Shutdown driver (#119)

Makefile.am

@@ -120,6 +120,7 @@ if WITH_DRIVERS
 libkernaux_la_SOURCES += \
 	src/drivers/console.c \
 	src/drivers/framebuffer.c \
+	src/drivers/shutdown.c \
 	src/drivers/qemu.c
 
 # Intel 8253-compatible programmable interval timer

include/Makefile.am

@@ -96,6 +96,7 @@ if WITH_DRIVERS
 nobase_include_HEADERS += \
 	kernaux/drivers/console.h \
 	kernaux/drivers/framebuffer.h \
+	kernaux/drivers/shutdown.h \
 	kernaux/drivers/qemu.h
 
 # Intel 8253-compatible programmable interval timer

include/kernaux/drivers/shutdown.h

@@ -0,0 +1,24 @@
+#ifndef KERNAUX_INCLUDED_DRIVERS_SHUTDOWN
+#define KERNAUX_INCLUDED_DRIVERS_SHUTDOWN
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdbool.h>
+
+// TODO: make this cross-platform
+#define KERNAUX_DRIVERS_SHUTDOWN_INT 3
+#define KERNAUX_DRIVERS_SHUTDOWN_ASM "int $3"
+
+bool kernaux_drivers_shutdown_is_doing();
+
+__attribute__((noreturn))
+void kernaux_drivers_shutdown_halt();
+void kernaux_drivers_shutdown_poweroff();
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

src/drivers/shutdown.c

@@ -0,0 +1,37 @@
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <kernaux/drivers/shutdown.h>
+#include <kernaux/drivers/qemu.h>
+
+#include <stdbool.h>
+
+static bool is_doing = false;
+
+bool kernaux_drivers_shutdown_is_doing()
+{
+    return is_doing;
+}
+
+void kernaux_drivers_shutdown_halt()
+{
+    is_doing = true;
+
+#ifdef ASM_X86
+    for (;;) __asm__ __volatile__(KERNAUX_DRIVERS_SHUTDOWN_ASM);
+#endif
+
+    volatile int x = 0;
+    for (;;) ++x;
+}
+
+void kernaux_drivers_shutdown_poweroff()
+{
+    is_doing = true;
+
+    kernaux_drivers_qemu_poweroff();
+
+    // If we can't poweroff then we halt
+    kernaux_drivers_shutdown_halt();
+}