FEXHeaderUtils: Adds ScopedSignalMaskWithMutex

This class allows a scoped region lock a mutex and mask signals.

This is necessary for thread and signal safety coming up

FEXHeaderUtils/FEXHeaderUtils/ScopedSignalMask.h

@@ -0,0 +1,46 @@
+#pragma once
+
+#include <FEXCore/Utils/CompilerDefs.h>
+#include <FEXCore/Utils/LogManager.h>
+
+#include <cstdint>
+#include <mutex>
+#include <signal.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+namespace FHU {
+  /**
+   * @brief A class that masks signals and locks a mutex until it goes out of scope
+   *
+   * Constructor order:
+   * 1) Mask signals
+   * 2) Lock Mutex
+   *
+   * Destructor Order:
+   * 1) Unlock Mutex
+   * 2) Unmask signals
+   */
+  class ScopedSignalMaskWithMutex final {
+    public:
+      ScopedSignalMaskWithMutex(std::mutex &_Mutex, uint64_t Mask = ~0ULL)
+        : Mutex {_Mutex} {
+        // Mask all signals, storing the original incoming mask
+        ::syscall(SYS_rt_sigprocmask, SIG_SETMASK, &Mask, &OriginalMask, sizeof(OriginalMask));
+
+        // Lock the mutex
+        Mutex.lock();
+      }
+
+      ~ScopedSignalMaskWithMutex() {
+        // Unlock the mutex
+        Mutex.unlock();
+
+        // Unmask back to the original signal mask
+        ::syscall(SYS_rt_sigprocmask, SIG_SETMASK, &OriginalMask, nullptr, sizeof(OriginalMask));
+      }
+    private:
+      uint64_t OriginalMask{};
+      std::mutex &Mutex;
+  };
+}