From 76c50c080bfd63dd26b92f0ddf5fede704bcba04 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 25 May 2004 18:08:59 +0000
Subject: [PATCH] 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.
---
src/timezone/pgtz.c | 271 +++++++++++++++++++++++++++++++++++---------
1 file changed, 216 insertions(+), 55 deletions(-)
diff --git a/src/timezone/pgtz.c b/src/timezone/pgtz.c
index 6d1af5f3a14..77a0533ab33 100644
--- a/src/timezone/pgtz.c
+++ b/src/timezone/pgtz.c
@@ -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;
+ if (systm->tm_isdst >= 0)
+ {
+ /* 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;
+ }
}
- return true;
-}
-
-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
-}
-
-
-#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;
+ /* Reject if leap seconds involved */
+ if (!tz_acceptable())
+ return false;
- 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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