De-duplicate cmUVSignalHackRAII

This was added separately in `cmCTestMultiProcessHandler` and
`cmQtAutoGenerator`.  Factor out the duplicate code into a common header
for re-use.

1 files changed, 44 insertions, 0 deletions

diff --git a/Source/cmUVSignalHackRAII.h b/Source/cmUVSignalHackRAII.h
new file mode 100644
index 0000000..c019aea
--- /dev/null
+++ b/Source/cmUVSignalHackRAII.h
@@ -0,0 +1,44 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#pragma once
+#include "cmConfigure.h" // IWYU pragma: keep
+
+#include "cm_uv.h"
+
+#if defined(CMAKE_USE_SYSTEM_LIBUV) && !defined(_WIN32) &&                    \
+  UV_VERSION_MAJOR == 1 && UV_VERSION_MINOR < 19
+#define CMAKE_UV_SIGNAL_HACK
+#include "cmUVHandlePtr.h"
+/*
+   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, nullptr, &hack_sa);
+    if (!(hack_sa.sa_flags & SA_RESTART)) {
+      hack_sa.sa_flags |= SA_RESTART;
+      sigaction(SIGCHLD, &hack_sa, nullptr);
+    }
+  }
+  ~cmUVSignalHackRAII()
+  {
+    this->HackSignal.stop();
+    uv_loop_close(&this->HackLoop);
+  }
+};
+#endif