[Crash-utility] [PATCH v2] Append time zone to output of date and time

[HAGIO KAZUHITO(萩尾 一仁)]

Currently it's not easy to distinguish which time zone the output of
DATE uses:

  crash> sys | grep DATE
        DATE: Thu Nov 29 06:44:02 2018

Let's introduce ctime_tz() function like ctime() but explicitly appends
the time zone to its result string.

        DATE: Thu Nov 29 06:44:02 JST 2018

Resolves: https://github.com/crash-utility/crash/issues/62
Suggested-by: Jacob Wen <jian.w.wen at oracle.com>
Signed-off-by: Kazuhito Hagio <k-hagio-ab at nec.com>
---
v1 -> v2
- Add comment about the fallbacks in ctime_tz()
- Add NULL check on timep

 defs.h   |  1 +
 help.c   |  3 +--
 kernel.c | 16 ++++++----------
 tools.c  | 32 ++++++++++++++++++++++++++++++++
 4 files changed, 40 insertions(+), 12 deletions(-)

diff --git a/defs.h b/defs.h
index 17e98763362b..e7dec7c672a6 100644
--- a/defs.h
+++ b/defs.h
@@ -5096,6 +5096,7 @@ char *strdupbuf(char *);
 void sigsetup(int, void *, struct sigaction *, struct sigaction *);
 #define SIGACTION(s, h, a, o) sigsetup(s, h, a, o)
 char *convert_time(ulonglong, char *);
+char *ctime_tz(time_t *);
 void stall(ulong);
 char *pages_to_size(ulong, char *);
 int clean_arg(void);
diff --git a/help.c b/help.c
index b707cfa58826..d3427a36829f 100644
--- a/help.c
+++ b/help.c
@@ -9299,8 +9299,7 @@ display_README(void)
 			fprintf(fp, "    GNU gdb %s\n", pc->gdb_version);
 		} else if (STREQ(README[i], README_DATE)) {
     			time(&time_now);               
-        		fprintf(fp, "            DATE: %s\n", 
-                		strip_linefeeds(ctime(&time_now)));
+			fprintf(fp, "            DATE: %s\n", ctime_tz(&time_now));
 		} else if (STREQ(README[i], README_HELP_MENU)) {
 			display_help_screen("    ");
 		} else if (STREQ(README[i], README_GPL_INFO)) {
diff --git a/kernel.c b/kernel.c
index f179375f2d3d..92bfe6329900 100644
--- a/kernel.c
+++ b/kernel.c
@@ -225,10 +225,9 @@ kernel_init()
 	get_xtime(&kt->date);
 	if (CRASHDEBUG(1))
 		fprintf(fp, "xtime timespec.tv_sec: %lx: %s\n", 
-			kt->date.tv_sec, strip_linefeeds(ctime(&kt->date.tv_sec)));
+			kt->date.tv_sec, ctime_tz(&kt->date.tv_sec));
 	if (kt->flags2 & GET_TIMESTAMP) {
-		fprintf(fp, "%s\n\n", 
-			strip_linefeeds(ctime(&kt->date.tv_sec)));
+		fprintf(fp, "%s\n\n", ctime_tz(&kt->date.tv_sec));
 		clean_exit(0);
 	}
 	
@@ -5178,7 +5177,7 @@ dump_log_entry(char *logptr, int msg_flags)
 		rem = (ulonglong)ts_nsec % (ulonglong)1000000000;
 		if (msg_flags & SHOW_LOG_CTIME) {
 			time_t t = kt->boot_date.tv_sec + nanos;
-			sprintf(buf, "[%s] ", strip_linefeeds(ctime(&t)));
+			sprintf(buf, "[%s] ", ctime_tz(&t));
 		}
 		else
 			sprintf(buf, "[%5lld.%06ld] ", nanos, rem/1000);
@@ -5553,8 +5552,7 @@ display_sys_stats(void)
 
 	if (ACTIVE())
 		get_xtime(&kt->date);
-        fprintf(fp, "        DATE: %s\n", 
-		strip_linefeeds(ctime(&kt->date.tv_sec))); 
+        fprintf(fp, "        DATE: %s\n", ctime_tz(&kt->date.tv_sec));
         fprintf(fp, "      UPTIME: %s\n", get_uptime(buf, NULL)); 
         fprintf(fp, "LOAD AVERAGE: %s\n", get_loadavg(buf)); 
 	fprintf(fp, "       TASKS: %ld\n", RUNNING_TASKS());
@@ -6043,10 +6041,8 @@ dump_kernel_table(int verbose)
 		kt->source_tree : "(not used)");
 	if (!(pc->flags & KERNEL_DEBUG_QUERY) && ACTIVE()) 
 		get_xtime(&kt->date);
-        fprintf(fp, "          date: %s\n",
-                strip_linefeeds(ctime(&kt->date.tv_sec)));
-        fprintf(fp, "    boot_ date: %s\n",
-                strip_linefeeds(ctime(&kt->boot_date.tv_sec)));
+        fprintf(fp, "          date: %s\n", ctime_tz(&kt->date.tv_sec));
+        fprintf(fp, "     boot_date: %s\n", ctime_tz(&kt->boot_date.tv_sec));
         fprintf(fp, "  proc_version: %s\n", strip_linefeeds(kt->proc_version));
         fprintf(fp, "   new_utsname: \n");
         fprintf(fp, "      .sysname: %s\n", uts->sysname);
diff --git a/tools.c b/tools.c
index 85c81668e40e..89352b1dc5f5 100644
--- a/tools.c
+++ b/tools.c
@@ -6318,6 +6318,38 @@ convert_time(ulonglong count, char *buf)
 }
 
 /*
+ * Convert a calendar time into a null-terminated string like ctime(), but
+ * the result string contains the time zone string and does not ends with a
+ * linefeed ('\n').  If localtime() or strftime() fails, fail back to return
+ * POSIX time (seconds since the Epoch) or ctime() string respectively.
+ *
+ * NOTE: The return value points to a statically allocated string which is
+ * overwritten by subsequent calls.
+ */
+char *
+ctime_tz(time_t *timep)
+{
+	static char buf[64];
+	struct tm *tm;
+	size_t size;
+
+	if (!timep)
+		return NULL;
+
+	tm = localtime(timep);
+	if (!tm) {
+		snprintf(buf, sizeof(buf), "%ld", *timep);
+		return buf;
+	}
+
+	size = strftime(buf, sizeof(buf), "%a %b %e %T %Z %Y", tm);
+	if (!size)
+		return strip_linefeeds(ctime(timep));
+
+	return buf;
+}
+
+/*
  *  Stall for a number of microseconds.
  */
 void
-- 
1.8.3.1