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

Documentation/EnvironmentVariables.md

@@ -51,7 +51,7 @@ names prefixed with `SWT_`.
 |-|:-:|-|
 | `SWT_BACKCHANNEL` | `CInt`/`HANDLE` | A file descriptor (handle on Windows) to which the exit test's events are written. |
 | `SWT_CAPTURED_VALUES` | `CInt`/`HANDLE` | A file descriptor (handle on Windows) containing captured values passed to the exit test. |
-| `SWT_CLOSEFROM` | `CInt` | Used on OpenBSD to emulate `posix_spawn_file_actions_addclosefrom_np()`. |
+| `SWT_CLOSEFROM` | `CInt` | Used on OpenBSD and Android to emulate `posix_spawn_file_actions_addclosefrom_np()`. |
 | `SWT_EXIT_TEST_ID` | `String` (JSON) | Specifies which exit test to run. |
 | `XCTestBundlePath`\* | `String` | Used on Apple platforms to determine if Xcode is hosting the test run. |
 

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]))),
@@ -428,6 +441,7 @@ extension Array where Element == PackageDescription.SwiftSetting {
       .enableExperimentalFeature("AvailabilityMacro=_swiftVersionAPI:macOS 13.0, iOS 16.0, tvOS 16.0, watchOS 9.0"),
       .enableExperimentalFeature("AvailabilityMacro=_typedThrowsAPI:macOS 15.0, iOS 18.0, watchOS 11.0, tvOS 18.0, visionOS 2.0"),
       .enableExperimentalFeature("AvailabilityMacro=_castingWithNonCopyableGenerics:macOS 15.0, iOS 18.0, watchOS 11.0, tvOS 18.0, visionOS 2.0"),
+      .enableExperimentalFeature("AvailabilityMacro=_posixSpawnAPI:Android 28.0"),
 
       .enableExperimentalFeature("AvailabilityMacro=_distantFuture:macOS 99.0, iOS 99.0, watchOS 99.0, tvOS 99.0, visionOS 99.0"),
     ]
@@ -457,8 +471,8 @@ 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(_posixSpawnAPI, *) 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/ABI/EntryPoints/EntryPoint.swift

@@ -31,7 +31,8 @@ func entryPoint(passing args: __CommandLineArguments_v0?, eventHandler: Event.Ha
   do {
 #if !SWT_NO_EXIT_TESTS
       // If an exit test was specified, run it. `exitTest` returns `Never`.
-      if let exitTest = ExitTest.findInEnvironmentForEntryPoint() {
+      if #available(_posixSpawnAPI, *),
+         let exitTest = ExitTest.findInEnvironmentForEntryPoint() {
         await exitTest()
       }
 #endif
@@ -674,7 +675,9 @@ public func configurationForEntryPoint(from args: __CommandLineArguments_v0) thr
 
 #if !SWT_NO_EXIT_TESTS
   // Enable exit test handling via __swiftPMEntryPoint().
-  configuration.exitTestHandler = ExitTest.handlerForEntryPoint()
+  if #available(_posixSpawnAPI, *) {
+    configuration.exitTestHandler = ExitTest.handlerForEntryPoint()
+  }
 #endif
 
   // Warning issues (experimental).

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(_posixSpawnAPI, *)
+#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(_posixSpawnAPI, *)
+#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(_posixSpawnAPI, *)
+#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(_posixSpawnAPI, *)
+#else
 @_unavailableInEmbedded
 @available(*, unavailable, message: "Exit tests are not available on this platform.")
 #endif
@@ -131,6 +133,7 @@ extension ExitTest {
 #if !SWT_NO_EXIT_TESTS
 // MARK: - Collection conveniences
 
+@available(_posixSpawnAPI, *)
 extension Array where Element == ExitTest.CapturedValue {
   init<each T>(_ wrappedValues: repeat each T) where repeat each T: Codable & Sendable {
     self.init()
@@ -143,6 +146,7 @@ extension Array where Element == ExitTest.CapturedValue {
   }
 }
 
