date: make help text more understandable; small shrink

   text    data     bss     dec     hex filename
 799025     641    7380  807046   c5086 busybox_old
 799009     641    7380  807030   c5076 busybox_unstripped

2 files changed, 68 insertions, 62 deletions

diff --git a/coreutils/date.c b/coreutils/date.c
index a8e3393..064f758 100644
--- a/coreutils/date.c
+++ b/coreutils/date.c
@@ -39,70 +39,70 @@ static void maybe_set_utc(int opt)
 }
 
 int date_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
-int date_main(int argc, char **argv)
+int date_main(int argc ATTRIBUTE_UNUSED, char **argv)
 {
-	time_t tm;
 	struct tm tm_time;
+	time_t tm;
 	unsigned opt;
 	int ifmt = -1;
-	char *date_str = NULL;
-	char *date_fmt = NULL;
-	char *filename = NULL;
-	char *isofmt_arg;
-	char *hintfmt_arg;
+	char *date_str;
+	char *fmt_dt2str;
+	char *fmt_str2dt;
+	char *filename;
+	char *isofmt_arg = NULL;
 
 	opt_complementary = "d--s:s--d"
 		USE_FEATURE_DATE_ISOFMT(":R--I:I--R");
 	opt = getopt32(argv, "Rs:ud:r:"
 			USE_FEATURE_DATE_ISOFMT("I::D:"),
 			&date_str, &date_str, &filename
-			USE_FEATURE_DATE_ISOFMT(, &isofmt_arg, &hintfmt_arg));
+			USE_FEATURE_DATE_ISOFMT(, &isofmt_arg, &fmt_str2dt));
+	argv += optind;
 	maybe_set_utc(opt);
 
 	if (ENABLE_FEATURE_DATE_ISOFMT && (opt & DATE_OPT_TIMESPEC)) {
-		if (!isofmt_arg) {
-			ifmt = 0; /* default is date */
-		} else {
-			static const char *const isoformats[] = {
-				"date", "hours", "minutes", "seconds"
-			};
-
-			for (ifmt = 0; ifmt < 4; ifmt++)
-				if (!strcmp(isofmt_arg, isoformats[ifmt]))
-					goto found;
-			/* parse error */
-			bb_show_usage();
- found: ;
+		ifmt = 0; /* default is date */
+		if (isofmt_arg) {
+			static const char isoformats[] ALIGN1 =
+				"date\0""hours\0""minutes\0""seconds\0";
+			ifmt = index_in_strings(isoformats, isofmt_arg);
+			if (ifmt < 0)
+				bb_show_usage();
 		}
 	}
 
-	/* XXX, date_fmt == NULL from this always */
-	if ((date_fmt == NULL) && (optind < argc) && (argv[optind][0] == '+')) {
-		date_fmt = &argv[optind][1];	/* Skip over the '+' */
-	} else if (date_str == NULL) {
+	fmt_dt2str = NULL;
+	if (argv[0] && argv[0][0] == '+') {
+		fmt_dt2str = &argv[0][1];	/* Skip over the '+' */
+		argv++;
+	}
+	if (!(opt & (DATE_OPT_SET | DATE_OPT_DATE))) {
 		opt |= DATE_OPT_SET;
-		date_str = argv[optind];
+		date_str = argv[0]; /* can be NULL */
 	}
 
 	/* Now we have parsed all the information except the date format
 	   which depends on whether the clock is being set or read */
 
-	if (filename) {
+	if (opt & DATE_OPT_REFERENCE) {
 		struct stat statbuf;
 		xstat(filename, &statbuf);
 		tm = statbuf.st_mtime;
 	} else
 		time(&tm);
 	memcpy(&tm_time, localtime(&tm), sizeof(tm_time));
-	/* Zero out fields - take her back to midnight! */
+
+	/* If date string is given, update tm_time, and maybe set date */
 	if (date_str != NULL) {
+		/* Zero out fields - take her back to midnight! */
 		tm_time.tm_sec = 0;
 		tm_time.tm_min = 0;
 		tm_time.tm_hour = 0;
 
 		/* Process any date input to UNIX time since 1 Jan 1970 */
 		if (ENABLE_FEATURE_DATE_ISOFMT && (opt & DATE_OPT_HINT)) {
-			strptime(date_str, hintfmt_arg, &tm_time);
+			if (strptime(date_str, fmt_str2dt, &tm_time) == NULL)
+				bb_error_msg_and_die(bb_msg_invalid_date, date_str);
 		} else if (strchr(date_str, ':') != NULL) {
 			/* Parse input and assign appropriately to tm_time */
 
@@ -181,55 +181,53 @@ int date_main(int argc, char **argv)
 	/* Display output */
 
