better-tzdefrules-handling.patch

diff --git a/src/timezone/localtime.c b/src/timezone/localtime.c
index a2260e5..e3029d8 100644
*** a/src/timezone/localtime.c
--- b/src/timezone/localtime.c
*************** static const char gmt[] = "GMT";
*** 54,60 ****
   * PG: We cache the result of trying to load the TZDEFRULES zone here.
   * tzdefrules_loaded is 0 if not tried yet, +1 if good, -1 if failed.
   */
! static struct state tzdefrules_s;
  static int	tzdefrules_loaded = 0;
  
  /*
--- 54,60 ----
   * PG: We cache the result of trying to load the TZDEFRULES zone here.
   * tzdefrules_loaded is 0 if not tried yet, +1 if good, -1 if failed.
   */
! static struct state *tzdefrules_s = NULL;
  static int	tzdefrules_loaded = 0;
  
  /*
*************** tzparse(const char *name, struct state *
*** 908,927 ****
  	stdname = name;
  	if (lastditch)
  	{
! 		/*
! 		 * This is intentionally somewhat different from the IANA code.  We do
! 		 * not want to invoke tzload() in the lastditch case: we can't assume
! 		 * pg_open_tzfile() is sane yet, and we don't care about leap seconds
! 		 * anyway.
! 		 */
  		stdlen = strlen(name);	/* length of standard zone name */
  		name += stdlen;
- 		if (stdlen >= sizeof sp->chars)
- 			stdlen = (sizeof sp->chars) - 1;
- 		charcnt = stdlen + 1;
  		stdoffset = 0;
- 		sp->goback = sp->goahead = false;	/* simulate failed tzload() */
- 		load_ok = false;
  	}
  	else
  	{
--- 908,917 ----
  	stdname = name;
  	if (lastditch)
  	{
! 		/* Unlike IANA, don't assume name is exactly "GMT" */
  		stdlen = strlen(name);	/* length of standard zone name */
  		name += stdlen;
  		stdoffset = 0;
  	}
  	else
  	{
*************** tzparse(const char *name, struct state *
*** 945,971 ****
  		name = getoffset(name, &stdoffset);
  		if (name == NULL)
  			return false;
- 		charcnt = stdlen + 1;
- 		if (sizeof sp->chars < charcnt)
- 			return false;
- 
- 		/*
- 		 * This bit also differs from the IANA code, which doesn't make any
- 		 * attempt to avoid repetitive loadings of the TZDEFRULES zone.
- 		 */
- 		if (tzdefrules_loaded == 0)
- 		{
- 			if (tzload(TZDEFRULES, NULL, &tzdefrules_s, false) == 0)
- 				tzdefrules_loaded = 1;
- 			else
- 				tzdefrules_loaded = -1;
- 		}
- 		load_ok = (tzdefrules_loaded > 0);
- 		if (load_ok)
- 			memcpy(sp, &tzdefrules_s, sizeof(struct state));
  	}
! 	if (!load_ok)
! 		sp->leapcnt = 0;		/* so, we're off a little */
  	if (*name != '\0')
  	{
  		if (*name == '<')
--- 935,957 ----
  		name = getoffset(name, &stdoffset);
  		if (name == NULL)
  			return false;
  	}
! 	charcnt = stdlen + 1;
! 	if (sizeof sp->chars < charcnt)
! 		return false;
! 
! 	/*
! 	 * The IANA code always tries tzload(TZDEFRULES) here.  We do not want to
! 	 * do that; it would be bad news in the lastditch case, where we can't
! 	 * assume pg_open_tzfile() is sane yet.  Moreover, the only reason to do
! 	 * it unconditionally is to absorb the TZDEFRULES zone's leap second info,
! 	 * which we don't want to do anyway.  Without that, we only need to load
! 	 * TZDEFRULES if the zone name specifies DST but doesn't incorporate a
! 	 * POSIX-style transition date rule, which is not a common case.
! 	 */
! 	sp->goback = sp->goahead = false;	/* simulate failed tzload() */
! 	sp->leapcnt = 0;			/* intentionally assume no leap seconds */
! 
  	if (*name != '\0')
  	{
  		if (*name == '<')
*************** tzparse(const char *name, struct state *
*** 996,1003 ****
  		}
  		else
  			dstoffset = stdoffset - SECSPERHOUR;
! 		if (*name == '\0' && !load_ok)
! 			name = TZDEFRULESTRING;
  		if (*name == ',' || *name == ';')
  		{
  			struct rule start;
--- 982,1019 ----
  		}
  		else
  			dstoffset = stdoffset - SECSPERHOUR;
! 		if (*name == '\0')
! 		{
! 			/*
! 			 * The POSIX zone name does not provide a transition-date rule.
! 			 * Here we must load the TZDEFRULES zone, if possible, to serve as
! 			 * source data for the transition dates.  Unlike the IANA code, we
! 			 * try to cache the data so it's only loaded once.
! 			 */
! 			if (tzdefrules_loaded == 0)
! 			{
! 				/* Allocate on first use */
! 				if (tzdefrules_s == NULL)
! 					tzdefrules_s = (struct state *) malloc(sizeof(struct state));
! 				if (tzdefrules_s != NULL)
! 				{
! 					if (tzload(TZDEFRULES, NULL, tzdefrules_s, false) == 0)
! 						tzdefrules_loaded = 1;
! 					else
! 						tzdefrules_loaded = -1;
! 					/* In any case, we ignore leap-second data from the file */
! 					tzdefrules_s->leapcnt = 0;
! 				}
! 			}
! 			load_ok = (tzdefrules_loaded > 0);
! 			if (load_ok)
! 				memcpy(sp, tzdefrules_s, sizeof(struct state));
! 			else
! 			{
! 				/* If we can't load TZDEFRULES, fall back to hard-wired rule */
! 				name = TZDEFRULESTRING;
! 			}
! 		}
  		if (*name == ',' || *name == ';')
  		{
  			struct rule start;