD) || os(Android)
 typealias ProcessID = pid_t
 #elseif os(Windows)
 typealias ProcessID = HANDLE
@@ -62,6 +62,7 @@ private let _posix_spawn_file_actions_addclosefrom_np = symbol(named: "posix_spa
 ///   resources.
 ///
 /// - Throws: Any error that prevented the process from spawning.
+@available(Android 28, *)
 func spawnExecutable(
   atPath executablePath: String,
   arguments: [String],
@@ -71,15 +72,16 @@ func spawnExecutable(
   standardError: borrowing FileHandle? = nil,
   additionalFileHandles: [UnsafePointer<FileHandle>] = []
 ) throws -> ProcessID {
-  // Darwin and Linux differ in their optionality for the posix_spawn types we
-  // use, so use this typealias to paper over the differences.
+  // Darwin, the BSDs, Linux, and Android all differ in their optionality for
+  // the posix_spawn types we use, so use this typealias and helper function to
+  // paper over the differences.
 #if SWT_TARGET_OS_APPLE || os(FreeBSD) || os(OpenBSD)
   typealias P<T> = T?
-#elseif os(Linux)
+#elseif os(Linux) || os(Android)
   typealias P<T> = T
 #endif
 
-#if SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD)
+#if SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD) || os(Android)
   return try withUnsafeTemporaryAllocation(of: P<posix_spawn_file_actions_t>.self, capacity: 1) { fileActions in
     let fileActions = fileActions.baseAddress!
     let fileActionsInitialized = posix_spawn_file_actions_init(fileActions)
@@ -92,7 +94,13 @@ func spawnExecutable(
 
     return try withUnsafeTemporaryAllocation(of: P<posix_spawnattr_t>.self, capacity: 1) { attrs in
       let attrs = attrs.baseAddress!
+#if os(Android)
+      let attrsInitialized = attrs.withMemoryRebound(to: posix_spawnattr_t?.self, capacity: 1) { attrs in
+        posix_spawnattr_init(attrs)
+      }
+#else
       let attrsInitialized = posix_spawnattr_init(attrs)
+#endif
       guard 0 == attrsInitialized else {
         throw CError(rawValue: attrsInitialized)
       }
@@ -194,6 +202,9 @@ func spawnExecutable(
       // spawned child process if we control its execution.
       var environment = environment
       environment["SWT_CLOSEFROM"] = String(describing: highestFD + 1)
+#elseif os(Android)
+      // Android does not have posix_spawn_file_actions_addclosefrom_np() nor
+      // closefrom(2), so we don't attempt this operation there.
 #else
 #warning("Platform-specific implementation missing: cannot close unused file descriptors")
 #endif
@@ -225,7 +236,11 @@ func spawnExecutable(
       }
 
       var pid = pid_t()
+#if os(Android)
+      let processSpawned = swt_posix_spawn(&pid, executablePath, fileActions, attrs, argv, environ)
+#else
       let processSpawned = posix_spawn(&pid, executablePath, fileActions, attrs, argv, environ)
+#endif
       guard 0 == processSpawned else {
         throw CError(rawValue: processSpawned)
       }
@@ -463,6 +478,7 @@ private func _escapeCommandLine(_ arguments: [String]) -> String {
 /// This function is a convenience that spawns the given process and waits for
 /// it to terminate. It is primarily for use by other targets in this package
 /// such as its cross-import overlays.
+@available(Android 28, *)
 package func spawnExecutableAtPathAndWait(
   _ executablePath: String,
   arguments: [String] = [],

Sources/Testing/ExitTests/WaitFor.swift

@@ -11,7 +11,7 @@
 #if !SWT_NO_PROCESS_SPAWNING
 internal import _TestingInternals
 
-#if SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD)
+#if SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD) || os(Android)
 /// Block the calling thread, wait for the target process to exit, and return
 /// a value describing the conditions under which it exited.
 ///
@@ -29,9 +29,9 @@ private func _blockAndWait(for pid: consuming pid_t) throws -> ExitStatus {
     if 0 == waitid(P_PID, id_t(pid), &siginfo, WEXITED) {
       switch siginfo.si_code {
       case .init(CLD_EXITED):
-        return .exitCode(siginfo.si_status)
+        return .exitCode(swt_siginfo_t_si_status(siginfo))
       case .init(CLD_KILLED), .init(CLD_DUMPED):
-        return .signal(siginfo.si_status)
+        return .signal(swt_siginfo_t_si_status(siginfo))
       default:
         throw SystemError(description: "Unexpected siginfo_t value. Please file a bug report at https://github.com/swiftlang/swift-testing/issues/new and include this information: \(String(reflecting: siginfo))")
       }
@@ -78,7 +78,7 @@ func wait(for pid: consuming pid_t) async throws -> ExitStatus {
 
   return try _blockAndWait(for: pid)
 }
-#elseif SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD)
+#elseif SWT_TARGET_OS_APPLE || os(Linux) || os(FreeBSD) || os(OpenBSD) || os(Android)
 /// A mapping of awaited child PIDs to their corresponding Swift continuations.
 private nonisolated(unsafe) let _childProcessContinuations = {
   let result = ManagedBuffer<[pid_t: CheckedContinuation<ExitStatus, any Error>], pthread_mutex_t>.create(
@@ -146,7 +146,7 @@ private let _createWaitThread: Void = {
     // continuation (if available) before reaping.
     var siginfo = siginfo_t()
     if 0 == waitid(P_ALL, 0, &siginfo, WEXITED | WNOWAIT) {
-      if case let pid = siginfo.si_pid, pid != 0 {
+      if case let pid = swt_siginfo_t_si_pid(siginfo), pid != 0 {
         let continuation = _withLockedChildProcessContinuations { childProcessContinuations, _ in
           childProcessContinuations.removeValue(forKey: pid)
         }
@@ -189,8 +189,9 @@ private let _createWaitThread: Void = {
     { _ in
       // Set the thread name to help with diagnostics. Note that different
       // platforms support different thread name lengths. See MAXTHREADNAMESIZE
-      // on Darwin, TASK_COMM_LEN on Linux, MAXCOMLEN on FreeBSD, and _MAXCOMLEN
-      // on OpenBSD. We try to maximize legibility in the available space.
+      // on Darwin, TASK_COMM_LEN on Linux, MAXCOMLEN on FreeBSD, _MAXCOMLEN on
+      // OpenBSD, and MAX_TASK_COMM_LEN on Android. We try to maximize
+      // legibility in the available space.
 #if SWT_TARGET_OS_APPLE
       _ = pthread_setname_np("Swift Testing exit test monitor")
 #elseif os(Linux)
@@ -201,6 +202,8 @@ private let _createWaitThread: Void = {
       pthread_set_name_np(pthread_self(), "SWT ex test monitor")
 #elseif os(OpenBSD)
       pthread_set_name_np(pthread_self(), "SWT exit test monitor")
+#elseif os(Android)
+      _ = pthread_setname_np(pthread_self(), "SWT ExT monitor")
 #else
 #warning("Platform-specific implementation missing: thread naming unavailable")
 #endif
@@ -233,6 +236,7 @@ private let _createWaitThread: Void = {
 ///
 /// On Apple platforms, the libdispatch-based implementation above is more
 /// efficient because it does not need to permanently reserve a thread.
+@available(Android 28, *)
 func wait(for pid: consuming pid_t) async throws -> ExitStatus {
   let pid = consume pid