add experimental utility with which to enhance ghash/ with tzdata

contrib/addtzname/.gitignore

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+*.o
+.DS_Store
+addtzname

contrib/addtzname/Makefile

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+
+CFLAGS=-I../..	\
+	-DTZDATADB="\"../../sundry/zonedetect/ZoneDetect/out/timezone16.bin\""
+
+OBJS=../../json.o ../../zonedetect.o ../../geohash.o
+
+addtzname: addtzname.c $(OBJS)
+	$(CC) $(CFLAGS) -o addtzname addtzname.c $(OBJS)

contrib/addtzname/README.md

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+# addtzname
+
+Use at your own risk.
+
+Basically, after taking a backup, this is:
+
+- `o` is the path to your existing STORAGEDIR
+- `n` is a new directory
+
+```console
+$ mkdir n
+$ ot-recorder -S n --initialize
+
+$ ocat -S o --dump | ./addtzname | ocat -S n --load
+$ ocat -S n --dump | head  # verify JSON contains tzname
+
+# when you're ready:
+$ cp n/ghash/* ....../o/ghash/
+```
+

contrib/addtzname/addtzname.c

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+/*
+ * OwnTracks Recorder
+ * Copyright (C) 2024 Jan-Piet Mens <jpmens@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include "json.h"
+#include "geohash.h"
+#include "zonedetect.h"
+
+int main(int argc, char **argv)
+{
+	char buf[BUFSIZ];
+	char *s, *geohash, *js;
+	JsonNode *json, *j;
+
+	static ZoneDetect *zdb = NULL;
+
+	zdb = ZDOpenDatabase(TZDATADB);
+	if (zdb == NULL) {
+		perror("Can't open zdb");
+		exit(2);
+	}
+
+	while (fgets(s = buf, sizeof(buf), stdin) != NULL) {
+		// find first space
+		if ((geohash = strtok(buf, " ")) != NULL) {
+			js = buf + strlen(geohash) + 1;
+			// puts(js);
+			if ((json = json_decode(js)) == NULL) {
+				if (strncmp(buf, "friends", 7) &&
+				    strncmp(buf, "topic2tid", 9) &&
+				    strncmp(buf, "wp", 2)) {
+					fprintf(stderr, "Can't decode %s\n", buf);
+				}
+				continue;
+			}
+			if ((j = json_find_member(json, "tzname")) == NULL) {
+				char *tz;
+
+				GeoCoord g = geohash_decode(geohash);
+
+				if ((tz = ZDHelperSimpleLookupString(zdb, g.latitude, g.longitude)) != NULL) {
+					json_append_member(json, "tzname", json_mkstring(tz));
+					ZDHelperSimpleLookupStringFree(tz);
+				}
+			}
+			js = json_stringify(json, NULL);
+			printf("%s %s\n", geohash, js);
+			free(js);
+			json_delete(json);
+		}
+	}
+	return 0;
+}