+@available(_posixSpawnAPI, *)
 extension Collection where Element == ExitTest.CapturedValue {
   /// Cast the elements in this collection to a tuple of their wrapped values.
   ///

Sources/Testing/ExitTests/ExitTest.Condition.swift

@@ -10,7 +10,9 @@
 
 private import _TestingInternals
 
-#if SWT_NO_EXIT_TESTS
+#if !SWT_NO_EXIT_TESTS
+@available(_posixSpawnAPI, *)
+#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(_posixSpawnAPI, *)
+#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(_posixSpawnAPI, *)
+#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(_posixSpawnAPI, *)
+#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(_posixSpawnAPI, *)
+#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(_posixSpawnAPI, *)
+#else
 @_unavailableInEmbedded
 @available(*, unavailable, message: "Exit tests are not available on this platform.")
 #endif
@@ -149,6 +151,7 @@ public struct ExitTest: Sendable, ~Copyable {
 #if !SWT_NO_EXIT_TESTS
 // MARK: - Current
 
+@available(_posixSpawnAPI, *)
 extension ExitTest {
   /// Storage for ``current``.
   ///
@@ -189,7 +192,19 @@ extension ExitTest {
 
 // MARK: - Invocation
 
+#if os(Android) && !SWT_NO_DYNAMIC_LINKING
+/// Close a range of file descriptors.
+///
+/// This function declaration is provided because `close_range()` is only
+/// declared if `_GNU_SOURCE` is set, but setting it causes build errors due to
+/// conflicts with Swift's Glibc module.
+private let _close_range = symbol(named: "close_range").map {
+  castCFunction(at: $0, to: (@convention(c) (CUnsignedInt, CUnsignedInt, CInt) -> CInt).self)
+}
+#endif
+
 @_spi(ForToolsIntegrationOnly)
+@available(_posixSpawnAPI, *)
 extension ExitTest {
   /// Disable crash reporting, crash logging, or core dumps for the current
   /// process.
@@ -223,6 +238,21 @@ 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
@@ -278,11 +308,16 @@ extension ExitTest {
     }
 #endif
 
-#if os(OpenBSD)
+#if os(OpenBSD) || (os(Android) && !SWT_NO_DYNAMIC_LINKING)
     // OpenBSD does not have posix_spawn_file_actions_addclosefrom_np().
     // However, it does have closefrom(2), which we call here as a best effort.
+    // Android has close_range(2) which serves the same purpose.
     if let from = Environment.variable(named: "SWT_CLOSEFROM").flatMap(CInt.init) {
+#if os(OpenBSD)
       _ = closefrom(from)
+#else
+      _ = _close_range?(CUnsignedInt(bitPattern: from), .max, 0)
+#endif
     }
 #endif
 
@@ -307,6 +342,7 @@ extension ExitTest {
 
 // MARK: - Discovery
 
+@available(_posixSpawnAPI, *)
 extension ExitTest {
   /// A type representing an exit test as a test content record.
   fileprivate struct Record: Sendable, DiscoverableAsTestContent {
@@ -405,6 +441,7 @@ extension ExitTest {
 }
 
 @_spi(ForToolsIntegrationOnly)
+@available(_posixSpawnAPI, *)
 extension ExitTest {
   /// Find the exit test function at the given source location.
   ///
@@ -458,6 +495,7 @@ extension ExitTest {
 /// This function contains the common implementation for all
 /// `await #expect(processExitsWith:) { }` invocations regardless of calling
 /// convention.
+@available(_posixSpawnAPI, *)
 func callExitTest(
   identifiedBy exitTestID: (UInt64, UInt64, UInt64, UInt64),
   encodingCapturedValues capturedValues: [ExitTest.CapturedValue],
@@ -544,6 +582,7 @@ extension ABI {
 }
 
 @_spi(ForToolsIntegrationOnly)
+@available(_posixSpawnAPI, *)
 extension ExitTest {
   /// A barrier value to insert into the standard output and standard error
   /// streams immediately before and after the body of an exit test runs in
@@ -662,7 +701,7 @@ 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 +738,7 @@ 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:))
     }