openGauss-server/src/common/interfaces/libpq/libpq-events.cpp

/* -------------------------------------------------------------------------
 *
 * libpq-events.cpp
 *	  functions for supporting the libpq "events" API
 *
 * Portions Copyright (c) 2020 Huawei Technologies Co.,Ltd.
 * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  src/common/interfaces/libpq/libpq-events.cpp
 *
 * -------------------------------------------------------------------------
 */
#include "postgres_fe.h"

#include "libpq/libpq-fe.h"
#include "libpq/libpq-int.h"

/*
 * Registers an event proc with the given PGconn.
 *
 * The same proc can't be registered more than once in a PGconn.  This
 * restriction is required because we use the proc address to identify
 * the event for purposes such as PQinstanceData().
 *
 * The name argument is used within error messages to aid in debugging.
 * A name must be supplied, but it needn't be unique.  The string is
 * copied, so the passed value needn't be long-lived.
 *
 * The passThrough argument is an application specific pointer and can be set
 * to NULL if not required.  It is passed through to the event proc whenever
 * the event proc is called, and is not otherwise touched by libpq.
 *
 * The function returns a non-zero if successful.  If the function fails,
 * zero is returned.
 */
int PQregisterEventProc(PGconn* conn, PGEventProc proc, const char* name, void* passThrough)
{
    int i;
    PGEventRegister regevt;

    if ((proc == NULL) || (conn == NULL) || (name == NULL) || !*name)
        return FALSE; /* bad arguments */

    for (i = 0; i < conn->nEvents; i++) {
        if (conn->events[i].proc == proc)
            return FALSE; /* already registered */
    }

    if (conn->nEvents >= conn->eventArraySize) {
        PGEvent* e = NULL;
        int newSize;

        newSize = conn->eventArraySize ? conn->eventArraySize * 2 : 8;
        e = (PGEvent*)malloc(newSize * sizeof(PGEvent));

        if (e == NULL)
            return FALSE;

        if (conn->events != NULL) {
            int rcs = memcpy_s(e, newSize * sizeof(PGEvent), conn->events, conn->eventArraySize * sizeof(PGEvent));
            securec_check_c(rcs, "\0", "\0");
            free(conn->events);
        }

        conn->eventArraySize = newSize;
        conn->events = e;
    }

    conn->events[conn->nEvents].proc = proc;
    conn->events[conn->nEvents].name = strdup(name);
    if (conn->events[conn->nEvents].name == NULL)
        return FALSE;
    conn->events[conn->nEvents].passThrough = passThrough;
    conn->events[conn->nEvents].data = NULL;
    conn->events[conn->nEvents].resultInitialized = FALSE;
    conn->nEvents++;

    regevt.conn = conn;
    if (!proc(PGEVT_REGISTER, &regevt, passThrough)) {
        conn->nEvents--;
        free(conn->events[conn->nEvents].name);
        conn->events[conn->nEvents].name = NULL;
        return FALSE;
    }

    return TRUE;
}

/*
 * Set some "instance data" for an event within a PGconn.
 * Returns nonzero on success, zero on failure.
 */
int PQsetInstanceData(PGconn* conn, PGEventProc proc, void* data)
{
    int i;

    if ((conn == NULL) || (proc == NULL))
        return FALSE;

    for (i = 0; i < conn->nEvents; i++) {
        if (conn->events[i].proc == proc) {
            conn->events[i].data = data;
            return TRUE;
        }
    }

    return FALSE;
}

/*
 * Obtain the "instance data", if any, for the event.
 */
void* PQinstanceData(const PGconn* conn, PGEventProc proc)
{
    int i;

    if ((conn == NULL) || (proc == NULL))
        return NULL;

    for (i = 0; i < conn->nEvents; i++) {
        if (conn->events[i].proc == proc)
            return conn->events[i].data;
    }

    return NULL;
}

/*
 * Set some "instance data" for an event within a PGresult.
 * Returns nonzero on success, zero on failure.
 */
int PQresultSetInstanceData(PGresult* result, PGEventProc proc, void* data)
{
    int i;

    if ((result == NULL) || (proc == NULL))
        return FALSE;

    for (i = 0; i < result->nEvents; i++) {
        if (result->events[i].proc == proc) {
            result->events[i].data = data;
            return TRUE;
        }
    }

    return FALSE;
}

/*
 * Obtain the "instance data", if any, for the event.
 */
void* PQresultInstanceData(const PGresult* result, PGEventProc proc)
{
    int i;

    if ((result == NULL) || (proc == NULL))
        return NULL;

    for (i = 0; i < result->nEvents; i++)
        if (result->events[i].proc == proc)
            return result->events[i].data;

    return NULL;
}

/*
 * Fire RESULTCREATE events for an application-created PGresult.
 *
 * The conn argument can be NULL if event procedures won't use it.
 */
int PQfireResultCreateEvents(PGconn* conn, PGresult* res)
{
    int i;

    if (res == NULL)
        return FALSE;

    for (i = 0; i < res->nEvents; i++) {
        if (!(res->events[i].resultInitialized)) {
            PGEventResultCreate evt;

            evt.conn = conn;
            evt.result = res;
            if (!(res->events[i].proc(PGEVT_RESULTCREATE, &evt, res->events[i].passThrough)))
                return FALSE;

            res->events[i].resultInitialized = TRUE;
        }
    }

    return TRUE;
}