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Add code to identify_system_timezone() to try all zones in the zic
database, not just ones that we cons up POSIX names for. This looks grim but it seems to take less than a second even on a relatively slow machine, and since it only happens once during postmaster startup, that seems acceptable.
This commit is contained in:
Tom Lane
parent
17ff18141c
commit
76c50c080b
@ -6,7 +6,7 @@
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* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/timezone/pgtz.c,v 1.14 2004/05/24 02:30:29 tgl Exp $
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* $PostgreSQL: pgsql/src/timezone/pgtz.c,v 1.15 2004/05/25 18:08:59 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -15,18 +15,39 @@
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#include "postgres.h"
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#include <ctype.h>
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#include <sys/stat.h>
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#include "miscadmin.h"
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#include "pgtime.h"
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#include "pgtz.h"
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#include "storage/fd.h"
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#include "tzfile.h"
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#include "utils/elog.h"
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#include "utils/guc.h"
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#define T_DAY ((time_t) (60*60*24))
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#define T_MONTH ((time_t) (60*60*24*31))
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struct tztry
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{
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char std_zone_name[TZ_STRLEN_MAX + 1],
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dst_zone_name[TZ_STRLEN_MAX + 1];
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#define MAX_TEST_TIMES 10
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int n_test_times;
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time_t test_times[MAX_TEST_TIMES];
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};
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static char tzdir[MAXPGPATH];
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static int done_tzdir = 0;
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static bool scan_available_timezones(char *tzdir, char *tzdirsub,
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struct tztry *tt);
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/*
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* Return full pathname of timezone data directory
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*/
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char *
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pg_TZDIR(void)
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{
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@ -41,62 +62,8 @@ pg_TZDIR(void)
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}
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/*
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* Try to determine the system timezone (as opposed to the timezone
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* set in our own library).
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* Get GMT offset from a system struct tm
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*/
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#define T_DAY ((time_t) (60*60*24))
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#define T_MONTH ((time_t) (60*60*24*31))
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struct tztry
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{
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char std_zone_name[TZ_STRLEN_MAX + 1],
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dst_zone_name[TZ_STRLEN_MAX + 1];
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#define MAX_TEST_TIMES 5
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int n_test_times;
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time_t test_times[MAX_TEST_TIMES];
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};
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static bool
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compare_tm(struct tm *s, struct pg_tm *p)
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{
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if (s->tm_sec != p->tm_sec ||
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s->tm_min != p->tm_min ||
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s->tm_hour != p->tm_hour ||
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s->tm_mday != p->tm_mday ||
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s->tm_mon != p->tm_mon ||
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s->tm_year != p->tm_year ||
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s->tm_wday != p->tm_wday ||
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s->tm_yday != p->tm_yday ||
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s->tm_isdst != p->tm_isdst)
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return false;
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return true;
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}
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static bool
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try_timezone(char *tzname, struct tztry *tt)
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{
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int i;
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struct tm *systm;
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struct pg_tm *pgtm;
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if (!pg_tzset(tzname))
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return false; /* can't handle the TZ name at all */
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/* Check for match at all the test times */
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for (i = 0; i < tt->n_test_times; i++)
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{
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pgtm = pg_localtime(&(tt->test_times[i]));
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if (!pgtm)
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return false; /* probably shouldn't happen */
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systm = localtime(&(tt->test_times[i]));
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if (!compare_tm(systm, pgtm))
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return false;
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}
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return true;
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}
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static int
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get_timezone_offset(struct tm *tm)
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{
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@ -113,20 +80,22 @@ get_timezone_offset(struct tm *tm)
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#endif
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}
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/*
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* Grotty kluge for win32 ... do we really need this?
