libbb: introduce and use strftime_[YYYYMMDD]HHMMSS()

function                                             old     new   delta
strftime_fmt                                           -      53     +53
strftime_YYYYMMDDHHMMSS                                -      12     +12
strftime_HHMMSS                                        -      12     +12
human_time                                            44      43      -1
fmtstr_t                                               9       -      -9
step_time                                            361     345     -16
watch_main                                           261     232     -29
------------------------------------------------------------------------------
(add/remove: 3/1 grow/shrink: 0/3 up/down: 77/-55)             Total: 22 bytes
   text	   data	    bss	    dec	    hex	filename
 919203	    932	  17692	 937827	  e4f63	busybox_old
 919209	    932	  17692	 937833	  e4f69	busybox_unstripped

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

7 files changed, 35 insertions, 12 deletions

diff --git a/coreutils/stat.c b/coreutils/stat.c
index c8677ebaa..dc9d81c35 100644
--- a/coreutils/stat.c
+++ b/coreutils/stat.c
@@ -127,7 +127,7 @@ static const char *human_time(time_t t)
         /*static char buf[sizeof("YYYY-MM-DD HH:MM:SS.000000000")] ALIGN1;*/
 #define buf bb_common_bufsiz1
 
-        strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S.000000000", localtime(&t));
+        strcpy(strftime_YYYYMMDDHHMMSS(buf, sizeof(buf), &t), ".000000000");
         return buf;
 #undef buf
 }
diff --git a/include/libbb.h b/include/libbb.h
index 79a37a759..6dd4d7cae 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -523,7 +523,8 @@ struct BUG_too_small {
 
 void parse_datestr(const char *date_str, struct tm *ptm) FAST_FUNC;
 time_t validate_tm_time(const char *date_str, struct tm *ptm) FAST_FUNC;
-
+char *strftime_HHMMSS(char *buf, unsigned len, time_t *tp) FAST_FUNC;
+char *strftime_YYYYMMDDHHMMSS(char *buf, unsigned len, time_t *tp) FAST_FUNC;
 
 int xsocket(int domain, int type, int protocol) FAST_FUNC;
 void xbind(int sockfd, struct sockaddr *my_addr, socklen_t addrlen) FAST_FUNC;
diff --git a/libbb/login.c b/libbb/login.c
index 8a82c6add..8f080b775 100644
--- a/libbb/login.c
+++ b/libbb/login.c
@@ -16,7 +16,6 @@
 #define LOGIN " login: "
 
 static const char fmtstr_d[] ALIGN1 = "%A, %d %B %Y";
-static const char fmtstr_t[] ALIGN1 = "%H:%M:%S";
 
 void FAST_FUNC print_login_issue(const char *issue_file, const char *tty)
 {
@@ -73,7 +72,7 @@ void FAST_FUNC print_login_issue(const char *issue_file, const char *tty)
                                 strftime(buf, sizeof(buf), fmtstr_d, localtime(&t));
                                 break;
                         case 't':
-                                strftime(buf, sizeof(buf), fmtstr_t, localtime(&t));
+                                strftime_HHMMSS(buf, sizeof(buf), &t);
                                 break;
                         case 'l':
                                 outbuf = tty;
diff --git a/libbb/time.c b/libbb/time.c
index e2b938471..57e14b66c 100644
--- a/libbb/time.c
+++ b/libbb/time.c
@@ -187,6 +187,27 @@ time_t FAST_FUNC validate_tm_time(const char *date_str, struct tm *ptm)
         return t;
 }
 
+static char* strftime_fmt(char *buf, unsigned len, time_t *tp, const char *fmt)
+{
+        time_t t;
+        if (!tp) {
+                tp = &t;
+                time(tp);
+        }
+        /* Returns pointer to NUL */
+        return buf + strftime(buf, len, fmt, localtime(tp));
+}
+
+char* FAST_FUNC strftime_HHMMSS(char *buf, unsigned len, time_t *tp)
+{
+        return strftime_fmt(buf, len, tp, "%H:%M:%S");
+}
+
+char* FAST_FUNC strftime_YYYYMMDDHHMMSS(char *buf, unsigned len, time_t *tp)
+{
+        return strftime_fmt(buf, len, tp, "%Y-%m-%d %H:%M:%S");
+}
+
 #if ENABLE_MONOTONIC_SYSCALL
 
 #include <sys/syscall.h>
diff --git a/networking/ntpd.c b/networking/ntpd.c
index 79b7c3793..0f4319ef2 100644
--- a/networking/ntpd.c
+++ b/networking/ntpd.c
@@ -887,11 +887,11 @@ step_time(double offset)
 
         VERB2 {
                 tval = tvc.tv_sec;
-                strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", localtime(&tval));
+                strftime_YYYYMMDDHHMMSS(buf, sizeof(buf), &tval);
                 bb_error_msg("current time is %s.%06u", buf, (unsigned)tvc.tv_usec);
         }
         tval = tvn.tv_sec;
-        strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", localtime(&tval));
+        strftime_YYYYMMDDHHMMSS(buf, sizeof(buf), &tval);
         bb_error_msg("setting time to %s.%06u (offset %+fs)", buf, (unsigned)tvn.tv_usec, offset);
 
         /* Correct various fields which contain time-relative values: */
diff --git a/networking/ntpd_simple.c b/networking/ntpd_simple.c
index 55bded8ff..3e7fc4719 100644
--- a/networking/ntpd_simple.c
+++ b/networking/ntpd_simple.c
@@ -378,7 +378,7 @@ step_time_once(double offset)
                 bb_perror_msg_and_die("settimeofday");
 
         tval = tv.tv_sec;
-        strftime(buf, sizeof(buf), "%a %b %e %H:%M:%S %Z %Y", localtime(&tval));
+        strftime_YYYYMMDDHHMMSS(buf, sizeof(buf), &tval);
 
         bb_error_msg("setting clock to %s (offset %fs)", buf, offset);
 
diff --git a/procps/watch.c b/procps/watch.c
index 36af1cca7..0397f21bf 100644
--- a/procps/watch.c
+++ b/procps/watch.c
@@ -69,7 +69,6 @@ int watch_main(int argc UNUSED_PARAM, char **argv)
                 printf("\033[H""\033[J");
                 if (!(opt & 0x2)) { // no -t
                         const unsigned time_len = sizeof("1234-67-90 23:56:89");
-                        time_t t;
 
                         // STDERR_FILENO is procps3 compat:
                         // "watch ls 2>/dev/null" does not detect tty size
@@ -79,10 +78,13 @@ int watch_main(int argc UNUSED_PARAM, char **argv)
                                 free(header);
                                 header = xasprintf("Every %us: %-*s", period, (int)width, cmd);
                         }
-                        time(&t);
-                        if (time_len < width)
-                                strftime(header + width - time_len, time_len,
-                                        "%Y-%m-%d %H:%M:%S", localtime(&t));
+                        if (time_len < width) {
+                                strftime_YYYYMMDDHHMMSS(
+                                        header + width - time_len,
+                                        time_len,
+                                        /*time_t*:*/ NULL
+                                );
+                        }
 
                         // compat: empty line between header and cmd output
                         printf("%s\n\n", header);