xs_wire.h

/* SPDX-License-Identifier: MIT */
/*
 * Details of the "wire" protocol between Xen Store Daemon and client
 * library or guest kernel.
 * Copyright (C) 2005 Rusty Russell IBM Corporation
 */

#ifndef _XS_WIRE_H
#define _XS_WIRE_H

enum xsd_sockmsg_type
{
    XS_CONTROL,
#define XS_DEBUG XS_CONTROL
    XS_DIRECTORY,
    XS_READ,
    XS_GET_PERMS,
    XS_WATCH,
    XS_UNWATCH,
    XS_TRANSACTION_START,
    XS_TRANSACTION_END,
    XS_INTRODUCE,
    XS_RELEASE,
    XS_GET_DOMAIN_PATH,
    XS_WRITE,
    XS_MKDIR,
    XS_RM,
    XS_SET_PERMS,
    XS_WATCH_EVENT,
    XS_ERROR,
    XS_IS_DOMAIN_INTRODUCED,
    XS_RESUME,
    XS_SET_TARGET,
    /* XS_RESTRICT has been removed */
    XS_RESET_WATCHES = XS_SET_TARGET + 2,
    XS_DIRECTORY_PART,

    XS_TYPE_COUNT,      /* Number of valid types. */

    XS_INVALID = 0xffff /* Guaranteed to remain an invalid type */
};

#define XS_WRITE_NONE "NONE"
#define XS_WRITE_CREATE "CREATE"
#define XS_WRITE_CREATE_EXCL "CREATE|EXCL"

/* We hand errors as strings, for portability. */
struct xsd_errors
{
    int errnum;
    const char *errstring;
};
#define XSD_ERROR(x) { x, #x }
static struct xsd_errors xsd_errors[] __attribute__((unused)) = {
    XSD_ERROR(EINVAL),
    XSD_ERROR(EACCES),
    XSD_ERROR(EEXIST),
    XSD_ERROR(EISDIR),
    XSD_ERROR(ENOENT),
    XSD_ERROR(ENOMEM),
    XSD_ERROR(ENOSPC),
    XSD_ERROR(EIO),
    XSD_ERROR(ENOTEMPTY),
    XSD_ERROR(ENOSYS),
    XSD_ERROR(EROFS),
    XSD_ERROR(EBUSY),
    XSD_ERROR(EAGAIN),
    XSD_ERROR(EISCONN),
    XSD_ERROR(E2BIG)
};

struct xsd_sockmsg
{
    uint32_t type;  /* XS_??? */
    uint32_t req_id;/* Request identifier, echoed in daemon's response.  */
    uint32_t tx_id; /* Transaction id (0 if not related to a transaction). */
    uint32_t len;   /* Length of data following this. */

    /* Generally followed by nul-terminated string(s). */
};

enum xs_watch_type
{
    XS_WATCH_PATH = 0,
    XS_WATCH_TOKEN
};

/* Inter-domain shared memory communications. */
#define XENSTORE_RING_SIZE 1024
typedef uint32_t XENSTORE_RING_IDX;
#define MASK_XENSTORE_IDX(idx) ((idx) & (XENSTORE_RING_SIZE-1))
struct xenstore_domain_interface {
    char req[XENSTORE_RING_SIZE]; /* Requests to xenstore daemon. */
    char rsp[XENSTORE_RING_SIZE]; /* Replies and async watch events. */
    XENSTORE_RING_IDX req_cons, req_prod;
    XENSTORE_RING_IDX rsp_cons, rsp_prod;
    uint32_t server_features; /* Bitmap of features supported by the server */
    uint32_t connection;
    uint32_t error;
};

/* Violating this is very bad.  See docs/misc/xenstore.txt. */
#define XENSTORE_PAYLOAD_MAX 4096

/* Violating these just gets you an error back */
#define XENSTORE_ABS_PATH_MAX 3072
#define XENSTORE_REL_PATH_MAX 2048

/* The ability to reconnect a ring */
#define XENSTORE_SERVER_FEATURE_RECONNECTION 1
/* The presence of the "error" field in the ring page */
#define XENSTORE_SERVER_FEATURE_ERROR        2

/* Valid values for the connection field */
#define XENSTORE_CONNECTED 0 /* the steady-state */
#define XENSTORE_RECONNECT 1 /* guest has initiated a reconnect */

/* Valid values for the error field */
#define XENSTORE_ERROR_NONE    0 /* No error */
#define XENSTORE_ERROR_COMM    1 /* Communication problem */
#define XENSTORE_ERROR_RINGIDX 2 /* Invalid ring index */
#define XENSTORE_ERROR_PROTO   3 /* Protocol violation (payload too long) */

#endif /* _XS_WIRE_H */