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Add code to identify_system_timezone() to try all zones in the zic

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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.
REL8_0_STABLE
Tom Lane 22 years ago
parent 17ff18141c
commit 76c50c080b
1 changed files with 216 additions and 55 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 269
      src/timezone/pgtz.c

269
src/timezone/pgtz.c
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@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/timezone/pgtz.c,v 1.14 2004/05/24 02:30:29 tgl Exp $
* $PostgreSQL: pgsql/src/timezone/pgtz.c,v 1.15 2004/05/25 18:08:59 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -15,18 +15,39 @@
#include "postgres.h"
#include <ctype.h>
#include <sys/stat.h>
#include "miscadmin.h"
#include "pgtime.h"
#include "pgtz.h"
#include "storage/fd.h"
#include "tzfile.h"
#include "utils/elog.h"
#include "utils/guc.h"
#define T_DAY ((time_t) (60*60*24))
#define T_MONTH ((time_t) (60*60*24*31))
struct tztry
{
char std_zone_name[TZ_STRLEN_MAX + 1],
dst_zone_name[TZ_STRLEN_MAX + 1];
#define MAX_TEST_TIMES 10
int n_test_times;
time_t test_times[MAX_TEST_TIMES];
};
static char tzdir[MAXPGPATH];
static int done_tzdir = 0;
static bool scan_available_timezones(char *tzdir, char *tzdirsub,
struct tztry *tt);
/*
* Return full pathname of timezone data directory
*/
char *
pg_TZDIR(void)
{
@ -41,22 +62,69 @@ pg_TZDIR(void)
}
/*
* Try to determine the system timezone (as opposed to the timezone
* set in our own library).
* Get GMT offset from a system struct tm
*/
#define T_DAY ((time_t) (60*60*24))
#define T_MONTH ((time_t) (60*60*24*31))
static int
get_timezone_offset(struct tm *tm)
{
#if defined(HAVE_STRUCT_TM_TM_ZONE)
return tm->tm_gmtoff;
#elif defined(HAVE_INT_TIMEZONE)
#ifdef HAVE_UNDERSCORE_TIMEZONE
return -_timezone;
#else
return -timezone;
#endif
#else
#error No way to determine TZ? Can this happen?
#endif
}
struct tztry
/*
* Grotty kluge for win32 ... do we really need this?
*/
#ifdef WIN32
#define TZABBREV(tz) win32_get_timezone_abbrev(tz)
static char *
win32_get_timezone_abbrev(const char *tz)
{
char std_zone_name[TZ_STRLEN_MAX + 1],
dst_zone_name[TZ_STRLEN_MAX + 1];
#define MAX_TEST_TIMES 5
int n_test_times;
time_t test_times[MAX_TEST_TIMES];
};
static char w32tzabbr[TZ_STRLEN_MAX + 1];
int l = 0;
const char *c;
for (c = tz; *c; c++)
{
if (isupper((unsigned char) *c))
w32tzabbr[l++] = *c;
}
w32tzabbr[l] = '\0';
return w32tzabbr;
}
#else
#define TZABBREV(tz) (tz)
#endif
/*
* Convenience subroutine to convert y/m/d to time_t
*/
static time_t
build_time_t(int year, int month, int day)
{
struct tm tm;
memset(&tm, 0, sizeof(tm));
tm.tm_mday = day;
tm.tm_mon = month - 1;
tm.tm_year = year - 1900;
return mktime(&tm);
}
/*
* Does a system tm value match one we computed ourselves?
*/
static bool
compare_tm(struct tm *s, struct pg_tm *p)
{
@ -73,12 +141,16 @@ compare_tm(struct tm *s, struct pg_tm *p)
return true;
}
/*
* See if a specific timezone setting matches the system behavior
*/
static bool
try_timezone(char *tzname, struct tztry *tt)
try_timezone(const char *tzname, struct tztry *tt)
{
int i;
struct tm *systm;
struct pg_tm *pgtm;
char cbuf[TZ_STRLEN_MAX + 1];
if (!pg_tzset(tzname))
return false; /* can't handle the TZ name at all */
@ -92,51 +164,25 @@ try_timezone(char *tzname, struct tztry *tt)
systm = localtime(&(tt->test_times[i]));
if (!compare_tm(systm, pgtm))
return false;
}
return true;
}
static int
get_timezone_offset(struct tm *tm)
if (systm->tm_isdst >= 0)
{
#if defined(HAVE_STRUCT_TM_TM_ZONE)
return tm->tm_gmtoff;
#elif defined(HAVE_INT_TIMEZONE)
#ifdef HAVE_UNDERSCORE_TIMEZONE
return -_timezone;
#else
return -timezone;
#endif
#else
#error No way to determine TZ? Can this happen?
#endif
/* Check match of zone names, too */
if (pgtm->tm_zone == NULL)
return false;
memset(cbuf, 0, sizeof(cbuf));
strftime(cbuf, sizeof(cbuf) - 1, "%Z", systm); /* zone abbr */
if (strcmp(TZABBREV(cbuf), pgtm->tm_zone) != 0)
return false;
}
}
/* Reject if leap seconds involved */
if (!tz_acceptable())
return false;
#ifdef WIN32
#define TZABBREV(tz) win32_get_timezone_abbrev(tz)
