trans.h

openGFS , a kind of file system.

/*
 *
 *    Copyright 1999 Regents of the University of Minnesota
 *    Portions Copyright 1999-2001 Sistina Software, Inc.
 *    Portions Copyright 2001 The OpenGFS Project
 *
 *    This is free software released under the GNU General Public License.
 *    There is no warranty for this software.  See the file COPYING for
 *    details.
 *
 *    See the file AUTHORS for a list of contributors.
 *
 */
#ifndef _GNBD_TRANS_H
#define _GNBD_TRANS_H

/*
 * The io Header structure and its types.
 * This gets tacked onto the beginning of every piece of data that is
 * passed through.
 */
#define tioRequest  0x10
#define tioReply    0x20
#define tioReadReq  (tioRequest|0x02)
#define tioReadRpl  (tioReply|0x02)
#define tioWriteReq (tioRequest|0x03)
#define tioWriteRpl (tioReply|0x03)
#define tioShutdown 0x0e
struct tio_hdr_s {
	uint64_t key;
	uint32_t len;
	uint64_t offset;
	uint8_t err;
	uint8_t type;
} __attribute__ ((packed));
typedef struct tio_hdr_s theader_t;
#define theader_len sizeof(theader_t)	/* lazy programmer. */

/*
 * ok.
 * Clients send out Requests and get replies.  All client server
 * interaction is done in this maner.
 * The meaning of the len and offset fields change depending on the type.
 * The meaning of all other fields is constant.
 * So:
 *  type is the type of this header. Types are defined above.
 *  key  is for the client to match requests with replies.
 *  err  is nonzero if the server had an error processing a request.
 * For Read Requests:
 *  len  is the amount of space the client has waiting for reply
 * For Read Replies:
 *  len  is the amount of data that is following this header.
 * For Read Requests:
 *  offset is where to find that data we want.
 * For Write Requests:
 *  offset is where to put the data we're sending.
 * For other conditions the fields should be ignored. (unless I confused
 * something here)
 */

/*
 * This struct holds some various bits of info that we need before the
 * client can really get going.
 */
struct tio_info_s {
	uint64_t devsize;
	uint8_t readonly;
} __attribute__ ((packed));
typedef struct tio_info_s tio_info_t;

/*
 * The new login structures.  We send a lgReq to the server, and get a
 * lgRpl back.
 *
 * For the loginRequest, you need to tell the server which device you
 * want.  This is really only for servers that server multiple block
 * devices.  In most cases this will probably be ignored.
 */
struct lgReq_s {
	char devname[32];
} __attribute__ ((packed));
typedef struct lgReq_s lgReq_t;

struct lgRpl_s {
	uint64_t devsize;
	uint8_t success:1;
	uint8_t readonly:1;
} __attribute__ ((packed));
typedef struct lgRpl_s lgRpl_t;

#endif /* _GNBD_TRANS_H */