compat.c

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/*-------------------------------------------------------------------------
 *
 * compat.c
 *      Reimplementations of various backend functions.
 *
 * Portions Copyright (c) 2013-2025, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *      src/bin/pg_waldump/compat.c
 *
 * This file contains client-side implementations for various backend
 * functions that the rm_desc functions in *desc.c files rely on.
 *
 *-------------------------------------------------------------------------
 */
 
/* ugly hack, same as in e.g pg_controldata */
#define FRONTEND 1
#include "postgres.h"
 
#include <time.h>
 
#include "utils/datetime.h"
 
/* copied from timestamp.c */
pg_time_t
timestamptz_to_time_t(TimestampTz t)
{
    pg_time_t   result;
 
    result = (pg_time_t) (t / USECS_PER_SEC +
                          ((POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY));
    return result;
}
 
/*
 * Stopgap implementation of timestamptz_to_str that doesn't depend on backend
 * infrastructure.  This will work for timestamps that are within the range
 * of the platform time_t type.  (pg_time_t is compatible except for possibly
 * being wider.)
 *
 * XXX the return value points to a static buffer, so beware of using more
 * than one result value concurrently.
 *
 * XXX: The backend timestamp infrastructure should instead be split out and
 * moved into src/common.  That's a large project though.
 */
const char *
timestamptz_to_str(TimestampTz t)
{
    static char buf[MAXDATELEN + 1];
    char        ts[MAXDATELEN + 1];
    char        zone[MAXDATELEN + 1];
    time_t      result = (time_t) timestamptz_to_time_t(t);
    struct tm  *ltime = localtime(&result);
 
    strftime(ts, sizeof(ts), "%Y-%m-%d %H:%M:%S", ltime);
    strftime(zone, sizeof(zone), "%Z", ltime);
 
    snprintf(buf, sizeof(buf), "%s.%06d %s",
             ts, (int) (t % USECS_PER_SEC), zone);
 
    return buf;
}