static char *
win32_get_timezone_abbrev(char *tz)
{
static char w32tzabbr[TZ_STRLEN_MAX + 1];
int l = 0;
char *c;
for (c = tz; *c; c++)
{
if (isupper(*c))
w32tzabbr[l++] = *c;
}
w32tzabbr[l] = '\0';
return w32tzabbr;
return true;
}
#else
#define TZABBREV(tz) tz
#endif
/*
* Try to identify a timezone name (in our terminology) that matches the
@ -155,6 +201,7 @@ identify_system_timezone(void)
int std_ofs = 0;
struct tztry tt;
struct tm *tm;
char tmptzdir[MAXPGPATH];
char cbuf[TZ_STRLEN_MAX + 1];
/* Initialize OS timezone library */
@ -225,6 +272,20 @@ identify_system_timezone(void)
}
}
/*
* Add a couple of historical dates as well; without this we are likely
* to choose an accidental match, such as Antartica/Palmer when we
* really want America/Santiago. Ideally we'd probe some dates before
* 1970 too, but that is guaranteed to fail if the system TZ library
* doesn't cope with DST before 1970.
*/
tt.test_times[tt.n_test_times++] = build_time_t(1970, 1, 15);
tt.test_times[tt.n_test_times++] = build_time_t(1970, 7, 15);
tt.test_times[tt.n_test_times++] = build_time_t(1990, 4, 1);
tt.test_times[tt.n_test_times++] = build_time_t(1990, 10, 1);
Assert(tt.n_test_times <= MAX_TEST_TIMES);
/* We should have found a STD zone name by now... */
if (tt.std_zone_name[0] == '\0')
{
@ -234,7 +295,17 @@ identify_system_timezone(void)
return NULL; /* go to GMT */
}
/* If we found DST too then try STD<ofs>DST */
/* Search for a matching timezone file */
strcpy(tmptzdir, pg_TZDIR());
if (scan_available_timezones(tmptzdir,
tmptzdir + strlen(tmptzdir) + 1,
&tt))
{
StrNCpy(resultbuf, pg_get_current_timezone(), sizeof(resultbuf));
return resultbuf;
}
/* If we found DST then try STD<ofs>DST */
if (tt.dst_zone_name[0] != '\0')
{
snprintf(resultbuf, sizeof(resultbuf), "%s%d%s",
@ -270,6 +341,96 @@ identify_system_timezone(void)
return resultbuf;
}
/*
* Recursively scan the timezone database looking for a usable match to
* the system timezone behavior.
*
* tzdir points to a buffer of size MAXPGPATH. On entry, it holds the
* pathname of a directory containing TZ files. We internally modify it
* to hold pathnames of sub-directories and files, but must restore it
* to its original contents before exit.
*
* tzdirsub points to the part of tzdir that represents the subfile name
* (ie, tzdir + the original directory name length, plus one for the
* first added '/').
*
* tt tells about the system timezone behavior we need to match.
*
* On success, returns TRUE leaving the proper timezone selected.
* On failure, returns FALSE with a random timezone selected.
*/
static bool
scan_available_timezones(char *tzdir, char *tzdirsub, struct tztry *tt)
{
int tzdir_orig_len = strlen(tzdir);
bool found = false;
DIR *dirdesc;
dirdesc = AllocateDir(tzdir);
if (!dirdesc)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not open directory \"%s\": %m", tzdir)));
return false;
}
for (;;)
{
struct dirent *direntry;
struct stat statbuf;
errno = 0;
direntry = readdir(dirdesc);
if (!direntry)
{
if (errno)
ereport(LOG,
(errcode_for_file_access(),
errmsg("error reading directory: %m")));
break;
}
/* Ignore . and .., plus any other "hidden" files */
if (direntry->d_name[0] == '.')
continue;
snprintf(tzdir + tzdir_orig_len, MAXPGPATH - tzdir_orig_len,
"/%s", direntry->d_name);
if (stat(tzdir, &statbuf) != 0)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not stat \"%s\": %m", tzdir)));
continue;
}
if (S_ISDIR(statbuf.st_mode))
{
/* Recurse into subdirectory */
found = scan_available_timezones(tzdir, tzdirsub, tt);
if (found)
break;
}
else
{
/* Load and test this file */
found = try_timezone(tzdirsub, tt);
if (found)
break;
}
}
FreeDir(dirdesc);
/* Restore tzdir */
tzdir[tzdir_orig_len] = '\0';
return found;
}
/*
* Check whether timezone is acceptable.
*
@ -351,6 +512,6 @@ pg_timezone_initialize(void)
/* Select setting */
def_tz = select_default_timezone();
/* Tell GUC about the value. Will redundantly call pg_tzset() */
SetConfigOption("timezone", def_tz, PGC_POSTMASTER, PGC_S_ENV_VAR);
SetConfigOption("timezone", def_tz, PGC_POSTMASTER, PGC_S_ARGV);
}
}

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