date: factor out date parsing (in preparation for touch -d)

function                                             old     new   delta
parse_datestr                                          -     391    +391
sha512_process_block128                             1283    1310     +27
buffer_fill_and_print                                179     196     +17
nexpr                                                826     840     +14
unzip_main                                          1931    1939      +8
popstring                                            134     140      +6
qrealloc                                              33      36      +3
builtin_umask                                        121     123      +2
evalvar                                             1365    1363      -2
changepath                                           194     192      -2
do_compress                                         1698    1688     -10
hwclock_main                                         340     329     -11
cmdputs                                              414     402     -12
identify                                            4343    4329     -14
date_main                                           1186     687    -499
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 7/7 up/down: 468/-550)          Total: -82 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 63 insertions, 1 deletions

diff --git a/libbb/time.c b/libbb/time.c
index 850ac15..30b760f 100644
--- a/libbb/time.c
+++ b/libbb/time.c
@@ -6,9 +6,71 @@
  *
  * Licensed under GPL version 2, see file LICENSE in this tarball for details.
  */
-
 #include "libbb.h"
 
+void FAST_FUNC parse_datestr(const char *date_str, struct tm *tm_time)
+{
+	char end = '\0';
+	const char *last_colon = strrchr(date_str, ':');
+
+	if (last_colon != NULL) {
+		/* Parse input and assign appropriately to tm_time */
+
+		if (sscanf(date_str, "%u:%u%c",
+					&tm_time->tm_hour,
+					&tm_time->tm_min,
+					&end) >= 2) {
+			/* no adjustments needed */
+		} else if (sscanf(date_str, "%u.%u-%u:%u%c",
+					&tm_time->tm_mon, &tm_time->tm_mday,
+					&tm_time->tm_hour, &tm_time->tm_min,
+					&end) >= 4) {
+			/* Adjust dates from 1-12 to 0-11 */
+			tm_time->tm_mon -= 1;
+		} else if (sscanf(date_str, "%u.%u.%u-%u:%u%c", &tm_time->tm_year,
+					&tm_time->tm_mon, &tm_time->tm_mday,
+					&tm_time->tm_hour, &tm_time->tm_min,
+					&end) >= 5) {
+			tm_time->tm_year -= 1900; /* Adjust years */
+			tm_time->tm_mon -= 1; /* Adjust dates from 1-12 to 0-11 */
+		} else if (sscanf(date_str, "%u-%u-%u %u:%u%c", &tm_time->tm_year,
+					&tm_time->tm_mon, &tm_time->tm_mday,
+					&tm_time->tm_hour, &tm_time->tm_min,
+					&end) >= 5) {
+			tm_time->tm_year -= 1900; /* Adjust years */
+			tm_time->tm_mon -= 1; /* Adjust dates from 1-12 to 0-11 */
+//TODO: coreutils 6.9 also accepts "YYYY-MM-DD HH" (no minutes)
+		} else {
+			bb_error_msg_and_die(bb_msg_invalid_date, date_str);
+		}
+		if (end == ':') {
+			if (sscanf(last_colon + 1, "%u%c", &tm_time->tm_sec, &end) == 1)
+				end = '\0';
+			/* else end != NUL and we error out */
+		}
+	} else {
+		if (sscanf(date_str, "%2u%2u%2u%2u%u%c", &tm_time->tm_mon,
+				&tm_time->tm_mday, &tm_time->tm_hour, &tm_time->tm_min,
+				&tm_time->tm_year, &end) < 4)
+			bb_error_msg_and_die(bb_msg_invalid_date, date_str);
+		/* correct for century  - minor Y2K problem here? */
+		if (tm_time->tm_year >= 1900) {
+			tm_time->tm_year -= 1900;
+		}
+		/* adjust date */
+		tm_time->tm_mon -= 1;
+		if (end == '.') {
+			if (sscanf(strchr(date_str, '.') + 1, "%u%c",
+					&tm_time->tm_sec, &end) == 1)
+				end = '\0';
+			/* else end != NUL and we error out */
+		}
+	}
+	if (end != '\0') {
+		bb_error_msg_and_die(bb_msg_invalid_date, date_str);
+	}
+}
+
 #if ENABLE_MONOTONIC_SYSCALL
 
 #include <sys/syscall.h>