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*/
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#ifdef WIN32
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#define TZABBREV(tz) win32_get_timezone_abbrev(tz)
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static char *
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win32_get_timezone_abbrev(char *tz)
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win32_get_timezone_abbrev(const char *tz)
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{
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static char w32tzabbr[TZ_STRLEN_MAX + 1];
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int l = 0;
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char *c;
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const char *c;
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for (c = tz; *c; c++)
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{
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if (isupper(*c))
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if (isupper((unsigned char) *c))
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w32tzabbr[l++] = *c;
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}
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w32tzabbr[l] = '\0';
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@ -134,9 +103,86 @@ win32_get_timezone_abbrev(char *tz)
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}
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#else
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#define TZABBREV(tz) tz
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#define TZABBREV(tz) (tz)
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#endif
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/*
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* Convenience subroutine to convert y/m/d to time_t
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*/
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static time_t
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build_time_t(int year, int month, int day)
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{
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struct tm tm;
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memset(&tm, 0, sizeof(tm));
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tm.tm_mday = day;
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tm.tm_mon = month - 1;
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tm.tm_year = year - 1900;
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return mktime(&tm);
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}
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/*
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* Does a system tm value match one we computed ourselves?
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*/
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static bool
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compare_tm(struct tm *s, struct pg_tm *p)
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{
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if (s->tm_sec != p->tm_sec ||
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s->tm_min != p->tm_min ||
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s->tm_hour != p->tm_hour ||
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s->tm_mday != p->tm_mday ||
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s->tm_mon != p->tm_mon ||
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s->tm_year != p->tm_year ||
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s->tm_wday != p->tm_wday ||
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s->tm_yday != p->tm_yday ||
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s->tm_isdst != p->tm_isdst)
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return false;
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return true;
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}
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/*
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* See if a specific timezone setting matches the system behavior
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*/
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static bool
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try_timezone(const char *tzname, struct tztry *tt)
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{
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int i;
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struct tm *systm;
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struct pg_tm *pgtm;
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char cbuf[TZ_STRLEN_MAX + 1];
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if (!pg_tzset(tzname))
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return false; /* can't handle the TZ name at all */
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/* Check for match at all the test times */
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for (i = 0; i < tt->n_test_times; i++)
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{
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pgtm = pg_localtime(&(tt->test_times[i]));
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if (!pgtm)
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return false; /* probably shouldn't happen */
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systm = localtime(&(tt->test_times[i]));
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if (!compare_tm(systm, pgtm))
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return false;
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if (systm->tm_isdst >= 0)
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{
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/* Check match of zone names, too */
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if (pgtm->tm_zone == NULL)
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return false;
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memset(cbuf, 0, sizeof(cbuf));
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strftime(cbuf, sizeof(cbuf) - 1, "%Z", systm); /* zone abbr */
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if (strcmp(TZABBREV(cbuf), pgtm->tm_zone) != 0)
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return false;
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}
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}
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/* Reject if leap seconds involved */
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if (!tz_acceptable())
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return false;
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return true;
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}
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/*
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* Try to identify a timezone name (in our terminology) that matches the
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@ -155,6 +201,7 @@ identify_system_timezone(void)
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int std_ofs = 0;
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struct tztry tt;
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struct tm *tm;
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char tmptzdir[MAXPGPATH];
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char cbuf[TZ_STRLEN_MAX + 1];
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/* Initialize OS timezone library */
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@ -225,6 +272,20 @@ identify_system_timezone(void)
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}
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}
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/*
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* Add a couple of historical dates as well; without this we are likely
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* to choose an accidental match, such as Antartica/Palmer when we
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* really want America/Santiago. Ideally we'd probe some dates before
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* 1970 too, but that is guaranteed to fail if the system TZ library
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* doesn't cope with DST before 1970.
