Only download tzdata to avoid lzip; clean Makefile

This caches the zic.c source code (it's public domain) and switches to
download the tzdata archive from IANA. This is done solely to avoid lzip
which people don't seem to have installed on their machines or on CI.

I also renamed and cleaned up quite a bit of tzdb.mk to be consistent
with tzdata and tzcode references.

.circleci/config.yml

@@ -16,7 +16,7 @@ install_system_deps: &install_system_deps
   run:
     name: Install system dependencies
     command: |
-        apk add build-base lzip
+        apk add build-base
 
 jobs:
   build_elixir_1_11_otp_23:

.gitignore

@@ -26,4 +26,5 @@ nerves_time_zones-*.tar
 # Temporary files for e.g. tests
 /tmp
 
-/tzdb-*.tar.lz
+/tzdata*.tar.gz
+/tzcode/version.h

Makefile

@@ -43,12 +43,12 @@ OBJ = $(SRC:c_src/%.c=$(BUILD)/%.o)
 calling_from_make:
 	mix compile
 
-all: install tzdb
+all: install tzdata
 
 install: $(PREFIX) $(BUILD) $(NIF)
 
-tzdb:
-	$(MAKE) -f tzdb.mk all
+tzdata:
+	$(MAKE) -f tzdata.mk all
 
 $(OBJ): $(HEADERS) Makefile
 
@@ -64,4 +64,4 @@ $(PREFIX) $(BUILD):
 clean:
 	$(RM) $(NIF) $(OBJ)
 
-.PHONY: all clean calling_from_make install
+.PHONY: all clean calling_from_make install tzdata

mix.exs

@@ -3,9 +3,9 @@ defmodule NervesTimeZones.MixProject do
 
   @version "0.1.0"
   @source_url "https://github.com/nerves-time/nerves_time_zones"
-  @tzdb_version "2020f"
-  @tzdb_earliest_date to_string(System.os_time(:second) - 86400)
-  @tzdb_latest_date to_string(System.os_time(:second) + 10 * 365 * 86400)
+  @tzdata_version "2020f"
+  @tzdata_earliest_date to_string(System.os_time(:second) - 86400)
+  @tzdata_latest_date to_string(System.os_time(:second) + 10 * 365 * 86400)
 
   def project do
     [
@@ -17,10 +17,11 @@ defmodule NervesTimeZones.MixProject do
       source_url: @source_url,
       compilers: [:elixir_make | Mix.compilers()],
       make_env: %{
-        "TZDB_VERSION" => @tzdb_version,
-        "TZDB_EARLIEST_DATE" => @tzdb_earliest_date,
-        "TZDB_LATEST_DATE" => @tzdb_latest_date
+        "TZDATA_VERSION" => @tzdata_version,
+        "TZDATA_EARLIEST_DATE" => @tzdata_earliest_date,
+        "TZDATA_LATEST_DATE" => @tzdata_latest_date
       },
+      make_error_message: "",
       make_targets: ["all"],
       make_clean: ["clean"],
       docs: docs(),

tzcode/README.md

@@ -0,0 +1,6 @@
+# tzcode
+
+See https://www.iana.org/time-zones for code archives. These are cached here
+since the combined time zone code+data archive is lzip'd and many people don't
+have lzip installed. The data-only database is only gzipped.
+