Semi-automatically detect changes in timezone abbreviations.

Add an option to zic.c to dump out all non-obsolete timezone abbreviations
defined in the Olson database.  Comparing this list to its previous state
will clue us in when something happens that we may need to account for in
the tznames/ time zone abbreviation lists.  The README file's previous
exhortation to "just grep for differences" was completely useless advice,
in my now-considerable experience; but maybe this will be a bit more
useful.  As a starting point I built the same list from the tzdata files
as they existed in 2006, which is committed here as known_abbrevs.txt.
Comparison indeed turned up quite a few changes we had neglected to account
for, which I will commit separately.

Author: tglsfdc

src/timezone/.gitignore

@@ -1 +1,2 @@
 /zic
+/abbrevs.txt

src/timezone/Makefile

@@ -55,6 +55,11 @@ ifeq (,$(with_system_tzdata))
 endif
 	$(MAKE) -C tznames $@
 
+abbrevs.txt: zic $(TZDATAFILES)
+	mkdir junkdir
+	$(ZIC) -P -d junkdir -p '$(POSIXRULES)' $(TZDATAFILES) | LANG=C sort | uniq >abbrevs.txt
+	rm -rf junkdir
+
 installdirs:
 	$(MKDIR_P) '$(DESTDIR)$(datadir)'
 
@@ -65,4 +70,4 @@ endif
 	$(MAKE) -C tznames $@
 
 clean distclean maintainer-clean:
-	rm -f zic$(X) $(ZICOBJS)
+	rm -f zic$(X) $(ZICOBJS) abbrevs.txt

src/timezone/README

@@ -22,11 +22,17 @@ Since time zone rules change frequently in some parts of the world,
 we should endeavor to update the data files before each PostgreSQL
 release.
 
-At each update, we should check if time zone offsets have changed.
-Just search for the current or previous year and see what has changed.
-Sometimes a country changes its time zone offsets, for example Georgia
-in 2004.  Just grepping in the zic database files for 2004 is enough to
-spot such a change.  Then the files under tznames/ should be updated.
+While the files under data/ can just be duplicated when updating, manual
+effort is needed to update the time zone abbreviation lists under tznames/.
+These need to be changed whenever new abbreviations are invented or the
+UTC offset associated with an existing abbreviation changes.  To detect
+if this has happened, after installing new files under data/ do
+	gmake abbrevs.txt
+which will produce a file showing all abbreviations that are in current
+use according to the data/ files.  Compare this to known_abbrevs.txt,
+which is the list that existed last time the tznames/ files were updated.
+Update tznames/ as seems appropriate, then replace known_abbrevs.txt
+in the same commit.
 
 When there has been a new release of Windows (probably including Service
 Packs), the list of matching timezones need to be updated. Run the

