Initial reorg.

This is largely the same as #305, but updated for the current tree.

crates/runtime/signalhandlers/SignalHandlers.hpp

@@ -0,0 +1,45 @@
+#ifndef signal_handlers_h
+#define signal_handlers_h
+
+#include <stdint.h>
+#include <setjmp.h>
+#ifndef __cplusplus
+#include <stdbool.h>
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int8_t CheckIfTrapAtAddress(const uint8_t* pc);
+// Record the Trap code and wasm bytecode offset in TLS somewhere
+void RecordTrap(const uint8_t* pc, bool reset_guard_page);
+
+void* EnterScope(void*);
+void LeaveScope(void*);
+void* GetScope(void);
+void Unwind(void);
+
+// This function performs the low-overhead signal handler initialization that we
+// want to do eagerly to ensure a more-deterministic global process state. This
+// is especially relevant for signal handlers since handler ordering depends on
+// installation order: the wasm signal handler must run *before* the other crash
+// handlers and since POSIX signal handlers work LIFO, this function needs to be
+// called at the end of the startup process, after other handlers have been
+// installed. This function can thus be called multiple times, having no effect
+// after the first call.
+int
+EnsureEagerSignalHandlers(void);
+
+// Assuming EnsureEagerProcessSignalHandlers() has already been called,
+// this function performs the full installation of signal handlers which must
+// be performed per-thread. This operation may incur some overhead and
+// so should be done only when needed to use wasm.
+int
+EnsureDarwinMachPorts(void);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif // signal_handlers_h