evq · imihajlow · Jan 28, 2026 · Feb 2, 2026
diff --git a/.gitignore b/.gitignore
@@ -12,3 +12,4 @@
 build
 *.o
 example
+test/test
diff --git a/Makefile b/Makefile
@@ -1,5 +1,5 @@
 CC=gcc
-CFLAGS=-I.
+CFLAGS=-I. -std=gnu2x -Wall -Wextra -Werror
 DEPS = zones.h
 
 UTZ_DATA_DIR = vendor/tzdata
@@ -15,7 +15,7 @@ export UTZ_INCLUDES:=$(UTZ_INCLUDES)
 all: zones.h zones.c
 
 zones.h: $(UTZ_DATA_DIR) $(UTZ_INCLUDES) $(UTZ_WHITELIST) utils/generate_zones.py utils/utz.py
-	./utils/generate_zones.py
+	./utils/generate_zones.py -d vendor/tzdata -w $(UTZ_WHITELIST) -w whitelist-const.txt -b blacklist-const.txt -i majormetros
 zones.c: zones.h
 
 whitelist.txt: vendor/android/timezones.xml majormetros utils/compile_whitelist.py 
@@ -35,3 +35,9 @@ example/example: utz.o zones.o examples/example.o
 
 clean:
 	rm -f zones.h zones.c whitelist.txt utz.o zones.o examples/example.o example
+
+test: test/test
+	./test/test
+
+test/test: utz.o zones.o test/test.o
+	$(CC) $(CFLAGS) -o $@ $^ -I.
diff --git a/README.md b/README.md
@@ -27,6 +27,18 @@ packing all possible syntax of the source IANA tz database.
 Instead a subset corresponding to the what is needed to correctly parse  
 most zones is implemented.
 
+## Updating timezone database
+
+1. Install python requirements:
+	`pip3 install -r requirements.txt`
+2. If necessary, update vendor files in vendor/android, vendor/wikipedia, and vendor/tzdata
+3. Compile timezone links. To do that you need a [GeoNames](https://www.geonames.org/) username:
+	`./utils/compile_tzlinks.py -u <username>`
+4. Compile whitelisted timezones from the Android file:
+	`./utils/compile_whitelist.py`
+5. Finally, generate the database:
+	`./utils/generate_zones.py -d vendor/tzdata -w whitelist.txt -i majormetros`
+
 ## Links
 
 [zic man page and IANA tz database format documentation](https://linux.die.net/man/8/zic)

diff --git a/blacklist-const.txt b/blacklist-const.txt
@@ -0,0 +1,35 @@
+Asia/Oral
+Asia/Changzhou
+Asia/Chengdu
+Asia/Chongqing
+Asia/Guangzhou
+Asia/Hangzhou
+Asia/Harbin
+Asia/Jinan
+Asia/Nanchang
+Asia/Nanjing
+Asia/Qingdao
+Asia/Shantou
+Asia/Shenyang
+Asia/Shanghai
+Asia/Shenzhen
+Asia/Tianjin
+Asia/Wenzhou
+Asia/Wuhan
+Asia/Xi'an
+Asia/Nagoya
+Asia/Osaka
+Europe/Hamburg
+Europe/Stuttgart
+Europe/Barcelona
+Europe/Munich
+Europe/Rhine-Ruhr
+Asia/Calcutta
+Asia/Surat
+Asia/Pune
+Asia/Kolkata
+Asia/Hyderabad
+Asia/Chennai
+Asia/Bangalore
+Asia/Ahmedabad
+Asia/Mumbai
diff --git a/examples/example.c b/examples/example.c
@@ -8,22 +8,23 @@
 #include "zones.h"
 
 #include <stdio.h>
-void main() {
-  printf("Total library db size: %d B\n", sizeof(zone_rules) + sizeof(zone_abrevs) + sizeof(zone_defns) + sizeof(zone_names));
+int main() {
+  printf("Total library db size: %d B\n", sizeof(utz_zone_rules) + sizeof(utz_zone_abrevs) + sizeof(utz_zone_defns) + sizeof(utz_zone_names));
 
-  udatetime_t dt = {0};
-  dt.date.year = 17;
+  utz_datetime_t dt = {0};
+  dt.date.year = 2017;
   dt.date.month = 9;
   dt.date.dayofmonth = 26;
   dt.time.hour = 1;
   dt.time.minute = 0;
   dt.time.second = 0;
 
-  uzone_t active_zone;
-  get_zone_by_name("San Francisco", &active_zone);
-  uoffset_t offset;
-  char c = get_current_offset(&active_zone, &dt, &offset);
+  utz_zone_t active_zone;
+  utz_get_zone_by_name("San Francisco", &active_zone);
+  utz_offset_t offset;
+  char c = utz_get_current_offset(&active_zone, &dt, &offset);
   printf("%s, current offset: %d.%d\n", active_zone.name, offset.hours, offset.minutes / 60);
   printf(active_zone.abrev_formatter, c);
   printf("\n");
+  return 0;
 }
diff --git a/majormetros b/majormetros
@@ -5,16 +5,19 @@ Link	Asia/Kolkata	Asia/Delhi
 Link	Asia/Kolkata	Asia/Mumbai
 Link	Asia/Tokyo	Asia/Osaka
 Link	Asia/Shanghai	Asia/Wuhan
-Link	Asia/Chongqing	Asia/Chengdu
+Link	Asia/Shanghai	Asia/Chengdu
+Link	Asia/Shanghai	Asia/Chongqing
 Link	Asia/Shanghai	Asia/Tianjin
 Link	Asia/Shanghai	Asia/Hangzhou
-Link	Asia/Chongqing	Asia/Xi'an
+Link	Asia/Shanghai	Asia/Xi'an
 Link	Asia/Shanghai	Asia/Changzhou
 Link	America/Sao_Paulo	America/Rio_de_Janeiro
+Link	Asia/Shanghai	Asia/Shantou
 Link	Asia/Shanghai	Asia/Nanjing
 Link	Europe/Berlin	Europe/Rhine-Ruhr
 Link	Asia/Shanghai	Asia/Jinan
 Link	Asia/Kolkata	Asia/Bangalore
+Link	Asia/Shanghai	Asia/Harbin
 Link	Asia/Karachi	Asia/Lahore
 Link	Asia/Shanghai	Asia/Zhengzhou
 Link	Asia/Shanghai	Asia/Qingdao
@@ -24,7 +27,6 @@ Link	Asia/Kolkata	Asia/Hyderabad
 Link	Asia/Shanghai	Asia/Shenyang
 Link	Asia/Shanghai	Asia/Wenzhou
 Link	Asia/Shanghai	Asia/Nanchang
-Link	America/Chicago	America/DallasFort_Worth
 Link	America/Chicago	America/Houston
 Link	Asia/Kolkata	Asia/Ahmedabad
 Link	America/New_York	America/Washington,_D.C.

diff --git a/requirements.txt b/requirements.txt
@@ -1,4 +1,13 @@
-BeautifulSoup
-click
-geopy
-tzwhere
+appdirs==1.4.4
+beautifulsoup4==4.14.3
+click==8.3.1
+fissix==24.4.24
+geographiclib==2.1
+geopy==2.4.1
+modernize==0.8.0
+numpy==2.4.1
+pytz==2025.2
+shapely==2.1.2
+soupsieve==2.8.3
+typing_extensions==4.15.0
+tzwhere==3.0.3
-Original file line number
+Diff line change
@@ Expand Up / @@ -12,3 +12,4 @@ @@
     build
     *.o
     example
+    test/test