src/bin/pg_waldump/compat.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * compat.c
   4  *              Reimplementations of various backend functions.
   5  *
   6  * Portions Copyright (c) 2013-2024, PostgreSQL Global Development Group
   7  *
   8  * IDENTIFICATION
   9  *              src/bin/pg_waldump/compat.c
  10  *
  11  * This file contains client-side implementations for various backend
  12  * functions that the rm_desc functions in *desc.c files rely on.
  13  *
  14  *-------------------------------------------------------------------------
  15  */
  16
  17 /* ugly hack, same as in e.g pg_controldata */
  18 #define FRONTEND 1
  19 #include "postgres.h"
  20
  21 #include <time.h>
  22
  23 #include "utils/datetime.h"
  24
  25 /* copied from timestamp.c */
  26 pg_time_t
  27 timestamptz_to_time_t(TimestampTz t)
  28 {
  29         pg_time_t       result;
  30
  31         result = (pg_time_t) (t / USECS_PER_SEC +
  32                                                   ((POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY));
  33         return result;
  34 }
  35
  36 /*
  37  * Stopgap implementation of timestamptz_to_str that doesn't depend on backend
  38  * infrastructure.  This will work for timestamps that are within the range
  39  * of the platform time_t type.  (pg_time_t is compatible except for possibly
  40  * being wider.)
  41  *
  42  * XXX the return value points to a static buffer, so beware of using more
  43  * than one result value concurrently.
  44  *
  45  * XXX: The backend timestamp infrastructure should instead be split out and
  46  * moved into src/common.  That's a large project though.
  47  */
  48 const char *
  49 timestamptz_to_str(TimestampTz t)
  50 {
  51         static char buf[MAXDATELEN + 1];
  52         char            ts[MAXDATELEN + 1];
  53         char            zone[MAXDATELEN + 1];
  54         time_t          result = (time_t) timestamptz_to_time_t(t);
  55         struct tm  *ltime = localtime(&result);
  56
  57         strftime(ts, sizeof(ts), "%Y-%m-%d %H:%M:%S", ltime);
  58         strftime(zone, sizeof(zone), "%Z", ltime);
  59
  60         snprintf(buf, sizeof(buf), "%s.%06d %s",
  61                          ts, (int) (t % USECS_PER_SEC), zone);
  62
  63         return buf;
  64 }