cmCTestMultiProcessHandler: Add helper to make libuv use SA_RESTART

Prior to 1.19, libuv does not use SA_RESTART in its signal handler.
Add a helper to cause libuv to install its handler and then revise
the handler's flags to add SA_RESTART.

1 files changed, 37 insertions, 0 deletions

diff --git a/Source/CTest/cmCTestMultiProcessHandler.cxx b/Source/CTest/cmCTestMultiProcessHandler.cxx
index 6cdec8d65b..4a980d7585 100644
--- a/Source/CTest/cmCTestMultiProcessHandler.cxx
+++ b/Source/CTest/cmCTestMultiProcessHandler.cxx
@@ -22,6 +22,43 @@
 #include <stdlib.h>
 #include <utility>
 
+#if defined(CMAKE_USE_SYSTEM_LIBUV) && !defined(_WIN32) &&                    \
+  UV_VERSION_MAJOR == 1 && UV_VERSION_MINOR < 19
+#define CMAKE_UV_SIGNAL_HACK
+/*
+   libuv does not use SA_RESTART on its signal handler, but C++ streams
+   depend on it for reliable i/o operations.  This RAII helper convinces
+   libuv to install its handler, and then revises the handler to add the
+   SA_RESTART flag.  We use a distinct uv loop that never runs to avoid
+   ever really getting a callback.  libuv may fill the hack loop's signal
+   pipe and then stop writing, but that won't break any real loops.
+ */
+class cmUVSignalHackRAII
+{
+  uv_loop_t HackLoop;
+  cm::uv_signal_ptr HackSignal;
+  static void HackCB(uv_signal_t*, int) {}
+public:
+  cmUVSignalHackRAII()
+  {
+    uv_loop_init(&this->HackLoop);
+    this->HackSignal.init(this->HackLoop);
+    this->HackSignal.start(HackCB, SIGCHLD);
+    struct sigaction hack_sa;
+    sigaction(SIGCHLD, NULL, &hack_sa);
+    if (!(hack_sa.sa_flags & SA_RESTART)) {
+      hack_sa.sa_flags |= SA_RESTART;
+      sigaction(SIGCHLD, &hack_sa, NULL);
+    }
+  }
+  ~cmUVSignalHackRAII()
+  {
+    this->HackSignal.stop();
+    uv_loop_close(&this->HackLoop);
+  }
+};
+#endif
+
 class TestComparator
 {
 public: