Add optional meta-information to version-3 format.

* Makefile (ZFLAGS): Add a comment about how to enable meta-info.
* tzfile.5: Describe meta-information.
* zic.8: Document new options -n and -o, which cause zic to
generate meta-info.
* zic.c: Include <stddef.h>, for ptrdiff_t.
(genoption, genoptions, genname): New static vars.
(usage): Summarize new options.
(addgenoption, writevalue): New function.
(main, writezone): Add support for new options.

Makefile

@@ -250,6 +250,9 @@ LDFLAGS=	$(LFLAGS)
 zic=		./zic
 ZIC=		$(zic) $(ZFLAGS)
 
+# Uncomment this to put name and version info into zic output files.
+#ZFLAGS=	-n -o version='$(VERSION)'
+
 # The name of a Posix-compliant `awk' on your system.
 AWK=		awk
 

tzfile.5

@@ -154,6 +154,19 @@ First, the hours part of its transition times may be signed and range from
 from 0 through 24.  Second, DST is in effect all year if it starts
 January 1 at 00:00 and ends December 31 at 24:00 plus the difference
 between daylight saving and standard time.
+.PP
+Also, for version-3-format time zone files, the version-2 header and
+data are optionally followed by a section containing auxiliary
+meta-information that is not needed to process time stamps.  This
+section, if present, consists of the four magic bytes "=TZ\en"
+followed by zero or more newline-terminated byte strings, each
+containing a name-value pair separated by "=".  Names consist of ASCII
+letters, digits and underscores, and start with a letter; duplicate
+names are not allowed.  Two common names are "name", the Zone name for
+the data, and "version", the version number.  Values consist of any
+bytes except NUL, newline, and backslash; however, newline and
+backslash can represented via the two-byte strings "\en" and "\e\e"
+respectively.
 .SH SEE ALSO
 newctime(3), newtzset(3)
 .\" This file is in the public domain, so clarified as of

zic.8

@@ -15,6 +15,11 @@ zic \- time zone compiler
 .B \-l
 .I localtime
 ] [
+.B \-n
+] [
+.B \-o
+.IB name = value
+] [
 .B \-p
 .I posixrules
 ] [
@@ -62,6 +67,15 @@ will act as if the input contained a link line of the form
 .ti +.5i
 Link	\fItimezone\fP		localtime
 .TP
+.B "\-n"
+Store each zone's name into its generated file, as meta-information
+with the name "name" and value the zone's name.
+.TP
+.BI "\-o " name = value
+Store the given name-value pair into the generated file, as
+meta-information.  This option can be repeated, once for each distinct
+name.
+.TP
 .BI "\-p " timezone
 Use the given time zone's rules when handling POSIX-format
 time zone environment variables.

zic.c

@@ -9,6 +9,7 @@
 #include "tzfile.h"
 
 #include <stdarg.h>
+#include <stddef.h>
 
 #define	ZIC_VERSION	'3'
 
@@ -140,6 +141,9 @@ static int	yearistype(int year, const char * type);
 static int		charcnt;
 static int		errors;
 static const char *	filename;
+static const char **	genoption;
+static int		genoptions;
+static int		genname;
 static int		leapcnt;
 static int		leapseen;
 static zic_t		leapminyear;
@@ -432,7 +436,8 @@ static _Noreturn void
 usage(FILE *stream, int status)
 {
 	(void) fprintf(stream, _("%s: usage is %s \
-[ --version ] [ --help ] [ -v ] [ -l localtime ] [ -p posixrules ] \\\n\
+[ --version ] [ --help ] [ -v ] [ -l localtime ]\\\n\
+\t[ -n ] [ -o name=value ]... [ -p posixrules ] \\\n\
 \t[ -d directory ] [ -L leapseconds ] [ -y yearistype ] [ filename ... ]\n\
 \n\
 Report bugs to %s.\n"),
@@ -446,6 +451,31 @@ static const char *	directory;
 static const char *	leapsec;
 static const char *	yitcommand;
 
+static int
+addgenoption(char const *option)
+{
+	register char const *o = option;
+	register ptrdiff_t namelen;
+	register int i;
+	if (! (isascii (*o) && isalpha(*o)))
+		return 0;
+	while (*++o != '=')
+		if (! (isascii (*o) && (isalnum(*o) || *o == '_')))
+			return 0;
+	namelen = o - option;
+	if (INT_MAX < namelen)
+		return 0; /* fprintf won't work.  */
+	if (namelen == sizeof "name" - 1
+	    && memcmp(option, "name", namelen) == 0)
+		return 0;
+	for (i = 0; i < genoptions; i++)
+		if (strncmp(genoption[i], option, namelen  + 1) == 0)
+			return 0;
+	genoption = erealloc(genoption, (genoptions + 1) * sizeof *genoption);
+	genoption[genoptions++] = option;
+	return 1;
+}
+
 int
 main(int argc, char **argv)
 {
@@ -476,7 +506,7 @@ main(int argc, char **argv)
 		} else if (strcmp(argv[i], "--help") == 0) {
 			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:no:vsy:")) != EOF && c != -1)
 		switch (c) {
 			default:
 				usage(stderr, EXIT_FAILURE);
@@ -500,6 +530,17 @@ _("%s: More than one -l option specified\n"),
 					exit(EXIT_FAILURE);
 				}
 				break;
+			case 'n':
+				genname = TRUE;
+				break;
+			case 'o':
+				if (!addgenoption(optarg)) {
+					fprintf(stderr,
+						_("%s: %s: invalid -o option\n"),
+						progname, optarg);
+					exit(EXIT_FAILURE);
+				}
+				break;
 			case 'p':
 				if (psxrules == NULL)
 					psxrules = optarg;
@@ -1385,6 +1426,22 @@ is32(const zic_t x)
 	return INT32_MIN <= x && x <= INT32_MAX;
 }
 
+static void
+writevalue(FILE *fp, char const *v)
+{
+	fputc('=', fp);
+
+	for (; *v; v++)
+		if (*v == '\n')
+			fprintf(fp, "\\n");
+		else if (*v == '\\')
+			fprintf(fp, "\\\\");
+		else
+			fputc(*v, fp);
+
+	fputc('\n', fp);
+}
+
 static void
 writezone(const char *const name, const char *const string)
 {
@@ -1708,6 +1765,18 @@ writezone(const char *const name, const char *const string)
 				(void) putc(ttisgmts[i], fp);
 	}
 	(void) fprintf(fp, "\n%s\n", string);
+	if (genname || genoptions)
+		fprintf(fp, "=TZ\n");
+	if (genname) {
+		fprintf(fp, "name");
+		writevalue(fp, name);
+	}
+	for (i = 0; i < genoptions; i++) {
+		register char const *v = genoption[i];
+		register int namelen = strchr(v, '=') - v;
+		fprintf(fp, "%.*s", namelen, v);
+		writevalue(fp, v + namelen + 1);
+	}
 	if (ferror(fp) || fclose(fp)) {
 		(void) fprintf(stderr, _("%s: Error writing %s\n"),
 			progname, fullname);