    /* 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;
    };
    #ifdef EINVAL
    #define XSD_ERROR(x) { x, #x }
    /* LINTED: static unused */
    static const struct xsd_errors xsd_errors[]
    #if defined(__GNUC__)
    __attribute__((unused))
    #endif
        = {
        /* /!\ New errors should be added at the end of the array. */
        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),
        XSD_ERROR(EPERM),
    };
    #endif

    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
    };

    /*
     * `incontents 150 xenstore_struct XenStore wire protocol.
     *
     * 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 /* reconnect in progress */

    /* 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 */

    /*
     * Local variables:
     * mode: C
     * c-file-style: "BSD"
     * c-basic-offset: 4
     * tab-width: 4
     * indent-tabs-mode: nil
     * End:
     */