#ifndef XPC_BUFFER_H_
#define XPC_BUFFER_H_

#include <stddef.h>
#include <xpc/status.h>

#define XPC_BUFFER_IN(msg, offset, size)                                       \
	{                                                                      \
		.buf_flags = XPC_BUFFER_F_IN | XPC_BUFFER_F_REMOTE,            \
		.buf_origin = (msg),                                           \
		.buf_offset = (offset),                                        \
		.buf_len = (size),                                             \
	}
#define XPC_BUFFER_OUT(msg, offset, size)                                      \
	{                                                                      \
		.buf_flags = XPC_BUFFER_F_OUT | XPC_BUFFER_F_REMOTE,           \
		.buf_origin = (msg),                                           \
		.buf_offset = (offset),                                        \
		.buf_len = (size),                                             \
	}

struct xpc_msg;

typedef enum xpc_buffer_flags {
	/* the buffer can be read from */
	XPC_BUFFER_F_IN = 0x01u,
	/* the buffer can be written to */
	XPC_BUFFER_F_OUT = 0x02u,
	/* the buffer is backed by a buffer located in another address space.
	 * the buffer can only be accessed via xpc_buffer_read and/or
	 * xpc_buffer_write */
	XPC_BUFFER_F_REMOTE = 0x04u,
	/* free the buffer backing this buffer when the buffer is discarded.
	 * this is only used for out-buffers. the buffer must have been
	 * allocated using xpc_context_alloc, as it will be freed via a call
	 * to xpc_context_free */
	XPC_BUFFER_F_FREE_ON_DISCARD = 0x08u,
} xpc_buffer_flags_t;

typedef struct xpc_buffer {
	xpc_buffer_flags_t buf_flags;
	union {
		/* fields that are only valid if F_OUT is set */
		struct {
			/* only valid if F_OUT is set. specifies the maximum
			 * number of chars that can be written to buf_buf,
			 * including the null terminator. */
			size_t buf_max;
			/* only valid if F_OUT is set.
			 * if F_FREE_ON_DISCARD is set, must be either NULL or
			 * allocated via xpc_context_alloc */
			const char *buf_ptr;
		};

		/* fields that are only valid if F_IN is set */
		struct {
			/* only valid if F_IN is set. offset of the buffer data
			 * within the associated message. used when reading
			 * buffer data from a message. */
			size_t buf_offset;
		};
	};

	/* only valid if F_REMOTE is set.
	 * used to read/write buffer data from/to the sender's address
	 * space. */
	const struct xpc_msg *buf_origin;

	/* valid for both F_IN and F_OUT buffers.
	 * F_IN: specifies the length of the incoming buffer data.
	 * F_OUT: specifies how many bytes from buf_ptr to send. */
	size_t buf_len;
} xpc_buffer_t;

extern xpc_status_t xpc_buffer_read(
	const xpc_buffer_t *s,
	void *out,
	size_t max,
	size_t *nr_read);
extern xpc_status_t xpc_buffer_write(
	xpc_buffer_t *s,
	const void *in,
	size_t len,
	size_t *nr_written);

#endif