banan-os/kernel/include/kernel/Process.h

#pragma once

#include <BAN/String.h>
#include <BAN/StringView.h>
#include <BAN/Vector.h>
#include <kernel/Credentials.h>
#include <kernel/FS/Inode.h>
#include <kernel/Memory/FixedWidthAllocator.h>
#include <kernel/Memory/GeneralAllocator.h>
#include <kernel/Memory/Heap.h>
#include <kernel/Memory/VirtualRange.h>
#include <kernel/SpinLock.h>
#include <kernel/Terminal/TTY.h>
#include <kernel/Thread.h>

#include <sys/stat.h>

namespace LibELF { class ELF; }

namespace Kernel
{

	class Process
	{
		BAN_NON_COPYABLE(Process);
		BAN_NON_MOVABLE(Process);

	public:
		using entry_t = Thread::entry_t;

		struct userspace_info_t
		{
			uintptr_t entry { 0 };
			int argc { 0 };
			char** argv { nullptr };
			char** envp { nullptr };
		};

	public:
		static Process* create_kernel(entry_t, void*);
		static BAN::ErrorOr<Process*> create_userspace(const Credentials&, BAN::StringView);
		~Process();

		[[noreturn]] void exit(int status);

		void add_thread(Thread*);
		void on_thread_exit(Thread&);

		BAN::ErrorOr<void> set_termios(const termios&);

		pid_t pid() const { return m_pid; }

		BAN::ErrorOr<Process*> fork(uintptr_t rsp, uintptr_t rip);
		BAN::ErrorOr<void> exec(BAN::StringView path, const char* const* argv, const char* const* envp);

		int block_until_exit();
		BAN::ErrorOr<pid_t> wait(pid_t pid, int* stat_loc, int options);

		BAN::ErrorOr<void> setenvp(char** envp);

		BAN::ErrorOr<int> open(BAN::StringView, int);
		BAN::ErrorOr<int> openat(int, BAN::StringView, int);
		BAN::ErrorOr<void> close(int fd);
		BAN::ErrorOr<size_t> read(int fd, void* buffer, size_t count);
		BAN::ErrorOr<size_t> write(int fd, const void* buffer, size_t count);
		BAN::ErrorOr<void> creat(BAN::StringView name, mode_t);

		BAN::ErrorOr<void> seek(int fd, off_t offset, int whence);
		BAN::ErrorOr<off_t> tell(int fd);

		BAN::ErrorOr<void> fstat(int fd, struct stat*);
		BAN::ErrorOr<void> stat(BAN::StringView path, struct stat*, int flags);

		BAN::ErrorOr<void> mount(BAN::StringView source, BAN::StringView target);

		BAN::ErrorOr<void> read_next_directory_entries(int fd, DirectoryEntryList* buffer, size_t buffer_size);

		BAN::ErrorOr<BAN::String> working_directory() const;
		BAN::ErrorOr<void> set_working_directory(BAN::StringView);

		TTY& tty() { ASSERT(m_tty); return *m_tty; }

		BAN::ErrorOr<void*> allocate(size_t);
		void free(void*);

		void termid(char*) const;

		static Process& current() { return Thread::current().process(); }

		PageTable& page_table() { return m_page_table ? *m_page_table : PageTable::kernel(); }

		const userspace_info_t& userspace_info() const { return m_userspace_info; }

	private:
		Process(const Credentials&, pid_t);
		static Process* create_process(const Credentials&);
		static void register_process(Process*);

		// Load an elf file to virtual address space of the current page table
		static BAN::ErrorOr<BAN::UniqPtr<LibELF::ELF>> load_elf_for_exec(const Credentials&, BAN::StringView file_path, const BAN::String& cwd, const BAN::Vector<BAN::StringView>& path_env);
		
		// Copy an elf file from the current page table to the processes own
		void load_elf_to_memory(LibELF::ELF&);

		BAN::ErrorOr<BAN::String> absolute_path_of(BAN::StringView) const;

	private:
		struct OpenFileDescription
		{
			BAN::RefPtr<Inode> inode;
			BAN::String path;
			off_t offset { 0 };
			uint8_t flags { 0 };
		};

		BAN::ErrorOr<void> validate_fd(int);
		OpenFileDescription& open_file_description(int);
		BAN::ErrorOr<int> get_free_fd();


		struct ExitStatus
		{
			Semaphore semaphore;
			int exit_code { 0 };
			bool exited { false };
			int waiting { 0 };
		};

		Credentials m_credentials;

		BAN::Vector<OpenFileDescription> m_open_files;
		BAN::Vector<VirtualRange*> m_mapped_ranges;

		mutable RecursiveSpinLock m_lock;

		const pid_t m_pid = 0;
		BAN::String m_working_directory;
		BAN::Vector<Thread*> m_threads;

		BAN::Vector<BAN::UniqPtr<FixedWidthAllocator>> m_fixed_width_allocators;
		BAN::UniqPtr<GeneralAllocator> m_general_allocator;

		userspace_info_t m_userspace_info;
		ExitStatus m_exit_status;

		BAN::UniqPtr<PageTable> m_page_table;
		TTY* m_tty { nullptr };
	};

}