MemArena: report mapping failures instead of returning success

Horizon's CreateView printed 'Fatal error creating the view' and then returned base
anyway, so the caller recorded an unmapped address as a live view. Posix's
ftruncate failure was logged with a '// Should this be a failure?' - it is: the
mmaps afterwards succeed against a short file and the first touch past its end
raises SIGBUS, which is only hooked under __APPLE__.

Common/MemArenaHorizon.cpp

@@ -50,11 +50,13 @@ void *MemArena::CreateView(s64 offset, size_t size, void *base) {
 	if (R_FAILED(rc)) {
 		printf("Fatal error creating the view... base: %p offset: %p size: %p src: %p err: %d\n",
 			   (void *)base, (void *)offset, (void *)size, (void *)(memoryCodeBase + offset), rc);
-	} else {
-		printf("Created the view... base: %p offset: %p size: %p src: %p err: %d\n",
-			   (void *)base, (void *)offset, (void *)size, (void *)(memoryCodeBase + offset), rc);
+		// Returning base here reports success, so the caller happily uses an unmapped address
+		// and we take a fault later with nothing pointing back at this.
+		return nullptr;
 	}
 
+	printf("Created the view... base: %p offset: %p size: %p src: %p err: %d\n",
+		   (void *)base, (void *)offset, (void *)size, (void *)(memoryCodeBase + offset), rc);
 	return base;
 }
 

Common/MemArenaPosix.cpp

@@ -97,7 +97,11 @@ bool MemArena::GrabMemSpace(size_t size) {
 	}
 	if (ftruncate(fd, size) != 0) {
 		ERROR_LOG(Log::MemMap, "Failed to ftruncate %d (%s) to size %08x", (int)fd, ram_temp_file.c_str(), (int)size);
-		// Should this be a failure?
+		// This is a failure: the mmaps below succeed against a short file, and touching a page past
+		// its end raises SIGBUS - which is only hooked on __APPLE__, so elsewhere it's a bare crash.
+		close(fd);
+		fd = -1;
+		return false;
 	}
 #endif
 	return true;