Try stubbing pthread_setname_np and posix_spawn_file_actions_addclosefrom_np functions a different way

Author: grynspan

Sources/Testing/ExitTests/SpawnProcess.swift

@@ -98,7 +98,7 @@ func spawnExecutable(
       // least close all file descriptors higher than the highest inherited one.
       // We are assuming here that the caller didn't set FD_CLOEXEC on any of
       // these file descriptors.
-      _ = _posix_spawn_file_actions_addclosefrom_np?(fileActions.baseAddress!, highestFD + 1)
+      _ = swt_posix_spawn_file_actions_addclosefrom_np(fileActions.baseAddress!, highestFD + 1)
 #else
 #warning("Platform-specific implementation missing: cannot close unused file descriptors")
 #endif
@@ -191,20 +191,6 @@ func spawnExecutable(
 
 // MARK: -
 
-#if os(Linux) || os(FreeBSD)
-/// Close file descriptors above a given value when spawing a new process.
-///
-/// This symbol is provided because the underlying function was added to glibc
-/// relatively recently and may not be available on all targets. Checking
-/// `__GLIBC_REQ()` is insufficient because `_DEFAULT_SOURCE` may not be
-/// defined at the point spawn.h is first included.
-private let _posix_spawn_file_actions_addclosefrom_np = {
-  symbol(named: "posix_spawn_file_actions_addclosefrom_np").map {
-    unsafeBitCast($0, to: (@convention(c) (UnsafeMutablePointer<posix_spawn_file_actions_t>, CInt) -> CInt).self)
-  }
-}()
-#endif
-
 #if os(Windows)
 /// Create a temporary instance of `STARTUPINFOEXW` to pass to
 /// `CreateProcessW()`.

Sources/Testing/ExitTests/WaitFor.swift

@@ -109,7 +109,7 @@ private let _createWaitThreadImpl: Void = {
 #if SWT_TARGET_OS_APPLE
       _ = pthread_setname_np("Swift Testing exit test monitor")
 #elseif os(Linux)
-      _ = _pthread_setname_np?(pthread_self(), "SWT ExT monitor")
+      _ = swt_pthread_setname_np(pthread_self(), "SWT ExT monitor")
 #elseif os(FreeBSD)
       _ = pthread_set_name_np(pthread_self(), "SWT ex test monitor")
 #else
@@ -232,19 +232,4 @@ func wait(for processHandle: consuming HANDLE) async throws -> ExitCondition {
   return .exitCode(CInt(bitPattern: .init(status)))
 }
 #endif
-
-// MARK: -
-
-#if os(Linux)
-/// Set the name of the current thread.
-///
-/// This symbol is provided because `pthread_setname_np()` is only declared if
-/// `_GNU_SOURCE` is set, but setting it causes build errors due to conflicts
-/// with Swift's Glibc module.
-private let _pthread_setname_np = {
-  symbol(named: "pthread_setname_np").map {
-    unsafeBitCast($0, to: (@convention(c) (pthread_t, UnsafePointer<CChar>) -> CInt).self)
-  }
-}()
-#endif
 #endif

Sources/_TestingInternals/CMakeLists.txt

@@ -12,6 +12,7 @@ include(LibraryVersion)
 include(TargetTriple)
 add_library(_TestingInternals STATIC
   Discovery.cpp
+  Stubs.cpp
   Versions.cpp
   WillThrow.cpp)
 target_include_directories(_TestingInternals PUBLIC

Sources/_TestingInternals/Stubs.cpp

@@ -0,0 +1,43 @@
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2024 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for Swift project authors
+//
+
+/// This source file includes implementations of functions that _should_ simply
+/// be `static` stubs in Stubs.h, but which for technical reasons cannot be
+/// imported into Swift when defined in a header.
+///
+/// Do not, as a rule, add function implementations in this file. Prefer to add
+/// them to Stubs.h so that they can be inlined at compile- or link-time. Only
+/// include functions here if Swift cannot successfully import and call them
+/// otherwise.
+
+#if defined(__linux__) || defined(__FreeBSD__)
+#define _DEFAULT_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#include "Stubs.h"
+
+
+#if defined(__linux__)
+int swt_pthread_setname_np(pthread_t thread, const char *name) {
+  return pthread_setname_np(thread, name);
+}
+#endif
+
+#if defined(__linux__) || defined(__FreeBSD__)
+int swt_posix_spawn_file_actions_addclosefrom_np(posix_spawn_file_actions_t *fileActions, int from) {
+#if defined(__GLIBC_REQ) && __GLIBC_REQ(2, 34)
+  return posix_spawn_file_actions_addclosefrom_np(fileActions, from);
+#else
+#warning glibc too old for posix_spawn_file_actions_addclosefrom_np
+  return 0;
+#endif
+}
+#endif

Sources/_TestingInternals/include/Stubs.h

@@ -109,6 +109,25 @@ static char *_Nullable *_Null_unspecified swt_environ(void) {
 }
 #endif
 
+#if defined(__linux__)
+/// Set the name of the current thread.
+///
+/// This function declaration is provided because `pthread_setname_np()` is
+/// only declared if `_GNU_SOURCE` is set, but setting it causes build errors
+/// due to conflicts with Swift's Glibc module.
+SWT_EXTERN int swt_pthread_setname_np(pthread_t thread, const char *name);
+#endif
+
+#if defined(__linux__) || defined(__FreeBSD__)
+/// Close file descriptors above a given value when spawing a new process.
+///
+/// This symbol is provided because the underlying function was added to glibc
+/// relatively recently and may not be available on all targets. Checking
+/// `__GLIBC_REQ()` is insufficient because `_DEFAULT_SOURCE` may not be
+/// defined at the point spawn.h is first included.
+SWT_EXTERN int swt_posix_spawn_file_actions_addclosefrom_np(posix_spawn_file_actions_t *fileActions, int from);
+#endif
+
 #if !defined(__ANDROID__)
 #if __has_include(<signal.h>) && defined(si_pid)
 /// Get the value of the `si_pid` field of a `siginfo_t` structure.