mango/include/kernel/handle.h

#ifndef KERNEL_HANDLE_H_
#define KERNEL_HANDLE_H_

#include <kernel/bitmap.h>
#include <mango/status.h>
#include <mango/types.h>
#include <stddef.h>
#include <stdint.h>

/* subtract 32 bytes to account for the handle bitmap */
#define HANDLES_PER_TABLE ((4096 - 32) / sizeof(struct handle))
#define REFS_PER_TABLE    ((4096 - 64) / sizeof(struct handle_table *))

typedef uint32_t kern_handle_t;

typedef uintptr_t handle_flags_t;

struct task;
struct object;
struct vm_region;
struct handle_list;

struct handle {
	struct object *h_object;
	handle_flags_t h_flags;
};

struct handle_table {
	union {
		struct {
			/* bitmap tracks which bits in t_handle_list are
			 * allocated */
			DECLARE_BITMAP(t_handle_map, HANDLES_PER_TABLE);
			struct handle t_handle_list[HANDLES_PER_TABLE];
		} t_handles;

		struct {
			/* bitmap tracks which sub-tables are fully-allocated */
			DECLARE_BITMAP(t_subtable_map, REFS_PER_TABLE);
			struct handle_table *t_subtable_list[REFS_PER_TABLE];
		} t_subtables;
	};
};

extern struct handle_table *handle_table_create(void);
extern void handle_table_destroy(struct handle_table *tab);

extern kern_status_t handle_table_alloc_handle(
	struct handle_table *tab,
	struct handle **out_slot,
	kern_handle_t *out_handle);
extern kern_status_t handle_table_free_handle(
	struct handle_table *tab,
	kern_handle_t handle);
extern struct handle *handle_table_get_handle(
	struct handle_table *tab,
	kern_handle_t handle);

extern kern_status_t handle_table_transfer(
	struct vm_region *dst_region,
	struct handle_table *dst,
	kern_msg_handle_t *dst_handles,
	size_t dst_handles_max,
	struct vm_region *src_region,
	struct handle_table *src,
	kern_msg_handle_t *src_handles,
	size_t src_handles_count);

#endif