Register for notification I/O function handler

QNX SDP8.0Getting Started with the QNX OSDeveloperUser

Prototype:

int (*notify) ( resmgr_context_t *ctp,
               io_notify_t *msg,
               RESMGR_OCB_T *ocb )

Classification:

I/O

Default handler:

none

Helper functions:

iofunc_notify(), iofunc_notify_remove(), iofunc_notify_remove_strict(), iofunc_notify_trigger(), iofunc_notify_trigger_strict()

Client functions:

poll(), select(), ionotify()

Messages:

_IO_NOTIFY, _IO_NOTIFY64

Data structure:

struct _io_notify {
    uint16_t                    type;
    uint16_t                    combine_len;
    int32_t                     action;
    int32_t                     flags;
    struct __sigevent32         event;

    /* The fields `mgr` to `timo` are only valid if 
     * (flags & _NOTIFY_COND_EXTEN)
     * The full header must be present regardless of the flags.
     */
    int32_t                     mgr[2];    /* For use by manager */
    int32_t                     flags_extra_mask;
    int32_t                     flags_exten;
    int32_t                     nfds;
    int32_t                     fd_first;
    int32_t                     nfds_ready;
    int64_t                     timo;
    /* struct pollfd            fds[nfds]; */
};

struct _io_notify64 {
    uint16_t                    type;
    uint16_t                    combine_len;
    int32_t                     action;
    int32_t                     flags;
    struct __sigevent32         old_event;

    /* The fields `mgr` to `timo` are only valid if 
     * (flags & _NOTIFY_COND_EXTEN)
     * The full header must be present regardless of the flags.
     */
    int32_t                     mgr[2];    /* For use by manager */
    int32_t                     flags_extra_mask;
    int32_t                     flags_exten;
    int32_t                     nfds;
    int32_t                     fd_first;
    int32_t                     nfds_ready;
    int64_t                     timo;
    union {
        struct __sigevent32     event32;
        struct __sigevent64     event64;
    };
    /* struct pollfd            fds[nfds]; */
};

struct _io_notify_reply {
    uint32_t                    zero;
    uint32_t                    flags;   /* actions above */
    int32_t                     flags2;  /* flags above */
    struct __sigevent32         event;

    /* Following fields only updated by new managers (if valid) */
    int32_t                     mgr[2];    /* For use by manager */
    int32_t                     flags_extra_mask;
    int32_t                     flags_exten;
    int32_t                     nfds;
    int32_t                     fd_first;
    int32_t                     nfds_ready;
    int64_t                     timo;
    /* struct pollfd            fds[nfds]; */
};

struct _io_notify_reply64 {
    uint32_t                    zero;
    uint32_t                    flags;  /* actions */
    int32_t                     flags2; /* flags above */
    struct __sigevent32         old_event;

    /* Following fields only updated by new managers (if valid) */
    int32_t                     mgr[2];    /* For use by manager */
    int32_t                     flags_extra_mask;
    int32_t                     flags_exten;
    int32_t                     nfds;
    int32_t                     fd_first;
    int32_t                     nfds_ready;
    int64_t                     timo;
    union {
        struct __sigevent32     event32;
        struct __sigevent64     event64;
    };
    /* struct pollfd            fds[nfds]; */
};

typedef union {
    struct _io_notify           i;
    struct _io_notify64         i64;
    struct _io_notify_reply     o;
    struct _io_notify_reply64   o64;
} io_notify_t;

Description:

This handler is responsible for installing, polling, or removing a notification request. The action and flags determine the kind of notification operation and conditions; the event is a struct sigevent structure that defines the notification event (if any) that the client wishes to be signaled with. You'd use the MsgDeliverEvent() or iofunc_notify_trigger() functions to deliver the event to the client.

Returns:

The status via the helper macro _RESMGR_STATUS(); the flags are returned via message reply.

Referenced by:

resmgr_io_funcs_t I/O table

Page updated: June 11, 2026