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*/
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tt.test_times[tt.n_test_times++] = build_time_t(1970, 1, 15);
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tt.test_times[tt.n_test_times++] = build_time_t(1970, 7, 15);
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tt.test_times[tt.n_test_times++] = build_time_t(1990, 4, 1);
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tt.test_times[tt.n_test_times++] = build_time_t(1990, 10, 1);
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Assert(tt.n_test_times <= MAX_TEST_TIMES);
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/* We should have found a STD zone name by now... */
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if (tt.std_zone_name[0] == '\0')
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{
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@ -234,7 +295,17 @@ identify_system_timezone(void)
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return NULL; /* go to GMT */
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}
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/* If we found DST too then try STD<ofs>DST */
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/* Search for a matching timezone file */
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strcpy(tmptzdir, pg_TZDIR());
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if (scan_available_timezones(tmptzdir,
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tmptzdir + strlen(tmptzdir) + 1,
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&tt))
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{
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StrNCpy(resultbuf, pg_get_current_timezone(), sizeof(resultbuf));
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return resultbuf;
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}
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/* If we found DST then try STD<ofs>DST */
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if (tt.dst_zone_name[0] != '\0')
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{
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snprintf(resultbuf, sizeof(resultbuf), "%s%d%s",
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@ -270,6 +341,96 @@ identify_system_timezone(void)
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return resultbuf;
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}
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/*
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* Recursively scan the timezone database looking for a usable match to
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* the system timezone behavior.
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*
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* tzdir points to a buffer of size MAXPGPATH. On entry, it holds the
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* pathname of a directory containing TZ files. We internally modify it
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* to hold pathnames of sub-directories and files, but must restore it
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* to its original contents before exit.
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*
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* tzdirsub points to the part of tzdir that represents the subfile name
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* (ie, tzdir + the original directory name length, plus one for the
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* first added '/').
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*
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* tt tells about the system timezone behavior we need to match.
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*
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* On success, returns TRUE leaving the proper timezone selected.
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* On failure, returns FALSE with a random timezone selected.
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*/
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static bool
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scan_available_timezones(char *tzdir, char *tzdirsub, struct tztry *tt)
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{
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int tzdir_orig_len = strlen(tzdir);
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bool found = false;
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DIR *dirdesc;
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dirdesc = AllocateDir(tzdir);
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if (!dirdesc)
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{
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ereport(LOG,
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(errcode_for_file_access(),
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errmsg("could not open directory \"%s\": %m", tzdir)));
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return false;
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}
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for (;;)
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{
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struct dirent *direntry;
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struct stat statbuf;
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errno = 0;
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direntry = readdir(dirdesc);
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if (!direntry)
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{
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if (errno)
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ereport(LOG,
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(errcode_for_file_access(),
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errmsg("error reading directory: %m")));
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break;
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}
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/* Ignore . and .., plus any other "hidden" files */
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if (direntry->d_name[0] == '.')
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continue;
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snprintf(tzdir + tzdir_orig_len, MAXPGPATH - tzdir_orig_len,
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"/%s", direntry->d_name);
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if (stat(tzdir, &statbuf) != 0)
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{
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ereport(LOG,
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(errcode_for_file_access(),
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errmsg("could not stat \"%s\": %m", tzdir)));
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continue;
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}
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if (S_ISDIR(statbuf.st_mode))
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{
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/* Recurse into subdirectory */
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found = scan_available_timezones(tzdir, tzdirsub, tt);
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if (found)
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break;
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}
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else
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{
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/* Load and test this file */
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found = try_timezone(tzdirsub, tt);
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if (found)
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break;
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}
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}
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FreeDir(dirdesc);
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/* Restore tzdir */
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tzdir[tzdir_orig_len] = '\0';
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return found;
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}
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/*
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* Check whether timezone is acceptable.
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*
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@ -351,6 +512,6 @@ pg_timezone_initialize(void)
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/* Select setting */
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def_tz = select_default_timezone();
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/* Tell GUC about the value. Will redundantly call pg_tzset() */
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SetConfigOption("timezone", def_tz, PGC_POSTMASTER, PGC_S_ENV_VAR);
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SetConfigOption("timezone", def_tz, PGC_POSTMASTER, PGC_S_ARGV);
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}
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}
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