Begin C++ API: Add exile.hpp with exile_launch() wrappers

exile.hpp

@@ -0,0 +1,175 @@
+#include "exile.h"
+#include <functional>
+#include <iostream>
+#include <string>
+#include <tuple>
+#include <memory>
+#include <sys/wait.h>
+
+#ifndef EXILE_MMAP_SIZE
+#define EXILE_MMAP_SIZE 128 * 1024 * 1024 //128MB
+#endif
+
+
+template<typename T, typename U, typename ... Args>
+class launch_arg
+{
+	static_assert(std::is_trivially_copyable_v<T>);
+	static_assert(!std::is_pointer_v<T>);
+
+public:
+	struct exile_policy *policy;
+	T *result_shm;
+	U fn;
+	std::tuple<Args...> args;
+
+	launch_arg(struct exile_policy *policy, T *result_shm, U fn, Args && ... args) : policy(policy),
+	result_shm(result_shm), fn(fn), args(std::forward<Args>(args)...) {}
+
+};
+
+template<typename T, typename U, typename ... Args>
+class launch_arg_serializer
+{
+	static_assert(std::is_copy_constructible_v<T>);
+
+public:
+	struct exile_policy *policy;
+	char *serialize_buffer;
+	size_t n;
+	U fn;
+	std::tuple<Args...> args;
+
+	const std::function<size_t (const T &, char *, size_t n)> &serializer;
+	const std::function<T(const char * buf, size_t n)> &deserializer;
+
+	launch_arg_serializer(struct exile_policy *policy, char *serialize_buffer, size_t n, const std::function<size_t (const T &, char *, size_t)> &serializer, const std::function<T(const char *, size_t)> &deserializer, U fn, Args && ... args) : policy(policy), serialize_buffer(serialize_buffer), n(n), fn(fn), args(std::forward<Args>(args)...), serializer(serializer), deserializer(deserializer)  {}
+};
+
+template<typename T, typename U, typename ... Args>
+int exile_clone_handle_trivial(void * arg)
+{
+	static_assert(std::is_trivially_copyable_v<T>);
+	static_assert(!std::is_pointer_v<T>);
+
+	launch_arg<T, U, Args...> *launchargs = (launch_arg<T, U,  Args...> *) arg;
+	int ret = exile_enable_policy(launchargs->policy);
+	if(ret != 0)
+	{
+		EXILE_LOG_ERROR("exile_enable_policy() failed: %s\n", strerror(errno));
+		return 1;
+	}
+	T result = std::apply(launchargs->fn, launchargs->args);
+	std::cout << result;
+	memcpy(launchargs->result_shm, &result, sizeof(T));
+	return 0;
+}
+
+template<typename T, typename U, typename ... Args>
+int exile_clone_handle_serializer(void * arg)
+{
+	static_assert(std::is_copy_constructible_v<T>);
+
+	launch_arg_serializer<T, U, Args...> *launchargs = (launch_arg_serializer<T, U, Args...> *) arg;
+	int ret = exile_enable_policy(launchargs->policy);
+	if(ret != 0)
+	{
+		EXILE_LOG_ERROR("exile_enable_policy() failed: %s\n", strerror(errno));
+		return 1;
+	}
+	T result = std::apply(launchargs->fn, launchargs->args);
+	/* TODO: exception handling */
+	/* TODO: ugly :S */
+	char *target = launchargs->serialize_buffer + sizeof(size_t);
+	size_t n = launchargs->n - sizeof(size_t);
+
+	size_t size = launchargs->serializer(result, target, n);
+	memcpy(launchargs->serialize_buffer, &size, sizeof(size_t));
+
+	return 0;
+}
+
+static int do_clone(int (*clonefn)(void *), void *launcharg)
+{
+	struct rlimit rlimit;
+	int ret = getrlimit(RLIMIT_STACK, &rlimit);
+	if(ret != 0)
+	{
+		EXILE_LOG_ERROR("Failed to get stack size: %s\n", strerror(errno));
+		return ret;
+	}
+	size_t size = rlimit.rlim_cur;
+	char *stack = (char *) calloc(1, size);
+	if(stack == NULL)
+	{
+		EXILE_LOG_ERROR("Failed to allocate stack memory for child\n");
+		return 1;
+	}
+	stack += size;
+
+	ret = clone(clonefn, stack, 17 /* SIGCHLD */, launcharg);
+	int status = 0;
+	waitpid(ret, &status, __WALL);
+	if(WIFEXITED(status))
+	{
+		return WEXITSTATUS(status);
+	}
+	/* TODO: exception or what? */
+	return 23;
+}
+
+template<typename T, typename U, typename ... Args>
+T exile_launch_trivial(struct exile_policy *policy, U fn, Args && ... args)
+{
+	size_t mapsize = sizeof(T);
+	T * sharedbuf =  (T *) mmap(NULL, mapsize , PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
+	if(sharedbuf == NULL)
+	{
+		throw std::runtime_error(std::string("mmap failed: ") + strerror(errno));
+	}
+
+	std::shared_ptr<void> deleter(nullptr, [sharedbuf, mapsize](...){ munmap(sharedbuf, mapsize); });
+	launch_arg<T, U, Args...> launcharg(policy, sharedbuf, fn, std::forward<Args>(args)...);
+
+	int (*clonefn)(void *) = &exile_clone_handle_trivial<T, U, Args...>;
+	/* TODO: exception or what? */
+	int ret = do_clone(clonefn, &launcharg);
+	if(ret == 0)
+	{
+		return *sharedbuf;
+	}
+	throw std::runtime_error(std::string("clone() failed: " + std::to_string(ret)));
+	return T();
+}
+
+
+
+template<typename T, typename U, typename ... Args>
+T exile_launch(struct exile_policy *policy, const std::function<size_t (const T &, char *, size_t)> &serializer, const std::function<T(const char *, size_t)> &deserializer, U fn, Args && ... args)
+{
+	size_t mapsize = EXILE_MMAP_SIZE;
+	char *sharedbuf =  (char *) mmap(NULL, mapsize , PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
+	if(sharedbuf == NULL)
+	{
+		throw std::runtime_error(std::string("mmap failed: ") + strerror(errno));
+	}
+	std::shared_ptr<void> deleter(nullptr, [sharedbuf, mapsize](...){ munmap(sharedbuf, mapsize); });
+
+
+	launch_arg_serializer<T, U, Args...> launcharg(policy, sharedbuf, mapsize, serializer, deserializer, fn,												   std::forward<Args>(args)...);
+
+	int (*clonefn)(void *) = &exile_clone_handle_serializer<T, U, Args...>;
+	/* TODO: exception or what? */
+	int ret = do_clone(clonefn, &launcharg);
+	if(ret == 0)
+	{
+		size_t size = 0;
+		memcpy(&size, sharedbuf, sizeof(size));
+
+		return deserializer(sharedbuf + sizeof(size_t), size);
+	}
+	throw std::runtime_error(std::string("clone() failed: " + std::to_string(ret)));
+	return T();
+
+}
+