 	/* Deal with format string */
-
-	if (date_fmt == NULL) {
+	if (fmt_dt2str == NULL) {
 		int i;
-		date_fmt = xzalloc(32);
+		fmt_dt2str = xzalloc(32);
 		if (ENABLE_FEATURE_DATE_ISOFMT && ifmt >= 0) {
-			strcpy(date_fmt, "%Y-%m-%d");
+			strcpy(fmt_dt2str, "%Y-%m-%d");
 			if (ifmt > 0) {
 				i = 8;
-				date_fmt[i++] = 'T';
-				date_fmt[i++] = '%';
-				date_fmt[i++] = 'H';
+				fmt_dt2str[i++] = 'T';
+				fmt_dt2str[i++] = '%';
+				fmt_dt2str[i++] = 'H';
 				if (ifmt > 1) {
-					date_fmt[i++] = ':';
-					date_fmt[i++] = '%';
-					date_fmt[i++] = 'M';
-				}
-				if (ifmt > 2) {
-					date_fmt[i++] = ':';
-					date_fmt[i++] = '%';
-					date_fmt[i++] = 'S';
+					fmt_dt2str[i++] = ':';
+					fmt_dt2str[i++] = '%';
+					fmt_dt2str[i++] = 'M';
+					if (ifmt > 2) {
+						fmt_dt2str[i++] = ':';
+						fmt_dt2str[i++] = '%';
+						fmt_dt2str[i++] = 'S';
+					}
 				}
  format_utc:
-				date_fmt[i++] = '%';
-				date_fmt[i] = (opt & DATE_OPT_UTC) ? 'Z' : 'z';
+				fmt_dt2str[i++] = '%';
+				fmt_dt2str[i] = (opt & DATE_OPT_UTC) ? 'Z' : 'z';
 			}
 		} else if (opt & DATE_OPT_RFC2822) {
 			/* Undo busybox.c for date -R */
 			if (ENABLE_LOCALE_SUPPORT)
 				setlocale(LC_TIME, "C");
-			strcpy(date_fmt, "%a, %d %b %Y %H:%M:%S ");
+			strcpy(fmt_dt2str, "%a, %d %b %Y %H:%M:%S ");
 			i = 22;
 			goto format_utc;
 		} else /* default case */
-			date_fmt = (char*)"%a %b %e %H:%M:%S %Z %Y";
+			fmt_dt2str = (char*)"%a %b %e %H:%M:%S %Z %Y";
 	}
 
 #define date_buf bb_common_bufsiz1
-	if (*date_fmt == '\0') {
+	if (*fmt_dt2str == '\0') {
 		/* With no format string, just print a blank line */
 		date_buf[0] = '\0';
 	} else {
 		/* Handle special conversions */
-
-		if (strncmp(date_fmt, "%f", 2) == 0) {
-			date_fmt = (char*)"%Y.%m.%d-%H:%M:%S";
+		if (strncmp(fmt_dt2str, "%f", 2) == 0) {
+			fmt_dt2str = (char*)"%Y.%m.%d-%H:%M:%S";
 		}
 
 		/* Generate output string */
-		strftime(date_buf, sizeof(date_buf), date_fmt, &tm_time);
+		strftime(date_buf, sizeof(date_buf), fmt_dt2str, &tm_time);
 	}
 	puts(date_buf);
 
diff --git a/include/usage.h b/include/usage.h
index 450f801..e7e9002 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -558,22 +558,30 @@
        "world\n"
 
 #define date_trivial_usage \
-       "[OPTION]... [MMDDhhmm[[CC]YY][.ss]] [+FORMAT]"
+       "[OPTION]... [+FMT] [TIME]"
 #define date_full_usage \
-       "Display current time in the given FORMAT, or set system date\n" \
+       "Display time (using +FMT), or set time\n" \
      "\nOptions:" \
+     "\n	-u		Work in UTC (don't convert to local time)" \
      "\n	-R		Output RFC-822 compliant date string" \
-     "\n	-d STRING	Display time described by STRING, not 'now'" \
 	USE_FEATURE_DATE_ISOFMT( \
-     "\n	-I[TIMESPEC]	Output an ISO-8601 compliant date/time string" \
-     "\n			TIMESPEC='date' (or missing) for date only," \
+     "\n	-I[SPEC]	Output ISO-8601 compliant date string" \
+     "\n			SPEC='date' (default) for date only," \
      "\n			'hours', 'minutes', or 'seconds' for date and" \
      "\n			time to the indicated precision" \
-     "\n	-D hint		Use 'hint' as date format, via strptime()" \
 	) \
-     "\n	-s STRING	Set time described by STRING" \
-     "\n	-r FILE		Display the last modification time of FILE" \
-     "\n	-u		Print or sets Coordinated Universal Time" \
+     "\n	-d TIME		Display TIME, not 'now'" \
+     "\n	-r FILE		Display last modification time of FILE" \
+     "\n	[-s] TIME	Set time to TIME" \
+	USE_FEATURE_DATE_ISOFMT( \
+     "\n	-D FMT		Use FMT for str->date conversion" \
+	) \
+     "\n" \
+     "\nRecognized formats for TIME:" \
+     "\n	[hh:]mm:ss" \
+     "\n	mon.day-hh:mm[:ss]" \
+     "\n	year.mon.day-hh:mm[:ss]" \
+     "\n	MMDDhhmm[[YY]YY][.ss]" \
 
 #define date_example_usage \
        "$ date\n" \