Kernel: moved read/write_from_user out of Process

kernel/kernel/UserCopy.cpp

@@ -0,0 +1,40 @@
+#include <kernel/UserCopy.h>
+
+extern "C" bool safe_user_memcpy(void*, const void*, size_t);
+extern "C" bool safe_user_strncpy(void*, const void*, size_t);
+static inline bool is_valid_user_address(const void* user_addr, size_t size)
+{
+	const vaddr_t user_vaddr = reinterpret_cast<vaddr_t>(user_addr);
+	if (BAN::Math::will_addition_overflow<vaddr_t>(user_vaddr, size))
+		return false;
+	if (user_vaddr + size > USERSPACE_END)
+		return false;
+	return true;
+}
+BAN::ErrorOr<void> Kernel::read_from_user(const void* user_addr, void* out, size_t size)
+{
+	if (!is_valid_user_address(user_addr, size))
+		return BAN::Error::from_errno(EFAULT);
+	if (!safe_user_memcpy(out, user_addr, size))
+		return BAN::Error::from_errno(EFAULT);
+	return {};
+}
+
+BAN::ErrorOr<void> Kernel::read_string_from_user(const char* user_addr, char* out, size_t max_size)
+{
+	max_size = BAN::Math::min<size_t>(max_size, USERSPACE_END - reinterpret_cast<vaddr_t>(user_addr));
+	if (!is_valid_user_address(user_addr, max_size))
+		return BAN::Error::from_errno(EFAULT);
+	if (!safe_user_strncpy(out, user_addr, max_size))
+		return BAN::Error::from_errno(EFAULT);
+	return {};
+}
+
+BAN::ErrorOr<void> Kernel::write_to_user(void* user_addr, const void* in, size_t size)
+{
+	if (!is_valid_user_address(user_addr, size))
+		return BAN::Error::from_errno(EFAULT);
+	if (!safe_user_memcpy(user_addr, in, size))
+		return BAN::Error::from_errno(EFAULT);
+	return {};
+}