src/timezone/known_abbrevs.txt

@@ -0,0 +1,200 @@
+ACT	-18000
+ADDT	-7200	D
+ADT	-10800	D
+ADT	14400	D
+AFT	16200
+AKST	-32400
+ALMST	25200	D
+AMT	-14400
+AMT	14400
+ANAT	39600
+APT	-10800	D
+AQTT	14400
+AQTT	18000
+ART	-10800
+AST	-14400
+AST	10800
+AWT	-10800	D
+AZOT	-3600
+AZST	18000	D
+BDT	21600
+BEAT	9000
+BEAUT	9885
+BNT	28800
+BOT	-14400
+BRT	-10800
+BTT	21600
+CAST	10800	D
+CAT	7200
+CCT	23400
+CDT	-14400	D
+CDT	-18000	D
+CDT	32400	D
+CEST	7200	D
+CET	3600
+CHAST	45900
+CHOST	36000	D
+CIT	28800
+CKHST	-34200	D
+CLT	-14400
+COT	-18000
+CPT	-18000	D
+CST	-21600
+CST	28800
+CST	34200
+CVT	-3600
+CWT	-18000	D
+CXT	25200
+ChST	36000
+DAVT	25200
+DDUT	36000
+EAST	-21600
+EAT	10800
+ECT	-18000
+EDT	-14400	D
+EEST	10800	D
+EET	7200
+EGST	0	D
+EPT	-14400	D
+EST	-18000
+EST	36000
+FJT	43200
+FKT	-10800
+FNT	-7200
+GALT	-21600
+GAMT	-32400
+GEST	14400	D
+GFT	-10800
+GILT	43200
+GMT	0
+GMT+1	-3600
+GMT+10	-36000
+GMT+11	-39600
+GMT+12	-43200
+GMT+2	-7200
+GMT+3	-10800
+GMT+4	-14400
+GMT+5	-18000
+GMT+6	-21600
+GMT+7	-25200
+GMT+8	-28800
+GMT+9	-32400
+GMT-1	3600
+GMT-10	36000
+GMT-11	39600
+GMT-12	43200
+GMT-13	46800
+GMT-14	50400
+GMT-2	7200
+GMT-3	10800
+GMT-4	14400
+GMT-5	18000
+GMT-6	21600
+GMT-7	25200
+GMT-8	28800
+GMT-9	32400
+GST	-7200
+GST	14400
+GYT	-14400
+HAST	-36000
+HKT	28800
+HOVST	28800	D
+HST	-36000
+ICT	25200
+ICT	28800
+IDDT	14400	D
+IOT	21600
+IRDT	16200	D
+IRKT	25200
+IST	23400	D
+JST	32400
+KDT	36000	D
+KGST	21600	D
+KOST	43200
+KRAT	21600
+KST	28800
+LHST	39600	D
+LINT	50400
+LKT	21600
+MAGT	36000
+MART	-34200
+MAWT	21600
+MDDT	-18000	D
+MDT	-21600	D
+MET	3600
+MHT	43200
+MMT	23400
+MPT	-21600	D
+MST	-25200
+MUT	14400
+MVT	18000
+MWT	-21600	D
+MYT	28800
+NCT	39600
+NDDT	-5400	D
+NFT	41400
+NOVST	25200	D
+NPT	20700
+NRT	43200
+NUT	-39600
+NZST	43200
+OMST	18000
+ORAT	18000
+PET	-18000
+PETT	39600
+PGT	36000
+PHOT	46800
+PKT	18000
+PMDT	-7200	D
+PONT	39600
+PPT	-25200	D
+PST	-28800
+PWT	-25200	D
+PWT	32400
+PYST	-10800	D
+QYZT	21600
+RET	14400
+ROTT	-10800
+SAKT	36000
+SAMT	14400
+SAST	10800	D
+SAST	7200
+SBT	39600
+SCT	14400
+SGT	28800
+SRT	-10800
+SST	-39600
+SYOT	10800
+TAHT	-36000
+TFT	18000
+TJT	18000
+TKT	-36000
+TMT	18000
+TOST	50400	D
+TRUT	36000
+TVT	43200
+UCT	0
+ULAST	32400	D
+UTC	0
+UYHST	-9000	D
+UZT	18000
+VET	-14400
+VLAST	32400
+VOST	21600
+VUT	39600
+WAKT	43200
+WARST	-10800	D
+WART	-14400
+WAST	7200	D
+WAT	-3600
+WAT	0
+WAT	3600
+WEST	3600	D
+WET	0
+WFT	43200
+WGST	-7200	D
+WIT	25200
+WST	-39600
+WST	28800
+YAKT	28800
+YEKT	18000

src/timezone/zic.c

@@ -181,6 +181,8 @@ static int	max_year;
 static zic_t min_time;
 static int	min_year;
 static int	noise;
+static int	print_abbrevs;
+static zic_t print_cutoff;
 static const char *rfilename;
 static int	rlinenum;
 static const char *progname;
@@ -457,7 +459,7 @@ static void
 usage(FILE *stream, int status)
 {
 	(void) fprintf(stream, _("%s: usage is %s \
-[ --version ] [ --help ] [ -v ] [ -l localtime ] [ -p posixrules ] \\\n\
+[ --version ] [ --help ] [ -v ] [ -P ] [ -l localtime ] [ -p posixrules ] \\\n\
 \t[ -d directory ] [ -L leapseconds ] [ -y yearistype ] [ filename ... ]\n\
 \n\
 Report bugs to tz@elsie.nci.nih.gov.\n"),
@@ -498,7 +500,7 @@ main(int argc, char *argv[])
 		{
 			usage(stdout, EXIT_SUCCESS);
 		}
-	while ((c = getopt(argc, argv, "d:l:p:L:vsy:")) != EOF && c != -1)
+	while ((c = getopt(argc, argv, "d:l:p:L:vPsy:")) != EOF && c != -1)
 		switch (c)
 		{
 			default:
@@ -561,6 +563,10 @@ main(int argc, char *argv[])
 			case 'v':
 				noise = TRUE;
 				break;
+			case 'P':
+				print_abbrevs = TRUE;
+				print_cutoff = time(NULL);
+				break;
 			case 's':
 				(void) printf("%s: -s ignored\n", progname);
 				break;
@@ -1780,6 +1786,21 @@ writezone(const char *name, const char *string)
 				puttzcode(gmtoffs[i], fp);
 				(void) putc(isdsts[i], fp);
 				(void) putc((unsigned char) indmap[abbrinds[i]], fp);
+
+				/* Print current timezone abbreviations if requested */
+				if (print_abbrevs && pass == 2 &&
+					(ats[i] >= print_cutoff || i == typecnt - 1))
+				{
+					char *thisabbrev = &thischars[indmap[abbrinds[i]]];
+
+					/* filter out assorted junk entries */
+					if (strcmp(thisabbrev, GRANDPARENTED) != 0 &&
+						strcmp(thisabbrev, "zzz") != 0)
+						fprintf(stdout, "%s\t%ld%s\n",
+								thisabbrev,
+								gmtoffs[i],
+								isdsts[i] ? "\tD" : "");
+				}
 			}
 		if (thischarcnt != 0)
 			(void) fwrite((void *) thischars,